COMMON-MODE FILTER AND TERMINAL DEVICE

Abstract

 This application relates to a common-mode filter and a terminal device. The common-mode filter includes a first coil group, a second coil group, and a third coil group, which are parallel to each other and are a first magnetic layer, a first coil layer, one or more middle coil layers, a second coil layer, and a second magnetic layer that are sequentially disposed. The first coil group includes a first cable in each coil layer. The second coil group includes a second cable in each coil layer. The third coil group includes a third cable in each coil layer. Cables of each coil group are connected together through cable holes of the coil group, and at least two of a plurality of cables in a same coil layer are wound in parallel. According to the common-mode filter and the terminal device provided in embodiments of this application, distances from all coil groups of the common-mode filter to the first magnetic layer and the second magnetic layer are consistent in a same phase, so that symmetry between different coil groups is improved and a longitudinal transfer loss of the common-mode filter is reduced.

Description

[0001] This application claims priority to Chinese Patent Application No. 202011311813.4, filed with the China National Intellectual Property Administration on November 20, 2020 and entitled "COMMON-MODE FILTER AND TERMINAL DEVICE", which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

[0002] This application relates to the field of electronic technologies, and in particular, to a common-mode filter and a terminal device.

BACKGROUND

[0003] As terminal products such as a mobile phone, a smart tablet, and a portable computer are increasingly smaller in size and thinner in thickness, a space distance from a radio frequency antenna to a high-speed data transmission interface (for example, a mobile industry processor interface (Mobile Industry Processor Interface, MIPI for short) alliance, a serdes (short for SERializer (serializer)/DESerializer (deserializer)) interface, or a transmission interface (Embedded Display Port, eDP for short) that supports embedded digital audio and video) used in a multimedia system, for example, a camera (Camera) or a display (Display), is increasingly smaller, coupling between the radio frequency antenna and the interface is also stronger. Consequently, a high-speed data transmission manner such as the MIPI causes greater interference to a radio frequency system, and is more likely to be affected by radio frequency transmit power. This becomes a key factor that affects electromagnetic compatible coexistence between a radio frequency on the terminal product such as a mobile phone and a multimedia system. To resolve a problem of coexistence between the radio frequency and high-speed differential data transmission modules such as an MIPI, a Serdes, and an eDP, a common-mode filter with high common-mode suppression, low longitudinal transfer loss, and good symmetry is required, to resolve a problem that a common-mode filter in a related technology has poor symmetry and easily converts common-mode noise into differential-mode noise, which reduces a filtering effect of the common-mode filter on common-mode interference noise.

SUMMARY

[0004] In view of this, a common-mode filter with high symmetry and low longitudinal transfer loss, and a terminal device are proposed.

[0005] According to a first aspect, an embodiment of this application provides a common-mode filter. The common-mode filter includes: a plurality of coil groups, a plurality of cable holes, and a first magnetic layer, a second magnetic layer, and a plurality of coil layers that are parallel to each other. The plurality of coil groups include at least a first coil group, a second coil group, and a third coil group, the plurality of cable holes include at least a first cable hole, a second cable hole, and a third cable hole, the plurality of coil layers include a first coil layer, at least one middle coil layer, and a second coil layer, and at least a first cable, a second cable, and a third cable are disposed in each coil layer. The first coil layer, the middle coil layer, and the second coil layer are sequentially stacked between the first magnetic layer and the second magnetic layer. The first coil group includes the first cable in each coil layer, the second coil group includes the second cable in each coil layer, and the third coil group includes the third cable in each coil layer. The first cable hole is configured to connect a plurality of first cables of the first coil group, the second cable hole is configured to connect a plurality of second cables of the second coil group, and the third cable hole is configured to connect a plurality of third cables of the third coil group. At least two of the first cable, the second cable, and the third cable in a same coil layer are wound in parallel. In this way, distances from all coil groups to the first magnetic layer and the second magnetic layer are consistent in a same phase, so that symmetry between different coil groups is improved and a longitudinal transfer loss of the common-mode filter is reduced.

[0006] According to a second aspect, an embodiment of this application provides a common-mode filter. The common-mode filter includes: a plurality of coil groups, a plurality of cable holes, and a first magnetic layer, a second magnetic layer, and a plurality of coil layers that are parallel to each other. The plurality of coil groups include at least a first coil group, a second coil group, and a third coil group, the plurality of cable holes include at least a first cable hole, a second cable hole, and a third cable hole, the plurality of coil layers include a first coil layer, at least one middle coil layer, and a second coil layer, and at least a first cable, a second cable, and a third cable are disposed in each coil layer. The first coil layer, the middle coil layer, and the second coil layer are sequentially disposed between the first magnetic layer and the second magnetic layer. The first coil group includes the first cable in each coil layer, the second coil group includes the second cable in each coil layer, and the third coil group includes the third cable in each coil layer. The first cable hole is configured to connect a plurality of first cables of the first coil group, the second cable hole is configured to connect a plurality of second cables of the second coil group, and the third cable hole is configured to connect a plurality of third cables of the third coil group. At least two of the first cable, the second cable, and the third cable in a same coil layer are wound in parallel, and cable widths of a same coil group meet any one of the following cases: A width of the first cable and a width of the second cable each are a first cable width, a width of the third cable is a second cable width, and the first cable width is different from the second cable width; or a width of the first cable, a width of the second cable, and a width of the third cable are all different, the width of the first cable is a first cable width, and the width of the second cable is a second cable width. The first cable width and the second cable width meet: W1=p1×W2, where W1 is the first cable width, W2 is the second cable width, p1 is a proportional coefficient, and p1 ∈ [0.5, 0.8] or p1 ∈ [2, 3].

[0007] According to the foregoing disposing, distances from all coil groups to the first magnetic layer and the second magnetic layer are consistent in a same phase, so that symmetry between different coil groups is improved and a longitudinal transfer loss of the common-mode filter is reduced. In addition, because the cable width of each coil group is set based on a preset width proportion relationship, impedance differences caused by different total lengths of the plurality of cables in different coil groups, different cable thicknesses of different coil groups caused by processing technologies, and inconsistent phases of the cables in different coil groups caused by position settings of the cable holes may be further improved. The cable widths of different coil groups may be adjusted by adjusting the width proportion relationship, so that the different coil groups have similar or same characteristic impedances, the symmetry between different coil groups is improved, and the longitudinal transfer loss of the common-mode filter is reduced.

[0008] According to the first aspect and the second aspect, in a first possible implementation of the common-mode filter, a first relative position relationship exists among a first cable, a second cable, and a third cable in the first coil layer, a second relative position relationship exists among a first cable, a second cable, and a third cable in the second coil layer, and a middle relative position relationship exists among a first cable, a second cable, and a third cable in the middle coil layer. The first relative position relationship, the second relative position relationship, and the middle relative position relationship are the same, and center lines of the first cable hole for connection of the first cables in adjacent coil layers, the second cable hole for connection of the second cables in adjacent coil layers, and the third cable hole for connection of the third cables in adjacent coil layers are all located on a same cross section perpendicular to all coil layers. In this way, distances from all coil groups to the first magnetic layer and the second magnetic layer are consistent in a same phase, and in each coil layer, relative position relationships between cables of different coil groups are the same, so that the symmetry between different coil groups is further improved and the longitudinal transfer loss of the common-mode filter further is reduced.

[0009] According to the first aspect and the second aspect, in a second possible implementation of the common-mode filter, a first relative position relationship exists among a first cable, a second cable, and a third cable in the first coil layer, a second relative position relationship exists among a first cable, a second cable, and a third cable in the second coil layer, and a middle relative position relationship exists among a first cable, a second cable, and a third cable in the middle coil layer. The first relative position relationship, the second relative position relationship, and the middle relative position relationship are different, and a first total length of a plurality of first cables of the first coil group, a second total length of a plurality of second cables of the second coil group, and a third total length of a plurality of third cables of the third coil group are the same. In this way, distances from all coil groups to the first magnetic layer and the second magnetic layer are consistent in a same phase. In addition, relative position relationships between cables of different coil groups in each coil layer are changed, so that total lengths of the cables of different coil groups are the same. This further improves the symmetry between different coil groups and reduces the longitudinal transfer loss of the common-mode filter.

[0010] According to the first aspect and the second aspect, in a third possible implementation of the common-mode filter, a first relative position relationship exists among a first cable, a second cable, and a third cable in the first coil layer, a second relative position relationship exists among a first cable, a second cable, and a third cable in the second coil layer, and a middle relative position relationship exists among a first cable, a second cable, and a third cable in the middle coil layer. The first relative position relationship, the second relative position relationship, and the middle relative position relationship are the same, and a first total length of a plurality of first cables of the first coil group, a second total length of a plurality of second cables of the second coil group, and a third total length of a plurality of third cables of the third coil group are the same. In this way, distances from all coil groups to the first magnetic layer and the second magnetic layer are consistent in a same phase. In addition, on a basis that relative position relationships between cables of different coil groups in each coil layer are the same, lengths of cables in different coil layers are changed, so that total lengths of the cables of different coil groups are the same. This further improves the symmetry between different coil groups and reduces the longitudinal transfer loss of the common-mode filter.

[0011] According to the first aspect, the second aspect, the first possible implementation, the second possible implementation, or the third possible implementation, in a fourth possible implementation of the common-mode filter, the common-mode filter further includes a reference ground structure, the reference ground structure is insulated from all first cables, all second cables, and all third cables, and the reference ground structure is insulated from both the first magnetic layer and the second magnetic layer. By disposing the reference ground structure,

[0012] According to the fourth possible implementation, in a fifth possible implementation of the common-mode filter, the reference ground structure includes a first auxiliary layer and a second auxiliary layer.

[0013] The first auxiliary layer is located between the first coil layer and the first magnetic layer, and a first reference ground cable corresponding to the first cable, the second cable, and the third cable in the first coil layer is disposed in the first auxiliary layer.

[0014] The second auxiliary layer is located between the second coil layer and the second magnetic layer, and a second reference ground cable corresponding to the first cable, the second cable, and the third cable in the second coil layer is disposed in the second auxiliary layer. In this way, distances from all coil groups to the first magnetic layer and the second magnetic layer are consistent in a same phase. In addition, by disposing the first auxiliary layer and the second auxiliary layer including the reference ground cables, different coil groups have similar ground impedances. This further improves the symmetry between different coil groups and reduces the longitudinal transfer loss of the common-mode filter.

[0015] According to the fourth possible implementation, in a sixth possible implementation of the common-mode filter, the reference ground structure includes a first accompanying reference ground cable, a middle accompanying reference ground cable, and a second accompanying reference ground cable. A first accompanying reference ground cable of one or more first target cables of the first cable, the second cable, and the third cable in the first coil layer is disposed in the first coil layer, and the first accompanying reference ground cable is located on one side or two sides of the first target cable.

[0016] A middle accompanying reference ground cable of one or more middle target cables of the first cable, the second cable, and the third cable in the middle coil layer is disposed in the middle coil layer, and the middle accompanying reference ground cable is located on one side or two sides of the middle target cable.

[0017] A second accompanying reference ground cable of one or more second target cables of the first cable, the second cable, and the third cable in the second coil layer is disposed in the second coil layer, and the second accompanying reference ground cable is located on one side or two sides of the second target cable. In this way, distances from all coil groups to the first magnetic layer and the second magnetic layer are consistent in a same phase. In addition, by disposing the accompanying reference ground cable, different coil groups have similar ground impedances. This further improves the symmetry between different coil groups and reduces the longitudinal transfer loss of the common-mode filter.

[0018] According to the sixth possible implementation, in a seventh possible implementation of the common-mode filter, the first accompanying reference ground cable, the middle accompanying reference ground cable, and the second accompanying reference ground cable are connected. In this way, in comparison with the fourth possible implementation, this possible implementation further ensures that different coil groups have similar ground impedances.

[0019] According to the fourth possible implementation, in an eighth possible implementation of the common-mode filter, the reference ground structure includes at least one of the following metal reference ground layers:

a first metal reference ground layer, located between the first coil layer and the first magnetic layer;

a second metal reference ground layer, located between the second coil layer and the second magnetic layer;

a third metal reference ground layer, located between the first coil layer and the middle coil layer, and provided with a first accommodating hole that accommodates a first cable hole, a second cable hole, and a third cable hole that pass through the third metal reference ground layer;

a fourth metal reference ground layer, located between the second coil layer and the middle coil layer, and provided with a second accommodating hole that accommodates the first cable hole, the second cable hole, and the third cable hole that pass through the third metal reference ground layer; and

a middle metal reference ground layer, where there are one or more middle metal reference ground layers, and each middle metal reference ground layer is located between two middle coil layers, and is provided with a third accommodating hole that accommodates the first cable hole, the second cable hole, and the third cable hole that pass through the third metal reference ground layer. In this way, distances from all coil groups to the first magnetic layer and the second magnetic layer are consistent in a same phase. In addition, in comparison with the common-mode filter in another possible implementation, the common-mode filter in this possible implementation disposes the metal reference ground layer, so that different coil groups have similar ground impedances. This further improves the symmetry between different coil groups and reduces the longitudinal transfer loss of the common-mode filter.

