(19)
(11)EP 3 202 038 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
16.09.2020 Bulletin 2020/38

(21)Application number: 15782021.8

(22)Date of filing:  01.10.2015
(51)International Patent Classification (IPC): 
H03K 5/24(2006.01)
H03K 19/094(2006.01)
(86)International application number:
PCT/GB2015/052883
(87)International publication number:
WO 2016/051192 (07.04.2016 Gazette  2016/14)

(54)

COMPARATOR

KOMPARATOR

COMPARATEUR


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(30)Priority: 01.10.2014 GB 201417379

(43)Date of publication of application:
09.08.2017 Bulletin 2017/32

(73)Proprietor: PragmatIC Printing Ltd
Sedgefield Durham TS21 3FG (GB)

(72)Inventor:
  • DE OLIVEIRA, Joao
    Longstanton CB24 3GY (GB)

(74)Representative: HGF 
1 City Walk
Leeds LS11 9DX
Leeds LS11 9DX (GB)


(56)References cited: : 
US-A- 4 237 388
US-A- 5 798 658
US-A- 4 410 815
US-A1- 2004 135 598
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description

    FIELD OF THE INVENTION



    [0001] This invention relates to a comparator, which may also be described as a comparator circuit, stage, or module, and to apparatus comprising a comparator.

    BACKGROUND



    [0002] Comparators are well-known electronic circuits, for incorporation in a wide variety of circuits and apparatus. Fig:1 shows a generic symbol representation of a comparator, where VCC is the positive power supply, VDD is the negative power supply, or can be ground, e+ is the input positive sense (voltage range is normally VDD + X to VCC - Y), and e- is the input negative sense (voltage range is normally VDD + X to VCC - Y). When the voltage applied to e+ is higher than the voltage applied to e-, the OUTPUT signal is a logic 1 (close to VCC). When the voltage applied to e+ is lower than the voltage applied to e-, the OUTPUT signal is a logic 0 (close to VDD). The simple basic accuracy (Input offset voltage), is the lowest difference between e+ and e- that will be recognized and trigger the right OUTPUT level. Input offset voltage is typically a few mV to a few tens of mV.

    [0003] The current comparator implementations typically use differential, mirror current for the front stage, followed by an amplification stage. This requires close to identical transistors, in most cases using complementary transistors as well. Their accuracy (or precision) is mostly linked to the variation between transistors, and even a very small variation has an amplified error effect. Thus, problems associated with known comparators are the need to use closely matched transistors, and the errors associated with use of transistors not closely matched.

    [0004] US5798658A discloses source-coupled logic with reference controlled inputs.

    [0005] US4410815A discloses a high speed gallium arsenide (GaAs) integrated circuit which converts GaAs input or source signals to voltage levels for directly driving emitter coupled logic (ECL) circuits.

    [0006] US4237388A discloses an inverter circuit operating at a high speed and with low power consumption, which comprises a first bipolar transistor having a collector coupled to the output of the circuit, a second bipolar transistor having a collector coupled to the base of the first transistor and means responsive to at least one input signal to produce a first signal for driving the first transistor and a second signal complementary to the first signal for driving the second transistor substantially at the same time.

    BRIEF SUMMARY OF THE DISCLOSURE



    [0007] It is an aim or certain embodiments of the invention to overcome at least partly, obviate, or mitigate against, at least one of the problems associated with the prior art.

    [0008] One aspect of the present invention provides a comparator for comparing a first input voltage with a second input voltage and generating a corresponding output voltage, the comparator comprising: a first input terminal for receiving the first input voltage: a second input terminal for receiving the second input voltage; an output terminal for outputting the output voltage; a first supply rail for providing a first supply voltage; and a second supply rail for providing a second supply voltage, the comparator further comprising: a follower stage comprising a first follower stage supply terminal coupled to the first supply rail, a second follower stage supply terminal coupled to the second supply rail, a follower stage input terminal coupled to the second input terminal, and a follower stage output terminal for providing a follower stage output voltage; an inverter stage comprising a first inverter stage supply terminal coupled to the first supply rail, a second inverter stage supply terminal coupled to the follower stage output terminal, an inverter stage input terminal coupled to the first input terminal, and an inverter stage output terminal for providing an inverter stage output voltage and coupled to the output terminal; a controllable switching device arranged to couple the first follower stage supply terminal to the first supply rail, the switching device being controllable to switch between a first state, in which it electrically connects the first follower supply terminal to the first supply rail, and a second state, in which it electrically disconnects the first follower supply terminal from the first supply rail; control means arranged to control the controllable switching device; and filtering means arranged between the inverter stage output terminal and the comparator output terminal to filter at least one frequency component from the output voltage, wherein said control means comprises an oscillator, having an output arranged to control the switching device to alternate between the first and second states, the oscillator output has a fundamental frequency, and the filtering means is arranged to filter out at least said fundamental frequency.

