Self-adaptive power amplification
View Patent ↗In one embodiment a mixed-signal adaptive integrated circuit is comprised of a pre-distortion circuit operable to receive an RF input signal and to add a pre-distortion signal to the RF input signal to thereby provide a pre-distorted RF input signal, and a power amplifier coupled to the pre-distortion circuit and operable to receive the pre-distorted RF input signal and to provide an amplified RF output signal. The circuit further comprises a compensation module operable to receive the RF input signal and to provide a compensation signal, an auxiliary amplifier coupled to the compensation module and operable to selectively add the compensation signal to the amplified RF output signal, and a signal analyzer operable to receive and process the RF input signal and an RF output feedback signal to generate a first digital control signal for the pre-distortion circuit and a second digital control signal for the compensation module. A method for adaptive control of such a mixed-signal integrated circuit is also provided.
1. A mixed-signal adaptive integrated circuit receiving an RF input signal and coupled to a power amplifier, comprising:
a first pre-distortion circuit operable to receive the RF input signal and to add a first pre-distortion signal to the RF input signal to thereby provide a first pre-distorted RF input signal which is provided to the power amplifier to provide the amplified RF output signal;
a compensation module operable to receive the RF input signal and to provide a compensation signal, wherein the compensation module is coupled to an auxiliary amplifier which receives the compensation signal and is operable to amplify the compensation signal, to selectively add the amplified compensation signal to the amplified RF output signal when a burst pulse appears in the amplified RF output signal, and to provide a compensated output signal; and
a signal analyzer operable to process the RF input signal and the compensated output signal to generate, based on an error signal derived from digitally delay-matching the RF input signal and the compensated output signal, a first digital control signal for the first pre-distortion circuit, and a second digital control signal for the compensation module, wherein the first digital control signal provides a group of coefficients for a polynomial function of an envelope of the RF input signal.
2. The circuit of claim 1 , wherein the group of coefficients of the first digital control signal adaptively vary with time to adjust the first pre-distortion circuit.
3. The circuit of claim 1 , wherein the second digital control signal includes a time delay control signal.
4. The circuit of claim 1 , wherein the second digital control signal includes a group of coefficients to adjust a post-cancellation circuit.
5. The circuit of claim 1 , wherein the second digital control signal includes a delay, magnitude, and phase matching signal.
6. The circuit of claim 1 , wherein the compensation module includes a delay circuit operable to delay the RF input signal and a post-cancellation circuit operable to receive the delayed RF input signal and to provide the compensation signal to the auxiliary amplifier.
7. The circuit of claim 1 , wherein the compensation module includes a delay, magnitude, and phase matching circuit controlled by minimizing RF error power.
8. The circuit of claim 1 , wherein the compensation module includes a delay, magnitude, and phase matching circuit controlled by minimizing an out-of-band emission of the RF feedback signal.
9. The circuit of claim 1 , wherein the signal analyzer includes a digital controller to provide the first and second digital control signals.
10. The circuit of claim 9 , wherein the digital controller comprises one of a microprocessor and a digital signal processor.
11. The circuit of claim 1 wherein the auxiliary amplifier is operable not to receive the first pre-distortion signal and not to receive the first pre-distorted RF input signal.
12. The circuit of claim 11 wherein the compensation module comprises a second pre-distortion circuit operable to effect pre-distortion in the compensation signal for the auxiliary amplifier.
13. The circuit of claim 1 wherein the compensation module comprises a second pre-distortion circuit operable to effect pre-distortion in the compensation signal for the auxiliary amplifier.
14. The circuit of claim 1 wherein the compensation signal is a version of the RF input signal and is amplified by the auxiliary amplifier.
15. A method for adaptive control of a mixed-signal integrated circuit, the mixed-signal integrated circuit receiving an RF input signal and coupled to a power amplifier, the method comprising:
receiving the RF input signal at a first pre-distortion circuit;
adding a first pre-distortion signal to the RF input signal to provide a first pre-distorted RF input signal to the power amplifier;
generating an amplified RF output signal from the power amplifier;
receiving the RF input signal into a compensation module to provide a compensation signal;
receiving the compensation signal into an auxiliary amplifier to provide an amplified compensation signal when a burst pulse appears in the amplified RF output signal;
selectively adding the amplified compensation signal to the amplified RF output signal to provide a compensated output signal; and
analyzing the RF input signal and the compensated output signal to generate, based on an error signal derived from digitally delay-matching the RF input signal and the compensated output signal, a first digital control signal for providing the first pre-distortion signal and a second digital control signal for providing the compensation signal, wherein the first digital control signal provides a group of coefficients for a polynomial function of an envelope of the RF input signal.
