Continuous closed-loop power control system including modulation injection in a wireless transceiver power amplifier

• US 20040198270A1
• Filed: 03/18/2003
• Published: 10/07/2004
• Est. Priority Date: 11/02/2000
• Status: Active Grant

• Current Assignee: Xueshan Technologies Inc. (Wi-LAN Inc.)
• Original Assignee: Skyworks Solutions Incorporated
• Inventors: Fagg, Russell J., Rozenblit, Dmitriy, Damgaard, Morten, Domino, William J.
• Granted Patent: US 7,099,636 B2
• Time in Patent Office: Days
• US Class Current: 455/126
• CPC Class Codes: H03F 1/0272 by using a signal derived from the output signal
• CPC Class Codes: H03F 2200/294 the amplifier being a low noise amplifier [LNA]
• CPC Class Codes: H03F 2200/372 Noise reduction and elimination in amplifier
• CPC Class Codes: H04B 2001/0416 having gain or transmission power control
• CPC Class Codes: H04W 52/52 using AGC [Automatic Gain Control] circuits or amplifiers

Abstract

A single continuous closed-loop power control feedback system provides seamless power control for a power amplifier and also enables an AM signal to be injected into the power amplifier through the power amplifiers'"'"' control port. The AM signal is developed by an I/Q modulator and supplied to a comparator located in the power control loop. By using leakage from the power amplifier as feedback to a phase locked loop during initial power amplifier power ramp-up, the single continuous closed-loop power control system provides continuous feedback to the phase locked loop during the entire power amplification ramp-up period and eliminates the need for multiple feedback loops.

Claims

1. A closed feedback loop power amplifier circuit, comprising:

a power amplifier;

a power control loop configured to receive an output of the power amplifier and configured to supply a feedback signal;

a phase locked loop configured to supply a phase modulated (PM) signal to the power amplifier and configured to supply an amplitude modulated (AM) signal to the power control loop, the phase locked loop also configured to receive the feedback signal from the power control loop; and

where the power control loop adjusts the output power of the amplifier while applying the AM signal to a control port of the power amplifier.

2. The circuit of claim 1, further comprising a modulator in the phase locked loop, the modulator configured to receive an in-phase (I) and quadrature (Q) component of a transmit signal the modulator configured to develop the AM signal.

3. The circuit of claim 1, further comprising a modulator in the phase locked loop, the modulator configured to receive an in-phase (I) and quadrature (Q) component of a transmit signal, the modulator configured to develop the PM signal.

4. The circuit of claim 1, further comprising:

a comparator;

a first power detector configured to receive the output of the power amplifier and configured to supply a first input to the comparator; and

a second power detector configured to receive the AM signal from a modulator within the phase locked loop and configured to supply a second input to the comparator, where the comparator develops an error signal used to control the instantaneous output power of the power amplifier.

5. The circuit of claim 1, wherein the power control loop develops the feedback signal to the phase locked loop using leakage from the power amplifier.

6. A power amplifier circuit, comprising:

a power amplifier;

a phase locked loop having a modulator, the modulator configured to develop a phase modulated (PM) signal and an amplitude modulated (AM) signal from the in-phase (I) and quadrature (Q) components of a baseband transmit signal; and

a power control feedback loop configured to receive an output of the power amplifier and the AM signal from the modulator, the power control feedback loop configured to control the output power of the power amplifier.

7. The circuit of claim 6, further comprising:

a comparator;

a first power detector configured to receive the output of the power amplifier and configured to supply a first input to the comparator; and

a second power detector configured to receive the AM signal from the modulator and configured to supply a second input to the comparator, where the comparator develops an error signal used to control the output power of the power amplifier.

8. The system of claim 7, wherein the AM signal modulates a control port of the power amplifier.

9. The system of claim 6, further comprising a mixer in the phase locked loop, the mixer configured to receive the AM signal and the PM signals from the modulator and supply a modulated signal to the power amplifier, the modulated signal including the AM signal and the PM signal.

10. The system of claim 9, wherein the power amplifier provides an output signal including an AM signal and a PM signal.

11. A power amplifier circuit, comprising:

a power amplifier;

a phase locked loop coupled to the power amplifier; and

a power control loop including a modulator, the modulator configured to supply a phase modulated (PM) signal to the phase locked loop and configured to supply an amplitude (AM) signal to a control input of the power amplifier.

12. The circuit of claim 11, further comprising a phase inverter in the power control loop, the phase inverter configured to invert the phase of the AM signal and supply a control signal to the power amplifier, the control signal including the AM signal.