    [0009] Advantageously, if the offset voltages of the follower and inverter stages are very similar, the comparator output voltage may switch (alternate) between two states in close and accurate correspondence with the first input voltage exceeding the second voltage and vice versa. Thus, the comparator output may accurately reflect the relationship (comparison) between the two input voltages.

    [0010] In certain embodiments, the follower stage comprises tuning means for adjusting the follower stage output voltage as a function of voltage provided to the follower stage input terminal. Advantageously, this can enable the offset voltages of the two stages to be made very similar, thereby improving accuracy of the comparator output. In certain embodiments the follower stage tuning means comprises a resistor, which may be a variable resistor.

    [0011] Similarly, in certain embodiments, the inverter stage comprises tuning means for adjusting the inverter stage output voltage as a function of voltage provided to the inverter stage input terminal. Again, this tuning means may comprise a resistor, which may be fixed or variable.

    [0012] Certain embodiments further comprise signal conditioning means (e.g. a signal conditioning stage, circuit, or module) coupled between the inverter stage output terminal and the comparator output terminal. This signal conditioning means may convert the inverter output signal (which may be regarded as a "half-digital" signal, to a signal having a wider range (e.g. to a "full-digital" signal, such as a signal alternating between two supply voltages).

    [0013] In certain embodiments, the inverter stage output voltage has a first range, in use, determined by the voltage applied to the first supply rail and by the follower stage output voltage, and the signal conditioning means is adapted to generate, from the inverter stage output voltage, a comparator output voltage at the comparator output terminal having a second range, where the second range is larger than the first range. In certain embodiments the second range extends substantially from a voltage supplied to the first supply rail to a voltage supplied to the second supply rail.

    [0014] In certain embodiments the first supply voltage is a positive supply voltage.

    [0015] In certain embodiments said second supply rail is connected to ground (in other words, said second supply rail may be a ground rail).

    [0016] In certain embodiments the comparator further comprises a voltage converter (e.g. a DC to DC converter) coupled to the first and second supply rails and to the second follower stage supply terminal and arranged to generate a negative supply voltage and supply said negative supply voltage to the second follower stage supply terminal.

    [0017] In certain embodiments the second supply voltage is a negative supply voltage.

    [0018] In certain embodiments the follower stage comprises a transistor. In certain embodiments this transistor is an enhancement mode field effect transistor, FET. In certain embodiments this FET has a gate terminal coupled to the follower stage input terminal, a drain terminal coupled to the first follower stage supply terminal, and a source terminal coupled to the follower stage output terminal and to the second follower stage supply terminal. In certain embodiments the source terminal is coupled to the second follower stage supply terminal by a resistor.

    [0019] In certain embodiments, the inverter stage comprises a transistor. In certain embodiments, this inverter stage transistor is an enhancement mode field effect transistor, FET, but in alternative embodiments different mode FETs may be used (e.g. depletion mode FETs). In certain embodiments, the inverter stage FET has a gate terminal coupled to the inverter stage input terminal, a drain terminal coupled to the first inverter stage supply terminal and to the inverter stage output terminal, and a source terminal coupled to the follower stage output terminal. In certain embodiments, the inverter stage FET drain terminal is coupled to the first inverter stage supply terminal by a resistor.

    [0020] The filtering means may, for example, be a band pass filter. The filtering means may be arranged to filter a range, or band, of frequencies from the output voltage.

    [0021] In certain embodiments, the filtering means is arranged to filter out a band of frequencies, including the fundamental frequency.

    [0022] Another aspect of the invention provides apparatus including a comparator in accordance with any of the above-mentioned aspects or embodiments. For example, in certain embodiments the apparatus is an operational amplifier.

