Dual-band, dual-mode power amplifier

• US 6,298,244 B1
• Filed: 06/10/1998
• Issued: 10/02/2001
• Est. Priority Date: 07/03/1997
• Status: Expired due to Fees

• Current Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Original Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Inventors: Meadows, Ronald C., Boesch, Ronald D.
• Primary Examiner(s): Bost, Dwayne
• Assistant Examiner(s): CRAVER, CHARLES R
• Application Number:
  US09/094,515
• Time in Patent Office: 1,210 Days
• Field of Search: 455/91, 455/93, 455/188, 455/114, 455/137, 455/553, 455/143, 455/144, 455/232.1, 455/239.1, 455/241.1, 330/295, 330/302, 330/305, 330/306, 330/310, 330/51, 330/126, 330/133
• US Class Current: 455/553.1
• CPC Class Codes: H03F 2200/111 the amplifier being a dual or triple band amplifier, e.g. 900 and 1800 MHz, e.g. switched or not switched, simultaneously or not
• CPC Class Codes: H03F 2203/7209 the gated amplifier being switched from a first band to a second band
• CPC Class Codes: H03F 3/24 of transmitter output stages
• CPC Class Codes: H03F 3/72 Gated amplifiers, i.e. amplifiers which are rendered operative or inoperative by means of a control signal
• CPC Class Codes: H03H 11/30 Automatic matching of source impedance to load impedance
• CPC Class Codes: H03H 7/38 Impedance-matching networks
• CPC Class Codes: H03H 7/46 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 diplex 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.

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:

a first driver amplifier for amplifying RF signals in a first frequency band;

first and second final amplifiers;

a diplex matching circuit coupled to said first final amplifier; and

a switching network coupled between said first driver amplifier and said first and second final amplifiers wherein the switching network selectively couples said first driver amplifier to said first and second final amplifiers in response to said amplifier circuit being placed in a linear or nonlinear mode of operation, respectively;

a low pass matching circuit coupled to an output of said second final amplifier; and

switching circuitry, coupled to a first output of said diplex matching circuit and an output of said low pass matching circuit, for selectively coupling said first diplex matching circuit output or said low pass matching circuit output to an output line when said amplifier circuit is selectively placed in linear mode or nonlinear mode, respectively.

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

a second driver amplifier for amplifying RF signals in a second frequency band; and

wherein said switching network includes a first switch coupled between said first driver amplifier and said first final amplifier.

3. A power amplifier circuit as recited in claim 2, wherein said switching network further includes a node coupled to an output of said second driver amplifier, a second switch coupled between said node and an input of said first final amplifier and a third switch coupled between said node and an input of said second final amplifier.

4. A power amplifier circuit as recited in claim 3, further comprising a first filter disposed between the output of said first driver amplifier and said first switch, and a second filter disposed between said second driver amplifier and said node.

5. A power amplifier as recited in claim 4, where in said first and second filters are surface acoustic wave filters.

6. A power amplifier as recited in claim 2, further comprising a harmonic trap coupled to an output of said first final amplifier.

7. 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:

a first driver amplifier for amplifying RF signals in a first frequency band;

first and second final amplifiers;

a diplex matching circuit coupled to said first final amplifier;

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

a low pass matching circuit coupled to an output of said second final amplifier; and

switching circuitry, coupled to a first output of said diplex matching circuit and an output of said low pass matching circuit, for selectively coupling said first diplex matching circuit output or said low pass matching circuit output to an output line when said amplifier circuit is selectively placed in linear mode or nonlinear mode, respectively.

8. 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:

a driver amplifier stage having a high band output and a low band output;

a final amplifier stage having a linear amplifier and a nonlinear amplifier; and

a switching network having more than one switch between the driver amplifier stage and the final amplifier stage for coupling the low band output to one of the linear and nonlinear amplifiers responsive to a mode selection so that the low band output is coupled to the linear amplifier during low band operations in the linear mode and so that the low band output is coupled to the nonlinear amplifier during low band operations in the nonlinear mode.

