Power Amplifier Predistortion Using Real-Time Lookup Table Feedback
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Solution Overview
Problem
Power amplifiers operating in saturation regions produce non-linear output, leading to intermodulation products and harmonics that interfere with system operation, and existing linearization methods are complex, computationally intensive, or limited to specific signal types and bandwidths.
Innovation Solution
A model-free sample-based approach for power amplifier linearization in real-time using a lookup table to pre-distort input signals, with pre-distortion values updated based on comparisons between actual and expected output signals, allowing for dynamic compensation of non-linear amplifier behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If power amplifiers operate in saturation regions to achieve high output powers with high efficiencies, then power efficiency is improved, but non-linearity increases causing intermodulation products and harmonics
Solution Approach 1:
The patent applies pre-distortion to the input signal before amplification, where the pre-distortion values are determined in advance and stored in lookup tables. This preliminary modification of the input signal compensates for the anticipated non-linear distortion that will occur during saturation amplification, allowing the amplifier to operate efficiently while producing a linearized output.
Solution Approach 2:
The patent implements a feedback mechanism where the actual output signal from the power amplifier is compared with the expected linear output signal. The error signal generated from this comparison is used to update and refine the pre-distortion values in the lookup tables, enabling continuous adaptation and optimization of the linearization process.
2Object-generated harmful factors
If existing linearization methods are used to reduce non-linearity, then linearity is improved, but device complexity and computational requirements increase
Solution Approach 1:
The patent replaces complex computational linearization algorithms with simpler lookup tables that store pre-calculated pre-distortion values. Instead of performing heavy real-time computations, the system retrieves pre-computed values from the lookup tables, significantly reducing computational complexity and device requirements while maintaining effective linearization performance.
Solution Approach 2:
The complex computational work of determining distortion compensation values is performed in advance during system initialization or calibration, and the results are stored in lookup tables. This preliminary computation eliminates the need for complex real-time calculations during signal processing, reducing device complexity and computational burden during operation.
3Object-generated harmful factors
If existing linearization methods are used, then linearity is improved, but adaptability to different signal types and bandwidths is limited
Solution Approach 1:
The patent implements dynamic adaptability by allowing the lookup tables to be updated in real-time based on feedback from the actual output signal. The system can adapt to different signal types, bandwidths, and amplifier operating conditions by continuously refining the pre-distortion values, making the linearization process versatile and applicable to various communication scenarios without requiring redesign.
Solution Approach 2:
The patent creates a universal linearization solution that can handle different signal types and bandwidths through the feedback-driven update mechanism. The same basic architecture with lookup tables and feedback comparison can be applied across various power amplifier configurations and signal conditions, making the system multi-functional and highly adaptable without requiring signal-specific customization.
Data Source
AI summary
An apparatus includes at least one processing device configured to obtain samples of an input signal to be amplified and, in real-time, pre-distort at least some of the samples using pre-distortion values from at least one lookup table. The pre-distorted samples are to be converted into an analog signal that is amplified by at least one power amplifier. The pre-distortion values at least partially compensate for a non-linear operation of the at least one power amplifier. The at least one processing device is also configured to compare an output signal generated by the at least one power amplifier to an expected signal to identify errors between the output and expected signals. The at least one processing device is further configured to update one or more pre-distortion values in the at least one lookup table based on the identified errors.