    [0023] As will be appreciated from the following description, in certain embodiments the comparator approach uses N type transistors only, and relies on offsetting the threshold voltages, Vth, of the two input transistors.(linked to e+ and e-). The closer the Vth of those two transistors, the higher the comparator accuracy is. The accuracy is also achieved by keeping the linearity under control over the input range. For a better linearity, a positive and negative voltage can be applied. In certain embodiments, the comparator may utilise different transistors, i.e. transistors, such as P type transistors, other than N type transistors. In certain embodiments, the comparator may comprise transistors of more than one type, for example it may utilise both N and P type transistors.

    BRIEF DESCRIPTION OF THE DRAWINGS



    [0024] Embodiments and examples useful for understanding the invention are further described hereinafter with reference to the accompanying drawings, in which:

    Fig. 1 is a general representation of a comparator;

    Fig. 2 shows a comparator useful for understanding the invention;

    Fig. 3 illustrates a follower stage which may be used in embodiments of the invention;

    Fig. 4 illustrates an inverter stage which may be used in embodiments;

    Fig. 5 shows a signal conditioning stage which may be used in embodiments;

    Figs. 6, 7, and 8 show further comparators useful for understanding the invention; and

    Fig. 9 shows a comparator embodying the invention.


    DETAILED DESCRIPTION



    [0025] Referring now to the figures, Fig 2 is a block diagram of a comparator useful for understanding the invention. The comparator 100 is for comparing a first input voltage e+ with a second input voltage e- and generating a corresponding output voltage. The comparator 100 comprises: a first input terminal 1 for receiving the first input voltage: a second input terminal 2 for receiving the second input voltage; an output terminal 3 for outputting the output voltage; a first supply rail 4 for providing a first supply voltage (VCC); and a second supply rail 5 for providing a second supply voltage. The comparator further comprises: a follower stage 6 comprising a first follower stage supply terminal 61 coupled to the first supply rail 4, a second follower stage supply terminal 62 coupled to the second supply rail 5, a follower stage input terminal 63 coupled to the second input terminal 2, and a follower stage output terminal 64 for providing a follower stage output voltage; and an inverter stage 7 comprising a first inverter stage supply terminal 71 coupled to the first supply rail 4, a second inverter stage supply terminal 72 coupled to the follower stage output terminal 64, an inverter stage input terminal 73 coupled to the first input terminal 1, and an inverter stage output terminal 74 for providing an inverter stage output voltage and coupled to the output terminal 3.In this example the first input terminal 1 is directly connected to the inverter input terminal 73 and is provided with first input voltage (or signal) (e+), and the second input terminal 2 is directly connected to the follower stage input terminal 63 and is provided with second input signal or voltage (e-).

    [0026] A, indicated as 6 in the figure, is a follower stage with its output (e-Ref) equal to (e-) minus the follower stage transistor threshold voltage (Vth_e-). To identify the two Vths of the two transistors (of the follower and inverter stages respectively), we shall call them respectively (Vth_e-) and (Vth_e+)

    [0027] B, indicated as 7 in the figure, is an inverter stage with its reference (i.e. the low supply voltage) being (e-Ref), so its output (e+lnverter) will be triggered when (e+) is higher than (e-Ref) plus its own (Vth_e+).

    [0028] So, B (e+lnverter) is triggered when e+ > (e-Ref) + Vth_e+, where (e-Ref) = (e-) - Vth_e-

    [0029] So (e+lnverter) is triggered when e+ > ((e-) + Vth_e-) - Vth_e+

    [0030] So (e+lnverter) is triggered when e+ > ((e-) + Vth_e-) - Vth_e+, and with everything else being equal, the comparator would trigger when e+ > e-.

    [0031] B's output signal (e+lnverter), is only a "half digital signal", where its high level is close to VCC, but its low level is proportional to e- input, so a signal conditioning and conversion from "half digital signal" to digital is required in certain embodiments. This signal conditioning and conversion to a full digital signal (e.g. alternating between two supply rail voltages) is provided by the signal conditioning module 8 illustrated in fig. 2, coupled between the inverter output terminal 74 and the comparator output terminal 3.

