Multi-Antenna Digital Pre-Distortion for Shared PA Linearization
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Solution Overview
Problem
In wireless communication systems, power amplifiers operating near the compression point introduce non-linear behavior, leading to degraded adjacent channel leakage power ratio (ACLR) and error vector magnitude (EVM), which affects the efficiency and performance of multi-antenna transmission techniques like MIMO.
Innovation Solution
Implementing a digital pre-distortion (DPD) technique that applies a pre-distorted input signal to power amplifiers to achieve a linear output response, compensating for non-linear behavior by using a single DPD processing circuit for multiple power amplifiers operating at the same compression point, with varying collector voltage and bias adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If power amplifiers operate near the compression point to increase efficiency, then power amplifier efficiency is improved, but non-linear behavior increases causing degraded ACLR and EVM
Solution Approach 1:
The patent applies digital pre-distortion to the input signal before it reaches the power amplifier. The pre-distortion processing circuit modifies the input signal in advance to compensate for the expected non-linear behavior of the power amplifier, thereby canceling out the distortion and achieving linear output while maintaining high efficiency operation near the compression point.
2Reliability
If separate DPD processing circuits are used for each power amplifier in multi-antenna systems, then each amplifier can be individually optimized, but device complexity increases
Solution Approach 1:
The patent implements a single DPD processing circuit that serves multiple power amplifiers in a multi-antenna system. This universal circuit applies pre-distortion to signals destined for multiple amplifiers, reducing the overall system complexity while still enabling effective linearization across all power amplifier channels.
3Use of energy by moving object
If power amplifiers in multi-antenna systems operate at different compression points, then each amplifier can operate optimally, but a single DPD circuit cannot effectively linearize all outputs
Solution Approach 1:
The patent controls all power amplifiers in the multi-antenna system to operate at the same compression point. This equalization of operating conditions ensures that a single DPD processing circuit can effectively linearize the output of all amplifiers, maintaining both system efficiency and linearization effectiveness without requiring multiple separate DPD circuits.
Data Source
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AI summary
Certain aspects of the present disclosure relate to methods and apparatus for power amplifier control. A power amplifier network includes a first path comprising a first power amplifier. The power amplifier network further includes a second path comprising a second power amplifier. The power amplifier network further includes a common input path to both the first path and the second path. The power amplifier network further includes a first power control network for controlling a first signal applied to the first power amplifier. The power amplifier network further includes a second power control network for controlling a second signal applied to the second power amplifier, wherein the first power control network is different from the second power control network.