[0020] According to the eighth possible implementation, in a ninth possible implementation of the common-mode filter, when there are a plurality of metal reference ground layers, the plurality of metal reference ground layers are connected through a reference ground hole, and the reference ground hole is disposed in one or more of the first coil layer, the second coil layer, and the middle coil layer. In addition, in comparison with the sixth possible implementation, this possible implementation can further reduce differences between the ground impedances of the different coil groups.

[0021] According to any one of the first aspect, the second aspect, or the foregoing nine possible implementations, in a tenth possible implementation of the common-mode filter, the common-mode filter further includes a third magnetic layer and a fourth magnetic layer parallel to each other. The first coil layer, the middle coil layer, and the second coil layer are located between the third magnetic layer and the fourth magnetic layer, the third magnetic layer is perpendicular to the first magnetic layer and the second magnetic layer, and the fourth magnetic layer is perpendicular to the first magnetic layer and the second magnetic layer. In this way, distances from all coil groups to the first magnetic layer, the second magnetic layer, the third magnetic layer, and the fourth magnetic layer are consistent in a same phase. In addition, in comparison with a common-mode filter disposed in a manner of including only the first magnetic layer and the second magnetic layer, this common-mode filter enables a plurality of coil groups to be in a same magnetic environment in two dimensions. This further improves the symmetry between different coil groups and reduces the longitudinal transfer loss of the common-mode filter.

[0022] According to the tenth possible implementation, in an eleventh possible implementation of the common-mode filter, the common-mode filter further includes a fifth magnetic layer and a sixth magnetic layer parallel to each other.

[0023] The first coil layer, the middle coil layer, and the second coil layer are located between the fifth magnetic layer and the sixth magnetic layer, the fifth magnetic layer is perpendicular to the first magnetic layer, the second magnetic layer, the third magnetic layer, and the fourth magnetic layer, and the sixth magnetic layer is perpendicular to the first magnetic layer, the second magnetic layer, the third magnetic layer, and the fourth magnetic layer. In this way, distances from all coil groups to the first magnetic layer, the second magnetic layer, the third magnetic layer, the fourth magnetic layer, the fifth magnetic layer, and the sixth magnetic layer are consistent in a same phase. In addition, in comparison with common-mode filters disposed in a manner of including only the first magnetic layer and the second magnetic layer and a manner of including only the first magnetic layer, the second magnetic layer, the third magnetic layer, and the fourth magnetic layer, this common-mode filter enables a plurality of coil groups to be in a same magnetic environment in three-dimension stereoscopic space. This further improves the symmetry between different coil groups and reduces the longitudinal transfer loss of the common-mode filter.

[0024] According to the fourth possible implementation, in a twelfth possible implementation of the common-mode filter, the reference ground structure includes a metal reference ground coating layer, and the metal reference ground coating layer coats on a surface of the common-mode filter. In this way, distances from all coil groups to the magnetic layer are consistent in a same phase. In addition, in comparison with a common-mode filter disposed in a manner in the first aspect, this common-mode filter enables a plurality of coil groups to be in a same reference ground environment, and have a same ground impedance in three-dimension stereoscopic space. This further improves the symmetry between different coil groups and reduces the longitudinal transfer loss of the common-mode filter.

[0025] According to the fourth possible implementation, in a thirteenth possible implementation of the common-mode filter, the reference ground structure further includes a pad and a metal reference ground strip that are connected to a terminal of each coil group. A part of each pad is located on a first side surface of the common-mode filter, and another part of each pad is located on one of a plurality of second side surfaces that are on the common-mode filter and that are connected to the first side surface. The metal reference ground strip is located between a plurality of pads, and surrounds at least a part of an area of the first side surface of the common-mode filter and the second side surface with the pad. In this way, distances from all coil groups to the magnetic layer are consistent in a same phase. In addition, in comparison with a common-mode filter disposed in a manner in the first aspect, this common-mode filter enables different coil groups to have similar ground impedances at the pad position. This further improves the symmetry between different coil groups and reduces the longitudinal transfer loss of the common-mode filter.

[0026] According to a third aspect, an embodiment of this application provides a terminal device, where the terminal device includes the common-mode filter according to any one of the first aspect, the second aspect, or the foregoing thirteen possible implementations.

[0027] These aspects or other aspects in this application may be clearer and more intelligible in descriptions in the following (plurality of) embodiments.

BRIEF DESCRIPTION OF DRAWINGS

[0028] The accompanying drawings, which may be included in this specification and constitute a part of this specification, together with this specification show example embodiments, or features and aspects of this application, and are used to explain principles of this application.

FIG. 1a, FIG. 1b, and FIG. 1c are schematic diagrams of cable structures of a common-mode filter in a related technology;

FIG. 1d is a three-dimensional diagram of a common-mode filter according to an embodiment of this application;

FIG. 1e is a main view of a common-mode filter according to an embodiment of this application;

FIG. 1f is a side view of a common-mode filter according to an embodiment of this application;

FIG. 1g is a top view of a common-mode filter according to an embodiment of this application;

FIG. 1h is a section view of a common-mode filter according to an embodiment of this application;

FIG. 2a is a section view of a common-mode filter according to an embodiment of this application;

FIG. 2b is a schematic diagram of a structure of a common-mode filter according to an embodiment of this application;

FIG. 2c is a schematic diagram of a structure of a coil layer of a common-mode filter according to an embodiment of this application;

FIG. 3a is a section view of a common-mode filter according to an embodiment of this application;

FIG. 3b is a schematic diagram of a structure of a common-mode filter according to an embodiment of this application;

FIG. 4 is a schematic diagram of a structure of a common-mode filter according to an embodiment of this application;

FIG. 5a is a section view of a common-mode filter according to an embodiment of this application;

FIG. 5b is a schematic diagram of a structure of a common-mode filter according to an embodiment of this application;

FIG. 6a and FIG. 6b are section views of common-mode filters according to an embodiment of this application;

FIG. 6c is a schematic diagram of a structure of a common-mode filter according to an embodiment of this application;

FIG. 7a is a section view of a common-mode filter according to an embodiment of this application;

FIG. 7b is a schematic diagram of a structure of a common-mode filter according to an embodiment of this application;

FIG. 7c is a schematic diagram of a structure of a common-mode filter according to an embodiment of this application;

FIG. 8a is a schematic diagram of a structure of a common-mode filter according to an embodiment of this application;

FIG. 8b is a section view of a common-mode filter according to an embodiment of this application;

FIG. 9a is a schematic diagram of a structure of a common-mode filter according to an embodiment of this application;

FIG. 9b is a section view of a common-mode filter according to an embodiment of this application;

FIG. 10a is a schematic diagram of a structure of a common-mode filter according to an embodiment of this application;

FIG. 10b is a section view of a common-mode filter according to an embodiment of this application;

FIG. 11a is a schematic diagram of a structure of a common-mode filter according to an embodiment of this application;

FIG. 11b is a section view of a common-mode filter according to an embodiment of this application;

FIG. 12a to FIG. 12d are a three-dimensional diagram and three views of a common-mode filter according to an embodiment of this application;

FIG. 13a to FIG. 13d are a three-dimensional diagram and three views of a common-mode filter according to an embodiment of this application;

FIG. 14a is a section view of a common-mode filter according to an embodiment of this application; and

FIG. 14b is a schematic diagram of a plurality of coil layers of a common-mode filter according to an embodiment of this application.

DESCRIPTION OF EMBODIMENTS

[0029] Various example embodiments, features, and aspects of this application are described in detail below with reference to the accompanying drawings. Same reference numerals in the accompanying drawings represent elements with same or similar functions. Although various aspects of the embodiments are illustrated in the accompanying drawing, the accompanying drawings are not necessarily drawn in proportion unless otherwise specified.

[0030] The specific term "example" herein means "used as an example or embodiment, or illustrative". Any embodiment described as an "example" is not necessarily explained as being superior or better than other embodiments.

[0031] In addition, to better describe this application, the following specific implementations provide many specific details. A person skilled in the art should understand that this application may also be implemented without some specific details. In some examples, methods, means, components, and circuits well known by a person skilled in the art are not described in detail, to highlight a main purpose of this application.

[0032] In a related technology, a common-mode inductor (a type of common-mode filter) usually includes two coils. The two coils have a same quantity of turns and a same phase, and are wound in parallel around a same iron core. Because common-mode coils are wound in a same phase, when equal-amplitude phase-inverted differential mode currents flow through the common-mode inductor, the differential mode currents can generate magnetic fields reverse to each other in the coil, so that the magnetic fields cancel each other and reduce an inductance effect. The common-mode inductor usually does not attenuate differential-mode currents, and a main factor affecting differential mode currents is a resistance of the common-mode inductor coils. When equal-amplitude in-phase common-mode currents flow through the common-mode inductor, because the common-mode currents are in a same direction, magnetic fields generated by the common-mode currents in a common-mode inductor coil are also in the same direction, so that an inductance reactance of the common-mode inductor coil is increased, and the coil exhibits high impedance. In this way, strong damping effect is produced, so that the common-mode current can be attenuated and a filtering effect can be achieved. Common-mode filters with more than two cables (that is, more than two coils) have wide application prospects in high-speed data transmission. For example, a common-mode filter oriented to MIPI (Mobile Industry Processor Interface, mobile industry processor interface) that is in a data transmission mode of C-PHY interface (PHY is short for port physical layer, English: Port Physical Layer, and C-PHY is a standard for the port physical layer specified in MIPI) is composed of three coils, and the three coils can filter common-mode noise through coupling and differential between two coils. In the related technology, FIG. 1a, FIG. 1b, and FIG. 1c are schematic diagrams of cable structures of a common-mode filter in the related technology. Cables marked as "A", "B", and "C" are cables of three different coil groups. As shown in FIG. 1a, the cables of the three coil groups are arranged in equilateral triangles, the cables of the "A" and "B" coil groups are in a same layer, and the cables of the "C" coil group are in a separate layer. In this way, distances from a ferrite to the cables of the three coil groups are different, resulting in different phases between different coil groups. When differential current signals flow through the common-mode filter and perform differential operation between two coils, it is difficult to completely cancel the common-mode current, so that a part of the common-mode current is converted into a differential mode current. Consequently, differential mode noise is formed. As shown in FIG. 1b, the cables of the three coil groups are also arranged in equilateral triangles, and the cables of the "A", "B", and "C" coil groups are all in different layers. In this way, distances from a ferrite to the cables of the three coil groups are different, resulting in different phases between different coil groups. Consequently, a problem that the common-mode current is converted into a differential mode current exists. As shown in FIG. 1c, the cables of the three coil groups are also arranged in equilateral triangles, the cables of the "A", "B", and "C" coil groups are in different layers, and cables of one coil group are wound in two layers. In this way, distances from a ferrite to the cables of the three coil groups are different, resulting in different phases between different coil groups. Consequently, a problem that the common-mode current is converted into a differential mode current exists. To sum up, a common-mode filter component with more than two cables in the related technology has a problem of poor symmetry, and common-mode noise is easily converted into differential mode noise, so that a filtering effect of the filter on common-mode interference noise is reduced. Generally, the characteristic of conversion from common-mode to differential mode of a common-mode filter is referred to as longitudinal transfer loss. How to provide a common-mode filter with high symmetry and low longitudinal transfer loss is a technical problem urgently to be resolved. To resolve the foregoing technical problem, this application provides a common-mode filter.

[0033] The common-mode filter provided in this application includes a plurality of coil groups, a plurality of cable holes, and a first magnetic layer, a second magnetic layer, a first coil layer, a middle coil layer, and a second coil layer that are parallel to each other. The first coil layer, the middle coil layer, and the second coil layer are sequentially disposed between the first magnetic layer and the second magnetic layer. The quantity of coil groups may be at least three, and a plurality of cables of each coil group are separately distributed in each coil layer. Lengths of cables of different coil groups in a same coil layer, relative position relationships between cables, and a cable width proportion are set, to obtain the common-mode filter with high symmetry and low longitudinal transfer loss. Structure layout settings such as a quantity of coil groups, a quantity of coil layers, and a quantity and positions of cable holes of common-mode filters with different use requirements may be correspondingly adjusted. A person skilled in the art may perform the setting based on a requirement, which is not limited in this application. To intuitively and clearly describe the layout of the coil groups in the common-mode filter, the following uses an example in which "three coil groups are disposed in the common-mode filter" for description, and "A", "B", and "C" respectively represent the three coil groups. When the quantity of coil groups is greater than 3, a person skilled in the art may make corresponding adjustments with reference to a layout setting of "disposing 3 coil groups in the common-mode filter", and details are not described in this application.