    [0032] Figs. 3 and 4 illustrate example implementations of follower and inverter stages A and B, where tuning the transistors geometry with respective matching of tuning resistors Re- and Re+, labelled 90 and 91 respectively, allows us to increase the comparator accuracy. In other words, the values of the two resistors may be tuned, selected, adjusted, or otherwise arranged to compensate for differences between the threshold voltages of the two enhancement mode FETS 10, 11, such that the resultant comparator output accurately switches in response to e+ exceeding e-, and vice versa. This provides a straightforward way of constructing a highly accurate comparator, without requiring very close matching of transistor properties. In the follower stage of fig. 3, (e-Ref) = (e-) - VGS, and within the operating range VGS = Vth, where VGS is the Gate-Source voltage. In the inverter stage of fig. 4, "e+Inverter" (i.e. the inverter output voltage) is referenced to (e-Ref), and within the operating range VGS = Vth when e+=e-. Tuning resistor 90 in fig. 3 is connected between the source of the FET 10 (which is connected to output terminal 64) and the second supply terminal 62 (which is connected to the second supply rail 5). In certain embodiments, resistor 90 has a fixed value. In other embodiments, resistor 90 is a variable resistor. Tuning resistor 91 in fig. 4 is connected between the drain of the FET 11 (which is connected to output terminal 74) and the first supply terminal 71 (which is connected to the first supply rail 4). In certain embodiments, resistor 91 has a fixed value. In other embodiments, resistor 91 is a variable resistor.

    [0033] Referring now to fig. 5, as described above, B's output signal (e+lnverter), is only a "half digital signal", where its high level is close to VCC, but its low level is proportional to e- input, So a signal conditioning and conversion from "half digital signal" to digital is required. A follower stage 81 is used in the signal conditioning stage 810, which may also be described as a signal conditioner, or signal conditioning circuit or module, to adapt the impedance to impact as little as possible the comparator front stages. Then we convert the "half digital signal" into a digital signal using an analog to digital converter 82 (which may also be described as an A/D stage or A/D means), followed by an inverter 83 to have the correct OUTPUT signal phase. The conversion from "half digital signal" into digital signal may be implemented using traditional sums of subtractions and voltage divisions, the details of which will be apparent to the skilled person and so are not set out in this specification.

    [0034] Fig 6, 7 and 8 illustrate several possible implementations in different examples useful for understanding the invention.

    [0035] In the comparator of fig. 6 only GND and +VCC are provided, and we create the negative signal (VDD) using a DC to DC converter 50 (the details of which will be apparent to be skilled person). This is a standalone device with better accuracy due to better linearity (as the comparator follower and inverter stages are provided with negative and positive supply voltages). Thus, the DC/DC converter has inputs 51, 52 connected to ground (the second supply rail 5 in this example) and to the first supply rail 4 respectively, and generates supply voltage VDD at an output terminal 53 which is connected to the second follower supply terminal 62. In this example, the second follower supply terminal 62 is thus coupled to the second supply rail via the voltage converter 50, which is itself connected to ground and to the first supply rail.

    [0036] Fig 7 illustrates a comparator providing the same accuracy/linearity as the comparator of fig. 6, but requires provision of an external negative voltage, as this example comprises no internal DC to DC converter able to generate a negative voltage from a positive voltage and ground.

    [0037] The comparator of fig. 8 is supplied with only GND and VCC, and does not incorporate a DC to DC converter for generating a negative supply voltage, so exhibits lower accuracy than those of figs. 6 and 7 due to decreased linearity. However, for applications where the comparator of fig. 8 provides sufficient accuracy and/or linearity, it may provide the advantages of greater simplicity/reduced complexity, and reduced cost. Thus, in this example, the second supply rail is a ground rail.

    [0038] Referring now to figure 9, this shows another comparator embodying the invention. This comparator has similar structure to that of the embodiment shown in fig. 2, but also incorporates some additional features, as follows. Generally, this embodiment has two additional parts, labelled C (an oscillator and switching device) and D (a pass band, or band pass, filter). The goal of this embodiment is to avoid potential "Bias Stress" effects, from transistors to comparator. Those potential "Bias Stress" effects are only seen at DC and low frequencies (typically sub 10Hz). Potential "Bias Stress" effects, have a detrimental effect on comparator functionality and accuracy. To address this problem, the present embodiment incorporates a controllable switching device 300, connected between the first follower supply terminal 61 and the first supply rail 4, such that the state of the switching device determines whether the supply voltage VCC is being supplied to the first follower supply terminal or not. Thus, the switch 300 (which may take a variety of forms, as will be apparent to the skilled person, is controllable to turn the voltage supply to the first follower supply terminal on an off (such that the voltage at that terminal alternates between VCC and zero volts, for example). The comparator 100 further comprises control means for controlling the switch 300, in this embodiment in the form an oscillator 30, connected to the positive supply rail 4 and to ground GND. The oscillator is arranged to provide a control signal 301 to the switch to control the switch's state. In this example the control signal is a substantially a square wave, and the switching device 300 is responsive to the control signal 301 to alternate (i.e. switch) between a closed state, in which it connects the supply rail 4 to follower terminal 61, and an open state, it which it disconnects the supply rail from follower terminal 61. The oscillator may have a minimum frequency of a few tens of Hz. By incorporating the oscillator in this manner and switching the device 300 on and off, this has the effect of switching ON/OFF the follower output (e- Ref) of the follower A, 6. This makes sure that, internally, the comparator is always operating in AC (alternating mode), even if inputs e+ and e- are DC. As the internal comparator structure is now operating in AC, there is no more "Bias Stress" effects, from transistors to comparator.

