Power amplifier arrangement and method for memory correction/linearization

• US 20060022751A1
• Filed: 07/28/2004
• Published: 02/02/2006
• Est. Priority Date: 07/28/2004
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Fuller, Arthur Thomas Gerald, Morris, Bradley John
• Granted Patent: US 7,095,278 B2
• Time in Patent Office: Days
• US Class Current: 330/136
• CPC Class Codes: H03F 1/0211 with control of the supply voltage or current
• CPC Class Codes: H03F 1/3258 based on polynomial terms
• CPC Class Codes: H03F 2200/102 A non-specified detector of a signal envelope being used in an amplifying circuit

Abstract

A device, system, and method are provided for a power amplifier arrangement. In embodiments of a Vdd modulated power amplifier arrangement, a memory correction block includes a Vdd predictor for predicting waveform distortions of a Vdd modulated power supply and a main-path corrector for pre-distorting the input to the power amplifier arrangement as a function of the input to the power amplifier arrangement, an input envelope signal determined as a function of the input to the power amplifier arrangement, and an output of the Vdd predictor. Embodiments of the invention provide for operating power amplifier arrangements having memory. In some embodiments, methods of training the Vdd predictor and the main-path corrector of the memory correction block are provided.

Claims

1. A power amplifier arrangement comprising:

a power supply adapted to supply a power supply signal to a power amplifier, the power supply being modulated as a function of an input signal supplied to the power amplifier arrangement;

the power amplifier adapted to receive a modified version of the input signal and amplify the modified version of the input signal to produce an output signal;

wherein the input signal is modified as a function of the input signal supplied to the power amplifier arrangement and a prediction of distortion of the power supply signal supplied to the power amplifier.

2. A power amplifier arrangement according to claim 1, wherein the power amplifier arrangement includes a memory correction module adapted to provide the modified input signal supplied to the power amplifier, the memory correction module modifying the input signal as a function of the input signal to the arrangement and a prediction of distortion of the power supply signal supplied to the power amplifier, the memory correction module being trained as a function of the output signal.

3. A power amplifier arrangement according to claim 2, wherein the memory correction module modifies the input signal as a function of a prediction of distortion of the power supply signal, wherein the distortion results from a dynamic impedance effect of the power amplifier as seen by the power supply.

4. A power amplifier arrangement according to claim 2, wherein the memory correction module modifies the input signal as a function of an input signal envelope of the input signal supplied to the power amplifier arrangement.

5. A power amplifier arrangement according to claim 2, wherein the memory correction module is comprised of:

a Vdd predictor adapted to predict waveform distortion of the power supply signal, wherein the Vdd predictor generates an output that is a function of a target power supply signal, the target power supply signal being modulated as a function of the input signal and unaffected by the waveform distortion; and

a main-path corrector adapted to modify the input signal supplied to the power amplifier arrangement as a function of the input signal supplied to the power amplifier arrangement and the output of the Vdd predictor.

6. A power amplifier arrangement according to claim 5, wherein inputs supplied to the main-path corrector comprise an input signal, the output of the Vdd predictor and an input envelope signal.

7. A power amplifier arrangement according to claim 5, wherein inputs supplied to the Vdd predictor comprise an input envelope signal and the target power supply signal.

8. A power amplifier arrangement according to claim 5, further comprising means for generating an input envelope signal prior to the Vdd predictor and the main-path corrector.

9. A power amplifier arrangement according to claim 1, further comprising means for modulating the power supply signal as a function of the input signal.

10. A power amplifier arrangement according to claim 9, wherein means for modulating the power supply signal are a function of an input envelope signal.

11. A power amplifier arrangement according to claim 9, wherein means for modulating the power supply signal comprise rectification of the input signal.

12. A power amplifier arrangement according to claim 11, wherein means for modulating the power supply signal further comprise filtering of the input signal.

13. A power amplifier arrangement according to claim 2, wherein the memory correction module is an application specific integrated circuit (ASIC).

