Dual Predistorter Compensation for Transient Amplifier Distortion
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Solution Overview
Problem
Amplifiers, particularly GaN amplifiers, experience instantaneous changes in distortion due to transient responses like Idq drift, making it challenging for existing distortion compensation techniques to keep up with these changes efficiently.
Innovation Solution
A dual predistorter system is employed, where a first predistorter handles gentle or non-temporally changing distortions and a second predistorter updates distortion compensation characteristics at a higher frequency to address instantaneous changes, with the second predistorter using a wired logic circuit for fast processing and the first predistorter employing a processor for software-based updates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If distortion compensation characteristics are updated frequently to track instantaneous changes in amplifier distortion, then compensation accuracy is improved, but processing load increases
Solution Approach 1:
The distortion compensation system is divided into two independent predistorters: a first predistorter that updates distortion compensation characteristics at a lower frequency, and a second predistorter that updates at a higher frequency. This segmentation allows each predistorter to operate at an optimal update frequency, with the second predistorter handling rapid changes and the first predistorter managing overall compensation, thereby improving accuracy without proportionally increasing processing load.
2Device complexity
If a single predistorter is used to handle all distortion changes, then device complexity is reduced, but compensation speed for instantaneous changes decreases
Solution Approach 1:
The system employs two predistorters with different update frequencies adapted to different types of distortion changes. The second predistorter operates dynamically at a higher frequency to track instantaneous distortion changes, while the first predistorter operates at a lower frequency for stable compensation. This dynamic multi-frequency approach enables the system to respond quickly to rapid changes without requiring all components to operate at maximum speed continuously.
Data Source
AI summary
A distortion compensation device includes: a first predistorter configured to compensate for a distortion in an amplifier; and a second predistorter configured to compensate for the distortion in the amplifier, and update distortion compensation characteristics at a higher frequency than that of the first predistorter.