    [0039] The pass band filter 20 is added at the output of the comparator (in fact, in this example, just before the comparator output terminal 3). The filter 20 is thus connected between the inverter output 74 and the comparator output 3. The embodiment of fig. 9 comprises module 8, connected between terminals 74 and 3, in series with the filter 20, but may be omitted in certain alternative embodiments. The band pass filter allows the comparator to get rid of the "unwanted" frequency component, introduced by the oscillator 30 controlling the switching device 300, from the output signal provided to terminal 3. In other words, in certain embodiments to filter is arranged to eliminate frequency components (from the comparator output) corresponding to the switching frequency of the switching device 300.

    [0040] Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of them mean "including but not limited to", and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

    [0041] Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.


    Claims

    1. A comparator (100) for comparing a first input voltage with a second input voltage and generating a corresponding output voltage, the comparator comprising:
    a first input terminal (1) for receiving the first input voltage:

    a second input terminal (2) for receiving the second input voltage;

    an output terminal (3) for outputting the output voltage;

    a first supply rail (4) for providing a first supply voltage; and

    a second supply rail (5) for providing a second supply voltage,

    the comparator further comprising:

    a follower stage (6) comprising a first follower stage supply terminal (61) coupled to the first supply rail, a second follower stage supply terminal (62) coupled to the second supply rail, a follower stage input terminal (63) coupled to the second input terminal, and a follower stage output terminal (64) for providing a follower stage output voltage;

    an inverter stage (7) comprising a first inverter stage supply terminal (71) coupled to the first supply rail, a second inverter stage supply terminal (72) coupled to the follower stage output terminal, an inverter stage input terminal (73) coupled to the first input terminal, and an inverter stage output terminal (74) for providing an inverter stage output voltage and coupled to the output terminal;

    characterized in that the comparator further comprises:

    a controllable switching device (300) arranged to couple the first follower stage supply terminal (61) to the first supply rail (4), the switching device being controllable to switch between a first state, in which it electrically connects the first follower supply terminal to the first supply rail, and a second state, in which it electrically disconnects the first follower supply terminal from the first supply rail;

    control means arranged to control the controllable switching device; and

    filtering means (20) arranged between the inverter stage output terminal (74) and the comparator output terminal (3) to filter at least one frequency component from the output voltage,

    wherein said control means comprises an oscillator (30), having an output arranged to control the switching device (300) to alternate between the first and second states, the oscillator output has a fundamental frequency, and the filtering means (20) is arranged to filter out at least said fundamental frequency.


     
    2. A comparator in accordance with claim 1, wherein the follower stage (6) comprises tuning means for adjusting the follower stage output voltage as a function of voltage provided to the follower stage input terminal.
     
    3. A comparator in accordance with claim 2, wherein the follower stage tuning means comprises a resistor (90).
     
    4. A comparator in accordance with any preceding claim, wherein the inverter stage (7) comprises tuning means for adjusting the inverter stage output voltage as a function of voltage provided to the inverter stage input terminal.
     
    5. A comparator in accordance with claim 4, wherein the inverter stage tuning means comprises a resistor (91).
     
    6. A comparator in accordance with any preceding claim, further comprising signal conditioning means (8) coupled between the inverter stage output terminal and the comparator output terminal.
     
    7. A comparator in accordance with claim 6, wherein the inverter stage output voltage has a first range, in use, determined by the voltage applied to the first supply rail and by the follower stage output voltage, and the signal conditioning means is adapted to generate, from the inverter stage output voltage, a comparator output voltage at the comparator output terminal having a second range, where the second range is larger than the first range.
     
