Power Amplifier Predistortion Coefficient Updating for Linearity
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Solution Overview
Problem
Existing power amplifier apparatuses face challenges in achieving both high power efficiency and linearity due to the complexity of computing Volterra series coefficients, which increases circuit size and complexity in distortion compensation.
Innovation Solution
A power amplifier apparatus that uses a digital signal processor to perform first and second distortion compensation processing on signals, updating distortion compensation coefficients to converge the difference between the processed signals, thereby simplifying the computation of LUT distortion compensation coefficients without directly computing Volterra series coefficients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Volterra series coefficients are computed directly for distortion compensation, then distortion compensation accuracy is improved, but circuit size and complexity increase
Solution Approach 1:
The patent extracts only the necessary distortion compensation coefficients from the Volterra series computation, rather than computing all coefficients. The coefficient updating unit selectively updates only those coefficients that are actually needed for distortion compensation, reducing the computational burden and circuit complexity while maintaining compensation accuracy.
Solution Approach 2:
The distortion compensation process is segmented into multiple stages: initial coefficient setting, iterative updating based on error signals, and selective application of updated coefficients. This segmentation allows the system to achieve accurate compensation through progressive refinement rather than requiring all coefficients to be computed simultaneously, reducing overall system complexity.
2Use of energy by moving object
If power amplifier operates in nonlinear region to increase power efficiency, then power efficiency is improved, but linearity deteriorates
Solution Approach 1:
The predistorter applies preliminary distortion to the input signal that is opposite in nature to the power amplifier's nonlinear distortion. By pre-compensating the signal with inverse distortion characteristics, the overall system maintains linearity even when the power amplifier operates in its nonlinear high-efficiency region.
Solution Approach 2:
The system uses feedback from the power amplifier output to continuously update the distortion compensation coefficients. The error signal generated by comparing the actual output with the expected output is used to adjust the predistorter coefficients, ensuring that linearity is maintained dynamically as operating conditions change.
Data Source
AI summary
A power amplifier apparatus that includes a processor that performs a first distortion compensation processing on an input signal using a distortion compensation coefficient to obtain a first signal and an amplifier that amplifies the first signal. The processor performs a second distortion compensation processing the amplified signal using the distortion compensation coefficient to obtain a second signal and updates the distortion compensation coefficient to enable convergence between the first signal and the second signal.