Dual-band, dual-mode power amplifier with reduced power loss

• US 6,188,877 B1
• Filed: 10/22/1998
• Issued: 02/13/2001
• Est. Priority Date: 07/03/1997
• Status: Expired due to Term

• Current Assignee: Unwired Planet LLC (JP Morgan Chase & Co)
• Original Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Inventors: Meadows, Ronald C., Boesch, Ronald D.
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): Kincaid, Lester G.
• Application Number:
  US09/177,233
• Time in Patent Office: 845 Days
• Field of Search: 455/74, 455/78, 455/80, 455/93, 455/124, 455/127, 455/552, 455/553, 455/426, 455/114, 455/117, 375/216, 370/321, 370/347, 330/124.R, 330/126, 330/129, 333/124, 333/129, 333/132
• US Class Current: 455/74
• CPC Class Codes: H03H 11/30 Automatic matching of source impedance to load impedance
• CPC Class Codes: H03H 11/34 Networks for connecting several sources or loads working on different frequencies or frequency bands, to a common load or source for use in multiplex transmission systems H04J1/00
• CPC Class Codes: H04B 1/005 adapting radio receivers, transmitters andtransceivers for operation on two or more bands, i.e. frequency ranges
• CPC Class Codes: H04B 1/0458 Arrangements for matching and coupling between power amplifier and antenna or between amplifying stages matching circuits in general H03H
• CPC Class Codes: H04B 1/406 with more than one transmission mode, e.g. analog and digital modes

Abstract

A power amplifier circuit has a driver amplifier stage including a low band driver amplifier and a high band driver amplifier. A final amplifier stage includes a linear mode amplifier for amplifying digitally modulated signals and a saturated (nonlinear) mode amplifier for amplifying frequency modulated (analog) signals. A switching network interconnects the driver amplifier stage and the final amplifier stage. Depending on the desired mode of operation, an appropriate driver amplifier can be coupled to an appropriate final amplifier to most effectively and efficiently amplify analog or digital RF signals in either of a plurality of frequency bands. A matching circuit is coupled to the linear mode final amplifier for impedance matching and for separating D-AMPS (800 MHz band) and PCS (1900 MHz band) digital signals. A power impedance matching circuit is coupled to the output of the saturated mode final amplifier. In one embodiment, an isolator is coupled to the output of one or more of the low band or high band outputs of the duplex matching circuit. In the low band analog path, a duplexer is provided ahead of the coupling means for reducing the RF power requirements on the coupling means. The switching network and input filter stage may precede a driver amplifier stage.

Claims

1. A power amplifier circuit for amplifying RF signals, said power amplifier circuit selectively operable in a linear mode or a nonlinear mode and selectively operable to amplify RF signals in a first frequency band or a second frequency band, comprising:

first and second RF input terminals for receiving RF signals in first and second frequency bands, respectively;

first and second final amplifiers;

a matching network having and input, a low-band output and a high-band output, the input of said matching network coupled to an output of said first final amplifier;

a switching network for selectively coupling said second RF input terminal to one of said first and second final amplifiers in response to said amplifier circuit being placed in a linear or nonlinear mode of operation, respectively; and

an isolator coupled between the high-band output of said matching network and a first output line.

2. A power amplifier circuit as recited in claim 1, further comprising:

an impedance matching circuit coupled to an output of said second final amplifier;

a duplexer coupled to an output of said impedance matching circuit; and

switching circuitry, coupled to the low-band output of said matching circuit and an output of said duplexer, for selectively coupling one of the low-band output of said matching network or the output of said duplexer to a second output line when said amplifier circuit is selectively placed in linear mode or nonlinear mode, respectively.

3. A power amplifier circuit as recited in claim 2, further comprising:

an isolator coupled between the low-band output of said matching network and said switching circuitry.

4. A power amplifier circuit as recited in claim 3, wherein said first and second output lines are coupled to a diplexer.

5. A power amplifier circuit as recited in claim 3, further comprising:

first and second driver amplifiers coupled to said first and second RF input terminals, respectively;

said switching network includes a node coupled to an output of said second driver amplifier, a first switch coupled between said first driver amplifier and an input of said first final amplifier, a second switch coupled between said node and said input of said first final amplifier and a third switch coupled between said node and an input of said second final amplifier.

