Distributed balanced duplexer

• US 20060019611A1
• Filed: 07/21/2004
• Published: 01/26/2006
• Est. Priority Date: 07/21/2004
• Status: Abandoned Application

• Current Assignee: Nokia Corporation
• Original Assignee: Nokia Corporation
• Inventors: Mages, Phillip J.
• Application Number:
  US10/896,342
• Publication Number:
  US 20060019611A1
• Time in Patent Office: Days
• US Class Current: 455/73
• CPC Class Codes: H04B 1/52 Hybrid arrangements, i.e. arrangements for transition from single-path two-direction transmission to single-direction transmission on each of two paths or vice versa

Abstract

The present invention relates to a system and a method that employs a distributed balanced duplexer that can be utilized to facilitate concurrent signal transmission and reception. The system and method can be employed within mobile devices such as cell phones and utilize two-filters (e.g., acoustic) with substantially similar input/output impedances interfaced with two couplers (e.g., 3 dB hybrid), and a third filter in series with a receiver filter, which provide isolation and maintain the duplexer'"'"'s input/output impedance. The couplers interface the filters to front/back ends such as signal processors, transmitters and receivers. The novel aspects of the present invention mitigate the need to employ external directional couplers between the duplexer and front/back ends. The system and method further provides for separation and isolation of transmitters and receivers, which reduces noise coupling and enables the transmitter and receiver to be placed within close proximity.

Claims

1. A distributed balanced duplexer, comprising:

a first filter;

a second filter in parallel with the first filter, the first and second filters having a substantially similar input and output impedance;

a first coupler that simultaneously interfaces the first and second filters to a transmit signal source and a first termination; and

a second coupler that interfaces the first and second filters to an antenna via a third filter, to a receiver filter and to a second termination.

2. The duplexer of claim 1, wherein the first coupler outputs a first signal portion with a first signal power toward the first filters and a second signal portion with a second signal power toward the second filter, wherein the sum of the first and second signal powers does not exceed a total signal power of the signal input to the first coupler.

3. The duplexer of claim 2, wherein the first and second signal powers are determined by a power ratio.

4. The duplexer of claim 2, wherein the first and second signal powers are each about one half the total signal power.

5. The duplexer of claim 2, wherein the first and second filters are configured such that if one filter becomes inoperable, the other filter can be utilized to process the input signal with the total signal power.

6. The duplexer of claim 1, wherein the distributed balanced duplexer buffers an input and an output stage.

7. The duplexer of claim 1, wherein the first and second couplers comprise 3 dB hybrid couplers comprising one of a Lange coupler and a discrete coupler.

8. The duplexer of claim 7, wherein the Lange coupler provides isolation between the first and second filters and the transmit signal source and the first and second filters and the third filter and the antenna.

9. The duplexer of claim 1, wherein the first and second terminations is about 50 Ω

.

10. The duplexer of claim 1, wherein the first and second filters comprise acoustic filters comprising SAW and BAW filters.

11. The duplexer of claim 1 employed within at least one of a mobile phone, a web phone, a personal data assistant (PDA), a hand-held PC, a pocket PC, a palm-pilot, a laptop, a tablet PC, a Notepad, a GPS, a pager, a personal computer, a mainframe, and a workstation.

12. The duplexer of claim 1, wherein the first and second couplers divert reflected power into the first and second terminations, respectively.

13. The duplexer of claim 1, wherein the first and second couplers reduce reflected energy by combining reflected energy that is 180 degrees out of phase.

14. The duplexer of claim 1, wherein the first and second filters are employed in the reception of a signal to improve low noise amplifier and antenna matching.

15. The duplexer of claim 1, wherein the third filter increases receiver band impedance.

16. The duplexer of claim 1, wherein the third filter provides isolation between the first and second filters and the antenna.

34. The duplexer of claim 1, wherein the first coupler comprises a Wilkinson power divider and the second coupler comprises a Wilkinson power combiner.

