Power Amplifier Bias Synchronization for TDD DPD Linearity
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Solution Overview
Problem
In time division duplex (TDD) scenarios, the input signal to the power amplifier (PA) varies between high and low, leading to a mismatch between the learned and actual PA features, which deteriorates the performance of digital predistortion (DPD) systems due to nonlinear behavior.
Innovation Solution
A bias circuit synchronized with the timing feature of the power amplifier's switch signal in TDD scenarios generates a bias signal with varying voltage, stabilizing the PA's feature and improving linear performance by compensating for nonlinear changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the PA works in saturation interval to improve energy conversion efficiency, then energy conversion efficiency is improved, but nonlinear feature deteriorates transmission quality
Solution Approach 1:
The DPD circuit applies predistortion to the input signal before it reaches the PA, pre-compensating for the nonlinear distortion that will be introduced by the PA operating in saturation mode. This preliminary anti-action counteracts the harmful nonlinear effects, allowing the PA to operate efficiently while maintaining transmission quality
Solution Approach 2:
The system uses feedback to continuously monitor and adjust the predistortion parameters. By measuring the actual output of the PA and comparing it with the desired output, the DPD circuit can adaptively update its distortion compensation model, ensuring optimal performance under varying operating conditions
2Adaptability or versatility
If the input signal of PA varies in TDD scenario, then adaptability to TDD is improved, but mismatch between learned and actual PA features deteriorates DPD performance
Solution Approach 1:
The bias circuit dynamically adjusts the bias signal level based on the instantaneous input signal level in TDD mode. When the input signal transitions between high and low states, the bias circuit相应地 adjusts the bias voltage to maintain optimal PA operating conditions, preventing feature mismatch and maintaining DPD performance
Solution Approach 2:
The system changes the bias signal parameter dynamically according to the input signal conditions in TDD scenario. By adjusting the bias voltage level in response to signal variations, the PA's operating point is optimized for different signal levels, maintaining consistent nonlinear characteristics that DPD can accurately model
Data Source
AI summary
This application discloses a wireless communication apparatus and a signal processing method. The wireless communication apparatus includes a power amplifier and a bias circuit. The power amplifier includes a signal input port, a signal output port, a power supply port, and a bias port. The power amplifier is configured to: receive a power supply signal through the power supply port, receive a bias signal through the bias port, receive a radio frequency signal through the signal input port, and output a power amplified radio frequency signal. The bias circuit is configured to generate the bias signal. A timing feature of the bias signal is synchronized with a timing feature of a switch signal of a power amplifier, to compensate for a nonlinear change in the TDD scenario.