Power Amplifier Distortion Compensation for Multi-Antenna ACLR Control
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Solution Overview
Problem
Existing methods for updating distortion compensation coefficients in power amplifiers for wireless communication devices face inaccuracies due to variations in electrical lengths of feedback paths, leading to insufficient compensation of nonlinear distortion and elevated adjacent channel leakage ratio (ACLR).
Innovation Solution
A wireless communication device with a distortion compensation unit that operates in two modes: the first mode sets individual inverse functions for each power amplifier and updates their coefficients, while the second mode uses weighted addition of these inverse functions to derive an integrated inverse function for comprehensive distortion compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If feedback signals from multiple antenna elements are multiplexed to update distortion compensation coefficients, then the system can attempt to compensate distortion across all power amplifiers, but the update accuracy deteriorates due to phase differences and delay time differences caused by varying electrical lengths of feedback paths
Solution Approach 1:
The patent divides the distortion compensation into separate processes for each power amplifier. Instead of multiplexing feedback signals from all antenna elements and attempting to update a single distortion compensation coefficient, the system processes feedback signals separately for each power amplifier, updating individual distortion compensation coefficients. This segmentation eliminates the problem of phase differences and delay time differences affecting update accuracy.
Solution Approach 2:
The patent applies local quality by treating each power amplifier's distortion compensation independently. Each power amplifier has its own distortion compensation coefficient that is updated using its corresponding feedback signal, rather than using a unified approach that requires all feedback signals to be perfectly synchronized. This allows each power amplifier to be compensated according to its specific characteristics.
2Measurement precision
If feedback signals are switched in terms of time to calculate error with transmission signals, then phase differences and delay time differences are avoided, but the feedback signals are from different timings so that calculation accuracy of distortion compensation coefficient is deteriorated
Solution Approach 1:
The patent segments the feedback signal processing by associating each feedback signal with its specific power amplifier and timing. Instead of switching feedback signals from different timings and attempting to calculate errors, the system maintains separate processing paths for each power amplifier's feedback signal, ensuring that errors are calculated using feedback signals that correspond to the same transmission signal timing for each individual power amplifier.
3Device complexity
If a single distortion compensation coefficient is updated using multiplexed feedback signals, then the system structure remains simple, but the adjacent channel leakage ratio cannot be sufficiently suppressed across all power amplifiers
Solution Approach 1:
The patent segments the distortion compensation into multiple independent coefficient updates, one for each power amplifier. This requires separate feedback paths and processing for each power amplifier, increasing system complexity. However, this segmentation enables sufficient suppression of adjacent channel leakage ratio across all power amplifiers by ensuring that each power amplifier's distortion is compensated independently and accurately.
Solution Approach 2:
The patent applies local quality by giving each power amplifier its own distortion compensation coefficient and processing path. This allows each power amplifier to be optimized independently for distortion compensation, which is necessary to sufficiently suppress adjacent channel leakage ratio across all power amplifiers, even though it increases overall system complexity.
Data Source
AI summary
A wireless communication device includes: a plurality of power amplifiers provided for a plurality of respective antenna elements, each of the power amplifiers amplifying a signal; a distortion compensation unit that executes distortion compensation of a transmission signal by using an inverse function corresponding to nonlinear distortion generated in the power amplifiers; and a controller that operates by switching a first mode and a second mode, the first mode setting individual inverse functions for the respective power amplifiers in the distortion compensation unit and updating coefficients of the individual inverse functions, the second mode suspending the update of the coefficients of the individual inverse functions and setting, in the distortion compensation unit, an integrated inverse function acquired by performing weighted addition of the individual inverse functions.