Power Amplifier Predistortion Circuit With Adaptive Parameter Estimation
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Solution Overview
Problem
Implementing a predistortion circuit in devices with programmable logic to reduce distortion in power amplifiers is challenging due to the need for dynamic parameter generation and adaptation to varying signal conditions.
Innovation Solution
An integrated circuit with a predistortion circuit, sample capture buffers, and an estimator circuit that generates parameters based on output from the power amplifier, using dual-port random access memories and an embedded processor to adapt coefficients for effective distortion reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a predistortion circuit is implemented in a device with programmable logic, then distortion reduction capability is improved, but device complexity increases
Solution Approach 1:
The patent combines the predistortion circuit, estimator circuit, sample capture buffers, and parameter buffers into a single integrated circuit device. This merging approach integrates multiple functions (distortion compensation, parameter estimation, signal capture, and memory management) into one unified system, improving distortion reduction capability while managing overall device complexity through consolidation rather than separate discrete components
Solution Approach 2:
The integrated circuit is designed with configurable logic that can function as both a predistortion circuit for distortion reduction and an estimator circuit for generating parameters. The dual-port random access memory serves multiple purposes: storing captured samples, holding parameter sets, and providing data to both the predistortion and estimator functions. This multi-functionality reduces the need for separate dedicated components, addressing the complexity issue
2Measurement precision
If dynamic parameter generation and adaptation is implemented, then signal quality is improved, but device complexity increases
Solution Approach 1:
The patent implements dynamic parameter adaptation where the estimator circuit continuously generates updated parameter sets based on captured output samples from the power amplifier. The system adapts to varying signal conditions by adjusting predistortion parameters in real-time, improving signal quality across different operating conditions. This dynamic behavior is achieved through feedback from the captured samples to the estimator, enabling the system to respond to changing conditions without requiring overly complex manual intervention
Solution Approach 2:
The system employs feedback by capturing the output signal from the power amplifier through sample capture buffers and feeding it back to the estimator circuit. The estimator uses this feedback information to generate updated parameter sets that compensate for nonlinearities and distortion. This closed-loop feedback mechanism improves signal quality by continuously adapting to actual amplifier behavior, while the feedback path is efficiently managed within the integrated circuit architecture
3Adaptability or versatility
If multiple parameter sets are stored and selected based on power levels, then adaptability is improved, but memory requirements increase
Solution Approach 1:
The patent stores multiple parameter sets in memory, each optimized for different power levels or operating conditions. The system selects and applies the appropriate parameter set based on the current power level of the input signal, enabling adaptation to varying operating conditions. This approach improves adaptability by having pre-computed parameters for different scenarios, while the memory requirement is managed by storing only essential parameter data rather than full signal models
Data Source
AI summary
An integrated circuit having a circuit for reducing distortion in a power amplifier is disclosed. The integrated circuit comprises a predistortion circuit coupled to receive a signal to be amplified; sample capture buffers coupled to an output of the predistortion circuit and an input/output port of the integrated circuit; and an estimator circuit coupled to the sample capture buffers, wherein the estimator circuit generates parameters for the predistortion circuit based upon the output of the predistortion circuit and an output of the power amplifier received at the input/output port of the integrated circuit. A method of reducing distortion in a power amplifier is also disclosed.