13. The circuit of claim 11, wherein the AM signal is developed from baseband in-phase (I) and quadrature (Q) components of a transmit signal supplied to the modulator.

14. The circuit of claim 11, wherein the AM signal modulates the control input of the power amplifier.

15. A power amplifier control circuit, comprising:

a power amplifier;

a power control loop coupled to the power amplifier; and

a phase locked loop coupled to the power control loop, where the power control loop provides a feedback signal to the phase locked loop, the feedback signal derived using leakage from the power amplifier during a time when the power amplifier is not operating.

16. The circuit of claim 15, wherein the power control loop provides a feedback signal to the phase locked loop, the feedback signal derived from the output power of the power amplifier during a time when the power amplifier is operating.

17. A method for providing closed feedback to a power amplifier, the method comprising the steps of:

providing a power amplifier;

receiving an output of the power amplifier in a power control loop, the power control loop configured to supply a feedback signal;

supplying a phase modulated (PM) signal from a phase locked loop to the power amplifier;

supplying an amplitude modulated (AM) signal from the phase locked loop to the power control loop;

receiving in the phase locked loop the feedback signal from the power control loop; and

adjusting the output power of the amplifier while applying the AM signal to a control port of the power amplifier.

18. The method of claim 17, further comprising the steps of:

receiving in a modulator an in-phase (I) and quadrature (Q) component of a transmit signal; and

developing the AM signal and the PM signal in the modulator.

19. The method of claim 17, further comprising the steps of:

supplying the output of the power amplifier to a first power detector;

supplying the output of the first power detector to a first input of a comparator;

supplying the AM signal to a second power detector, the second power detector configured to supply a second input to the comparator; and

developing, in the comparator, an error signal used to control the instantaneous output power of the power amplifier.

20. The method of claim 17, further comprising the step of developing the feedback signal using leakage from the power amplifier.

21. A method for operating a power amplifier, the method comprising the steps of:

providing a power amplifier and a power control loop;

developing a feedback signal in the power control loop; and

providing the feedback signal to a phase locked loop, the feedback signal derived using leakage from the power amplifier during a time when the power amplifier is not operating.

22. The method of claim 21, further comprising the step of deriving the feedback signal from the output power of the power amplifier during a time when the power amplifier is operating.

23. A computer readable medium having a program for providing closed feedback to a power amplifier, the program comprising logic for performing the steps of:

providing a power amplifier;

receiving an output of the power amplifier in a power control loop, the power control loop configured to supply a feedback signal;

supplying a phase modulated (PM) signal from a phase locked loop to the power amplifier;

supplying an amplitude modulated (AM) signal from the phase locked loop to the power control loop;

receiving in the phase locked loop the feedback signal from the power control loop; and

adjusting the output power of the amplifier while applying the AM signal to a control port of the power amplifier.

24. The program of claim 23, further comprising logic for performing the steps of:

receiving in a modulator an in-phase (I) and quadrature (Q) component of a transmit signal; and

developing the AM signal and the PM signal in the modulator.

25. The program of claim 23, further comprising logic for performing the steps of:

supplying the output of the power amplifier to a first power detector;

supplying the output of the first power detector to a first input of a comparator;

supplying the AM signal to a second power detector, the second power detector configured to supply a second input to the comparator; and

developing, in the comparator, an error signal used to control the instantaneous output power of the power amplifier.

26. The program of claim 23, further comprising logic for performing the step of developing the feedback signal using leakage from the power amplifier.

27. A computer readable medium having a program for operating a power amplifier, the program comprising logic for performing the steps of:

providing a power amplifier and a power control loop;

developing a feedback signal in the power control loop; and

providing the feedback signal to a phase locked loop, the feedback signal derived using leakage from the power amplifier during a time when the power amplifier is not operating.

28. The program of claim 27, further comprising logic for performing the step of deriving the feedback signal from the output power of the power amplifier during a time when the power amplifier is operating.

29. A closed feedback loop power amplifier circuit, comprising:

a power amplifier means;

a means for a power control loop configured to receive an output of the power amplifier means and configured to supply a feedback signal;

a means for a phase locked loop configured to supply a phase modulated (PM) signal to the power amplifier means and configured to supply an amplitude modulated (AM) signal to the means for the power control loop, the means for the phase locked loop also configured to receive the feedback signal from the means for the power control loop; and

where the means for the power control loop adjusts the output power of the amplifier means while applying the AM signal to a control port of the power amplifier means.