Adjustable electronic duplexer

• US 20030174763A1
• Filed: 12/09/2002
• Published: 09/18/2003
• Est. Priority Date: 12/07/2001
• Status: Active Grant

• Current Assignee: Ecole de technologie superieure
• Original Assignee: Ecole de technologie superieure
• Inventors: Kouki, Ammar B.
• Granted Patent: US 7,330,500 B2
• Time in Patent Office: Days
• US Class Current: 375/219
• CPC Class Codes: H04B 1/525 with means for reducing leakage of transmitter signal into the receiver

Abstract

A duplexer for a communication device having a transmission unit, a reception unit and a shared antenna. The shared antenna transmits a portion of a transmission signal provided by the transmission unit and receiving a reception signal. The duplexer generates a leakage signal from the transmission unit toward the reception unit. The leakage signal being added to the reception signal. The duplexer comprises a first signal path between the transmission unit and the reception unit. The first signal path comprises a filter unit filtering the reception signal. The filtering unit provides a filtered signal to the reception unit. The duplexer further comprises a second signal path between the transmission unit and the reception unit. The second signal path comprises a cancellation unit which receives a sample of the transmission signal and produces a compensation signal. The injection of the compensation signal to the first signal path substantially reduces the leakage signal, thereby producing a substantially leakage-free reception signal.

Claims

1. A duplexer for a communication device having a transmission unit, a reception unit and a shared antenna, the shared antenna transmitting a portion of a transmission signal provided by the transmission unit and receiving a reception signal, said duplexer generating a leakage signal from the transmission unit toward the reception unit, said leakage signal being added to the reception signal, the duplexer comprising:

a. a first signal path between said transmission unit and said reception unit, said first signal path comprising a filter unit filtering the reception signal, the filtering unit providing a filtered signal to the reception unit; and

b. a second signal path between said transmission unit and said reception unit, said second signal path comprising a cancellation unit receiving a sample of the transmission signal and producing a compensation signal;

whereby an injection of the compensation signal to the first signal path substantially reduces the leakage signal, thereby producing a substantially leakage-free reception signal.

2. The duplexer according to claim 1, wherein said cancellation unit comprises:

a. an attenuator for attenuating the sample of the transmission signal to an amplitude substantially equal to the amplitude of said leakage signal; and

b. a phase-converter for shifting the phase of the transmission signal substantially 180-degree relative to the phase of the leakage signal.

3. The duplexer according to claim 1, further comprising a first coupling unit at a juncture between said first and second signal paths for providing said injection of the compensation signal to the first signal path.

4. The duplexer according to claim 3, wherein said first coupling unit is located downstream from said filter unit.

5. The duplexer according to claim 4, wherein said cancellation unit comprises:

a. an attenuator for attenuating the sample of the transmission signal to an amplitude substantially equal to the amplitude of said leakage signal; and

b. a phase-converter for shifting the phase of the transmission signal substantially 180-degree relative to the phase of the leakage signal.

6. The duplexer according to claim 5, further comprising a second coupling unit at a juncture between said first and second signal paths for providing said sample of the transmission signal to said compensation unit.

7. The duplexer according to claim 6, wherein said filtering unit comprises a band-pass filter.

8. The duplexer according to claim 7, wherein said filtering unit comprises a YIG filter.

9. The duplexer according to claim 6, wherein said filtering unit comprises a filter having poor filtering characteristics.

10. The duplexer according to claim 6, wherein the attenuation of said attenuator and the shifting of said phase-converter are variable according to a control voltage.

11. The duplexer according to claim 10, further comprising a third signal path between said first signal path and said compensation unit, said third signal path comprising a control unit receiving a sample of the substantially leakage-free reception signal and producing said control voltage for input to said compensation unit.

12. The duplexer according to claim 11 wherein said filtering unit comprises a band-pass filter.

13. The duplexer according to claim 12, wherein said filtering unit comprises a YIG filter.

14. The duplexer according to claim 11, wherein said filtering unit comprises a filter having poor filtering characteristics.

15. In a telecommunication unit having a shared antenna, a transmission unit and a reception unit, a method for canceling the interference generated by said transmission unit in said reception unit, said interference caused by a leakage signal from the transmission unit toward the reception unit, said leakage signal being added to the reception signal, the method comprising:

a. acquiring a sample of a transmission signal provided by the transmission unit;

b. computing a compensation signal having an amplitude substantially equal to the amplitude of the leakage signal received by the reception unit and a phase substantially 180-degree shifted from the phase of the leakage signal received by the reception unit; and

c. injecting the compensation signal in the reception unit for substantially reducing the leakage signal, thereby producing a substantially leakage-free reception signal.

16. The method of claim 15, further comprising controlling the amplitude and phase-shift of the compensation signal in accordance with a control voltage which is a function of said substantially leakage-free reception signal.

17. The method of claim 15, further comprising filtering said reception signal with a filter having poor filtering characteristics.

18. In a telecommunication unit having a shared antenna, a transmission unit and a reception unit, a method for transmitting a portion of a first signal provided by said transmission unit and receiving a second signal using said reception unit, said transmission unit generating a leakage signal from the transmission unit toward the reception unit, said leakage signal being added to the second signal, the method comprising:

a. transmitting the portion of the first signal provided by the transmission unit;

b. acquiring a sample of the first signal provided by the transmission unit;

c. computing a compensation signal having an amplitude substantially equal to the amplitude of the leakage signal received by the reception unit and a phase substantially 180-degree shifted from the phase of the leakage signal received by the reception unit;

d. receiving the second signal; and

e. injecting the compensation signal into the second signal for substantially reducing the leakage signal, thereby producing a substantially leakage-free reception signal.

19. The method of claim 18, further comprising controlling the amplitude and phase-shift of the compensation signal in accordance with a control voltage which is a function of said substantially leakage-free reception signal.

20. The method of claim 18, further comprising filtering said reception signal with a filter having poor filtering characteristics.