[0034] FIG. 1d is a three-dimensional diagram of a common-mode filter according to an embodiment of this application. FIG. 1e is a main view of a common-mode filter according to an embodiment of this application. FIG. 1f is a side view of a common-mode filter according to an embodiment of this application. FIG. 1g is a top view of a common-mode filter according to an embodiment of this application. FIG. 1h is a section view of a common-mode filter according to an embodiment of this application. FIG. 1h is a section view obtained by performing sectioning along a location of a dashed box area s3 in FIG. 1f. To facilitate understanding of a cable layout of a coil group in this application, only a part associated with the coil group is shown in the section view FIG. 1h. A dashed box area s2 in FIG. 1e, the dashed box area s3 in FIG. 1f, and a dashed box area s1 in FIG. 1g correspond to a same spatial area of the common-mode filter.

[0035] An embodiment of this application provides a common-mode filter. As shown in FIG. 1h, the common-mode filter includes a plurality of coil groups (where differences between cables of different coil groups are not shown in FIG. 1h), a plurality of cable holes, and a first magnetic layer 11, a second magnetic layer 12, and a plurality of coil layers that are parallel to each other, where the plurality of coil layers include a first coil layer 21, a second coil layer 22, and one or more middle coil layers 23 (where in FIG. 1h, a plurality of middle coil layers are used as an example). At least a first cable, a second cable, and a third cable are disposed on each coil layer. The plurality of coil groups include at least a first coil group A, a second coil group B, and a third coil group C (where because FIG. 1h does not limit relative position relationships of cables of different coil groups in the same coil layer, FIG. 1h does not show the first coil group A, the second coil group B, and the third coil group C differently, but reference may be made to illustrations in FIG. 2a, FIG. 3a, FIG. 5a, FIG. 6a, FIG. 6b, FIG. 7a, FIG. 14a). The plurality of cable holes include at least a first cable hole, a second cable hole, and a third cable hole (not shown in FIG. 1h).

[0036] The first coil layer 21, the middle coil layer 23, and the second coil layer 22 are sequentially disposed between the first magnetic layer 11 and the second magnetic layer 12.

[0037] The first coil group A includes first cables in all coil layers. To be specific, the first coil group A includes a first cable in the first coil layer 21, a first cable in the second coil layer 22, and a first cable in the middle coil layer 23. The second coil group B includes second cables in all coil layers. To be specific, the second coil group B includes a second cable in the first coil layer 21, a second cable in the second coil layer 22, and a second cable in the middle coil layer 23. The third coil group C includes third cables in all coil layers. To be specific, the third coil group C includes a third cable in the first coil layer 21, a third cable in the second coil layer 22, and a third cable in the middle coil layer 23.

[0038] The first cable hole is configured to connect a plurality of first cables of the first coil group, the second cable hole is configured to connect a plurality of second cables of the second coil group, and the third cable hole is configured to connect a plurality of third cables of the third coil group. At least two of the first cable, the second cable, and the third cable in a same coil layer are wound in parallel.

[0039] In this embodiment of this application, different coil groups are insulated from each other. An insulation layer of an insulation material such as a dielectric may be added to each cable surface. Alternatively, insulation between different coil groups is implemented by disposing intervals between different cables of a same coil layer, and the insulating material such as the dielectric is disposed between adjacent coil layers. For example, the insulating material may be a resin material, a ceramic material, a polymer material, or the like. A person skilled in the art may set a manner of implementing mutual insulation between different coil groups based on a requirement. This is not limited in this application.

[0040] In this embodiment of this application, the first cable hole, the second cable hole, and the third cable hole that are disposed in each middle coil layer are not connected or are not in contact with each other, and are insulated from each other, to ensure mutual insulation between different coil groups. Materials filled in the first cable hole, the second cable hole, and the third cable hole are metal, which may be completely the same as the cable material of a corresponding coil group. For example, the materials are metal with good conductivity such as copper, silver, gold, and tungsten. Alternatively, a different metal may be used for the cables of the corresponding coil group. For example, the cable material of the coil group is copper metal, and filling materials in the cable holes are silver metal. This is not limited in this application.

[0041] In this embodiment of this application, materials of the first magnetic layer 11 and the second magnetic layer 12 may be magnetic materials such as ferrite, for example, an alloy, a monomer, or oxide that includes an element such as Fe, Co, Ni, or Mn. This is not limited in this application. In addition, adjacent layers in the first magnetic layer 11, the second magnetic layer 12, and the plurality of coil layers (including the first coil layer 21, the second coil layer 22, and the one or more middle coil layers 23) are insulated from each other. Insulation between adjacent layers may be implemented by adding an insulation layer or the like. A material of the insulation layer may be an insulation material such as a resin material, a ceramic material, or a polymer material. This is not limited in this application. The first magnetic layer and the second magnetic layer are provided with spatial sizes such as thicknesses, lengths, and widths, and the thicknesses, the lengths, and the widths of the first magnetic layer and the second magnetic layer may be set based on limitations of a processing technology, a longitudinal transfer loss, a differential mode loss, a return loss, an impedance indicator parameter, and the like. This is not limited in this application. However, to simplify a structure of the common-mode filter, strengthen cables, and ensure position relationships between and between layers in the common-mode filter, sizes of the first magnetic layer and the second magnetic layer are not described in detail in the accompanying drawings of this application. However, this cannot be considered as a limitation of this application.

[0042] In this embodiment of this application, that at least two of the plurality of cables in a same coil layer are wound in parallel may include: Two or more cables are wound in parallel. As shown in each of FIG. 2b, FIG. 2c, and FIG. 3b, a plurality of cables in each coil layer are wound in parallel. That the at least two of the plurality of cables in the same coil layer are wound in parallel may include: All or a part of each cable in the cables that are wound in parallel participates in winding of "all the cables that are wound in parallel", and another part of each cable in the cables that are wound in parallel participates in parallel winding of one or more other cables in "all the cables that are wound in parallel". In this way, a distance from each cable in a same coil layer to the first magnetic layer is consistent, and a distance from each cable to the second magnetic layer is also consistent (where distances from a plurality of cables in a same coil layer to the first magnetic layer and distances from the plurality of cables in the same coil layer to the second magnetic layer are different). At least two cables in a same coil layer are wound in parallel means that cables that need to be wound in parallel in a same coil layer are wound in parallel. The cables wound in parallel have a same phase.

[0043] For example, as shown in the following FIG. 2b and FIG. 2c, a plurality of cables in each coil layer are all wound in parallel, and a full length of each cable participates in parallel winding of the plurality of cables. As shown in the following FIG. 3b, a plurality of cables in each coil layer are all wound in parallel. However, due to different cable lengths, some cables cannot participate in parallel winding with all other cables in the same coil layer in full length. A remaining length that does not participate in "parallel winding with all other cables in the same coil layer" continues to be wound in parallel with one or more of remaining cables until the full length is used up. If the cable is the longest cable in the coil layer, the remaining length of the cable cannot be used in any parallel winding. For example, in "the 1st layer", a first cable a, a second cable b, and a third cable c are wound in parallel, but only a full length of the shortest second cable b participates in parallel winding of the three cables. Apart of the first cable b participates in parallel winding of the three cables, and a part of the first cable a participates in parallel winding with the third cable c. Apart of the third cable c participates in parallel winding of the three cables, another part of the third cable c participates in parallel winding with the second cable b, and the last part of the third cable c does not participate in parallel winding. As shown in FIG. 4, although all cables in each coil layer are wound in parallel, due to limitations of different cable lengths, in "the 6th layer", only a small part of a second cable b participates in parallel winding of three cables, and the remaining part is wound in parallel with a third cable c; only a small part of a first cable a participates in parallel winding of the three cables, a large part of the first cable a participates in parallel winding with the third cable c, and no winding is performed on another small part; and only a small part of the third cable c participates in parallel winding of the three cables, a small part of the third cable c participates in parallel winding with the first cable a, and no winding is performed on a small part of the third cable c.

[0044] It should be noted that, in an actual manufacturing process of a common-mode filter, a plurality of coil layers, a first magnetic layer, and a second magnetic layer are in direct contact and closely attached together. In the examples provided in the accompanying drawings of this application, a distance between different layers is merely used to illustrate a structure of the common-mode filter more clearly, and is not limited in this application.

[0045] By disposing the common-mode filter in the manner shown in FIG. 1h, distances from all coil groups including at least the first coil group, the second coil group, and the third coil group to the first magnetic layer and the second magnetic layer are consistent in a same phase, so that symmetry between different coil groups is improved and a longitudinal transfer loss of the common-mode filter is reduced.

[0046] FIG. 2a is a section view of a common-mode filter according to an embodiment of this application. FIG. 2b is a schematic diagram of a structure of a common-mode filter according to an embodiment of this application. FIG. 2a is a section view obtained by performing sectioning along a location of a dashed box area s3 in FIG. 1h. To facilitate understanding of a cable layout of a coil group in this application, only a part associated with the coil group is shown in the section view FIG. 2a. In a possible implementation, in each coil layer, relative position relationships between cables of different coil groups are the same. In a same coil layer, center lines of cable holes of all coil groups are located on a same cross section perpendicular to the coil layer. Different segments of each cable in a same coil layer may be perpendicular to, parallel to, or located on the cross section. There is a first relative position relationship among a first cable that belongs to a first coil group A, a second cable that belongs to a second coil group B, and a third cable that belongs to a third coil group C in a first coil layer 21. There is a second relative position relationship among a first cable that belongs to a first coil group A, a second cable that belongs to a second coil group B, and a third cable that belongs to a third coil group C in a second coil layer. There is a middle relative position relationship among a first cable that belongs to a first coil group A, a second cable that belongs to a second coil group B, and a third cable that belongs to a third coil group C in a middle coil layer. As shown in FIG. 2a and FIG. 2b, the first relative position relationship, the second relative position relationship, and the middle relative position relationship are the same, and center lines of the first cable hole Aa, the second cable hole Bb, and the third cable hole Cc that are for connection of cables in adjacent coil layers are all located on a same cross section perpendicular to all coil layers. "Circular dashed boxes" disposed on cables in FIG. 2b are positions of cable holes connected to the cables.

[0047] As shown in FIG. 2b, in each coil layer, cables marked as "a", "b", and "c" are respectively a first cable, a second cable, and a third cable of a coil layer in which the cables are located. To be specific, the first cable is marked as "a", the second cable is marked as "b", and the third cable is marked as "c". In this case, a plurality of cables of the first coil group A are cables marked as "a" in the first coil layer, namely, "the 1st layer", the middle coil layers, namely, "the 2nd layer to the 5th layer", and the second coil layer, namely, "the 6th layer". A plurality of cables of the second coil group B are cables marked as "b" in the first coil layer, namely, "the 1st layer", the middle coil layers, namely, "the 2nd layer to the 5th layer", and the second coil layer, namely, "the 6th layer". A plurality of cables of the third coil group C are cables marked as "c" in the first coil layer, namely, "the 1st layer", the middle coil layers, namely, "the 2nd layer to the 5th layer", and the second coil layer, namely, "the 6th layer".

[0048] In this implementation, the first relative location relationship, the second relative location relationship, and the middle relative location relationship may refer to an adjacency relationship or a neighboring relationship between cables. As shown in FIG. 2b, "the first relative position relationship, the second relative position relationship, and the middle relative position relationship are the same" means that in each of the first coil layer, namely, "the 1st layer", the middle coil layers, namely, "the 2nd layer to the 5th layer", and the second coil layer, namely, "the 6th layer", a relative position relationship is that the first cable a is on an outermost side, the third cable c is on an innermost side, and the second cable b is between the first cable a and the third cable c, that is, the three cables are in a position relationship of "a-b-c".

[0049] In this implementation, as shown in FIG. 2b, "the 3rd layer" in the middle coil layers 23 and "a first cable hole Aa, a second cable hole Bb, and a third cable hole Cc for implementing cable connection in each coil group in the 2nd layer and the 3rd layer" are used as an example. The first cable hole Aa corresponding to the first coil group A, the first cable hole Bb corresponding to the second coil group B, and the first cable hole Cc corresponding to the third coil group C are disposed in "the 3rd layer" and between "the 3rd layer" and "the 2nd layer". Center lines of the first cable hole Aa, the second cable hole Bb, and the third cable hole Cc (namely, dashed lines shown in FIG. 2b) are located in a same section M, and the section M is perpendicular to all coil layers. However, the first cable a, the second cable b, and the third cable c in "the 3rd layer" each have a plurality of different segments. By using the first cable a in "the 3rd layer" as an example, the first cable a includes segments a1, a2, a3, a4, and a5, where the segment a1 is perpendicular to the section M, the segment a2 is parallel to the section M, the segment a3 is perpendicular to the section M, the segment a4 is parallel to the section M, and the segment a5 is perpendicular to section M. Similarly, center lines of "a first cable hole Aa, a second cable hole Bb, and a third cable hole Cc for cable connection of each coil group in the 1st layer and the 2nd layer", "a first cable hole Aa, a second cable hole Bb, and a third cable hole Cc for cable connection of each coil group in the 3rd layer and the 4th layer", "a first cable hole Aa, a second cable hole Bb, and a third cable hole Cc for cable connection of each coil group in the 4th layer and the 5th layer", and "a first cable hole Aa, a second cable hole Bb, and a third cable hole Cc for cable connection of each coil group in the 5th layer and the 6th layer" are also located in corresponding sections.

