Adaptive digital predistortion linearization and feed-forward correction of RF power amplifier
First Claim
1. A method for correcting amplitude and phase distortion of an RF power amplifier comprising:
- (a) performing RF amplifier distortion measurements upon a digitized baseband input signal that is exclusive of RF amplifier distortion and is representative of the complex waveform of a signal to be up-converted and amplified by said RF power amplifier and upon a digitized baseband output signal representative of the complex waveform of an amplified output signal derived from said RF power amplifier, so as to generate complex weights representative of said amplitude and phase distortion of said RF power amplifier; and
(b) performing at least one ofpredistorting said digitized baseband input signal to be converted to analog format, up-converted from baseband, and applied to said RF power amplifier, in accordance with a first complex weight selected in accordance with an input signal to be amplified by said RF power amplifier, andmodifying said digitized baseband input signal in accordance with a second complex weight selected in accordance with said input signal to be amplified by said RF power amplifier, so as to derive a baseband feed-forward correction signal, converting said baseband feed-forward correction signal to analog format, up-converting from baseband the analog feed-forward correction signal and combining the up-converted analog feed-forward correction signal with an amplified output signal from said RF power amplifier.
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Abstract
A digitally implemented, look-up table-based, predistortion and feed-forward correction signal processing mechanism compensates for distortion generated in the RF power amplifier. The input signal to the RF amplifier is stored for comparison with the measured the RF output. In each of predistortion and feed-forward signal processing paths, the magnitude of the complex waveform of the input signal is extracted to derive a read-out address to a dual-port RAM which stores weights to be multiplied by the input signal. In the predistortion signal processing path, the product is coupled to the RF power amplifier. In the feed-forward correction loop, the product is amplified by an auxiliary feed-forward RF amplifier and coupled into the amplified output signal path of the RF power amplifier.
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Citations
14 Claims
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1. A method for correcting amplitude and phase distortion of an RF power amplifier comprising:
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(a) performing RF amplifier distortion measurements upon a digitized baseband input signal that is exclusive of RF amplifier distortion and is representative of the complex waveform of a signal to be up-converted and amplified by said RF power amplifier and upon a digitized baseband output signal representative of the complex waveform of an amplified output signal derived from said RF power amplifier, so as to generate complex weights representative of said amplitude and phase distortion of said RF power amplifier; and (b) performing at least one of predistorting said digitized baseband input signal to be converted to analog format, up-converted from baseband, and applied to said RF power amplifier, in accordance with a first complex weight selected in accordance with an input signal to be amplified by said RF power amplifier, and modifying said digitized baseband input signal in accordance with a second complex weight selected in accordance with said input signal to be amplified by said RF power amplifier, so as to derive a baseband feed-forward correction signal, converting said baseband feed-forward correction signal to analog format, up-converting from baseband the analog feed-forward correction signal and combining the up-converted analog feed-forward correction signal with an amplified output signal from said RF power amplifier. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A signal processing arrangement for correcting for amplitude and phase distortion in an RF power amplifier comprising:
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a digital distortion measurement unit which is operative to perform RF amplifier distortion measurements upon a digitized baseband input signal that is exclusive of RF amplifier distortion and is representative of the complex waveform of a signal to be up-converted and amplified, by said RF power amplifier and upon a digitized baseband output signal representative of the complex waveform of an amplified output signal derived from said RF power amplifier, and thereby produce first complex weights representative of said amplitude and phase distortion of said RF power amplifier; and a predistortion unit which is operative to predistort said digitized baseband input signal to be converted to analog format, up-converted from baseband, and applied to said RF power amplifier in accordance with a first complex weight produced by said distortion measurement unit, that is selected in accordance with an input signal to be amplified by said RF power amplifier. - View Dependent Claims (12, 13, 14)
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Specification