6. A power amplifier circuit as recited in claim 5, further comprising a first filter disposed between said first driver amplifier and said first switch, and a second filter disposed between said second driver amplifier and said node.

7. A power amplifier as recited in claim 6, where in said first and second filters are surface acoustic wave filters.

8. A power amplifier as recited in claim 2, further comprising:

an isolator coupled between said impedance matching circuit and said switching circuitry.

10. A power amplifier circuit as recited in claim 1, further comprising:

an isolator coupled between the high-band output of said matching network and a first output line.

17. A power amplifier as recited in claim 10, further comprising:

an isolator coupled between said impedance matching circuit and said switching circuitry.

9. A power amplifier circuit for amplifying RF signals, said power amplifier circuit selectively operable in a linear mode or a nonlinear mode and selectively operable to amplify RF signals in a first frequency band or a second frequency band, comprising:

first and second RF input terminals for receiving RF signals in first and second frequency bands, respectively;

first and second driver amplifiers;

first and second final amplifiers coupled to said first and second driver amplifiers, respectively;

a matching network having and input, a low-band output and a high-band output, the input of said matching network coupled to an output of said first final amplifier;

a switching network for selectively coupling said second RF input terminal to one of said first and second driver amplifiers in response to said amplifier circuit being placed in a linear or nonlinear mode of operation, respectively.

11. A power amplifier circuit as recited in claim 9, further comprising:

an impedance matching circuit coupled to an output of said second final amplifier;

a duplexer coupled to an output of said impedance matching circuit; and

switching circuitry, coupled to the low-band output of said matching circuit and an output of said duplexer, for selectively coupling one of the low-band output of said matching network or the output of said duplexer to a second output line when said amplifier circuit is selectively placed in linear mode or nonlinear mode, respectively.

12. A power amplifier circuit as recited in claim 11, further comprising:

an isolator coupled between the low-band output of said matching network and said switching circuitry.

13. A power amplifier circuit as recited in claim 12, wherein said first and second output lines are coupled to a diplexer.

14. A power amplifier circuit as recited in claim 12, wherein:

said switching network includes a node coupled to said second RF input terminal, a first switch coupled between said first RF input terminal and an input of said first driver amplifier, a second switch coupled between said node and said input of said first driver amplifier and a third switch coupled between said node and an input of said second driver amplifier.

15. A power amplifier circuit as recited in claim 14, further comprising a first filter disposed between said first RF input terminal and said first switch, and a second filter disposed between said second RF input terminal and said node.

16. A power amplifier as recited in claim 15, where in said first and second filters are surface acoustic wave filters.

18. A power amplifier circuit for amplifying RF signals, said power amplifier circuit selectively operable in a linear mode or a nonlinear mode and selectively operable to amplify RF signals in a first frequency band or a second frequency band, comprising:

first and second RF input terminals for receiving RF signals in first and second frequency bands, respectively;

a first TDMA final amplifier coupled to said first RF input terminal;

a second TDMA final amplifier;

a saturated amplifier; and

a switching network for selectively coupling said second RF input terminal to one of said second TDMA amplifier and said saturated amplifier in response to said amplifier circuit being placed in a linear or nonlinear mode of operation, respectively.

19. A power amplifier as recited in claim 18, further comprising:

a first isolator coupled to an output of said first TDMA amplifier;

a second isolator coupled to an output of said second TDMA amplifier; and

a duplexer coupled to an output of said saturated amplifier.

20. A power amplifier as recited in claim 19, further comprising:

switching circuitry coupled to an output of said second isolator and an output of said duplexer, for selectively coupling said output of said second TDMA amplifier and said output of said saturated amplifier to a first output line responsive to said amplifier circuit being placed in a TDMA mode or a saturated mode, respectively.

21. A power amplifier circuit for amplifying RF signals, said power amplifier circuit selectively operable in a TDMA mode or a nonlinear mode and selectively operable to amplify RF signals in a first frequency band or a second frequency band, comprising:

a switching network having a high band input and a low band input;

a driver amplifier stage coupled to said switching network; and

a final amplifier stage having a TDMA amplifier and a saturated amplifier;

wherein said low band input is coupled to one of said TDMA amplifier or said saturated amplifier in response to a selection of TDMA mode or analog mode.