14. A power amplifier arrangement according to claim 2, wherein the memory correction module is a field programmable gate array (FPGA).

15. A power supply arrangement according to claim 5 further comprising:

a Vdd predictor training function adapted to train the Vdd predictor;

a main path corrector training function adapted to train the main path corrector.

16. A power amplifier arrangement according to claim 15 wherein:

the Vdd predictor training function is adapted to train the Vdd predictor using the target power supply signal, the power supply signal and the input signal;

the main path corrector training function is adapted to train the main path corrector using the modified input signal, the output signal and the power supply signal.

17. A computer useable medium having computer readable program code means embodied therein for performing memory correction in a power amplifier arrangement according to claim 1, the computer readable code means comprising:

code means for predicting waveform distortion of the power supply signal, wherein the code means generates an output that is a function of a target power supply signal, the target power supply signal being modulated as a function of the input signal supplied to the amplifier arrangement and unaffected by the waveform distortion; and

code means for modifying the input signal supplied to the power amplifier arrangement as a function of the input signal to the power amplifier arrangement and the output of the code means for predicting waveform distortion.

28. A wireless communications base station transmitter including a power amplifier arrangement according to claim 1.

29. A communications network including a power amplifier arrangement according to claim 1.

30. A method of providing a signal transmission service over a communications network including a power amplifier arrangement according to claim 1.

18. A method of operating a power amplifier arrangement comprising a power amplifier and a power supply, the method comprising the steps of:

modulating a power supply signal of the power supply as a function of an input signal supplied to the power amplifier arrangement, the power supply signal being supplied to the power amplifier;

modifying the input signal supplied to the power amplifier arrangement as a function of the input signal supplied to the power amplifier arrangement and a prediction of distortion of the power supply signal supplied to the power amplifier.

19. A method according to claim 18, wherein the step of modifying further includes the steps of:

Vdd prediction for predicting waveform distortion of the power supply signal, wherein the Vdd predictor generates an output that is a function of a target power supply signal, the target power supply signal being modulated as a function of the input signal supplied to the amplifier arrangement and unaffected by the waveform distortion; and

main-path correction for modifying the input signal supplied to the power amplifier arrangement as a function of the input signal to the power amplifier arrangement and the output of the Vdd predictor.

20. A method according to claim 18, wherein the step of modifying further comprises converting signals represented in a fixed-point domain to signals represented in a floating-point domain and vice versa.

21. A method according to claim 19, further comprising a training step for determining programmable parameters used during at least one of Vdd prediction and main-path correction.

22. A method according to claim 21, wherein the training step involves using a least squares optmization process according to the equation φ

=[U^H·

U]<sup>−

1</sup>Y where U is a M×

N matrix of system inputs, Y is a M×

1 vector of a corresponding outputs, φ

is a N×

1 vector of the resulting programmable parameters, M is a number of samples captured per iteration, N is a number of discrete sample weightings and superscript H pertaining to U^H represents a conjugate transpose operator.

23. A method according to claim 21, wherein the training step involves segmenting of a solution space into a plurality of ranges to aid in reducing complexity of determining programmable parameters or to enhance performance.

24. A method according to claim 23, wherein a an overlap is provided between adjacent segments in the plurality of ranges.

25. A method according to claim 23, wherein the step of Vdd prediction further comprises the step of interchanging programmable parameters somewhere in the overlap.

26. A method according to claim 23, wherein the step of main-path correction further comprises the step of interchanging programmable parameters somewhere in the overlap.

27. A memory correction module for a power amplifier arrangement comprising:

a Vdd predictor adapted for predicting waveform distortion of the power supply voltage, wherein the Vdd predictor generates an output that is a function of a target power supply voltage, the target power supply voltage modulated as a function of an input supplied to the power amplifier arrangement and unaffected by the waveform distortion; and

a main-path corrector adapted for modifying the input supplied to the power amplifier arrangement as a function of the input to the power amplifier arrangement and the output of the Vdd predictor.