High efficiency power amplifier

• US 5,880,633 A
• Filed: 05/08/1997
• Issued: 03/09/1999
• Est. Priority Date: 05/08/1997
• Status: Expired due to Term

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Cygan, Lawrence F., Leizerovich, Gustavo D.
• Primary Examiner(s): Mullins, James B.
• Application Number:
  US08/854,129
• Time in Patent Office: 670 Days
• Field of Search: 330/84, 330/124 R, 330/149, 330/151, 330/293, 332/123, 332/159, 332/160, 332/162, 375/297, 455/126
• US Class Current: 330/84
• CPC Class Codes: H03F 1/0222 by using a signal derived from the input signal
• CPC Class Codes: H03F 1/0288 using a main and one or several auxiliary peaking amplifiers whereby the load is connected to the main amplifier using an impedance inverter, e.g. Doherty amplifiers
• CPC Class Codes: H03F 1/3247 using feedback acting on predistortion circuits H03F1/3264 takes precedence
• CPC Class Codes: H03F 1/345 using hybrid or directional couplers
• CPC Class Codes: H03F 2200/57 Separate feedback of real and complex signals being present

Abstract

A high efficiency power amplifier 600 consists of a non-linear radio frequency (RF) Doherty power amplifier (67) and a linearization circuit, such as, for example, a Cartesian Feedback circuit (33), an RF feedback circuit (38), an IF feedback circuit (48), or a feedforward circuit (55). The Doherty amplification stage (67) may be implemented with a BJTs, FETs, HBTs, H-FETs, PHEMTs, or any other type power transistor technology or device.

Claims

1. A high efficiency power amplifier comprising:

a Doherty amplifier stage, having an input path, for amplifying an input signal and producing an output corresponding thereto, said Doherty amplifier stage exhibiting non-linear amplitude and phase characteristics; and

a Cartesian feedback linearization circuit, coupled to the Doherty amplifier stage, said Cartesian feedback linearization circuit responsive to receipt of the output for generating an error signal that is subtracted from the input path in order to linearize and correct the non-linear amplitude and phase characteristics of the output.

2. A high efficiency power amplifier according to claim 1 wherein said Doherty amplifier stage comprises transistors selected from the group consisting of:

field effect transistor (FET) devices;

heterostructure field effect transistor (H-FET) devices;

bipolar junction transistor (BJT) devices;

hetero junction bipolar transistor (HBT) devices; and

pseudomorphic high electron mobility transistor (PHEMT).

3. A high efficiency power amplifier according to claim 1 wherein said linearization circuit comprises a RF feedback linearization circuit.

4. A high efficiency power amplifier according to claim 1 wherein said linearization circuit comprises an intermediate frequency (IF) feedback linearization circuit.

5. A high efficiency power amplifier according to claim 1 wherein said Doherty amplifier stage operates over a plurality frequencies ranging from 800 MHz to 900 MHz.

6. A high efficiency power amplifier according to claim 1 wherein said Doherty amplifier stage operates over a plurality frequencies ranging from 1.4 GHz to 1.6 GHz.

7. A high efficiency power amplifier according to claim 1 wherein said Doherty amplifier stage provides a power out of between 5 milliwatts and 10 watts.

8. A high efficiency power amplifier circuit having an input path, said circuit comprising:

a power splitter for receiving an input signal and providing a first and a second output signal, said first and said second output signal having a different phase;

an amplifier stage, coupled to the power splitter, having a carrier amplifier for amplifying said first output signal and a peak amplifier for amplifying said second output signal;

a combiner, coupled to the amplifier stage, for producing an output corresponding thereto, said output exhibiting non-linear amplitude and phase characteristics; and

a Cartesian feedback linearization circuit, coupled to the combiner, said Cartesian feedback linearization circuit responsive to receipt of the output for generating an error signal that is subtracted from the input path in order to linearize and correct the non-linear amplitude and phase characteristics of the output.

9. A high efficiency power amplifier according to claim 8 wherein said carrier amplifier comprises a multiple stage device.

10. A high efficiency power amplifier according to claim 8 wherein said peak amplifier comprises a multiple stage device.

11. A high efficiency power amplifier according to claim 8 wherein said amplifier stage operates over a plurality frequencies ranging from 800 MHz to 900 MHz.

12. A high efficiency power amplifier according to claim 8 wherein said amplifier stage operates over a plurality frequencies ranging from 1.4 GHz to 1.6 GHz.

13. A high efficiency power amplifier according to claim 8 wherein said amplifier stage provides a power out of between 5 milliwatts and 10 watts.

14. A radio frequency (RF) communications device having a high efficiency power amplifier, said power amplifier comprising:

a Doherty amplifier stage for amplifying an input and producing an output corresponding thereto, said Doherty amplifier stage exhibiting non-linear amplitude and phase characteristics; and

a Cartesian feedback linearization circuit, coupled to the Doherty amplifier stage, said Cartesian feedback linearization circuit responsive to receipt of the output for linearizing and correcting the non-linear amplitude and phase characteristics of the output.

15. A radio frequency (RF) communications device according to claim 14 wherein said Doherty amplifier stage comprises a multiple stage device.

16. A radio frequency (RF) communications device according to claim 14 wherein said Doherty amplifier stage operates over a plurality frequencies ranging from 800 MHz to 900 MHz.

17. A radio frequency (RF) communications device according to claim 14 wherein said Doherty amplifier stage operates over a plurality frequencies ranging from 1.4 GHz to 1.6 GHz.

18. A radio frequency (RF) communications device according to claim 14 wherein said Doherty amplifier stage provides a power out of between 5 milliwatts and 10 watts.