[0050] It should be noted that, in FIG. 2b, FIG. 3b, FIG. 4, FIG. 5b, FIG. 6c, FIG. 7b, FIG. 7c, and FIG. 14b in this application, to simplify a winding manner of cables in a plurality of coil groups and clearly describe a winding structure, a quantity of winding turns of a first cable, a second cable, and a third cable of each coil layer is less than 2. In actual production and manufacturing, a quantity of winding turns of the first cable, the second cable, and the third cable of each coil layer may be any quantity of one or more turns. In addition, to avoid a stress problem caused by point discharge and right-angle bending, and to make a differential mode loss and a return loss of the common-mode filter smaller, a corner position of the cables during winding may be made into an arc shape (as shown in the following FIG. 2c).

[0051] In this implementation, a quantity of the plurality of coil layers may be set based on limitations of a longitudinal transfer loss, a differential mode loss, a return loss, and an impedance indicator parameter of the common-mode filter.

[0052] In this implementation, a first cable hole Aa, a second cable hole Bb, and a third cable hole Cc that are needed for cable connection of a coil group between two adjacent coil layers (the first coil layer and an adjacent middle coil layer, the second coil layer and an adjacent middle coil layer, or two adjacent middle coil layers) may be disposed in any one of the two coil layers, or may be disposed between the two coil layers. Alternatively, the first cable hole Aa, the second cable hole Bb, and the third cable hole Cc may run through each coil layer. Connection positions (positions where the cable hole contacts the coil layer) corresponding to the first cable hole Aa, the second cable hole Bb, and the third cable hole Cc in different coil layers may be the same or may be different. Positions of the first cable hole Aa, the second cable hole Bb, and the third cable hole Cc may be set based on actual requirements, provided that it is ensured that electrical connections of the cables in the first coil group, the second coil group, and the third coil group can be implemented by using the first cable hole Aa, the second cable hole Bb, and the third cable hole Cc. This is not limited in this application. For example, a first cable hole Aa, a second cable hole Bb, and a third cable hole Cc that are required for electrical connection between cables in a coil group between the first coil layer and an adjacent middle coil layer may be disposed in the middle coil layer, may be disposed in the first coil layer, or may be disposed between the first coil layer and the middle coil layer. A first cable hole Aa, a second cable hole Bb, and a third cable hole Cc that are required for electrical connection between cables in a coil group between the second coil layer and an adjacent middle coil layer may be disposed in the middle coil layer, may be disposed in the second coil layer, or may be disposed between the middle coil layer and the second coil layer. A first cable hole Aa, a second cable hole Bb, and a third cable hole Cc that are required for connection between cables in a coil group between two adjacent middle coil layers may be disposed in any one of the two middle coil layers, or may be disposed between the two middle coil layers. It should be noted that, actually, different coil layers are in direct contact and closely attached together. In the example provided in FIG. 2b in this application, lengths of the first cable hole Aa, the second cable hole Bb, and the third cable hole Cc are far longer than a thickness of the coil layer, so that a structure of the common-mode filter is more clearly shown. Actual lengths of the first cable hole Aa, the second cable hole Bb, and the third cable hole Cc in the common-mode filter are not limited.

[0053] By disposing the common-mode filter in the manner shown in FIG. 2a and FIG. 2b, distances from all coil groups to the first magnetic layer and the second magnetic layer are consistent in a same phase. In addition, in comparison with the common-mode filter disposed in the manner shown in FIG. 1h, in each coil layer of this common-mode filter, relative position relationships between cables of different coil groups are the same, so that symmetry between different coil groups is further improved and a longitudinal transfer loss of the common-mode filter further is reduced.

[0054] In this embodiment of this application, each cable of different coil groups has a thickness and a width, and there may also be a cable spacing between adjacent cables in a same coil layer. In addition, the thickness and the width of the cable, and the cable spacing may be set based on limitations of a longitudinal transfer loss, a differential mode loss, a return loss, an impedance indicator parameter, a processing technology, and the like of the common-mode filter. A length, a width, and a thickness of an appearance of the common-mode filter used for the terminal device are 0.1 mm to 1 mm, that is, a length, a width, and a height of three-dimensional space occupied by the common-mode filter are 0.1 mm to 1 mm. An example in which a length, a width, and a thickness of a common-mode filter are 1 mm is used. When the common-mode filter uses technologies such as a low-temperature ceramic (Low Temperature Co-fired Ceramic, LTCC for short), a thin film lamination technology, and an integrated passive device (Integrated Passive Device, IPD for short) technology, due to limitations of the technologies, a size of the common-mode filter, a longitudinal transfer loss, a differential mode loss, a return loss, and an impedance, the cable width is 5 µm to 30 µm, and the cable spacing is 5 µm to 30 µm. When the common-mode filter is processed and manufactured by using a printing or electroplating technology, the cable thickness may be 0.1 µm to 10 µm. A person skilled in the art may set the cable thickness, the cable width, and the cable spacing based on an actual design requirement of the common-mode filter. This is not limited in this application. It is considered that when the common-mode filter is used, it needs to be ensured that the impedance of the common-mode filter is small, that is, the differential mode loss is small, in other words, a differential-mode current is not lost. Therefore, when the common-mode filter is manufactured, a distance between the cable layers should be large enough to avoid an existence of stray capacitors, and the cable should be thick enough to avoid excessive direct current resistance. In addition, the common-mode filter should also have a specific filtering frequency band, and the filtering frequency band control is generally implemented by adding a ferromagnetic material. To be specific, the ferromagnetic material is added on an upper surface and a lower surface of the common-mode filter. The ferromagnetic material has a tangent of a loss angle, which is in a function relationship with a frequency. At some frequencies, the tangent value of the loss angle is large. If a common-mode noise current flows through the common-mode filter, a magnetic field generated by the common-mode current is dissipated in the ferromagnetic material in a form of thermal energy. In addition, the common-mode filter provided in this application may be manufactured independently. A size of the manufactured common-mode filter is large, and may meet design requirements of the common-mode filter on the cable thickness and the cable width as much as possible. The common-mode filter may be manufactured by using various manufacturing technologies, and manufacturing of the common-mode filter has low resource costs, low time costs, and high reliability.

[0055] In a possible implementation, cable widths of different cables in each coil layer of the common-mode filter is set based on a preset width proportion relationship.

[0056] The width proportion relationship may include any one of the following relationships: A plurality of coil groups include one or more target coil groups and at least two same-width coil groups, cables of different same-width coil groups have a same first cable width, and there is a different first width proportion relationship between a second cable width of a cable of each target coil group and the first cable width; a plurality of coil groups include one or more target coil groups and at least two same-width coil groups, cables of different same-width coil groups have a same first cable width, cables of different target coil groups have a same second cable width, and there is a second width proportion relationship between the second cable width and the first cable width; cable widths of cables of all coil groups are different from each other, and there is a third width proportion relationship between cable widths of cables of different coil groups; or there is a corresponding fourth width proportion relationship between cable widths of different cables in each coil layer.

[0057] The cable width of cables of each coil group may be a width of all cables of the coil group in different coil layers. Different cables of the same coil group may be set to have a same cable width, or different cables of the same coil group may be set to have cable widths that are not completely the same or cable widths that are different from each other. When different cables of a same coil group have a same cable width, if a width proportion relationship is set, a first cable width of a same-width coil group may be first determined, and then cable widths of a target coil group are adjusted based on the width proportion relationship. A width proportional relationship between a first cable width W1 and a second cable width W2 is: W1=p1×W2, p1 is a proportional coefficient, and p1 ∈ [0.5, 0.8] or p1 ∈ [2, 3]. A plurality of cables in a same coil layer may be further set to have cable widths that are not completely the same. A reference cable may be first determined from the plurality of cables. A fourth proportional relationship between a cable width w1 of the reference cable and a cable width w2 of the other cables is: w1=p1×w2, where p1 is a proportional coefficient, and P1 ∈ [0.5, 0.8] or P1 ∈ [2, 3].

[0058] In this way, because the cable width of each coil group is set based on a preset width proportion relationship, impedance differences caused by different total lengths of the plurality of cables in different coil groups, different cable thicknesses of different coil groups caused by processing technologies, and inconsistent phases of the cables in different coil groups caused by position settings of the cable holes may be further improved. The cable widths of different coil groups may be adjusted by adjusting the width proportion relationship, so that the different coil groups have similar or same characteristic impedances, the symmetry between different coil groups is improved, and the longitudinal transfer loss of the common-mode filter is reduced. When thicknesses of the cables are the same, a smaller cable width corresponds to a larger impedance. Because an impedance value is inversely proportional to a cross-sectional area of the cable, the smaller the cable width, the smaller the cross-sectional area of the cable.

[0059] For ease of describing different manners of setting the width proportion relationship, the following uses an example in which the plurality of coil groups include a first coil group A, a second coil group B, and a third coil group C for description. FIG. 2c is a schematic diagram of a structure of a coil layer of a common-mode filter according to an embodiment of this application. A difference between FIG. 2c and FIG. 2b lies in that in FIG. 2c, a cable width is set, and a cabling corner is set to an arc shape. Therefore, FIG. 2c shows only cables of a first coil layer "the 1st layer". There is only one target coil group, and in a plurality of coil groups, all coil groups except "one target coil group" are same-width coil groups. As shown in FIG. 2c, when the plurality of coil groups include the first coil group A, the second coil group B, and the third coil group C, any one of the first coil group A, the second coil group B, and the third coil group C may be selected as the target coil group, and other coil groups are the same-width coil groups. For example, the third coil group C is the target coil group, and the first coil group A and the second coil group B are same-width coil groups. In this case, W1a=W1b=p1^∗W2c, and p1 ∈ [0.5, 0.8]. Because a first cable a of the first coil group A, a second cable b of the second coil group B, and a third cable c of the third coil group C are sequentially disposed from outside to inside, and a quantity of winding turns is greater than 1, a cable width of the first cable a and a cable width of the second cable b may be reduced. However, the impedance cannot be adjusted by increasing a cable width of the third cable c. This is because when it is ensured that the first cable a, the second cable b, and the third cable c have a same cable spacing and a same coupling status, increasing the width of the third cable c makes the third cable c and the first cable a closer to each other, and even causes a short circuit caused by connection between the third cable c and the first cable a.

[0060] In descriptions of the following embodiments of this application, actually, the cables shown in FIG. 3b, FIG. 4, FIG. 5b, FIG. 6c, FIG. 7b, FIG. 7c, FIG. 8a, FIG. 9a, FIG. 10a, FIG. 11a, and FIG. 14b are all cables with the thickness and width shown in FIG. 2b. However, to simplify a structure of the common-mode filter, strengthen the cables, and ensure a position relationship between layers of the common-mode filter, in FIG. 3b, FIG. 4, FIG. 5b, FIG. 6c, FIG. 7b, FIG. 7c, FIG. 8a, FIG. 9a, FIG. 10a, FIG. 11a, and FIG. 14b, only "lines" with widths are used to illustrate the cables.

[0061] In the example shown in FIG. 2b in this embodiment of this application, diameters of the first cable hole Aa, the second cable hole Bb, and the third cable hole Cc are the same as widths of cables connected to the first cable hole Aa, the second cable hole Bb, and the third cable hole Cc. Actually, the diameters of the cable holes may be set based on a processing technology (such as a laser drilling or photolithography technology), an electrical connection requirement between the cables, and the width of the cables. The diameters of the cable holes may be greater than, less than, or equal to the widths of the cables connected to the cable holes. This is not limited in this application. Similarly, two ends of each cable in the middle coil layers, one end of each cable in the first coil layers, and one end of each cable in the second coil layers in FIG. 3b, FIG. 4, FIG. 5b, FIG. 6c, FIG. 7b, FIG. 7c, FIG. 8a, FIG. 9a, FIG. 10a, FIG. 11a, and FIG. 14b each are drawn with cable holes (namely, circles of different gray scales shown in the figures). For ease of indicating a position of a cable hole, a diameter of the cable hole is greater than a width of a cable connected to the cable hole. However, in practice, the diameter of the cable hole may be greater than, less than, or equal to the width of the cable connected to the cable hole. In other words, size relationships between diameters of cable holes and widths of cables connected to the cable holes shown in FIG. 2b, FIG. 3b, FIG. 4, FIG. 5b, FIG. 6c, FIG. 7b, FIG. 7c, FIG. 8a, FIG. 9a, FIG. 10a, FIG. 11a, and FIG. 14b are not limited in this application.