16. The method of claim 15 , further comprising extracting information from analyzing the RF input signal and the compensated output signal, the information including gain, group delay, and waveform distortion.
17. The method of claim 15 , further comprising generating an optimized bias voltage signal for one of the power amplifier and the auxiliary amplifier from analyzing the RF input signal and the compensated output signal.
18. The method of claim 15 , wherein the first digital control signal controls the first pre-distortion circuit.
19. The method of claim 15 , wherein the second digital control signal includes a time delay signal.
20. The method of claim 15 , wherein the second digital control signal includes a group of coefficients that controls the post-cancellation circuit.
21. The method of claim 15 , wherein the second digital control signal includes a delay, magnitude, and phase matching signal.
22. The method of claim 15 wherein the auxiliary amplifier does not receive the first pre-distortion signal and does not receive the first pre-distorted RF input signal.
23. The method of claim 22 wherein the compensation module comprises a second pre-distortion circuit which effects pre-distortion in the compensation signal for the auxiliary amplifier.
24. The method of claim 15 wherein the compensation module comprises a second pre-distortion circuit which effects pre-distortion in the compensation signal for the auxiliary amplifier.
25. The method of claim 15 wherein the compensation signal is a version of the RF input signal and is amplified by the auxiliary amplifier.
26. An amplifier circuit operable to amplify an RF input signal and to provide an output signal comprising an amplified version of the RF input signal, the amplifier circuit comprising:
a first module operable to amplify the RF input signal and to provide a first output signal comprising a first amplified version of the RF input signal, the first module comprising:
a first pre-distortion subsystem operable to receive the RF input signal and to provide a first pre-distorted RF input signal according to a group of coefficients for a polynomial function of an envelope of the RF input signal; and
a first amplifier coupled to the first pre-distortion subsystem and operable to receive and amplify the first pre-distorted RF input signal and to provide the first output signal;
a post-cancellation module coupled to an auxiliary amplifier, wherein (a) the post-cancellation module is operable to receive the RF input signal and to provide a second output signal which is combined with the first output signal to provide the output signal of the amplifier circuit, and (b) the second output signal either comprises, when the first output signal is clipped by saturation of the first amplifier, a second amplified version of the RF input signal generated by the auxiliary amplifier or is a predefined value; and
a signal analyzer operable to process the RF input signal and the output signal of the amplifier circuit to generate, based on an error signal derived from digitally delay-matching the RF input signal and the compensated output signal, one or more control signals for the first module and the post-cancellation module.
27. The circuit of claim 26 , wherein the control signals comprise signals representing values of the group of coefficients and wherein the values of the group of coefficients adaptively vary.
28. The circuit of claim 26 wherein the post-cancellation module comprises a second pre-distortion subsystem operable to receive the RF input signal and to provide a second pre-distorted RF input signal for pre-distorting the second amplified version of the RF input signal.
29. An amplification method performed by an amplifier circuit for amplifying an RF input signal and providing an output signal comprising an amplified version of the RF input signal, the amplification method comprising:
in a first module amplifying the RF input signal and providing a first output signal comprising a first amplified version of the RF input signal, the amplifying by the first module comprising:
a first pre-distortion subsystem receiving the RF input signal and providing a first pre-distorted RF input signal according to a group of coefficients for a polynomial function of an envelope of the RF input signal; and
a first amplifier coupled to the first pre-distortion subsystem and receiving and amplifying the first pre-distorted RF input signal and providing the first output signal;
in a post-cancellation module receiving the RF input signal and providing a second output signal which is combined with the first output signal to provide the output signal of the amplifier circuit, wherein the second output signal either comprises, when the first output signal is clipped by saturation of the first amplifier, a second amplified version of the RF input signal generated by an auxiliary amplifier or is a predefined value; and
in a signal analyzer, processing the RF input signal and the output signal of the amplifier circuit to generate, based on an error signal derived from digitally delay matching the RF input signal and the compensated output signal, one or more control signals for the first module and the post-cancellation module.
30. The method of claim 29 wherein the post-cancellation module comprises a second pre-distortion subsystem receiving the RF input signal and providing a second pre-distorted RF input signal for pre-distorting the second amplified version of the RF input signal.
31. The method of claim 29 , wherein the control signals comprise signals representing values of the group of coefficients and wherein the values of the group of coefficients adaptively vary.