Active compensation for power amplifier gain droop

• US 9,755,603 B2
• Filed: 02/25/2016
• Issued: 09/05/2017
• Est. Priority Date: 07/07/2015
• Status: Active Grant

• Current Assignee: MediaTek, Inc.
• Original Assignee: MediaTek, Inc.
• Inventors: Fong, Keng Leong, Chee, YuenHui
• Primary Examiner(s): HA, DAC V
• Application Number:
  US15/053,158
• Publication Number:
  US 20170012590A1
• Time in Patent Office: 558 Days
• CPC Class Codes: H03F 2200/411 the output amplifying stage of an amplifier comprising two power stages
• CPC Class Codes: H03F 2200/451 the amplifier being a radio frequency amplifier
• CPC Class Codes: H03F 3/19 with semiconductor devices only
• CPC Class Codes: H03F 3/245 with semiconductor devices only
• CPC Class Codes: H03G 3/3042 in modulators, frequency-changers, transmitters or power amplifiers transmission power control in bidirectional transmission systems H04W52/04
• CPC Class Codes: H04B 1/0475 with means for limiting noise, interference or distortion H04B1/0483 takes precedence
• CPC Class Codes: H04B 17/13 of power amplifiers, e.g. gain or non-linearity
• CPC Class Codes: H04B 2001/0416 having gain or transmission power control

Abstract

Some embodiments relate to a method and circuit for gain compensation. The method includes detecting a strength of an output signal generated by a power amplifier of a transmitter in response to a commanded transmission signal. The method also includes comparing the detected strength of the output signal to a delayed version of a detected strength of the commanded transmission signal to obtain an error signal. The method further includes compensating for gain drop of the output signal by adjusting a gain of the transmitter based on the error signal.

Claims

1. A method for gain compensation comprising:

(A) detecting a strength of an output signal generated by a power amplifier of a transmitter in response to a commanded transmission signal;

(B) comparing the detected strength of the output signal to a detected strength of the commanded transmission signal to obtain an error signal;

(C) compensating for gain drop of the output signal by adjusting a gain of the transmitter based on the error signal,

wherein (A), (B) and (C) are performed during a transmission of a single packet.

2. The method for gain compensation of claim 1, wherein the duration of the transmission of the packet is between 10 microseconds and 100 milliseconds.

3. The method for gain compensation of claim 1, further comprising:

(D) delaying the detected strength of the commanded transmission signal prior to (B).

4. The method of claim 3, wherein the detected strength of the commanded transmission signal is delayed in (D) to temporally align the detected strength of the commanded transmission signal with the detected strength of the output signal.

5. The method for gain compensation of claim 1, wherein (C) is performed by a digital circuit.

6. The method for gain compensation of claim 1, wherein (C) is performed by an analog circuit.

7. The method of claim 1, wherein compensating for gain drop of the output signal is performed to render the strength of the output signal constant.

8. A circuit for gain compensation comprising:

circuitry configured to;

(A) detect a strength of an output signal generated by a power amplifier of a transmitter in response to a commanded transmission signal;

(B) compare the detected strength of the output signal to a detected strength of the commanded transmission signal to obtain an error signal;

(C) compensate for gain drop of the output signal by adjusting a gain of the transmitter based on the error signal,

wherein (A), (B) and (C) are performed during a transmission of a single packet.

9. The circuit for gain compensation of claim 8, wherein the circuitry is further configured to:

(D) delay the detected strength of the commanded transmission signal prior to (B).

10. The circuit for gain compensation of claim 9, wherein the commanded transmission signal is delayed in (D) to temporally align the detected strength of the commanded transmission signal with the detected strength of the output signal.

11. The circuit for gain compensation of claim 8, further comprising at least one analog-to-digital-converter to digitize the detected strength of the output signal prior to (B).

12. The circuit for gain compensation of claim 8, wherein the circuit for gain compensation is configured to compensate for gain drop with a digital circuit.

13. The circuit for gain compensation of claim 8, wherein the circuit for gain compensation is configured to compensate for gain drop with an analog circuit.

14. The circuit for gain compensation of claim 8, wherein the circuit is configured to compensate for gain drop of the output signal to render the strength of the output signal constant.