[0062] FIG. 3a is a section view of a common-mode filter according to an embodiment of this application. FIG. 3b is a schematic diagram of a structure of a common-mode filter according to an embodiment of this application. FIG. 3a is a section view obtained by performing sectioning along a location of a dashed box area s3 in FIG. 1f. To facilitate understanding of a cable layout of a coil group in this application, only a part associated with the coil group is shown in the section view FIG. 3a. In a possible implementation, total winding lengths of different coil groups are similar, the total length is a sum of lengths of a plurality of cables in a same coil group, and relative position relationships between cables of different coil groups in each coil layer are different. As shown in FIG. 3a and FIG. 3b, there is a first relative position relationship among a first cable that belongs to a first coil group A, a second cable that belongs to a second coil group B, and a third cable that belongs to a third coil group C in a first coil layer 21. There is a second relative position relationship among a first cable that belongs to a first coil group A, a second cable that belongs to a second coil group B, and a third cable that belongs to a third coil group C in a second coil layer. There is a middle relative position relationship among a first cable that belongs to a first coil group A, a second cable that belongs to a second coil group B, and a third cable that belongs to a third coil group C in a middle coil layer. The first relative position relationship, the second relative position relationship, and the middle relative position relationship are different, and a first total length of a plurality of cables of the first coil group A, a second total length of a plurality of cables of the second coil group B, and a third total length of a plurality of cables of the third coil group C are the same.

[0063] In this implementation, in an actual processing process of the common-mode filter, the first total length, the second total length, and the third total length are affected by a processing technology, and the three cannot be actually completely the same. Therefore, in this application, "the first total length, the second total length, and the third total length are the same" is a theoretical status, and "the first total length, the second total length, and the third total length" in an actually manufactured common-mode filter are basically the same and approximately equal. Alternatively, a length difference may be set based on indicator requirements related to the common-mode filter, such as a differential mode loss, a longitudinal transfer loss, and a required total winding length of a plurality of cables in each coil group, so that an actual length difference among the first total length, the second total length, and the third total length is less than or equal to the length difference, to ensure that total winding lengths of cables in different coil groups are as the same as possible, and further improve symmetry between the different coil groups. A smaller length difference indicates that total winding lengths of the different coil groups are closer (to be specific, the first total length, the second total length, and the third total length are closer), and symmetry between the different coil groups is better.

[0064] In this implementation, as shown in FIG. 3a and FIG. 3b, relative position relationships between cables of different coil groups in each coil layer are different. A relative position relationship among a first cable a, a second cable b, and a third cable c in "the 1st layer" (the first coil layer 21) may be "a-b-c", a relative position relationship among a first cable a, a second cable b, and a third cable c in "the 2nd layer" (the middle coil layer 23) is "c-a-b", a relative position relationship among a first cable a, a second cable b, and a third cable c in "the 3rd layer" (the middle coil layer 23) is "b-c-a", a relative position relationship among a first cable a, a second cable b, and a third cable c in "the 4th layer" (the middle coil layer 23) is "c-a-b", a relative position relationship among a first cable a, a second cable b, and a third cable c in "the 5th layer" (the middle coil layer 23) is "b-c-a", and a relative position relationship among a first cable a, a second cable b, and a third cable c in "the 6th layer" (the second coil layer 22) is "a-b-c". That is, in the plurality of coil layers, a plurality of layers having the same relative position relationship among the first cable a, the second cable b, and the third cable c are "the 1st layer and the 6th layer". However, relative position relationships among the first cable a, the second cable b, and the third cable c in all coil layers are not completely the same. For example, relative position relationships among the first cable a, the second cable b, and the third cable c in the 1st layer and the 6th layer, the 3rd layer and the 5th layer, and the 2nd layer and the 4th layer are separately the same, and relative position relationships in the other different layers are different.

[0065] In this implementation, a quantity of the plurality of coil layers and a sum of winding lengths of each coil group may be set based on limitations of a longitudinal transfer loss, a return loss, and an impedance indicator parameter of the common-mode filter. This is not limited in this application.

[0066] By disposing the common-mode filter in the manner shown in FIG. 3a and FIG. 3b, distances from all coil groups to the first magnetic layer and the second magnetic layer are consistent in a same phase. In addition, in comparison with the common-mode filter disposed in the manner shown in FIG. 2a and FIG. 2b, in this common-mode filter, relative position relationships between cables of different coil groups in each coil layer are changed (to be specific, the first relative position relationship, the second relative position relationship, and the middle relative position relationship are changed), so that total lengths of the cables of different coil groups are similar. This further improves the symmetry between different coil groups and reduces the longitudinal transfer loss of the common-mode filter.

[0067] In a possible implementation, FIG. 4 is a schematic diagram of a structure of a common-mode filter according to an embodiment of this application. A difference between manners of disposing different coil groups in a plurality of coil layers shown in FIG. 4 and FIG. 3a and FIG. 3b lies in that relative position relationships between cables are disposed differently. As shown in FIG. 4, the first relative position relationship, the second relative position relationship, and the middle relative position relationship are the same, and a first total length of a plurality of cables of the first coil group, a second total length of a plurality of cables of the second coil group, and a third total length of a plurality of cables of the third coil group are the same.

[0068] In this implementation, as shown in FIG. 4, relative position relationships among the first cable a, the second cable b, and the third cable c in each coil layer are the same (that is, the first relative position relationship, the second relative position relationship, and the middle relative position relationship are the same). However, to meet a requirement that total winding lengths between different coil groups are the same, winding lengths of the first cable, the second cable, and/or the third cable of a same coil group may be greater than or equal to one entire round, or may be less than one entire round. In other words, lengths of the first cable, the second cable, and the third cable in a same coil layer are not limited.

[0069] By disposing the common-mode filter in the manner shown in FIG. 4, distances from all coil groups to the first magnetic layer and the second magnetic layer are consistent in a same phase. In addition, in comparison with the common-mode filter disposed in the manner shown in FIG. 2a and FIG. 2b, in this common-mode filter, on a basis that relative position relationships between cables of different coil groups in each coil layer are the same, lengths of cables in different coil layers are changed, so that total lengths of the cables of different coil groups are the same. This further improves the symmetry between different coil groups and reduces the longitudinal transfer loss of the common-mode filter.

[0070] Based on the several common-mode filters provided in FIG. 2a, FIG. 2b, FIG. 3a, FIG. 3b, and FIG. 4, in this application, the common-mode filter may further include a reference ground structure. The reference ground structure is insulated from each of the first cables, each of the second cables, and each of the third cables, and the reference ground structure is insulated from both the first magnetic layer and the second magnetic layer. The reference ground structure may become a "reference ground" of cables in each coil group through a connection to the ground pin, an air connection, a floating connection, or the like. This is not limited in this application. By disposing the reference ground structure, different coil groups may have similar or even the same ground matched impedances, so that symmetry between different coil groups is further improved and a longitudinal transfer loss of the common-mode filter is reduced.

[0071] An implementation of the reference ground structure may include the following implementations of Manner 1 to Manner 4. In the common-mode filter, one or more manners of Manner 1 to Manner 4 may be selected to dispose the reference ground structure.

[0072] Manner 1: The reference ground structure may be one or more internal reference ground layers located inside the common-mode filter, such as a "metal reference ground layer" described below.

[0073] Manner 2: The reference ground structure may be one or more internal reference ground conducting cable layers located inside the common-mode filter, and at least one reference ground cable that provides a "reference ground" for cables in an adjacent coil layer is disposed in the reference ground conducting cable layer. A corresponding reference ground conducting cable layer may be set for each coil layer; corresponding reference ground conducting cable layers may be set for some coil layers; or corresponding reference ground conductor layers may be set for some coil layers and used as a "reference ground" for all coil layers. For example, "a first auxiliary layer and a second auxiliary layer" described below are "reference ground" of all coil layers.

[0074] Manner 3: The reference ground structure may be one or more accompanying reference ground cables located in the coil layer of the common-mode filter, such as "a first accompanying reference ground cable, a middle accompanying reference ground cable, and a second accompanying reference ground cable" described below.

[0075] Manner 4: The reference ground structure may be a surface reference ground structure located on a surface of the common-mode filter, such as "a metal reference ground coating layer" or "a metal reference ground strip" described below.

[0076] It may be understood that a person skilled in the art may set a position in the common-mode filter, a structure, a size, and the like of the reference ground structure based on a requirement, provided that it is ensured that the reference ground structure can provide a reference ground for cables of the coil group. Different coil groups can have similar or even same ground matched impedances. This is not limited in this application.

[0077] FIG. 5a is a section view of a common-mode filter according to an embodiment of this application. FIG. 5b is a schematic diagram of a structure of a common-mode filter according to an embodiment of this application. FIG. 5a is a section view obtained by performing sectioning along a location of a dashed box area s3 in FIG. 1c. To facilitate understanding of a cable layout of a coil group in this application, only a part associated with the coil group is shown in the section view FIG. 5a. In a possible implementation, as shown in FIG. 5a and FIG. 5b, the reference ground structure may include a first auxiliary layer 31 and a second auxiliary layer 32. The first auxiliary layer 31 is located between the first coil layer 21 and the first magnetic layer 11, and the first auxiliary layer 31 is isolated from the first coil layer 21 by using an insulating medium, to prevent the first auxiliary layer 31 from being electrically connected to the first coil layer 21. The first auxiliary layer 31 is provided with a first reference ground cable 41 corresponding to the first cable a, the second cable b, and the third cable c in the first coil layer 21 separately. To be specific, the first reference ground cable 41 includes: a reference ground cable segment Da of the first cable a in the first coil layer 21, a reference ground cable segment Db of the second cable b in the first coil layer 21, and a reference ground cable segment Dc of the third cable c in the first coil layer 21. The second auxiliary layer 32 is located between the second coil layer 22 and the second magnetic layer 12. Similarly, the second auxiliary layer 32 is isolated from the second coil layer 22 by using an insulating medium, to prevent the second auxiliary layer 32 from being electrically connected to the second coil layer 22. The second auxiliary layer 32 is provided with a second reference ground cable 42 corresponding to the first cable a, the second cable b, and the third cable c in the second coil layer 22 separately. To be specific, the second reference ground cable 42 includes: a reference ground cable segment Fa of the first cable a in the second coil layer 22, a reference ground cable segment Fb of the second cable b in the second coil layer 22, and a reference ground cable segment Fc of the third cable c in the second coil layer 22.

[0078] In this implementation, the first auxiliary layer 31 and the second auxiliary layer 32 may be electrically connected through an auxiliary layer hole. The first auxiliary layer 31 and the second auxiliary layer 32 may also "float" between the magnetic layer and the coil layer, that is, the auxiliary layers do not need to be electrically connected. When the auxiliary layers are electrically connected through the auxiliary layer hole, the auxiliary layer hole cannot be electrically connected to any cable or cable hole in the coil layer.

[0079] To facilitate description of settings of the first auxiliary layer 31 and the second auxiliary layer 32 in the common-mode filter, only "FIG. 3a and FIG. 3b" are used as an example to describe the settings of adding the first auxiliary layer 31 and the second auxiliary layer 32 in FIG. 5a and FIG. 5b. A person skilled in the art may add the first auxiliary layer 31 and the second auxiliary layer 32 to the common-mode filters in "FIG. 2a and FIG. 2b", and "FIG. 4" according to the setting of the first auxiliary layer 31 and the second auxiliary layer 32 in FIG. 5a and FIG. 5b. Details are not described herein again.

[0080] In this implementation, as shown in FIG. 5a and FIG. 5b, positions and layouts of reference ground cable segments in the first reference ground cable 41 and the second reference ground cable 42 are the same as positions and layouts of corresponding cables, to ensure that different coil groups have similar ground impedances.

[0081] By disposing the common-mode filter in the manner shown in FIG. 5a and FIG. 5b, distances from all coil groups to the first magnetic layer and the second magnetic layer are consistent in a same phase. In addition, in comparison with the common-mode filter disposed in a manner of not adding the first auxiliary layer and the second auxiliary layer (that is, the manner corresponding to FIG. 2a, FIG. 2b, FIG. 4, and the like) in FIG. 3a, FIG. 3b, and the like, by disposing the first auxiliary layer and the second auxiliary layer including the reference ground cables, different coil groups have similar ground impedances. This further improves the symmetry between different coil groups and reduces the longitudinal transfer loss of the common-mode filter.

