DOHERTY POWER AMPLIFIER HAVING AM-AM COMPENSATION

• US 20160241209A1
• Filed: 02/12/2016
• Published: 08/18/2016
• Est. Priority Date: 02/15/2015
• Status: Active Grant

• Current Assignee: Skyworks Solutions Incorporated
• Original Assignee: Skyworks Solutions Incorporated
• Inventors: LEHTOLA, Philip John
• Granted Patent: US 9,806,681 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H03F 1/0261 with control of the polarisation voltage or current, e.g. gliding Class A
• 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 1/22 by use of cascode coupling, i.e. earthed cathode or emitter stage followed by earthed grid or base stage respectively
• CPC Class Codes: H03F 1/565 using inductive elements
• CPC Class Codes: H03F 2200/451 the amplifier being a radio frequency amplifier
• CPC Class Codes: H03F 2203/21127 the input bias current of a power amplifier being controlled, e.g. by an active current source or a current mirror
• CPC Class Codes: H03F 3/191 Tuned amplifiers H03F3/193, H03F3/195 take precedence
• CPC Class Codes: H03F 3/195 in integrated circuits
• CPC Class Codes: H03F 3/211 using a combination of several amplifiers H03F3/60 takes precedence
• CPC Class Codes: H03F 3/245 with semiconductor devices only

Abstract

A power amplification system includes a Doherty power amplifier (PA) configured to receive a voltage supply signal and a radio-frequency (RF) signal and generate an amplified RF signal using the voltage supply signal, the Doherty PA including a carrier amplifier and a peaking amplifier. A carrier amplifier bias circuit and a peaking amplifier bias circuit coupled to one or more of the carrier amplifier and the carrier amplifier bias circuit over a coupling path are provided wherein the peaking amplifier bias circuit is configured to provide a peaking bias signal to the peaking amplifier based on a saturation level of the carrier amplifier.

Claims

1. A power amplification system comprising:

a Doherty power amplifier (PA) configured to receive a voltage supply signal and a radio-frequency (RF) signal and generate an amplified RF signal using the voltage supply signal, the Doherty PA including a carrier amplifier and a peaking amplifier;

a carrier amplifier bias circuit; and

a peaking amplifier bias circuit coupled to one or more of the carrier amplifier and the carrier amplifier bias circuit over a coupling path and configured to provide a peaking amplifier bias signal to the peaking amplifier based on a saturation level of the carrier amplifier.

2. The system of claim 1 further comprising an output path configured to receive and route the amplified RF signal from the Doherty PA to a filter, the output path substantially free of an impedance transformation circuit.

3. The system of claim 2 wherein the carrier amplifier is operating at or close to a highest possible efficiency.

4. The system of claim 1 wherein the peaking amplifier bias signal is proportional to the saturation level of the carrier amplifier.

5. The system of claim 1 wherein the peaking amplifier bias circuit is configured so that a rapidly increasing base current of the carrier amplifier resulting from its approach to saturation is mirrored to the peaking amplifier bias circuit to thereby cause the peaking amplifier to be turned on abruptly.

6. The system of claim 1 wherein the peaking amplifier bias signal is based on a base current of a driver transistor of the carrier amplifier.

7. The system of claim 1 wherein the peaking amplifier bias signal is based on an output of the carrier amplifier.

8. The system of claim 1 wherein the carrier amplifier and the peaking amplifier each include cascode transistors.

9. A radio-frequency (RF) module comprising:

a packaging substrate configured to receive a plurality of components; and

a power amplification system implemented on the packaging substrate, the power amplification system including a power amplification system including a Doherty power amplifier (PA) configured to receive a radio-frequency (RF) signal and generate an amplified RF signal, the Doherty PA including a carrier amplifier and a peaking amplifier, the power amplification system further including a carrier amplifier bias circuit and a peaking amplifier bias circuit coupled to one or more of the carrier amplifier and the carrier amplifier bias circuit over a coupling path and configured to provide a peaking amplifier bias signal to the peaking amplifier based on a saturation level of the carrier amplifier.

10. The RF module of claim 9 wherein the peaking amplifier bias signal is proportional to the saturation level of the carrier amplifier.

11. The RF module of claim 9 wherein the peaking amplifier bias circuit is configured so that a rapidly increasing base current of the carrier amplifier resulting from its approach to saturation is mirrored to the peaking amplifier bias circuit to thereby cause the peaking amplifier to be turned on abruptly.

12. The RF module of claim 9 wherein the peaking amplifier bias signal is based on a base current of a driver transistor of the carrier amplifier.

13. The RF module of claim 9 wherein the peaking amplifier bias signal is based on an output of the carrier amplifier.

14. The RF module of claim 9 wherein the carrier amplifier and the peaking amplifier each include cascode transistors.

15. A wireless device comprising:

a transceiver configured to generate a radio-frequency (RF) signal;

a front-end module (FEM) in communication with the transceiver, the FEM including a packaging substrate configured to receive a plurality of components, the FEM further including a power amplification system implemented on the packaging substrate, the power amplification system including a Doherty power amplifier (PA) configured to receive the RF signal from the transceiver and generate an amplified RF signal, the Doherty PA including a carrier amplifier and a peaking amplifier, the power amplification system further including a carrier amplifier bias circuit and a peaking amplifier bias circuit coupled to one or more of the carrier amplifier and the carrier amplifier bias circuit over a coupling path and configured to provide a peaking amplifier bias signal to the peaking amplifier based on a saturation level of the carrier amplifier; and

an antenna in communication with the FEM, the antenna configured to transmit the amplified RF signal.

16. The wireless device of claim 15 wherein the peaking amplifier bias signal is proportional to the saturation level of the carrier amplifier.

17. The wireless device of claim 15 wherein the peaking amplifier bias circuit is configured so that a rapidly increasing base current of the carrier amplifier resulting from its approach to saturation is mirrored to the peaking amplifier bias circuit to thereby cause the peaking amplifier to be turned on abruptly.

18. The wireless device of claim 15 wherein the peaking amplifier bias signal is based on a base current of a driver transistor of the carrier amplifier.

19. The wireless device of claim 15 wherein the peaking amplifier bias signal is based on an output of the carrier amplifier.

20. The wireless device of claim 15 wherein the carrier amplifier and the peaking amplifier each include cascode transistors.