Power amplifier controller with polar transmitter

• US 7,783,269 B2
• Filed: 09/20/2007
• Issued: 08/24/2010
• Est. Priority Date: 09/20/2007
• Status: Active Grant

• Current Assignee: Quantance, Inc. (Skyworks Solutions Incorporated)
• Original Assignee: Quantance, Inc. (Skyworks Solutions Incorporated)
• Inventors: Drogi, Serge Francois, Vinayak, Vikas, Tomasz, Martin
• Primary Examiner(s): LE, NHAN T
• Application Number:
  US11/858,705
• Publication Number:
  US 20090081968A1
• Time in Patent Office: 1,069 Days
• Field of Search: 455/108, 455/110, 455/126, 455/127.1, 455/127.2, 455/232.1, 455/234.1, 455/240, 455/341, 375/297, 375/300, 375/302, 330/131, 330/136
• US Class Current: 455/126
• CPC Class Codes: H03F 1/0222 by using a signal derived from the input signal
• CPC Class Codes: H03F 1/0233 by using a signal derived from the output signal, e.g. bootstrapping the voltage supply
• CPC Class Codes: H03F 1/32 Modifications of amplifiers to reduce non-linear distortion by negative feedback H03F1/34
• CPC Class Codes: H03F 1/3241 using predistortion circuits H03F1/3211, H03F1/3217 take precedence
• CPC Class Codes: H03F 2200/324 An amplitude modulator or demodulator being used in the amplifier circuit
• CPC Class Codes: H03F 2200/451 the amplifier being a radio frequency amplifier
• CPC Class Codes: H03F 2200/78 A comparator being used in a controlling circuit of an amplifier
• CPC Class Codes: H03F 2200/99 A diode as rectifier being used as a detecting circuit in an amplifying circuit
• CPC Class Codes: H03F 3/24 of transmitter output stages
• CPC Class Codes: H04B 2001/0425 with linearisation using predistortion

Abstract

A power amplifier controller controls a power amplifier and is coupled to a polar modulator. The polar modulator generates an amplitude component and a phase-modulated component of the desired RF modulated signal, and outputs to the power amplifier controller. The power amplifier controller regenerates a combined phase and amplitude modulated RF signal to generate an input signal to a power amplifier by adjusting the gain of a VGA based on the amplitude component of the desired RF modulated signal. Concurrently, the power amplifier controller both controls an adjusted supply voltage to the PA and adjusts the gain of the VGA based upon an amplitude correction signal or amplitude error signal.

Claims

1. A power amplifier controller circuit for receiving from a polar transmitter a phase component and an amplitude component of a desired transmit signal and for controlling a power amplifier, the power amplifier coupled to receive and amplify an input signal and generate an output signal, the power amplifier controller circuit comprising:

an amplitude correction loop determining an amplitude correction signal indicative of an amplitude difference between the amplitude component of the desired transmit signal from the polar transmitter and an attenuated amplitude of the output signal;

a power supply providing a supply voltage to the power amplifier determined by at least a portion of the amplitude correction signal; and

one or more variable gain amplifiers collectively adjusting the amplitude of the input signal based upon a portion of the amplitude correction signal and at least a portion of the amplitude component of the desired transmit signal from the polar transmitter.

2. The power amplifier controller circuit of claim 1, further comprising a phase correction loop determining a phase error signal indicative of a phase difference between the phase component of the desired transmit signal from the polar transmitter and a phase of the output signal and adjusting the phase component of the desired transmit signal from the polar transmitter to reduce phase distortion generated by the power amplifier.

3. The power amplifier controller circuit of claim 2, wherein the phase correction loop comprises:

a phase comparator comparing the phase component of the desired transmit signal from the polar transmitter with the phase of the output signal to generate the phase error signal; and

a phase shifter coupled to the phase comparator and an input of the power amplifier, the phase shifter shifting the phase of the phase component of the desired transmit signal from the polar transmitter based upon the phase error signal.