[0082] Based on the several common-mode filters provided in FIG. 2a, FIG. 2b, FIG. 3a, FIG. 3b, and FIG. 4, FIG. 6a and FIG. 6b are section views of common-mode filters according to an embodiment of this application, and FIG. 6c is a schematic diagram of a structure of a common-mode filter according to an embodiment of this application. FIG. 6a and FIG. 6b is a section view obtained by performing sectioning along a location of a dashed box area s3 in FIG. 1f. To facilitate understanding of a cable layout of a coil group in this application, only a part associated with the coil group is shown in the section view FIG. 6a and FIG. 6b. In a possible implementation, as shown in FIG. 6a, FIG. 6b, and FIG. 6c, the reference ground structure may include a first accompanying reference ground cable, a middle accompanying reference ground cable, and a second accompanying reference ground cable. A first accompanying reference ground cable 51 of one or more cables in the first cable a, the second cable b, and the third cable c in the first coil layer 21 is disposed in the first coil layer 21, and the first accompanying reference ground cable 51 is located on one side or two sides of a first target cable. A middle accompanying reference ground cable 53 of one or more middle target cables of the first cable a, the second cable b, and the third cable c in the middle coil layer 23 is disposed in the middle coil layer 23, and the middle accompanying reference ground cable 53 is located on one side or two sides of the middle target cable. A second accompanying reference ground cable 52 of one or more second target cables of the first cable a, the second cable b, and the third cable c in the second coil layer 22 is disposed in the second coil layer 22, and the second accompanying reference ground cable 52 is located on one side or two sides of the second target cable. A material of the first accompanying reference ground cable, the middle accompanying reference ground cable, and the second accompanying reference ground cable and a material of the cable may be a same type of metal, or may be different types of metal.

[0083] FIG. 6a and FIG. 6c show only that the first accompanying reference ground cable 51 is disposed on one side (an outer side) of the first cable a, the second cable b, and the third cable c in the first coil layer 21, that is, the first cable a, the second cable b, and the third cable c in the first coil layer 21 are first target cables; and the second accompanying reference ground cable 52 is disposed on one side (an outer side) of the first cable a, the second cable b, and the third cable c in the second coil layer 22, that is, the first cable a, the second cable b, and the third cable c in the second coil layer 22 are second target cables; and a middle accompanying reference ground cable 53 is disposed on one side (an outer side) of the first cable a, the second cable b, and the third cable c in the middle coil layer 23, that is, the first cable a, the second cable b, and the third cable c in the middle coil layer 23 are middle target cables. FIG. 6b shows only that the first accompanying reference ground cable 51 is disposed on two sides of the first cable a, the second cable b, and the third cable c in the first coil layer 21, that is, the first cable a, the second cable b, and the third cable c in the first coil layer 21 are first target cables; and the second accompanying reference ground cable 52 is disposed on two sides of the first cable a, the second cable b, and the third cable c in the second coil layer 22, that is, the first cable a, the second cable b, and the third cable c in the second coil layer 22 are second target cables; and a middle accompanying reference ground cable 53 is disposed on two sides of the first cable a, the second cable b, and the third cable c in the middle coil layer 23, that is, the first cable a, the second cable b, and the third cable c in the middle coil layer 23 are middle target cables. For settings of the first accompanying reference ground cable 51, the second accompanying reference ground cable 52, and the middle accompanying reference ground cable 53 in another manner, refer to the examples provided in FIG. 6a, FIG. 6b, and FIG. 6c for layout. Details are not described in this application again.

[0084] In this implementation, in an actual cabling process, a position of the accompanying reference ground cable in each coil layer, a quantity of accompanying cables, and a specific cable in the first cable, the second cable, and the third cable to be accompanied may be set based on a usage requirement of the common-mode filter that needs to be met by layout settings of the first cable, the second cable, and the third cable in different coil layers. That is, settings of the accompanying reference ground cables in different coil layers may be the same or may be different. In this way, symmetry of different coil groups can be improved, and different coil groups have similar ground impedances. A person skilled in the art may adjust, based on an actual requirement, whether the reference ground cable is disposed for the first cable, the second cable, and the third cable in each coil layer, whether the reference ground cable is disposed on one side or on two sides, and whether the reference ground cable is disposed on an inner side or an outer side. This is not limited in this application.

[0085] For example, it is assumed that the plurality of coil layers are the 1st layer, the 2nd layer, ..., and the 6th layer, where "the 1st layer" is the first coil layer, "the 2nd layer to the 5th layer" are the middle coil layers, and "the 6th layer" is the second coil layer. In this case, in "the 1st layer", the first accompanying reference ground cable 51 may be disposed only on one side of the first cable a; in "the 2nd layer", the middle accompanying reference ground cable 53 may be disposed only on two sides of the first cable a; in "the 3rd layer", the middle accompanying reference ground cable 53 may be disposed only on two sides of the first cable a and the second cable b; in "the 4th layer", the middle accompanying reference ground cable 53 may be disposed only on two sides of the first cable a, the second cable b, and the third cable c; in "the 5th layer", the middle accompanying reference ground cable 53 may be disposed only on outer sides of the first cable a, the second cable b, and the third cable c; and in "the 6th layer", the second accompanying reference ground cable 52 may be disposed only on inner sides of the first cable a, the second cable b, and the third cable c.

[0086] By disposing the common-mode filter in the manner shown in FIG. 6a, FIG. 6b, and FIG. 6c, distances from all coil groups to the first magnetic layer and the second magnetic layer are consistent in a same phase. In addition, in comparison with the common-mode filter disposed in a manner of not disposing the accompanying reference ground cable (that is, the manner corresponding to FIG. 2a, FIG. 2b, FIG. 3a, FIG. 3b, and the like) in FIG. 4 and the like, by disposing the first accompanying reference ground cable, the second accompanying reference ground cable, and the middle accompanying reference ground cable, different coil groups have similar ground impedances. This further improves the symmetry between different coil groups and reduces the longitudinal transfer loss of the common-mode filter.

[0087] In a possible implementation, the accompanying reference ground cables in different coil layers may be connected together, to be specific, the first accompanying reference ground cable, the middle accompanying reference ground cable, and the second accompanying reference ground cable are connected together, or may not be connected together. Some or all of the accompanying reference ground cables in the first accompanying reference ground cable, the middle accompanying reference ground cable, and the second accompanying reference ground cable may be connected together or may not be connected together based on ground impedances of the different coil groups. When the first accompanying reference ground cable, the middle accompanying reference ground cable, and the second accompanying reference ground cable need to be connected, connection between the accompanying reference ground cables may be implemented by disposing holes in corresponding coil layers, or the connection between the first accompanying reference ground cable, the middle accompanying reference ground cable, and the second accompanying reference ground cable may be implemented through an external conducting cable. A material of the first accompanying reference ground cable, the middle accompanying reference ground cable, and the second accompanying reference ground cable may be metal. In this way, compared with a manner of not connecting the first accompanying reference ground cable, the middle accompanying reference ground cable, and the second accompanying reference ground cable, this manner can further ensure similar ground impedances of different coil groups.

[0088] In a possible implementation, the reference ground structure may include at least one of the following metal reference ground layers:

a first metal reference ground layer, located between the first coil layer and the first magnetic layer;

a second metal reference ground layer, located between the second coil layer and the second magnetic layer;

a third metal reference ground layer, located between the first coil layer and the middle coil layer, and provided with a first accommodating hole that accommodates a first cable hole, a second cable hole, and a third cable hole that pass through the third metal reference ground layer;

a fourth metal reference ground layer, located between the second coil layer and the middle coil layer, and provided with a second accommodating hole that accommodates the first cable hole, the second cable hole, and the third cable hole that pass through the third metal reference ground layer; and

a middle metal reference ground layer, where there are one or more middle metal reference ground layers, and each middle metal reference ground layer is located between two middle coil layers, and is provided with a third accommodating hole that accommodates the first cable hole, the second cable hole, and the third cable hole that pass through the third metal reference ground layer.

[0089] In this implementation, a quantity and types of metal reference ground layers may be determined based on a magnitude of a difference between ground impedances of different coil groups after different types of metal reference ground layers are set. For example, based on the several common-mode filters provided in FIG. 2a, FIG. 2b, FIG. 3a, FIG. 3b, and FIG. 4, FIG. 7a is a section view of a common-mode filter according to an embodiment of this application, and FIG. 7b is a schematic diagram of a structure of a common-mode filter according to an embodiment of this application. FIG. 7a is a section view obtained by performing sectioning along a location of a dashed box area s3 in FIG. 1f. To facilitate understanding of a cable layout of a coil group in this application, only a part associated with the coil group is shown in the section view FIG. 7a. As shown in FIG. 7a and FIG. 7b, the common-mode filter includes six coil layers, namely, "the 1st layer, the 2nd layer, ..., and the 6th layer". "The 1st layer" is the first coil layer, "the 2nd layer to the 5th layer" are the middle coil layers, and "the 6th layer" is the second coil layer. The reference ground structure includes a first metal reference ground layer 61, a second metal reference ground layer 62, a third metal reference ground layer 63, a fourth metal reference ground layer 64, and three middle metal reference ground layers 65. The third metal reference ground layer 63 is further provided with a first accommodating hole 630 corresponding to the first cable hole, the second cable hole, and the third cable hole that are for implementing "a cable connection between coil groups in the 1st layer and the 2nd layer". The fourth metal reference ground layer 64 is further provided with a second accommodating hole 640 corresponding to the first cable hole, the second cable hole, and the third cable hole that are for implementing "a cable connection between coil groups in the 5th layer and the 6th layer". The three middle metal reference ground layers 65 are further provided with third accommodating holes 650 corresponding to the first cable holes, the second cable holes, and the third cable holes that are for implementing "a cable connection between coil groups in the 2nd layer and the 3rd layer", "a cable connection between coil groups in the 3rd layer and the 4th layer", and "a cable connection between coil groups in the 4th layer and the 5th layer".

[0090] As shown in FIG. 7b, a same accommodating hole may be disposed for the first cable hole, the second cable hole, and the third cable hole that pass through the metal reference ground layer (where for example, the accommodating hole is the first accommodating hole, the second accommodating hole, or the third accommodating hole). The accommodating hole may accommodate the first cable hole, the second cable hole, and the third cable hole at the same time. Alternatively, a corresponding accommodating hole may be disposed for each cable hole. The accommodating hole and the accommodated cable holes are insulated from each other, and the insulation may be implemented by using dielectric insulation, setting physical spacings, or the like. In this way, cables of different coil groups in different coil layers are not connected together because they are in contact with the metal reference ground layer, to ensure mutual insulation between the different coil groups.

[0091] By disposing the common-mode filter in the manner shown in FIG. 7a and FIG. 7b, distances from all coil groups to the first magnetic layer and the second magnetic layer are consistent in a same phase. In addition, in comparison with the common-mode filter disposed in a manner of not adding the metal reference ground layer (that is, the manner corresponding to FIG. 3a, FIG. 3b, FIG. 4, and the like) in FIG. 2a, FIG. 2b, and the like, by disposing the at least one type of metal reference ground layer, different coil groups have similar ground impedances. This further improves the symmetry between different coil groups and reduces the longitudinal transfer loss of the common-mode filter.

[0092] In a possible implementation, when there are a plurality of metal reference ground layers, the plurality of metal reference ground layers are connected through a reference ground hole, the reference ground hole is disposed in one or more of the first coil layer, the second coil layer, and the middle coil layer, and there may be one or more reference ground holes.

[0093] In this implementation, FIG. 7c is a schematic diagram of a structure of a common-mode filter according to an embodiment of this application. A difference between the common-mode filter shown in FIG. 7c and the common-mode filters shown in FIG. 7b and FIG. 7a lies in that a reference ground hole 212 is disposed in a coil layer of the common-mode filter shown in FIG. 7c. A quantity and a size of the reference ground hole 212 may be set based on a requirement. This is not limited in this application. Based on the common-mode filters shown in FIG. 7b and FIG. 7a, a difference between ground impedances of different coil groups can be further reduced by disposing the reference ground hole.

[0094] In this implementation, the metal reference ground layer is disposed with spatial sizes such as a thickness, a length, and a width, and the thickness, the length, and the width of the metal reference ground layer may be set based on limitations of a processing technology, a longitudinal transfer loss, a differential mode loss, a return loss, an impedance indicator parameter, and the like. FIG. 7b and FIG. 7c illustrate more clearly locations of the metal reference ground layers with only "planes" and thicknesses thereof are not shown.

[0095] FIG. 8a is a schematic diagram of a structure of a common-mode filter according to an embodiment of this application. FIG. 8b is a section view of a common-mode filter according to an embodiment of this application. FIG. 8b is a section view obtained by performing sectioning along a location of a dashed box area s4 in FIG. 1g. To facilitate understanding of a cable layout of a coil group in this application, only a part associated with the coil group is shown in the section view FIG. 8b. In a possible implementation, as shown in FIG. 8a and FIG. 8b, the common-mode filter may further include a third magnetic layer 13 and a fourth magnetic layer 14 parallel to each other. The first coil layer 21, the middle coil layer 23, and the second coil layer 22 are located between the third magnetic layer 13 and the fourth magnetic layer 14, the third magnetic layer 13 is perpendicular to the first magnetic layer 11 and the second magnetic layer 12, and the fourth magnetic layer 14 is perpendicular to the first magnetic layer 11 and the second magnetic layer 12.

