Adaptive predistortion linearized amplifier system employing selective sampling
AssigneePowerwave Technologies, Inc.
InventorRichard Braithwaite
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Abstract
An adaptive predistortion linearized amplifier system employing selective sampling is disclosed. Two selective sampling methods of identifying valid measurements using information from the input signal are disclosed. The selective sampling process improves the convergence properties of tuning algorithms based on minimizing the gain error variance. It also reduces the number of data samples processed by the estimator used in the tuning process.
Claims20
An adaptive predistortion linearized amplifier system, comprising:
- an input receiving an input signal;
- a predistorter coupled to the input and performing a predistortion operation on the input signal using predistortion coefficients and providing a predistorted input signal;
- a power amplifier receiving and amplifying the predistorted input signal and providing an amplified signal;.
- an output coupled to the power amplifier and providing the amplified signal as an output signal;
- and
- an adaptation circuit coupled to the input and output and receiving sampled input and output signals therefrom, the adaptation circuit comprising a selective sampling circuit providing a reduced number of samples derived from the sampled input and output signals using a signal characteristic related to the input signal magnitude and an estimator coupled to the selective sampling circuit and performing an adaptation operation using the reduced number samples to determine updated predistortion coefficients, wherein the adaptation circuit is coupled to the predistorter and provides said updated predistortion coefficients to the predistorter.
A method for adaptive predistortion of an amplifier system having an input, an output and a power amplifier, comprising:
- receiving an input signal at the input of the amplifier system;
- predistorting the input signal using predistortion coefficients;
- amplifying the predistorted input signal and providing the amplified signal to the output as an output signal;
- sampling the input signal to provide input signal samples;
- sampling the output signal to provide output signal samples;
- reducing the number of input and output samples using a characteristic of the input signal related to the input signal magnitude;
- and
- adaptively adjusting the predistortion coefficients using the reduced number of samples.
A method for selecting a subset of time aligned input and output samples of an amplifier system for use in adaptive predistortion of the amplifier system, comprising:
- determining the value of the envelope of the input signal samples or another value related to the magnitude of the input signal;
- comparing said value among a group of N samples;
- selecting the input sample with the largest value in said group;
- and
- selecting an output sample time aligned with said selected input sample.
A method for selecting a subset of time aligned input and output samples of an amplifier system for use in adaptive predistortion of the amplifier system, comprising:
- determining the value of the envelope of the input signal samples or another value related to the magnitude of the input signal;
- determining the rate of change of said value;
- comparing the rate of change to a threshold level;
- selecting the input sample if the rate of change is below said threshold level;
- and
- selecting an output sample time aligned with said selected input sample.
Dependencies are inferred from the claim text.