4. The power amplifier controller circuit of claim 2, wherein the phase correction loop further comprises:

a phase delay block generating a delayed phase component of the desired transmit signal from the polar modulator;

wherein the phase correction loop compares the delayed phase component of the desired transmit signal from the polar transmitter to the phase of the output signal to determine the phase correction signal.

5. The power amplifier control circuit of claim 1, wherein the amplitude correction loop comprises:

a variable attenuator coupled to the power amplifier, the variable attenuator attenuating the output signal of the power amplifier;

an amplitude detector coupled to the variable attenuator, the amplitude detector detecting the attenuated amplitude of the output signal from the variable attenuator; and

an amplitude comparator coupled to the amplitude detector, the amplitude comparator comparing the amplitude component of the desired transmit signal from the polar transmitter with the detected attenuated amplitude of the output signal to generate the amplitude correction signal.

6. The power amplifier controller circuit of claim 1, wherein the amplitude correction loop comprises:

a gain control circuit receiving the amplitude correction signal and allocating a first portion of the amplitude correction signal to control the power supply and allocating a second portion of the amplitude correction signal to control the one or more variable gain amplifiers.

7. The power amplifier controller circuit of claim 6, wherein the gain control block comprises:

a first filter receiving the amplitude correction signal and outputting a first frequency range of the amplitude correction signal to control the power supply; and

a second filter receiving the amplitude correction signal and outputting a variable gain amplifier correction signal comprising a second frequency range of the amplitude correction signal to control the one or more variable gain amplifiers.

8. The power amplifier controller circuit of claim 7, wherein the gain control block receives a control signal coupled to the output of the second filter, the control signal controlling the average gain of the one or more variable gain amplifiers.

9. The power amplifier controller circuit of claim 7, where the gain control block further subtracts an offset from the first frequency range of the amplitude correction signal based on the average of the second frequency range of the amplitude correction signal and a control signal input.

10. The power amplifier controller of claim 7, wherein the gain control block further comprises:

a first adder coupled to the second filter and summing the variable gain amplifier correction signal and a control signal input to generate a summed output;

a lowpass filter receiving the summed output from the first adder and generating an average summed output; and

a second adder coupled between the lowpass filter and the first filter, the second adder summing the first frequency range outputted from the first filter and the average summed output from the lowpass filter to generate a power supply correction signal to control the power supply.

11. The power amplifier controller circuit of claim 1, wherein the amplitude correction loop further comprises:

an amplitude delay block generating a delayed amplitude component of the desired transmit signal from the polar modulator;

wherein the amplitude correction loop compares the delayed amplitude component of the desired transmit signal from the polar transmitter to the attenuated amplitude of the output signal to determine the amplitude correction signal.

12. The power amplifier control circuit of claim 1, wherein the power supply is a switched mode power supply.

13. The power amplifier control circuit of claim 1, wherein the power supply comprises:

a first power supply with a first efficiency, the first power supply receiving a first portion of the amplitude correction signal in a first frequency range and generating a first adjusted supply output based upon the first portion of the amplitude correction signal; and

a second power supply with a second efficiency higher than the first efficiency, the second power supply receiving a second portion of the amplitude correction signal in a second frequency range lower than the first frequency range and generating a second adjusted supply output based upon the second portion of the amplitude correction signal, the supply voltage including a combination of the first adjusted supply output and the second adjusted supply output.

14. The power amplifier control circuit of claim 13, wherein:

the first power supply is a linear regulator; and

the second power supply is a switched mode power supply.

15. The power amplifier control circuit of claim 13, wherein the amplitude correction loop further comprises:

a power combiner circuit coupled to the first power supply and the second power supply, the power combiner circuit combining the first adjusted supply output and the second adjusted supply output to generate the supply voltage provided to the power amplifier.

16. The power amplifier controller circuit of claim 1, further comprising a phase correction loop to reduce phase distortion generated by the power amplifier, the phase correction loop determining a difference between the phase component of the desired transmit signal from the polar transmitter and the phase of the output signal to generate a feedback phase correction signal, wherein the polar transmitter adjusts the phase component of the desired transmit signal responsive to the feedback phase correction signal.

