Adaptive digital predistortion for power amplifiers with real time modeling of memoryless complex gains
First Claim
1. An adaptive method for predistorting a signal to be transmitted, supplied by a signal source to an input of a power amplifier having an output for delivering an amplified output signal, comprising the steps of:
- predistorting the signal to be transmitted by means of predistortion amplitude and phase look-up table means interposed between the signal source and the input of the power amplifier;
producing a first feedback signal in response to the predistorted signal;
producing a second feedback signal in response to the amplified output signal from the power amplifier;
delaying at least one of the first and second feedback signals for eliminating any time lag between said first and second feedback signals;
modeling the power amplifier in response to the first and second feedback signals; and
updating the predistortion amplitude and phase look-up table means in response to said modeling of the power amplifier.
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Abstract
In an adaptive method and device for predistorting a signal to be transmitted, supplied by a signal source to an input of a power amplifier having a output for delivering an amplified output signal, the following steps are conducted: predistorting the signal to be transmitted by means of cascaded predistortion amplitude and phase look-up tables interposed between the signal source and the input of the power amplifier, producing a first feedback signal in response to the predistorted signal, producing a second feedback signal in response to the amplified output signal from the power amplifier, delaying the first feedback signal for eliminating any time lag between the first and second feedback signals, and real time modeling the predistortion amplitude and phase look-up tables in response to the first and second feedback signals in order to update these two tables. The position of the delay circuit (delaying step), that permits the use of the real time modeling procedure, eliminates the convergence time and the requirement for any iterative algorithms.
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Citations
18 Claims
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1. An adaptive method for predistorting a signal to be transmitted, supplied by a signal source to an input of a power amplifier having an output for delivering an amplified output signal, comprising the steps of:
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predistorting the signal to be transmitted by means of predistortion amplitude and phase look-up table means interposed between the signal source and the input of the power amplifier; producing a first feedback signal in response to the predistorted signal; producing a second feedback signal in response to the amplified output signal from the power amplifier; delaying at least one of the first and second feedback signals for eliminating any time lag between said first and second feedback signals; modeling the power amplifier in response to the first and second feedback signals; and updating the predistortion amplitude and phase look-up table means in response to said modeling of the power amplifier. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An adaptive device for predistorting a signal to be transmitted, supplied by a signal source to an input of a power amplifier having an output for delivering an amplified output signal, comprising:
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predistorter means comprising predistortion amplitude and phase look-up table means interposed between the signal source and the input of the power amplifier for amplitude and phase predistorting the signal to be transmitted; means for producing a first feedback signal in response to the predistorted signal from the predistorter means; means for producing a second feedback signal in response to the amplified output signal from the power amplifier; delay means for eliminating any time lag between the first and second feedback signals; means for modeling the power amplifier in response to the first and second feedback signals; and means for updating the predistortion amplitude and phase look-up table means in response to said modeling of the power amplifier. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17)
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18. An adaptive device for predistorting a signal to be transmitted, supplied by a signal source to an input of a power amplifier having an output for delivering an amplified output signal, comprising:
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predistorter means comprising predistortion amplitude and phase look-up table means interposed between the signal source and the input of the power amplifier for amplitude and phase predistorting the signal to be transmitted; means for producing a first feedback signal in response to the predistorted signal from the predistorter means; means for producing a second feedback signal in response to the amplified output signal from the power amplifier; delay means for eliminating any time lag between the first and second feedback signals; and means for updating the predistortion amplitude and phase look-up table means in response to the first and second feedback signals; wherein the predistortion amplitude and phase look-up table means comprises, in cascade, a one-dimensional predistortion amplitude look-up table and a one-dimensional predistortion phase look-up table; wherein said signal to be transmitted comprises an amplitude component and a phase component; and wherein said predistorter means comprises; said one-dimensional predistortion amplitude look-up table for producing a predistorted amplitude in response to the amplitude component of the signal to be transmitted; said one-dimensional predistortion phase look-up table for producing a predistorted phase in response to the predistorted amplitude; and means for combining the phase component of the signal to be transmitted, the predistorted amplitude and the predistorted phase into said predistorted signal.
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Specification