TDD receiver protection

• US 20070218852A1
• Filed: 02/02/2007
• Published: 09/20/2007
• Est. Priority Date: 03/15/2006
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Navini Networks, Inc. (Cisco Systems, Inc.)
• Inventors: Huynh, Viet
• Granted Patent: US 8,099,061 B2
• Time in Patent Office: Days
• US Class Current: 455/217
• CPC Class Codes: H04B 1/18 Input circuits, e.g. for coupling to an antenna or a transmission line coupling networks between antennas or lines and receivers independent of the nature of the receiver H03H
• CPC Class Codes: H04B 1/54 using the same frequency for two directions of communication H04B1/44 takes precedence

Abstract

A receiver protection circuit in a time-division duplex (TDD) system is disclosed, which comprises a first diode with an anode coupled to an input of a low-noise-amplifier (LNA) and a cathode coupled to a ground (GND), a controller coupled to the anode of the diode and configured to generate a first control signal for turning on the diode when the TDD system is in a transmission mode, and a load coupled to the diode, wherein a reflected transmit signal is shorted to the GND by the diode and the radio frequency (RF) energy carried in the reflected transmit signal is consumed by the load.

Claims

1. A receiver protection circuit in a time-division duplex (TDD) system, the receiver protection circuit comprising:

a first diode with an anode coupled to an input of a first low-noise-amplifier (LNA) and a cathode coupled to a ground (GND);

a first controller coupled to the anode of the first diode and configured to generate a first control signal for turning on the first diode when the TDD system is in a transmission mode; and

a load coupled to the diode,

wherein a reflected transmit signal is shorted to the GND by the diode and the radio frequency (RF) energy carried in the reflected transmit signal is consumed by the load.

2. The receiver protection circuit of claim 1, wherein the first diode is a p-type, intrinsic, n-type (PIN) diode.

3. The receiver protection circuit of claim 1, wherein the load is a resistive load.

4. The receiver protection circuit of claim 1 further comprising a RF choke coupled on a conduction path that carries the first control signal.

5. The receiver protection circuit of claim 1 further comprising a hybrid coupler coupled between a circulator and the first LNA.

6. The receiver protection circuit of claim 5, wherein the hybrid coupler has a 3 dB attenuation and 90°

phase shift.

7. The receiver protection circuit of claim 5 further comprising:

a second LNA coupled to the hybrid coupler in balance with the first LNA;

a second diode coupled to an input of the second LNA,

wherein the second diode is also turned on during the transmission mode by a second control signal.

8. The receiver protection circuit of claim 7, wherein the second control signal is generated either by a second controller or the first controller.

9. A receiver protection circuit in a time-division duplex (TDD) system, the receiver protection circuit comprising:

a first diode with an anode coupled to an input of a first low-noise-amplifier (LNA) and a cathode coupled to a ground (GND);

a first controller coupled to the anode of the first diode and configured to generate a first control signal for turning on the first diode when the TDD system is in a transmission mode;

a hybrid coupler coupled between a circulator and the first LNA; and

a load coupled to the diode through the hybrid couple,

wherein a reflected transmit signal is shorted to the GND by the diode and the radio frequency (RF) energy carried in the reflected transmit signal is consumed by the load.

10. The receiver protection circuit of claim 9, wherein the first diode is a p-type, intrinsic, n-type (PIN) diode.

11. The receiver protection circuit of claim 9, wherein the load is a resistive load.

12. The receiver protection circuit of claim 9, wherein the hybrid coupler has a 3 dB attenuation and 90°

phase shift.

13. The receiver protection circuit of claim 9 further comprising a RF choke coupled on a conduction path that carries the first control signal.

14. The receiver protection circuit of claim 9 further comprising

a second LNA coupled to the hybrid coupler in balance with the first LNA;

a second diode coupled to an input of the second LNA,

wherein the second diode is also turned on during the transmission mode by a second control signal.

15. The receiver protection circuit of claim 14, wherein the second control signal is generated either by a second controller or the first controller.

16. A receiver protection circuit in a time-division duplex (TDD) system, the receiver protection circuit comprising:

a hybrid coupler receiving one or more signals from a circulator;

a first and second low-noise-amplifiers (LNA) balanced to each other both coupled to the hybrid coupler;

a first diode with an anode coupled to an input of the first LNA and a cathode coupled to a ground (GND);

a second diode with anode coupled to an input of the second LNA and a cathode coupled to the GND;

at least one controller coupled to the anodes of both the first and second diodes and configured to generate a control signal for turning on both the first and second diodes when the TDD system is in a transmission mode; and

a load coupled to the hybrid coupler,

wherein a reflected transmit signal is shorted to the GND by the first and second diodes and the radio frequency (RF) energy carried in the reflected transmit signal is consumed by the load.

17. The receiver protection circuit of claim 16, wherein both the first and second diodes are p-type, intrinsic, n-type (PIN) diodes.

18. The receiver protection circuit of claim 16, wherein the load is a resistive load.

19. The receiver protection circuit of claim 16 further comprising a RF choke coupled on a conduction path that carries the first control signal.

20. The receiver protection circuit of claim 16, wherein the hybrid coupler has a 3 dB attenuation and 90°

phase shift.