Power Amplifier Predistortion for Wideband Linearity Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional power amplifier linearization techniques are limited in their ability to correct nonlinear distortion, especially at high power levels and varying operating conditions, leading to inefficiencies and interference in RF systems.
Innovation Solution
An adaptive predistortion linearization technique using higher-order polynomial models and real-time adaptive calibration to track and correct nonlinear distortion across a wide range of power levels, frequencies, and environmental conditions, incorporating advanced processing to adjust gain and phase shift filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional predistortion techniques with second-order or third-order polynomial transfer functions are used, then the linearity of power amplifier is improved, but the accuracy is insufficient for advanced RF systems with very high instantaneous bandwidths
Solution Approach 1:
The patent changes the parameter of polynomial order from traditional second-order or third-order to higher-order (fourth-order or above) transfer functions. This parameter change enables the system to accurately model and cancel irregular nonlinearities that cannot be captured by lower-order polynomials, thereby improving both linearity accuracy and distortion cancellation effectiveness in advanced RF systems with very high instantaneous bandwidths.
2Device complexity
If a single transfer function is used for power amplifier linearization, then the implementation is simple, but the technique is not suitable when operating conditions vary such as temperature, time, or frequency
Solution Approach 1:
The patent implements dynamic adaptability by making the transfer function parameters variable based on operating conditions. The system dynamically adjusts the higher-order transfer function parameters according to changes in temperature, time, and frequency, enabling the linearization technique to maintain accuracy across varying operating conditions while preserving implementation simplicity through a unified adaptive framework.
Solution Approach 2:
The patent changes the parameters of the transfer function to adapt to varying operating conditions. By modifying the higher-order transfer function parameters based on temperature, time, and frequency variations, the system maintains accurate linearization performance across different operating environments without requiring completely different transfer functions for each condition.
3Loss of energy
If power amplifier operates at high power levels to maximize efficiency, then the efficiency is improved, but the amplifier becomes more non-linear causing signal compression and spectral splatter
Solution Approach 1:
The patent applies preliminary action by implementing higher-order predistortion before the signal enters the power amplifier. The higher-order transfer function pre-compensates for the nonlinearities that will occur at high power levels, including irregular distortions that lower-order models cannot capture. This preliminary correction enables the amplifier to operate efficiently at high power levels while maintaining signal linearity and preventing spectral splatter.
Data Source
AI summary
The present invention provides an advanced adaptive predistortion linearization technique to dramatically reduce nonlinear distortion in power amplifiers over a very wide instantaneous bandwidth (up to 2 GHz) and over a wide range of amplifier types, input frequencies, signal types, amplitudes, temperature, and other environmental and signal conditions. In an embodiment of the invention, the predistortion linearization circuitry comprises (1) a higher-order polynomial model of an amplifier's gain and phase characteristics—higher than a third-order polynomial model; (2) an adaptive calibration technique; and (3) a heuristic calibration technique. The higher-order polynomial model is generated by introducing, for example, a plurality of multi-tone test signals with varying center frequency and spacing into the power amplifier. From the power amplifier's corresponding output, the nonlinearities are modeled by employing a higher-order curve fit to capture the irregularities in the nonlinear transfer function. Different distortion transfer functions can be implemented for different operating conditions. The adaptive calibration technique is based on a feedback analysis technique, which updates the applicable distortion transfer function by analyzing the error signal between the introduced input signal and the output signal in real-time. The heuristic calibration technique implements different distortion transfer functions based on historical operating conditions and optimal configurations of the power amplifier.