[0096] In this implementation, the fourth magnetic layer and the third magnetic layer are disposed with spatial sizes such as thicknesses, lengths, and widths, and the thicknesses, the lengths, and the widths of the fifth magnetic layer and the sixth magnetic layer may be set based on limitations of a processing technology, a longitudinal transfer loss, a differential mode loss, a return loss, an impedance indicator parameter, and the like. FIG. 8a illustrates more clearly locations of the third magnetic layer and the fourth magnetic layer with only "planes" and thicknesses thereof are not shown. Materials of the fourth magnetic layer and the third magnetic layer may be magnetic materials such as ferrite, and materials of the third magnetic layer and the fourth magnetic layer may be the same as or different from materials of the first magnetic layer and the second magnetic layer. This is not limited in this application.

[0097] By disposing the common-mode filter in the manner shown in FIG. 8a and FIG. 8b, distances from all coil groups to the first magnetic layer, the second magnetic layer, the third magnetic layer, and the fourth magnetic layer are consistent in a same phase. In addition, in comparison with a common-mode filter disposed in a manner of disposing only the first magnetic layer and the second magnetic layer (as shown in in FIG. 2a, FIG. 2b, FIG. 4, and the like) shown in FIG. 1h and the like, this common-mode filter enables a plurality of coil groups to be in a same magnetic environment in two dimensions. This further improves the symmetry between different coil groups and reduces the longitudinal transfer loss of the common-mode filter.

[0098] FIG. 9a is a schematic diagram of a structure of a common-mode filter according to an embodiment of this application. FIG. 9b is a section view of a common-mode filter according to an embodiment of this application. FIG. 9b is a section view obtained by performing sectioning along a location of a dashed box area s2 in FIG. 1e. To facilitate understanding of a cable layout of a coil group in this application, only a part associated with the coil group is shown in the section view 9b. In a possible implementation, as shown in FIG. 9a and FIG. 9b, when the common-mode filter includes the third magnetic layer 13 and the fourth magnetic layer 14 parallel to each other, the common-mode filter may further include a fifth magnetic layer 15 and a sixth magnetic layer 16 parallel to each other. The first coil layer 21, the middle coil layer 23, and the second coil layer 22 are located between the fifth magnetic layer 15 and the sixth magnetic layer 16, the fifth magnetic layer 15 is perpendicular to the first magnetic layer 11, the second magnetic layer 12, the third magnetic layer 13, and the fourth magnetic layer 14, and the sixth magnetic layer 16 is perpendicular to the first magnetic layer 11, the second magnetic layer 12, the third magnetic layer 13, and the fourth magnetic layer 14.

[0099] In this implementation, the fifth magnetic layer and the sixth magnetic layer are disposed with spatial sizes such as thicknesses, lengths, and widths, and the thicknesses, the lengths, and the widths of the fifth magnetic layer and the sixth magnetic layer may be set based on limitations of a processing technology, a longitudinal transfer loss, a differential mode loss, a return loss, an impedance indicator parameter, and the like. FIG. 9a illustrates more clearly locations of the fifth magnetic layer and the sixth magnetic layer with only "planes" and thicknesses thereof are not shown. Materials of the fifth magnetic layer and the sixth magnetic layer may be magnetic materials such as ferrite, and materials of the fifth magnetic layer and the sixth magnetic layer may be the same as or different from materials of the first magnetic layer, the second magnetic layer, the third magnetic layer, and the fourth magnetic layer. This is not limited in this application.

[0100] In this implementation, a lead-out hole of electrodes of the common-mode filter may be disposed in the first magnetic layer, the second magnetic layer, the third magnetic layer, the fourth magnetic layer, the fifth magnetic layer, and the sixth magnetic layer, to facilitate assembly and electrical connection of the common-mode filter in a circuit system. A person skilled in the art may set a location, a size, and the like of the lead-out hole based on a requirement. This is not limited in this application.

[0101] By disposing the common-mode filter in the manner shown in FIG. 9a and FIG. 9b, distances from all coil groups to the first magnetic layer, the second magnetic layer, the third magnetic layer, the fourth magnetic layer, the fifth magnetic layer, and the sixth magnetic layer are consistent in a same phase. In addition, in comparison with a common-mode filter disposed in a manner of disposing only the first magnetic layer and the second magnetic layer (as shown in FIG. 2a, FIG. 2b, FIG. 4, and the like) shown in FIG. 1h and the like, this common-mode filter enables a plurality of coil groups to be in a same magnetic environment in three-dimension stereoscopic space. This further improves the symmetry between different coil groups and reduces the longitudinal transfer loss of the common-mode filter.

[0102] In a possible implementation, the reference ground structure may include a metal reference ground coating layer, and the metal reference ground coating layer coats on a surface of the common-mode filter. The metal reference ground coating layer is configured to coat components included in the common-mode filter in the foregoing specification. By disposing the common-mode filter in the manner of adding the metal reference ground coating layer, distances from all coil groups to the magnetic layer are consistent in a same phase. In addition, in comparison with a common-mode filter disposed in a manner of not disposing the metal reference ground coating layer (as shown in FIG. 2a, FIG. 2b, FIG. 4, and the like) shown in FIG. 1h and the like, this common-mode filter enables a plurality of coil groups to be in a same reference ground environment, and have a same ground impedance in three-dimension stereoscopic space. This further improves the symmetry between different coil groups and reduces the longitudinal transfer loss of the common-mode filter.

[0103] For example, FIG. 10a is a schematic diagram of a structure of a common-mode filter according to an embodiment of this application. FIG. 10b is a section view of a common-mode filter according to an embodiment of this application. FIG. 10b is a section view obtained by performing sectioning along a location of a dashed box area s2 in FIG. 1e (or a dashed box area s4 in FIG. 1g). To facilitate understanding of a cable layout of a coil group in this application, only a part associated with the coil group is shown in the section view 10b. In a possible implementation, as shown in FIG. 10a and FIG. 10b, the metal reference ground coating layer 71 is configured to coat the first magnetic layer 11, the second magnetic layer 12, and the plurality of coil layers.

[0104] FIG. 11a is a schematic diagram of a structure of a common-mode filter according to an embodiment of this application. FIG. 11b is a section view of a common-mode filter according to an embodiment of this application. FIG. 11b is a section view obtained by performing sectioning along a location of a dashed box area s2 in FIG. 1e. To facilitate understanding of a cable layout of a coil group in this application, only a part associated with the coil group is shown in the section view 11b. In a possible implementation, as shown in FIG. 11a and FIG. 11b, the metal reference ground coating layer 71 is configured to coat a first magnetic layer 11, a second magnetic layer 12, a third magnetic layer 13, a fourth magnetic layer 14, a fifth magnetic layer 15, and a sixth magnetic layer 16, and a plurality of coil layers.

[0105] In this implementation, when the reference ground structure includes parts such as a metal reference ground layer, a first auxiliary layer, and a second auxiliary layer, these parts also need to be coated by the metal reference ground coating layer 71.

[0106] In this implementation, a lead-out hole of electrodes of the common-mode filter may be disposed in the metal reference ground coating layer, the first magnetic layer 11, the second magnetic layer 12, the third magnetic layer 13, the fourth magnetic layer 14, the fifth magnetic layer 15, and the sixth magnetic layer 16, to facilitate assembly and electrical connection of the common-mode filter in a circuit system. A person skilled in the art may set a location, a size, and the like of the lead-out hole based on a requirement. This is not limited in this application.

[0107] In this implementation, the metal reference ground coating layer is provided with a thickness, and the thickness of the metal reference ground coating layer may be set based on limitations of a processing technology, a longitudinal transfer loss, a differential mode loss, a return loss, an impedance indicator parameter, and the like. This is not limited in this application.

[0108] FIG. 12a is a three-dimensional diagram of a common-mode filter according to an embodiment of this application. FIG. 12b is a main view of a common-mode filter according to an embodiment of this application. FIG. 12c is a side view of a common-mode filter according to an embodiment of this application. FIG. 12d is a top view of a common-mode filter according to an embodiment of this application. FIG. 13a is a three-dimensional diagram of a common-mode filter according to an embodiment of this application. FIG. 13b is a main view of a common-mode filter according to an embodiment of this application. FIG. 13c is a side view of a common-mode filter according to an embodiment of this application. FIG. 13d is a top view of a common-mode filter according to an embodiment of this application. In a possible implementation, as shown in FIG. 12a to FIG. 12d and FIG. 13a to FIG. 13d, the reference ground structure may further include (a plurality of) pads 81 and a metal reference ground strip 91 that are located on a surface of the common-mode filter and are separately connected to a terminal of each coil group. One end that is of two ends of a cable in the first coil layer in each coil group and that is not connected to a cable in a same coil group in another coil layer is a terminal of the coil group. One end that is of two ends of a cable in the second coil layer in each coil group and that is not connected to a cable in a same coil group in another coil layer is another terminal of the coil group. One end that is of two ends of the first cable in the first coil layer in the first coil group and that is not connected to the first cable in the middle coil layer is a terminal of the first coil group. One end that is of two ends of the first cable in the second coil layer in the first coil group and that is not connected to the first cable in the middle coil layer is another terminal of the first coil group.

[0109] A part of each pad 81 is located on a first side surface (to be specific, a bottom surface of the common-mode filter in FIG. 12a to FIG. 12d and FIG. 13a to FIG. 13d) of the common-mode filter. Another part of each pad 81 is located on one of a plurality of second side surfaces (to be specific, side surfaces connected to the bottom surface of the common-mode filter in FIG. 12a to FIG. 12d and FIG. 13a to FIG. 13d) connected to the first side surface on the common-mode filter. The metal reference ground strip 91 is located between the plurality of pads 81 and surrounds at least the first side surface and a part of a second side surface with pads of the common-mode filter.

[0110] In this implementation, in the examples shown in FIG. 12a to FIG. 12d and FIG. 13a to FIG. 13d, it is assumed that the common-mode filter includes three coil groups and six pads 81, parts of the six pads 81 are located on the bottom surface (namely, the first side surface) of the common-mode filter, and other parts of three pads 81 (referred to as a first group of pads below) of the six pads 81 are located on a front side surface (namely, the second side surface) connected to the bottom surface of the common-mode filter. Other parts of the other three pads 81 (referred to as a second group of pads below) of the six pads 81 are located on a rear side surface (namely, the second side surface) connected to the bottom surface of the common-mode filter. As shown in FIG. 12a to FIG. 12d, the metal reference ground strip 91 may be located only between the first group of pads and the second group of pads, that is, a part of the metal reference ground strip 91 is in a middle area of the first side surface and passes through the first group of pads and the second group of pads. Other parts of the metal reference ground strip 91 are separately located on a left side and a right side of the common-mode filter, and heights of the parts of the metal reference ground strip 91 on the left side and the right side are at least equal to heights of the pads 81 on the front side and the rear side. This ensures that each pad can use the metal reference ground strip as a reference ground. As shown in FIG. 13a to FIG. 13d, the metal reference ground strip 91 continues to extend and surround the entire common-mode filter on the basis of FIG. 12a to FIG. 12d, to ensure that each pad can use the metal reference ground strip as the reference ground.

[0111] In this implementation, the metal reference ground strip is provided with a thickness and a width, and the thickness of the metal reference ground coating layer may be set based on limitations of a processing technology, a longitudinal transfer loss, a differential mode loss, a return loss, an impedance indicator parameter, and the like. This is not limited in this application.

[0112] By disposing the common-mode filter in the manner shown in FIG. 12a to FIG. 12d and FIG. 13a to FIG. 13d, distances from all coil groups to the magnetic layer are consistent in a same phase. In addition, in comparison with a common-mode filter disposed in the manner shown in FIG. 1h, this common-mode filter enables different coil groups to have similar ground impedances at the pad position. This further improves the symmetry between different coil groups and reduces the longitudinal transfer loss of the common-mode filter.

[0113] FIG. 14a is a section view of a common-mode filter according to an embodiment of this application. FIG. 14b is a schematic diagram of a plurality of coil layers of a common-mode filter according to an embodiment of this application. FIG. 14a is a section view obtained by performing sectioning along a location of a dashed box area s3 in FIG. 1f. To facilitate understanding of a cable layout of a coil group in this application, only a part associated with the coil group is shown in the section view FIG. 14a. In a possible implementation, differences between the common-mode filter shown in FIG. 14a and FIG. 14b and the common-mode filters in FIG. 2a and FIG. 2b, FIG. 3a and FIG. 3b, FIG. 4, FIG. 5a and FIG. 5b, FIG. 6a to FIG. 6c, FIG. 7a to FIG. 7c, FIG. 8a and FIG. 8b, FIG. 9a and FIG. 9b, FIG. 10a and FIG. 10b, FIG. 11a and FIG. 11b, FIG. 12a to FIG. 12d, and FIG. 13a to FIG. 13d are as follows: The common-mode filter shown in FIG. 14a and FIG. 14b includes four coil groups, the plurality of coil groups further include a fourth coil group D, the plurality of cable holes further include a fourth cable hole (not shown in the figure, refer to FIG. 2b and the setting of the cable holes in the related descriptions), and each fourth coil group D includes a fourth cable d in the first coil layer 21, a fourth cable d in the second coil layer 22, and a fourth cable d in the middle coil layer 23. The plurality of cables of the fourth coil group D are connected through the fourth cable hole, and the first cable a, the second cable b, the third cable c, and the fourth cable d in a same coil layer are wound in parallel.