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

a filter stage interposed between said driver stage and said switching network.

10. A method for operating a power amplifier 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, the method comprising:

amplifying RF signals in the first frequency band;

selectively coupling the RF signals in the first frequency band to one of a first final amplifier or a second final amplifier in response to the power amplifier being placed in linear or nonlinear mode of operation, respectively;

generating a first diplex output for RF signals amplified by the first final amplifier corresponding to the first frequency band,

generating a second diplex output for RF signals amplified by the first final amplifier corresponding to the second frequency band;

low pass filtering an output of the second final amplifier; and

selectively coupling one of the first diplex output or the low pass filtered output of the second final amplifier to an output line when the amplifier is selectively placed in a linear mode or nonlinear mode respectively.

11. A method according to claim 10 further comprising:

amplifying RF signals in the second frequency band; and

selectively coupling the amplified RF signals in the second frequency band to the first final amplifier when operating in the second frequency band.

12. A power amplifier for amplifying RF signals, the power amplifier being 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:

a first driver amplifier that amplifies RF signals in the first frequency band to generate amplified RF signals in the first frequency band;

a second driver amplifier that amplifies RF signals in the second frequency band to generate amplified RF signals in the second frequency band;

a first final amplifier;

a second final amplifier;

a switching network coupled between the first and second driver amplifiers and the first and second final amplifiers wherein the switching network selectively couples one of the driver amplifiers to one of the final amplifiers, wherein the switching network couples the amplified RF signals in the first frequency band to the first final amplifier when transmitting in the first frequency band during linear mode operations and to the second final amplifier when transmitting in the first frequency band during nonlinear mode operations;

a diplex matching circuit coupled to an output of the first final amplifier wherein the diplex matching circuit generates a first diplex output at a first diplex node when transmitting in the first frequency band and wherein the diplex matching circuit generates a second diplex output at a second diplex node when transmitting in the second frequency band; and

a switch that selectively couples one of the first diplex output and an output of the second final amplifier to an output line when transmitting in the first frequency band.

13. A power amplifier according to claim 12 wherein the switching network couples the amplified RF signals in the first frequency band to the first final amplifier when transmitting in the first frequency band during linear mode operations and to the second final amplifier when transmitting in the first frequency band during nonlinear mode operations.

14. A power amplifier according to claim 12 wherein the switching network couples the amplified RF signals in the second frequency band to the first final amplifier when transmitting in the second frequency band.

15. A power amplifier according to claim 12 further comprising:

a low pass filter coupled between the second final amplifier and the switch wherein the low pass filter passes the first frequency band and blocks the second frequency band.

16. A method for operating a power amplifier 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, the method comprising:

generating amplified RF signals in the first frequency band when transmitting in the first frequency band;

generating amplified RF signals in the second frequency band when transmitting in the second frequency band;

coupling the amplified RF signals in the first frequency band to a first final amplifier when transmitting in the first frequency band and operating in the linear mode;

coupling the amplified RF signals in the first frequency band to a second final amplifier when transmitting in the first frequency band and operating in the nonlinear mode; and

coupling the amplified RF signals in the second frequency band to the first final amplifier when transmitting in the second frequency band.

17. A method according to claim 16 further comprising:

generating a first diplex output from the first final amplifier when transmitting in the first frequency band when operating in the linear mode; and

generating a second diplex output from the first final amplifier when transmitting in the second frequency band when operating in the linear mode.

18. A method according to claim 17 further comprising:

selectively coupling one of the first diplex output and an output of the second final amplifier to an output line when transmitting in the first frequency band.

19. A method according to claim 18 further comprising:

low pass filtering the output of the second final amplifier before selectively coupling one of the first diplex output and the output of the second final amplifier to pass the first frequency band and to block the second frequency band.