    8. A comparator in accordance with claim 7, wherein said second range extends substantially from a voltage supplied to the first supply rail to a voltage supplied to the second supply rail.
     
    9. A comparator in accordance with any preceding claim wherein the first supply voltage is a positive supply voltage.
     
    10. A comparator in accordance with any preceding claim, wherein said second supply rail is connected to ground.
     
    11. A comparator in accordance with claim 10, further comprising a voltage converter (50) coupled to the first and second supply rails and to the second follower stage supply terminal and arranged to generate a negative supply voltage and supply said negative supply voltage to the second follower stage supply terminal.
     
    12. A comparator in accordance with any one of claims 1 to 9, wherein the second supply voltage is a negative supply voltage.
     
    13. A comparator in accordance with any preceding claim, wherein the follower stage (6) comprises a transistor (10).
     
    14. A comparator in accordance with any preceding claim, wherein the inverter stage (7) comprises a transistor (11).
     
    15. Apparatus including a comparator in accordance with any preceding claim.
     


    Ansprüche

    1. Komparator (100) zum Vergleichen einer ersten Eingangsspannung mit einer zweiten Eingangsspannung und zum Erzeugen einer entsprechenden Ausgangsspannung, wobei der Komparator umfasst:

    einen ersten Eingangsanschluss (1) zum Empfangen der ersten Eingangsspannung;

    einen zweiten Eingangsanschluss (2) zum Empfangen der zweiten Eingangsspannung;

    einen Ausgangsanschluss (3) zum Ausgeben der Ausgangsspannung;

    eine erste Versorgungsschiene (4) zum Bereitstellen einer ersten Versorgungsspannung; und

    eine zweite Versorgungsschiene (5) zum Bereitstellen einer zweiten Versorgungsspannung,

    wobei der Komparator ferner umfasst:

    eine Folgerstufe (6), umfassend einen ersten Folgerstufen-Versorgungsanschluss (61), der an die erste Versorgungsschiene gekoppelt ist, einen zweiten Folgerstufen-Versorgungsanschluss (62), der an die zweite Versorgungsschiene gekoppelt ist, einen Folgerstufen-Eingangsanschluss (63), der an den zweiten Eingangsanschluss gekoppelt ist, und einen Folgerstufen-Ausgangsanschluss (64) zum Bereitstellen einer Folgerstufen-Ausgangsspannung;

    eine Inverterstufe (7), umfassend einen ersten Inverterstufen-Versorgungsanschluss (71), der an die erste Versorgungsschiene gekoppelt ist, einen zweiten Inverterstufen-Versorgungsanschluss (72), der an den Folgerstufen-Ausgangsanschluss gekoppelt ist, einen Inverterstufen-Eingangsanschluss (73), der an den ersten Eingangsanschluss gekoppelt ist, und einen Inverterstufen-Ausgangsanschluss (74) zum Bereitstellen einer Inverterstufen-Ausgangsspannung, der an den Ausgangsanschluss gekoppelt ist;

    dadurch gekennzeichnet, dass der Komparator ferner umfasst:

    eine steuerbare Schaltvorrichtung (300), die dazu angeordnet ist, den ersten Folgerstufen-Versorgungsanschluss (61) an die erste Versorgungsschiene (4) zu koppeln, wobei die Schaltvorrichtung dazu steuerbar ist, zwischen einem ersten Zustand, in dem sie den ersten Folgerstufen-Versorgungsanschluss mit der ersten Versorgungsschiene verbindet, und einem zweiten Zustand, in dem sie den ersten Folgerstufen-Versorgungsanschluss von der ersten Versorgungsschiene elektrisch trennt, zu wechseln;

    ein Steuermittel, das dazu angeordnet ist, die steuerbare Schaltvorrichtung zu steuern; und

    ein Filtermittel (20), das zwischen dem Inverterstufen-Ausgangsanschluss (74) und dem Komparator-Ausgangsanschluss (3) angeordnet ist, um mindestens eine Frequenzkomponente aus der Ausgangsspannung zu filtern,

    wobei das Steuermittel einen Oszillator (30) umfasst, der einen Ausgang aufweist, der dazu angeordnet ist, die Schaltvorrichtung (300) so zu steuern, dass sie zwischen dem ersten und dem zweiten Zustand wechselt, der Oszillatorausgang eine Grundfrequenz aufweist und das Filtermittel (20) dazu angeordnet ist, mindestens die Grundfrequenz herauszufiltern.


