Transmission-reception separating filter with a PIN diode

• US 5,230,090 A
• Filed: 04/29/1991
• Issued: 07/20/1993
• Est. Priority Date: 05/23/1990
• Status: Expired due to Term

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Vester, Markus, Zametzer, Klaus
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): FAILE, ANDREW I
• Application Number:
  US07/692,691
• Time in Patent Office: 813 Days
• Field of Search: 455/78, 455/79, 455/80, 455/82, 455/83, 333/101, 333/103, 333/126, 333/129, 333/132, 307/259
• US Class Current: 455/80
• CPC Class Codes: G01R 33/3657 Decoupling of multiple RF coils wherein the multiple RF coils do not have the same function in MR, e.g. decoupling of a transmission coil from a receive coil
• CPC Class Codes: H04B 1/46 by voice-frequency signals; by pilot signals

Abstract

Transmission-Reception Separating Filter with a PIN diode. A PIN diode is arranged in the transmission channel of the transmission-reception separating filter that has the transmission channel for forwarding a high-frequency current from a transmitter to an antenna. A rectifier is provided that generates a control current for the PIN diode from the high-frequency current flowing in the transmission channel. As a result, a separate power supply is not required for controlling the PIN diode in the transmission channel.

Claims

1. A transmission-reception separating filter having a transmission channel for forwarding a high-frequency current from a transmitter to an antenna, at least one PIN diode being i the transmission channel, comprising:

at least one rectifier operationally connected to the at least one PIN diode that generates a control current for the at least one PIN diode from the high-frequency current flowing in the transmission channel; and

the rectifier having a rectifier part having a rectifier diode that is connected in a reverse direction relative to the at least one PIN diode, the rectifier diode having a carrier life span that is significantly shorter than a carrier life span of the at least one PIN diode.

2. The transmission-reception separating filter according to claim 1, wherein the transmission channel has a capacitor, said capacitor preventing the control current from flowing to the transmitter.

3. The transmission-reception separating filter according to claim 1, wherein an inductor is connected in series with the rectifier diode, whereby the series circuit of the rectifier diode and the inductor is connected in parallel to the at least one PIN diode.

4. The transmission-reception separating filter according to claim 3, wherein the inductor is bridged with an attenuating resistor.

5. The transmission-reception separating filter according to claim 1, wherein a plurality of PIN diodes are connected in a cascade circuit in the transmission channel, the plurality of PIN diodes being connected to one another via short line sections, at least one of the short line sections having a capacitance at a highest operating frequency of the high-frequency current that is significantly greater than a blocking capacitance of the PIN diodes, and wherein a rectifier is connected across each PIN diode in a reverse direction relative to the respective PIN diode.

6. The transmission-reception separating filter according to claim 5, wherein the plurality of PIN diodes comprise three PIN diodes that are connected in series.

7. The transmission-reception separating filter according to claim 1, wherein said separating filter is connected in a medical nuclear magnetic resonance apparatus.

8. A transmission-reception separating filter for use with at least a transmitter and an antenna, comprising:

a transmission channel connected between the transmitter and the antenna for forwarding a high-frequency current from the transmitter to the antenna, the high-frequency current being provided by the transmitter;

at least one PIN diode in said transmission channel;

at least one rectifier means having at least a rectifier diode connected in parallel to said at least one PIN diode, the rectifier diode connected in a reverse direction relative to said at least one PIN diode for generating a control current for the at least one PIN diode from the high-frequency current flowing in the transmission channel;

wherein the control current is generated only when the transmitter provides the high-frequency current and therefore the at least one PIN diode only being conductive when the high-frequency current flows in the transmission channel.

9. The transmission-reception separating filter according to claim 8, wherein the transmission channel has at least one capacitor, said capacitor preventing the control current from flowing to the transmitter.

10. The transmission-reception separating filter according to claim 8, wherein the rectifier diode has a carrier life span that is significantly shorter than a carrier life span of the PIN diode.

11. The transmission-reception separating filter according to claim 10, wherein an inductor is connected in series with the rectifier diode, whereby the series circuit of the rectifier diode and the inductor is connected in parallel to the PIN diode.

12. The transmission-reception separating filter according to claim 11, wherein the inductor is bridged with an attenuating resistor.

13. The transmission-reception separating filter according to claim 8, wherein the transmission reception separating filter has a plurality of rectifiers and has a plurality of PIN diodes that are connected in a cascade circuit in the transmission channel, the plurality of PIN diodes being connected to on another via short line sections, at least one of the short line sections having a capacitance at a highest operating frequency of the high-frequency current that is significantly greater than a blocking capacitance of the PIN diodes, and wherein a respective rectifier is connected across a respective PIN diode in a reverse direction relative to the respective PIN diode.

14. The transmission-reception separating filter according to claim 13, wherein three PIN diodes are connected in series.

18. The transmission-reception separating filter according to claim 13 wherein in each threshold means an inductor is connected in series with the rectifier diode, whereby each series circuit of the rectifier diode and the inductor is connected in parallel to the respective PIN diode.

19. The transmission-reception separating filter according to claim 18, wherein each inductor is bridged with a respective attenuating resistor.

15. A transmission-reception separating filter for use with a transmitter and an antenna, comprising:

a transmission channel connected between the transmitter and the antenna, for forwarding a high-frequency current form the transmitter to the antenna, the high-frequency current being provided by the transmitter;

a plurality of threshold means connected in series in said transmission channel for establishing a connection between the transmitter and the antenna only when the high-frequency current flows in the transmission channel;

each of said threshold means having at least a PIN diode and a rectifier diode, said rectifier diode connected across the PIN diode in a reverse direction relative to the PIN diode, the rectifier diode generating a control current for the PIN diode from the high-frequency current flowing in the transmission channel;

at least one line section for interconnecting the plurality of threshold means to one another;

wherein the control current is generated only when the transmitter provides the high-frequency current and therefore each of the PIN diodes only being conductive when the high-frequency current flows in the transmission channel.

16. The transmission-reception separating filter according to claim 15, wherein the transmission channel has at least one capacitor, said capacitor preventing the control current from flowing to the transmitter.

17. The transmission-reception separating filter according to claim 15, wherein each rectifier diode has a carrier life span that is significantly shorter than a carrier life span of the respective PIN diode.

20. The transmission-reception separating filter according to claim 15, wherein the at least one short line section has a capacitance at a highest operating frequency of the high-frequency current that is significantly greater than a blocking capacitance of the PIN diodes.

21. The transmission-reception separating filter according to claim 15, wherein a last threshold means of the plurality of threshold means that is connected to the antenna is connected in the transmission channel in an opposite direction relative to the other threshold means in the transmission channel.

22. The transmission-reception separating filter according to claim 21, wherein the other threshold means have their respective PIN diodes connected in a forward direction relative to the high-frequency current flowing from the transmitter to the receiver, and wherein the last threshold means has its respective PIN diode connected in a reverse direction relative to the high-frequency current flowing from the transmitter to the receiver.