Predistortion Delay Control for Power Amplifier Linearity
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Solution Overview
Problem
Conventional power amplifiers face a trade-off between linearity and power conversion efficiency, with high linearity requiring low efficiency and vice versa, and existing distortion compensation methods struggle to converge optimal distortion compensation coefficients when signal correlation is high, leading to degraded distortion suppression performance.
Innovation Solution
A power amplification device with a distortion compensation unit that generates predistortion signals using distortion compensation coefficients adjusted based on different delay amounts and controlled by correlation information, allowing for adaptive delay intervals to optimize distortion compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a power amplifier operates in a linear region to maintain high linearity, then the linearity is improved, but the power conversion efficiency deteriorates
Solution Approach 1:
The predistortion signal generating unit applies preliminary anti-action by generating a predistortion signal that pre-compensates for the nonlinear distortion before the signal reaches the power amplifier. This allows the power amplifier to operate in a nonlinear region (high efficiency) while the overall system maintains linearity through the预先 applied inverse distortion characteristics.
Solution Approach 2:
The predistortion signal acts as an intermediary between the input signal and the power amplifier. It introduces inverse nonlinear characteristics that counterbalance the amplifier's nonlinear distortion, enabling the system to achieve high linearity without requiring the amplifier to operate in its linear region, thus maintaining high power conversion efficiency.
2Device complexity
If distortion compensation coefficients are determined only by current time signal amplitude, then the device complexity is reduced, but the distortion suppression effect deteriorates when memory effect is present
Solution Approach 1:
The system dynamically adapts the delay time of the transversal filter based on the correlation between adjacent data sample points. When correlation is high, the delay time is increased to capture memory effects; when correlation is low, the delay time is reduced. This dynamic adjustment optimizes distortion suppression while avoiding unnecessary complexity in static configurations.
Solution Approach 2:
The patent changes the parameter of delay time in the transversal filter based on signal correlation characteristics. By adjusting this parameter dynamically, the system optimizes the distortion compensation performance for different signal conditions without requiring a completely different compensation architecture, thus balancing complexity and effectiveness.
3Device complexity
If the delay time in transversal filter is fixed, then the device complexity is reduced, but the distortion compensation performance deteriorates when signal correlation varies
Solution Approach 1:
The system transforms the fixed delay time structure into a dynamic one by automatically adjusting the delay time based on the correlation between adjacent data sample points. This allows the distortion compensation performance to adapt to varying signal conditions without significantly increasing device complexity, as the adjustment is performed through correlation calculation and automatic control.
Data Source
AI summary
A power amplifier amplifies a signal. An error signal calculating unit calculates an error signal in accordance with an input signal and an output from the power amplifier. A distortion compensation unit performs predistortion on the input signal by using distortion compensation coefficients that are generated in accordance with a plurality of delay signals obtained by giving different amounts of delay to the input signal and by using an error signal and outputs the input signal subjected to the predistortion to the signal amplifying unit. A tap interval control unit controls the delay intervals of the delay signals that are used for the predistortion performed by the distortion compensation unit in accordance with signal correlation information calculated from the input signal.