Adaptive compensation of RF amplifier distortion by injecting predistortion signal derived from respectively different functions of input signal amplitude
First Claim
1. A method for correcting for distortion in an RF power amplifier comprising the steps of:
- (a) monitoring an input signal applied to said RF power amplifier;
(b) monitoring an output signal derived from said RF power amplifier;
(c) measuring error contained in said output signal;
(d) generating a plurality of respectively different signal functions of the input signal monitored in step (a);
(e) controllably adjusting said plurality of respectively different signal functions generated in step (d) in accordance with the error measured in said output signal; and
(f) modifying said input signal in accordance with a combination of said plurality of respectively different signal functions generated in step (d), as controllably adjusted in step (e).
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Abstract
The envelope-dependency of the distortion-introducing behavior of an RF power amplifier is used to derive a predistortion signal, that is derived from a plurality of respectively different work function representative signals. Each work function signal, in turn, is based upon the envelope of the input signal to the RF power amplifier. Prior to being combined into a predistortion control signal, each work function signal is controllably weighted in accordance with an error measurement comparison of the amplifier input signal with the amplifier output signal. The error measurement function yields a measure of the error contained in the-amplifier output signal, and drives a weight adjustment control mechanism, which controllably varies a set of weights for each of in-phase and quadrature components of the respectively different signal functions, in such a manner as to minimize the measured error.
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Citations
25 Claims
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1. A method for correcting for distortion in an RF power amplifier comprising the steps of:
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(a) monitoring an input signal applied to said RF power amplifier; (b) monitoring an output signal derived from said RF power amplifier; (c) measuring error contained in said output signal; (d) generating a plurality of respectively different signal functions of the input signal monitored in step (a); (e) controllably adjusting said plurality of respectively different signal functions generated in step (d) in accordance with the error measured in said output signal; and (f) modifying said input signal in accordance with a combination of said plurality of respectively different signal functions generated in step (d), as controllably adjusted in step (e). - View Dependent Claims (2, 3, 4)
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5. A method for reducing distortion components introduced into an output signal produced by an RF power amplifier, to which an input signal to be amplified thereby is applied, said method comprising the steps of:
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(a) monitoring the instantaneous amplitude of said input signal applied to said RF power amplifier; (b) monitoring said output signal produced by said RF power amplifier; (c) measuring error contained in said output signal; (d) generating a plurality of respectively different signal functions of the input signal monitored in step (a); (e) controllably modifying said plurality of respectively different signal functions generated in step (d) in accordance with the error measured in said output signal; and (f) modifying said input signal in accordance with a combination of said plurality of respectively different signal functions generated in step (d), as controllably modified in step (e). - View Dependent Claims (6, 7, 8, 9)
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10. A signal processing arrangement for reducing distortion components introduced into an output signal produced by an RF amplifier, to which an input signal to be amplified thereby is applied, comprising:
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an error measurement unit which is operative to measure error in the output signal produced by the RF amplifier; a work function signal generator which is operative to generate a plurality of respectively different work function signals based upon the input signal to the RF amplifier; a work function signal adjustment unit which is operative to controllably adjust the plurality of respectively different work function signals generated by said work function signal generator in accordance with the error measured by the error measurement unit; and an input signal predistortion unit which is operative to modify the input signal to the RF amplifier in accordance with the plurality of respectively different work function signals as controllably adjusted by the work function signal adjustment unit. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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18. A signal processing arrangement for reducing distortion components introduced into an output signal produced by an RF amplifier, to which an input signal to be amplified thereby is applied, comprising:
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a work function signal generator which is operative to generate a plurality of respectively different work function signals as functions of the instantaneous amplitude of the input signal to the RF amplifier; an error measurement unit which is operative to measure error in the output signal produced by the RF amplifier; a work function signal adjustment unit which is operative to controllably adjust the work function signals generated by said work function signal generator in accordance with the error measured by the error measurement unit; and an input signal predistortion unit which is operative to modify the input signal to the RF amplifier in accordance with the work function signals as controllably adjusted by the work function signal adjustment unit. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25)
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Specification