[0114] As shown in FIG. 14b, in each coil layer, cables marked as "a", "b", "c" and "d" are respectively a first cable, a second cable, a third cable, and a fourth cable of a coil layer in which the cables are located. To be specific, the first cable is marked as "a", the second cable is marked as "b", the third cable is marked as "c", and the fourth cable is marked as "d". A plurality of cables of the first coil group A are cables marked as "a" in the first coil layer, namely, "the 1st layer", the middle coil layers, namely, "the 2nd layer to the 5th layer", and the second coil layer, namely, "the 6th layer". A plurality of cables of the second coil group B are cables marked as "b" in the first coil layer, namely, "the 1st layer", the middle coil layers, namely, "the 2nd layer to the 5th layer", and the second coil layer, namely, "the 6th layer". A plurality of cables of the third coil group C are cables marked as "c" in the first coil layer, namely, "the 1st layer", the middle coil layers, namely, "the 2nd layer to the 5th layer", and the second coil layer, namely, "the 6th layer". A plurality of cables of the fourth coil group D are cables marked as "d" in the first coil layer, namely, "the 1st layer", the middle coil layers, namely, "the 2nd layer to the 5th layer", and the second coil layer, namely, "the 6th layer".

[0115] In this implementation, with reference to the common-mode filters shown in FIG. 14a and FIG. 14b, four coil groups may be adjusted, another part (such as the metal reference ground coating layer) may be added, and a layout of cables in each coil layer may be adjusted. This is not limited in this application. A quantity of coil groups, thicknesses, widths, and cable spacings of cables in the coil group may be set based on a component requirement, a processing technology limitation, and the like. This is not limited in this application.

[0116] By disposing the common-mode filter in the manner shown in FIG. 14a and FIG. 14b, distances from all coil groups to the magnetic layer are consistent in a same phase. In addition, in comparison with a common-mode filter disposed in the manner of disposing only three coil groups (as shown in FIG. 2a, FIG. 2b, FIG. 4, and the like) shown in FIG. 1h and the like, this common-mode filter increases a quantity of coil groups in the common-mode filter, improves the symmetry between different coil groups, and reduces the longitudinal transfer loss of the common-mode filter.

[0117] The foregoing describes embodiments of this application. The foregoing descriptions are examples, are not exhaustive, and are not limited to the disclosed embodiments. Many modifications and variations will be apparent to a person of ordinary skill in the art without departing from the scope and spirit of the described embodiments. Embodiments in this application and the features in the embodiments may be mutually combined provided that they do not conflict with each other. Selection of terms used in this specification is intended to best explain embodiment principles, actual application, or improvements to technologies in the market, or to enable another person of ordinary skill in the art to understand the embodiments disclosed in this specification.

Claims

1. A common-mode filter, comprising: a plurality of coil groups, a plurality of cable holes, and a first magnetic layer, a second magnetic layer, and a plurality of coil layers that are parallel to each other, wherein the plurality of coil groups comprise at least a first coil group, a second coil group, and a third coil group, the plurality of cable holes comprise at least a first cable hole, a second cable hole, and a third cable hole, the plurality of coil layers comprise a first coil layer, at least one middle coil layer, and a second coil layer, and at least a first cable, a second cable, and a third cable are disposed in each coil layer;

the first coil layer, the middle coil layer, and the second coil layer are sequentially stacked between the first magnetic layer and the second magnetic layer;

the first coil group comprises the first cable in each coil layer, the second coil group comprises the second cable in each coil layer, and the third coil group comprises the third cable in each coil layer; and

the first cable hole is configured to connect a plurality of first cables of the first coil group, the second cable hole is configured to connect a plurality of second cables of the second coil group, and the third cable hole is configured to connect a plurality of third cables of the third coil group, wherein

at least two of the first cable, the second cable, and the third cable in a same coil layer are wound in parallel.

2. A common-mode filter, comprising: a plurality of coil groups, a plurality of cable holes, and a first magnetic layer, a second magnetic layer, and a plurality of coil layers that are parallel to each other, wherein the plurality of coil groups comprise at least a first coil group, a second coil group, and a third coil group, the plurality of cable holes comprise at least a first cable hole, a second cable hole, and a third cable hole, the plurality of coil layers comprise a first coil layer, at least one middle coil layer, and a second coil layer, and at least a first cable, a second cable, and a third cable are disposed in each coil layer;

the first coil layer, the middle coil layer, and the second coil layer are sequentially disposed between the first magnetic layer and the second magnetic layer; the first coil group comprises the first cable in each coil layer, the second coil group comprises the second cable in each coil layer, and the third coil group comprises the third cable in each coil layer; and

the first cable hole is configured to connect a plurality of first cables of the first coil group, the second cable hole is configured to connect a plurality of second cables of the second coil group, and the third cable hole is configured to connect a plurality of third cables of the third coil group, wherein

at least two of the first cable, the second cable, and the third cable in a same coil layer are wound in parallel, and cable widths of a same coil group meet any one of the following cases:

a width of the first cable and a width of the second cable each are a first cable width, a width of the third cable is a second cable width, and the first cable width is different from the second cable width; or

a width of the first cable, a width of the second cable, and a width of the third cable are all different, the width of the first cable is a first cable width, and the width of the second cable is a second cable width.

3. The common-mode filter according to claim 2, wherein
the first cable width and the second cable width meet:
W1=p1×W2, wherein W1 is the first cable width, W2 is the second cable width, p1 is a proportional coefficient, and p1 ∈ [0.5, 0.8] or p1 ∈ [2, 3].

4. The common-mode filter according to any one of claims 1 to 3, wherein a first relative position relationship exists among a first cable, a second cable, and a third cable in the first coil layer, a second relative position relationship exists among a first cable, a second cable, and a third cable in the second coil layer, and a middle relative position relationship exists among a first cable, a second cable, and a third cable in the middle coil layer, wherein
the first relative position relationship, the second relative position relationship, and the middle relative position relationship are the same, and center lines of the first cable hole for connection of first cables in adjacent coil layers, the second cable hole for connection of second cables in adjacent coil layers, and the third cable hole for connection of third cables in adjacent coil layers are all located on a same cross section perpendicular to all coil layers.

5. The common-mode filter according to any one of claims 1 to 3, wherein

a first relative position relationship exists among a first cable, a second cable, and a third cable in the first coil layer, a second relative position relationship exists among a first cable, a second cable, and a third cable in the second coil layer, and a middle relative position relationship exists among a first cable, a second cable, and a third cable in the middle coil layer, wherein

the first relative position relationship, the second relative position relationship, and the middle relative position relationship are the same, and a first total length of a plurality of first cables of the first coil group, a second total length of a plurality of second cables of the second coil group, and a third total length of a plurality of third cables of the third coil group are the same.

6. The common-mode filter according to any one of claims 1 to 3, wherein a first relative position relationship exists among a first cable, a second cable, and a third cable in the first coil layer, a second relative position relationship exists among a first cable, a second cable, and a third cable in the second coil layer, and a middle relative position relationship exists among a first cable, a second cable, and a third cable in the middle coil layer, wherein
the first relative position relationship, the second relative position relationship, and the middle relative position relationship are different, and a first total length of a plurality of first cables of the first coil group, a second total length of a plurality of second cables of the second coil group, and a third total length of a plurality of third cables of the third coil group are the same.

7. The common-mode filter according to any one of claims 1 to 6, wherein the common-mode filter further comprises at least one reference ground structure, the reference ground structure is insulated from all first cables, all second cables, and all third cables, and the reference ground structure is insulated from both the first magnetic layer and the second magnetic layer.

8. The common-mode filter according to claim 7, wherein the reference ground structure comprises a first auxiliary layer and a second auxiliary layer, wherein

the first auxiliary layer is located between the first coil layer and the first magnetic layer, and a first reference ground cable corresponding to the first cable, the second cable, and the third cable in the first coil layer is disposed in the first auxiliary layer; and

the second auxiliary layer is located between the second coil layer and the second magnetic layer, and a second reference ground cable corresponding to the first cable, the second cable, and the third cable in the second coil layer is disposed in the second auxiliary layer.

9. The common-mode filter according to claim 6 or 7, wherein the reference ground structure comprises a first accompanying reference ground cable, a middle accompanying reference ground cable, and a second accompanying reference ground cable, wherein

a first accompanying reference ground cable of one or more first target cables of the first cable, the second cable, and the third cable in the first coil layer is disposed in the first coil layer, and the first accompanying reference ground cable is located on one side or two sides of the first target cable;

a middle accompanying reference ground cable of one or more middle target cables of the first cable, the second cable, and the third cable in the middle coil layer is disposed in the middle coil layer, and the middle accompanying reference ground cable is located on one side or two sides of the middle target cable; and

a second accompanying reference ground cable of one or more second target cables of the first cable, the second cable, and the third cable in the second coil layer is disposed in the second coil layer, and the second accompanying reference ground cable is located on one side or two sides of the second target cable.

10. The common-mode filter according to claim 9, wherein the first accompanying reference ground cable, the middle accompanying reference ground cable, and the second accompanying reference ground cable are connected.

11. The common-mode filter according to any one of claims 7 to 10, wherein the reference ground structure comprises at least one of the following metal reference ground layers:

a first metal reference ground layer, located between the first coil layer and the first magnetic layer;

a second metal reference ground layer, located between the second coil layer and the second magnetic layer;

a third metal reference ground layer, located between the first coil layer and the middle coil layer, and provided with a first accommodating hole that accommodates a first cable hole, a second cable hole, and a third cable hole that pass through the third metal reference ground layer;

a fourth metal reference ground layer, located between the second coil layer and the middle coil layer, and provided with a second accommodating hole that accommodates the first cable hole, the second cable hole, and the third cable hole that pass through the third metal reference ground layer; and

a middle metal reference ground layer, wherein there are one or more middle metal reference ground layers, and each middle metal reference ground layer is located between two middle coil layers, and is provided with a third accommodating hole that accommodates the first cable hole, the second cable hole, and the third cable hole that pass through the third metal reference ground layer.

12. The common-mode filter according to claim 11, wherein when there are a plurality of metal reference ground layers, the plurality of metal reference ground layers are connected through a reference ground hole, and the reference ground hole is disposed in one or more of the first coil layer, the second coil layer, and the middle coil layer.

13. The common-mode filter according to any one of claims 1 to 12, wherein the common-mode filter further comprises a third magnetic layer and a fourth magnetic layer parallel to each other, and
the first coil layer, the middle coil layer, and the second coil layer are located between the third magnetic layer and the fourth magnetic layer, the third magnetic layer is perpendicular to the first magnetic layer and the second magnetic layer, and the fourth magnetic layer is perpendicular to the first magnetic layer and the second magnetic layer.

14. The common-mode filter according to claim 13, wherein the common-mode filter further comprises a fifth magnetic layer and a sixth magnetic layer parallel to each other, and
the first coil layer, the middle coil layer, and the second coil layer are located between the fifth magnetic layer and the sixth magnetic layer, the fifth magnetic layer is perpendicular to the first magnetic layer, the second magnetic layer, the third magnetic layer, and the fourth magnetic layer, and the sixth magnetic layer is perpendicular to the first magnetic layer, the second magnetic layer, the third magnetic layer, and the fourth magnetic layer.

15. The common-mode filter according to any one of claims 7 to 14, wherein the reference ground structure comprises a metal reference ground coating layer, and the metal reference ground coating layer coats on a surface of the common-mode filter.

16. The common-mode filter according to any one of claims 7 to 14, wherein the reference ground structure comprises a pad and a metal reference ground strip that are connected to a terminal of each coil group, wherein

a part of each pad is located on a first side surface of the common-mode filter, and another part of each pad is located on one of a plurality of second side surfaces that are on the common-mode filter and that are connected to the first side surface; and

the metal reference ground strip is located between a plurality of pads, and surrounds at least a part of an area of the first side surface of the common-mode filter and the second side surface with the pad.

17. The common-mode filter according to any one of claims 1 to 3, wherein the plurality of coil groups further comprise a fourth coil group, the plurality of cable holes further comprise a fourth cable hole, a fourth cable is further disposed in each coil layer, the fourth coil group comprises a fourth cable in each coil layer, a plurality of fourth cables of the fourth coil group are connected through the fourth cable hole, and at least two of the first cable, the second cable, the third cable, and the fourth cable in a same coil layer are wound in parallel.

18. The common-mode filter according to any one of claims 1 to 17, wherein the first cable, the second cable, and the third cable in the same coil layer are isolated through a dielectric, and different coil layers are isolated through the dielectric.

19. The common-mode filter according to claim 18, wherein a material of the dielectric is a ceramic material, and a material of the coil group and the cable hole is a metal material.

Drawing