17. The power amplifier controller circuit of claim 1, further comprising:

a phase delay block receiving the phase component of the desired transmit signal from the polar transmitter and generating a delayed phase component of the desired transmit signal;

a first phase modulator receiving the delayed phase component of the desired transmit signal and generating a delayed phase modulated signal;

a phase comparator comparing the delayed phase modulated signal with the phase of the output signal to generate a phase error signal; and

a second phase modulator receiving the phase component of the desired transmit signal from the polar transmitter and the phase error signal, the second phase modulator shifting the phase of the phase component to reduce phase distortion generated by the power amplifier and modulating the shifted phase component to generate a phase modulated component of the desired transmit signal.

18. A radio frequency (RF) transmitter circuit comprising:

a polar transmitter generating a phase component and an amplitude component of a desired transmit signal;

a power amplifier coupled to receive and amplify an input signal and generate an output signal;

an amplitude correction loop determining an amplitude correction signal indicative of an amplitude difference between the amplitude component of the desired transmit signal from the polar transmitter and an attenuated amplitude of the output signal;

a power supply providing a supply voltage to the power amplifier determined by at least a portion of the amplitude correction signal; and

one or more variable gain amplifiers collectively adjusting the amplitude of the input signal based upon a portion of the amplitude correction signal and at least a portion of the amplitude component of the desired transmit signal from the polar transmitter.

19. A method for controlling a power amplifier, the power amplifier coupled to receive and amplify an input signal and generate an output signal, the method comprising:

receiving from a polar transmitter, a phase component and an amplitude component of a desired transmit signal;

comparing the amplitude component of the desired transmit signal from the polar transmitter and an attenuated amplitude of the output signal to generate an amplitude correction signal indicative of an amplitude difference between the amplitude component of the desired transmit signal from the polar transmitter and the attenuated amplitude of the output signal;

adjusting a power supply voltage or bias to the power amplifier based upon at least a portion of the amplitude correction signal; and

adjusting the amplitude of the input signal based upon a portion of the amplitude correction signal and at least a portion of the amplitude component of the desired transmit signal from the polar transmitter.

20. The method of claim 19, wherein comparing the amplitude component of the desired transmit signal from the polar transmitter and the attenuated amplitude of the output signal comprises:

generating a delayed amplitude component of the desired transmit signal based on an RF path delay between the input signal and the output signal; and

comparing the delayed amplitude component of the desired transmit signal to the attenuated amplitude of the output signal.

21. The method of claim 19, further comprising:

filtering the amplitude correction signal to generate a first frequency range of the amplitude correction signal and a second frequency range of the amplitude correction signal;

allocating the first frequency range of the amplitude correction signal to adjust the supply voltage or bias; and

allocating the second frequency range of the amplitude correction signal to adjust the amplitude of the input signal.

22. The method of claim 19, further comprising:

comparing the phase component of the desired transmit signal from the polar transmitter to the phase of the output signal to generate a phase error signal indicative of a phase difference between the phase component of the desired transmit signal from the polar transmitter and the phase of the output signal; and

shifting the phase of the desired transmit signal responsive to the phase error signal to reduce phase distortion generated by the power amplifier.

23. The method of claim 22, wherein comparing the phase component of the desired transmit signal from the polar transmitter to the phase of the output signal comprises:

generating a delayed phase component of the desired transmit signal based on an RF path delay between the input signal and the output signal; and

comparing the delayed phase component of the desired transmit signal to the phase of the output signal.

24. The method of claim 19, further comprising:

generating a delayed phase component of the desired transmit signal based on an RF path delay between the input signal and the output signal;

modulating the delayed phase component of the desired transmit signal onto a carrier signal to generate a delayed phase modulated signal;

comparing the delayed phase modulated signal to the phase of the output signal to generate a phase error signal;

shifting the phase of the phase component of the desired transmit signal from the polar transmitter responsive to the phase error signal to generate a phase shifted phase component; and

modulating the phase shifted phase component onto the carrier signal.