Adjustable electronic duplexer

• US 7,330,500 B2
• Filed: 12/09/2002
• Issued: 02/12/2008
• Est. Priority Date: 12/07/2001
• Status: Expired due to Fees

• Current Assignee: Ecole de technologie superieure
• Original Assignee: Socovar S.E.C.
• Inventors: Kouki, Ammar B.
• Primary Examiner(s): Payne; David C.
• Assistant Examiner(s): DSOUZA, JOSEPH FRANCIS A
• Application Number:
  US10/314,414
• Publication Number:
  US 20030174763A1
• Time in Patent Office: 1,891 Days
• Field of Search: 330/151, 343/895, 455/22, 455/63.1, 455/78, 455/84, 455/296, 455/570, 375/247
• 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 is disclosed. 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 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 duplexer comprising:

a transmitter port adapted to receive a transmission signal from the transmission unit;

a receiver port adapted to transmit a reception signal to the reception unit;

an antenna port adapted to transmit the transmission signal to the shared antenna and receive the reception signal from the shared antenna;

a first signal path between said transmitter port and said receiver port;

a filter unit in said first signal path for filtering said reception signal, said filter unit causing a leakage signal to occur between said transmitter port and said receiver port;

a second signal path between said transmitter port and said receiver port; and

a cancellation unit in said second signal path adapted to receive a sample of the transmission signal and produce a compensation signal that is injected into the first signal path to substantially reduce the leakage 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 injecting 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 the attenuation of said attenuator and the shifting of said phase-converter are variable according to a control voltage.

10. The duplexer according to claim 9, 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 a substantially leakage-free reception signal and producing said control voltage for input to said compensation unit.

11. The duplexer according to claim 10, wherein said filtering unit comprises a band-pass filter.

12. The duplexer according to claim 11, wherein said filtering unit comprises a YIG filter.

13. A method for interfacing a transmission unit, a reception unit and a shared antenna within a duplexer, the method comprising:

receiving at a transmitter port a transmission signal from said transmission unit;

transmitting said transmission signal to said shared antenna via an antenna port;

receiving a reception signal from said shared antenna via said antenna port;

filtering said reception signal in a first signal path between said transmitter port and a receiver port, said filtering causing a leakage signal to occur between said transmitter port and said receiver port;

sampling said transmission signal and computing a compensation signal having an amplitude substantially equal to the amplitude of said leakage signal and a phase substantially 180-degree shifted from the phase of the leakage signal; and

injecting said compensation signal into said first signal path to be added to said reception signal and thereby substantially reduce said leakage signal.

14. The method of claim 13, further comprising controlling the amplitude and phase-shift of the compensation signal in accordance with a control voltage which is a function of a substantially leakage-free reception signal.