     
    2. Komparator nach Anspruch 1, wobei die Folgerstufe (6) Abstimmmittel zum Einstellen der Folgerstufen-Ausgangsspannung als Funktion der dem Folgerstufen-Eingangsanschluss bereitgestellten Spannung umfasst.
     
    3. Komparator nach Anspruch 2, wobei das Folgerstufen-Abstimmmittel einen Widerstand (90) umfasst.
     
    4. Komparator nach einem der vorhergehenden Ansprüche, wobei die Inverterstufe (7) Abstimmmittel zum Einstellen der Inverterstufen-Ausgangsspannung als Funktion der dem Inverterstufen-Eingangsanschluss bereitgestellten Spannung umfasst.
     
    5. Komparator nach Anspruch 4, wobei das Inverterstufen-Abstimmmittel einen Widerstand (91) umfasst.
     
    6. Komparator nach einem der vorhergehenden Ansprüche, ferner umfassend ein Signalkonditionierungsmittel (8), das zwischen dem Inverterstufen-Ausgangsanschluss und dem Komparator-Ausgangsanschluss gekoppelt ist.
     
    7. Komparator nach Anspruch 6, wobei die Inverterstufen-Ausgangsspannung in Verwendung einen ersten Bereich aufweist, der durch die an die erste Versorgungsschiene angelegte Spannung und durch die Folgerstufen-Ausgangsspannung bestimmt wird, und das Signalkonditionierungsmittel dazu angepasst ist, aus der Inverterstufen-Ausgangsspannung eine Komparator-Ausgangsspannung an dem Komparator-Ausgangsanschluss zu erzeugen, die einen zweiten Bereich aufweist, wobei der zweite Bereich größer als der erste Bereich ist.
     
    8. Komparator nach Anspruch 7, wobei sich der zweite Bereich im Wesentlichen von einer der ersten Versorgungsschiene zugeführten Spannung zu einer der zweiten Versorgungsschiene zugeführten Spannung erstreckt.
     
    9. Komparator nach einem der vorhergehenden Ansprüche, wobei die erste Versorgungsspannung eine positive Versorgungsspannung ist.
     
    10. Komparator nach einem der vorhergehenden Ansprüche, wobei die zweite Versorgungsschiene mit Masse verbunden ist.
     
    11. Komparator nach Anspruch 10, ferner umfassend einen Spannungswandler (50), der mit der ersten und der zweiten Versorgungsschiene und dem zweiten Folgerstufen-Versorgungsanschluss gekoppelt und dazu angeordnet ist, eine negative Versorgungsspannung zu erzeugen und die negative Versorgungsspannung dem zweiten Folgerstufen-Versorgungsanschluss zuzuführen.
     
    12. Komparator nach einem der Ansprüche 1 bis 9, wobei die zweite Versorgungsspannung eine negative Versorgungsspannung ist.
     
    13. Komparator nach einem der vorhergehenden Ansprüche, wobei die Folgerstufe (6) einen Transistor (10) umfasst.
     
    14. Komparator nach einem der vorhergehenden Ansprüche, wobei die Inverterstufe (7) einen Transistor (11) umfasst.
     
    15. Vorrichtung, die einen Komparator nach einem der vorhergehenden Ansprüche beinhaltet.
     


    Revendications

    1. Comparateur (100) permettant de comparer une première tension d'entrée à une seconde tension d'entrée et générer une tension de sortie correspondante, le comparateur comprenant:

    une première borne d'entrée (1) pour recevoir la première tension d'entrée ;

    une seconde borne d'entrée (2) pour recevoir la seconde tension d'entrée ;

    une borne de sortie (3) pour délivrer la tension de sortie ;

    un premier rail d'alimentation (4) pour fournir une première tension d'alimentation ; et

    un second rail d'alimentation (5) pour fournir une seconde tension d'alimentation,

    le comparateur comprenant en outre :

    un étage suiveur (6) comprenant une première borne d'alimentation d'étage suiveur (61) couplée au premier rail d'alimentation, une seconde borne d'alimentation d'étage suiveur (62) couplée au second rail d'alimentation, une borne d'entrée d'étage suiveur (63) couplée à la seconde borne d'entrée et une borne de sortie d'étage suiveur (64) pour fournir une tension de sortie d'étage suiveur ;

