EP 0724308 A3 19981014 - Antenna arrangement
Title (en)
Antenna arrangement
Title (de)
Antennenanordnung
Title (fr)
Agencement d'antenne
Publication
Application
Priority
US 36564494 A 19941229
Abstract (en)
[origin: EP0724308A2] A novel multiplex system is disclosed which overcomes the disadvantage of a parasitic diode which occurs upon use of MOS FET switches to switch between channels. A preferred embodiment of the invention is effected by connecting the power MOS FET 18,20 to the antenna 10,12 via a serially connected capacitor 14,16. Thus, in a disabled channel, the serially connected capacitor 14 may be charged up to the peak positive D.C. voltage of the antenna resonator circuit 24 of the enabled channel, via the parasitic diode. The capacitor 14 in the disabled channel is charged via the parasitic diode while a different transmit channel has been selected and when the antenna resonator 24 of that different channel, builds up the antenna resonance voltage. Once the voltage at the antenna resonator 24 is at the maximum, the capacitor 14 in the disabled channel is also charged up to the maximum voltage and therefore, the antenna resonance voltage of the enabled channel minus the stored voltage of the disabled channel capacitor 14 will never be less than zero. In conclusion, because the drain of the FET is held to a positive voltage, and the parasitic diode needs a negative voltage to conduct, the parasitic voltage stops conducting and will not conduct while the capacitor is charged to that positive voltage. Therefore, the FET is blocked to negative voltages. The disabled MOS FET 18 is also blocked for positive voltages because that is the basic function of the MOS FET switch 18. The parasitic diode is not conducting in this situation, because the diode is reversed biased in this case and therefore needs a negative voltage to conduct. <IMAGE>
IPC 1-7
IPC 8 full level
G01S 13/74 (2006.01); H01Q 3/24 (2006.01); H03K 19/0175 (2006.01); H04B 1/04 (2006.01)
CPC (source: EP)
H01Q 3/24 (2013.01)
Citation (search report)
- [X] US 4987392 A 19910122 - CLARK EDWARD T [US], et al
- [X] GB 2279212 A 19941221 - OKI ELECTRIC IND CO LTD [JP]
- [EL] EP 0740262 A2 19961030 - TEXAS INSTRUMENTS DEUTSCHLAND [DE]
- [PX] US 5465411 A 19951107 - KOIKE YUKINAGA [JP]
- [X] EP 0496610 A2 19920729 - TEXAS INSTRUMENTS HOLLAND [NL]
- [A] EP 0301127 A1 19890201 - TEXAS INSTRUMENTS DEUTSCHLAND [DE]
- [A] US 4857893 A 19890815 - CARROLL GARY T [US]
- [A] MOTOKI HIRANO ET AL: "KEYLESS ENTRY SYSTEM WITH RADIO CARD TRANSPONDER", IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, vol. 35, no. 2, 1 May 1988 (1988-05-01), pages 208 - 216, XP000096890
- [A] MIYATSUJI K ET AL: "A GAAS HIGH-POWER RF SINGLE-POLE DOUBLE-THROW SWITCH IC FOR DIGITALMOBILE COMMUNICATION SYSTEM", IEEE INTERNATIONAL SOLID STATE CIRCUITS CONFERENCE, vol. 37, 1 February 1994 (1994-02-01), pages 34/35, 305, XP000507050
Designated contracting state (EPC)
DE FR GB IT NL
DOCDB simple family (publication)
EP 0724308 A2 19960731; EP 0724308 A3 19981014; JP H08320376 A 19961203
DOCDB simple family (application)
EP 95120130 A 19951220; JP 34154695 A 19951227