Power Amplifier Predistortion LUT Offset Correction
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Solution Overview
Problem
Existing distortion compensation apparatuses for power amplifiers in wireless communication devices face challenges in effectively addressing nonlinear distortion and memory effects, leading to deteriorated performance due to offset issues in distortion compensation coefficients, which result in clipping and reduced accuracy.
Innovation Solution
A multi-LUT-type distortion compensation apparatus that employs multiple Look-Up Tables (LUTs) to generate pre-distortion signals by synthesizing multiple distortion compensation coefficients, incorporating offset correction processing to adjust coefficients and prevent clipping, thereby maintaining precision and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple LUTs are used to compensate for nonlinear distortion and memory effects, then distortion compensation performance is improved, but offset issues in distortion compensation coefficients cause clipping and reduced accuracy
Solution Approach 1:
The patent applies preliminary action by performing offset correction processing on distortion compensation coefficients before they are used in distortion compensation. The offset correction unit corrects offsets in advance, preventing coefficient clipping from occurring during the distortion compensation process. This preliminary correction ensures that coefficients remain within valid ranges and maintains accuracy throughout operation.
Solution Approach 2:
The patent implements feedback through a clipping detection mechanism that monitors distortion compensation coefficients. When clipping is detected, the system generates a clipping detection signal that triggers offset correction processing. This feedback loop ensures that coefficient values are continuously monitored and corrected to prevent accuracy degradation, maintaining reliable operation of the multi-LUT distortion compensation system.
2Device complexity
If distortion compensation coefficients are used without offset correction, then device complexity is reduced, but coefficient clipping occurs and compensation performance deteriorates
Solution Approach 1:
The system performs offset correction as a preliminary step before distortion compensation processing. By correcting offsets in advance, the system prevents coefficient clipping without requiring complex real-time intervention mechanisms. This approach adds minimal processing complexity while ensuring compensation accuracy is maintained throughout operation.
Solution Approach 2:
The offset correction unit operates autonomously to correct coefficients without requiring external intervention. The system self-regulates by detecting clipping conditions and automatically applying offset corrections, maintaining compensation accuracy through self-service operation rather than complex external control mechanisms.
Data Source
AI summary
A distortion compensation apparatus for performing distortion compensation processing by applying the inverse properties of distortion properties of the power amplifier to a transmission signal to be input to a power amplifier, includes a plurality of distortion compensation coefficient storage units configured to store a plurality of distortion compensation coefficients used for the distortion compensation processing, an offset correction processing unit configured to subject the distortion compensation coefficient stored in each of the plurality of distortion compensation coefficient storage units to offset correction processing, and to generate distortion compensation coefficients in the case that the offset correction processing has not been performed, corresponding to plurality of distortion compensation coefficient storage units, in a pseudo manner and a distortion compensation processing unit configured to subject the transmission signal to the distortion compensation processing based on the distortion compensation coefficients generated in a pseudo manner.