    un étage inverseur (7) comprenant une première borne d'alimentation d'étage inverseur (71) couplée au premier rail d'alimentation, une seconde borne d'alimentation d'étage inverseur (72) couplée à la borne de sortie d'étage suiveur, une borne d'entrée d'étage inverseur (73) couplée à la première borne d'entrée, et une borne de sortie d'étage inverseur (74) pour fournir une tension de sortie d'étage inverseur et couplée à la borne de sortie ; caractérisé en ce que le comparateur comprend en outre :
    un dispositif de commutation commandable (300) agencé pour coupler la première borne d'alimentation d'étage suiveur (61) au premier rail d'alimentation (4), le dispositif de commutation étant commandable pour commuter entre un premier état, dans lequel il branche électriquement la première borne d'alimentation de suiveur au premier rail d'alimentation, et un second état, dans lequel il débranche électriquement la première borne d'alimentation de suiveur du premier rail d'alimentation ; un moyen de commande conçu pour commander le dispositif de commutation commandable ; et un moyen de filtrage (20) disposés entre la borne de sortie d'étage inverseur (74) et la borne de sortie de comparateur (3) pour filtrer au moins une composante de fréquence de la tension de sortie, ledit moyen de commande comprenant un oscillateur (30), qui comporte une sortie conçue pour commander le dispositif de commutation (300) pour alterner entre les premier et second états, la sortie d'oscillateur présentant une fréquence fondamentale, et le moyen de filtrage (20) étant conçu pour filtrer au moins ladite fréquence fondamentale.


     
    2. Comparateur selon la revendication 1, ledit étage suiveur (6) comprenant un moyen de réglage pour ajuster la tension de sortie d'étage suiveur en fonction de la tension délivrée à la borne d'entrée d'étage suiveur.
     
    3. Comparateur selon la revendication 2, ledit moyen de réglage d'étage suiveur comprenant une résistance (90).
     
    4. Comparateur selon l'une quelconque des revendications précédentes, ledit étage inverseur (7) comprenant un moyen de réglage pour ajuster la tension de sortie d'étage inverseur en fonction de la tension délivrée à la borne d'entrée d'étage inverseur.
     
    5. Comparateur selon la revendication 4, ledit moyen de réglage d'étage inverseur comprenant une résistance (91).
     
    6. Comparateur selon l'une quelconque des revendications précédentes, comprenant en outre un moyen de conditionnement de signal (8) couplé entre la borne de sortie d'étage inverseur et la borne de sortie de comparateur.
     
    7. Comparateur selon la revendication 6, ladite tension de sortie d'étage inverseur présentant une première plage, lors de l'utilisation, déterminée par la tension appliquée au premier rail d'alimentation et par la tension de sortie d'étage suiveur, et ledit moyen de conditionnement de signal étant conçu pour générer, à partir de la tension de sortie d'étage inverseur, une tension de sortie de comparateur au niveau de la borne de sortie de comparateur présentant une seconde plage, la seconde plage étant plus grande que la première plage.
     
    8. Comparateur selon la revendication 7, ladite seconde plage s'étendant sensiblement d'une tension délivrée au premier rail d'alimentation à une tension délivrée au second rail d'alimentation.
     
    9. Comparateur selon l'une quelconque des revendications précédentes, ladite première tension d'alimentation étant une tension d'alimentation positive.
     
    10. Comparateur selon l'une quelconque des revendications précédentes, ledit second rail d'alimentation étant relié à la masse.
     
    11. Comparateur selon la revendication 10, comprenant en outre un convertisseur de tension (50) couplé aux premier et second rails d'alimentation et à la seconde borne d'alimentation d'étage suiveur et conçu pour générer une tension d'alimentation négative et délivrer ladite tension d'alimentation négative à la seconde borne d'alimentation d'étage suiveur.
     
    12. Comparateur selon l'une quelconque des revendications 1 à 9, ladite seconde tension d'alimentation étant une tension d'alimentation négative.
     
    13. Comparateur selon l'une quelconque des revendications précédentes, ledit étage suiveur (6) comprenant un transistor (10).
     
    14. Comparateur selon l'une quelconque des revendications précédentes, ledit étage inverseur (7) comprenant un transistor (11).
     
    15. Appareil comprenant un comparateur selon l'une quelconque des revendications précédentes.
     




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    Cited references

    REFERENCES CITED IN THE DESCRIPTION



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    Patent documents cited in the description