ELECTRONICALLY TUNABLE ACTIVE DUPLEXER

• US 20070247257A1
• Filed: 04/23/2007
• Published: 10/25/2007
• Est. Priority Date: 04/24/2006
• Status: Active Grant

• Current Assignee: Balamurugan Sundaram, Prasad Shastry
• Original Assignee: Bradley University
• Inventors: Sundaram, Balamurugan, Shastry, Prasad
• Granted Patent: US 7,576,627 B2
• Time in Patent Office: Days
• US Class Current: 333/132
• CPC Class Codes: H03F 1/56 Modifications of input or output impedances, not otherwise provided for
• CPC Class Codes: H03F 2200/451 the amplifier being a radio frequency amplifier
• CPC Class Codes: H03F 3/193 with field-effect devices H03F3/195 takes precedence
• CPC Class Codes: H03F 3/195 in integrated circuits
• CPC Class Codes: H03F 3/24 of transmitter output stages
• CPC Class Codes: H03F 3/605 Distributed amplifiers
• CPC Class Codes: H03H 11/344 Duplexers

Abstract

This invention provides a novel electronically tunable active duplexer for wireless transceiver applications. It relates to an active duplexer with full-duplex operation, permitting simultaneous transmission and reception of signals at same or different frequencies. It incorporates varactors, instead of fixed or mechanically adjustable capacitors, in phase shifting networks enabling one to electronically tune, with ease and precision, the frequency at which isolation is desired, over a band in both transmit and receive modes of operations. It can be implemented as a Monolithic Microwave Integrated Circuit (MMIC).

Claims

1. A duplexer comprising a first port, a second port, a third port, a fourth port, at least two distributed amplifier (DA) gain cells, and at least one tunable phase shifting network (TPSN) between and connecting the DA cells, wherein the TPSN comprises one or more tunable capacitors.

2. The duplexer of claim 1, wherein the duplexer is electronically tunable.

3. The duplexer of claim 1 or claim 2, wherein the one or more tunable capacitors are one or more varactors.

4. The duplexer of claim 3, wherein each DA cell comprises at least one signal amplifying device, resistor, inductor and capacitor.

5. The duplexer of claim 4, wherein each DA cell comprises a field effect transistor (FET) and gate and drain line inductors.

6. The duplexer of claim 5, wherein the FET is a gallium arsenide metal semiconductor field effect transistor (GaAsMESFET).

7. The duplexer of any one of claims 1-6, further comprising a receiver (R) bandpass filter connected to the third port or to the fourth port.

8. The duplexer of any one of claims 1-7, further comprising a transmission (T) bandpass filter connected to the first port or to the second port.

9. The duplexer of anyone of claims 1-8, wherein an antenna is connected to the fourth port and the second port is terminated.

10. The duplexer of claims 1-8, wherein an antenna is connected to the second port and the fourth port is terminated.

11. The duplexer of claims 1-8, wherein an antenna is connected to both the second and fourth ports.

12. The duplexer of claim 4 wherein the one or more inductor and the one or more capacitor are lumped elements.

13. The duplexer of claim 4 wherein the one or more inductor and the one or more capacitor are transmission lines.

14. An electronically tunable active duplexer comprising (a) a first port, (b) a second port, (c) a third port, (d) a fourth port, (e) two distributed amplifier gain (DA) cells, each of which comprises a gallium arsenide metal semiconductor field effect transistor (GaAsMESFET) and gate and drain line inductors, (f) a tunable phase shifting network (TPSN), which comprises at least one varactor and is located between and connecting the DA cells.

15. The electronically tunable active duplexer of claim 14 comprising a copper clad circuit board, series inductors of high impedance microstripelines, fixed shunt capacitors of low impedance microstripelines, and three varactors having a tunable capacitance range from about 0.63 pF to about 2.67 pF and operating in the frequency range of 1.58 to 1.88 GHz.

16. An electronically tunable active duplexer schematized in FIG. 2, comprising two tunable phase shifting networks (TPSN), two distributed amplifier (DA) gain cells, a first port (1) for transmission of a signal, a second port (2) for antenna or termination, a third port (3) for receiving a signal, a fourth port (4) for antenna or termination, such that TPSN, DA, (1), (2), (3) and (4) are operationally arrayed as depicted in FIG. 2, and wherein each TPSN comprises one or more tunable capacitors and one or more inductors.

17. The electronically tunable active duplexer of claim 16 wherein the one or more tunable capacitors are one or more varactors.

18. The electronically tunable active duplexer of claim 17, wherein each DA cell comprises at least one signal amplifying device, resistor, inductor and capacitor.

19. The electronically tunable active duplexer of claim 18, wherein each DA cell comprises a field effect transistor (FET) and gate and drain line inductors.

20. The electronically tunable active duplexer of claim 19, wherein the FET is a gallium arsenide metal semiconductor field effect transistor (GaAsMESFET).

21. The electronically tunable active duplexer of any one of claims 16-20, further comprising a receiver (R) bandpass filter connected to the third port or to the fourth port.

22. The electronically tunable active duplexer of any one of claims 16-21, further comprising a transmission (T) bandpass filter connected to the first port or to the second port.

23. The electronically tunable active duplexer of anyone of claims 16-22, wherein an antenna is connected to the fourth port and the second port is terminated.

24. The electronically tunable active duplexer of claims 16-22, wherein an antenna is connected to the second port and the fourth port is terminated.

25. The electronically tunable active duplexer of claims 16-22, wherein an antenna is connected to both the second and fourth ports.

26. The electronically tunable active duplexer of claim 18 wherein the one or more inductor and the one or more capacitor are lumped elements, and the duplexer is arrayed as schematically depicted in FIG. 3a or FIG. 3b.

27. The electronically tunable active duplexer of claim 18 wherein the one or more inductor and the one or more capacitor are transmission lines, and the duplexer is arrayed as schematically depicted in FIG. 3a or FIG. 3b.