35. The duplexer of claim 34, further comprising a phase shifter disposed between the Wilkinson power divider and one of the first and second filters.

17. A method for transmitting signals, comprising:

conveying a generated signal to a distributed balanced duplexer, the signal being divided into two portions, a first portion with a first signal power transmitted through a first filter of the balanced duplexer and a remaining portion transmitted through a second filter, the remaining portion associated with a remaining signal power;

terminating reflected signal power arising from the signal being divided into the two portions;

combining the first portion and second signal portions,

routing the first and second signal portions to an antenna via a third filter; and

transmitting the signal.

18. The method of claim 17, further comprising employing 3 dB hybrid couplers to divide and combine the generated signal.

19. The method of claim 18, wherein the 3 dB hybrid couplers are in series with the third filter.

20. The method of claim 18, further comprising providing isolation between the 3 dB hybrid couplers and a signal generating and a transmitting component.

21. A wireless device comprising:

a radio frequency transmitter and a radio frequency receiver coupled to an antenna via a duplexer, said duplexer comprising

a first filter;

a second filter in parallel with the first filter, the first and second filters having a substantially similar input and output impedance;

a first coupler that simultaneously interfaces the first and second filters to a transmit signal source and a first termination; and

a second coupler that couples the first and second filters to the antenna via a third filter, to a receiver filter and to a second termination.

22. The wireless device of claim 21, wherein the first coupler outputs a first signal portion with a first signal power toward the first filters and a second signal portion with a second signal power toward the second filter, wherein the sum of the first and second signal powers does not exceed a total signal power of the signal input to the first coupler.

23. The wireless device of claim 22, wherein the first and second signal powers are determined by a power ratio.

24. The wireless device of claim 22, wherein the first and second signal powers are each about one half the total signal power.

25. The wireless device of claim 22, wherein the first and second filters are configured such that if one filter becomes inoperable, the other filter can be utilized to process the signal with the total signal power.

26. The wireless device of claim 21, wherein the first and second couplers divert reflected signal power into the first and second terminations, respectively.

27. The wireless device of claim 21, wherein the third filter increases receiver band impedance.

28. The wireless device of claim 21, wherein the third filter provides isolation between the first and second filters and the antenna.

29. A transceiver comprising:

a signal source;

a first coupler having an input coupled to an output of the signal source, and an output coupled to a first termination;

first and second filters in parallel, each having an input coupled to an separate output of the first coupler;

a second coupler having separate inputs coupled to outputs of each of the first and second filters, and an output coupled to a second termination;

a third filter having an input coupled to an output of the second coupler and separate outputs coupled to an input of a receiver and to an input of a transmit antenna;

wherein the first coupler operates to divide an input signal having a total signal power into a first signal portion having a first signal power that is output to the first filter, and a second portion having a second signal power that is output to the second filter.

30. A transceiver comprising:

means for generating a signal to be transmitted;

means for dividing the signal to be transmitted into a first signal portion having a first signal power and a second signal portion having a second signal power;

filtering means for separately filtering the first and second signal portions;

means for combining the first and second signal power levels of the first and second signal portions after being separately filtered; and

an antenna having an input coupled to the means for combining.

31. The transceiver of claim 30, further comprising a feedback filtering means coupled between the means for combining and the antenna, said feedback filtering means further having an output coupled to a receiver of the transceiver.

32. The transceiver of claim 30, wherein at least one of the means for dividing and the means for combining comprise means for dumping reflected signal power.

33. A distributed balanced duplexer, comprising:

a first filter;

a second filter, the first and second filters having a substantially similar input and output impedance;

a first coupler that interfaces the first and second filters to a transmit signal source and a first termination; and

a second coupler that interfaces the first and second filters to an antenna via a third filter, to a receiver filter and to a second termination,

wherein the first coupler outputs at least a portion of an input signal to the first filter with a first signal power and at least a portion of the input signal to the second filter with a second signal power, wherein the sum of the first and second signal powers does not exceed a total signal power of the input signal.