Targeted Spectrum Predistortion for Low-Load DPD Updates
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Solution Overview
Problem
Existing amplifier systems face challenges in efficiently updating distortion compensation characteristics to address instantaneous changes in distortion, particularly in GaN amplifiers, which can degrade bit-error rate performance due to high processing loads required for frequent updates.
Innovation Solution
The implementation of an intermodulation distortion (IMD) filter module to generate a targeted filtered signal, a digital pre-distortion (DPD) coefficient estimation module to update signal generation coefficients, and a distortion compensation processing module to generate a pre-distorted signal, incorporating a gain mask and signal filter based on transmission measurements and requirements, such as 5G New Radio standards, to reduce spectral spreading and improve ACPR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If frequent updating of distortion compensation characteristics is performed to follow instantaneous changes in distortion, then bit-error rate performance is improved, but processing load increases making frequent updates difficult
Solution Approach 1:
The patent extracts only the relevant frequency components (desired signal frequencies and their intermodulation distortion products) from the full feedback signal spectrum. By applying a filter that selectively passes only these frequency components, the system reduces the amount of data that needs to be processed for coefficient updates, thereby lowering the processing load while maintaining accurate distortion compensation for the frequencies that matter.
Solution Approach 2:
The patent applies different processing treatments to different frequency components of the feedback signal. Specifically, it applies gain compensation selectively to certain frequency ranges and uses filtering to emphasize or suppress specific frequency bands. This localized processing approach allows the system to focus computational resources on the frequency components that most impact bit-error rate performance, rather than uniformly processing the entire spectrum.
2Adaptability or versatility
If full feedback signal processing is used to update distortion compensation coefficients, then comprehensive distortion coverage is achieved, but processing complexity and load increase
Solution Approach 1:
The patent extracts only the relevant frequency components (desired signal frequencies and their intermodulation distortion products) from the full feedback signal spectrum. By applying a filter that selectively passes only these frequency components, the system reduces the amount of data that needs to be processed for coefficient updates, thereby lowering the processing load while maintaining accurate distortion compensation for the frequencies that matter.
Solution Approach 2:
The patent applies partial action by selectively processing only the frequency components that are most relevant to distortion compensation performance. Rather than applying uniform processing across the entire feedback signal spectrum, the system focuses computational effort on specific frequency bands where distortion compensation has the greatest impact on bit-error rate, achieving effective distortion coverage with reduced processing complexity.
Data Source
AI summary
Various embodiments of the present disclosure relate to transmitter systems, methods, and instructions for signal predistortion. The transmitter system includes an intermodulation distortion (IMD) filter module configured to filter a detected feedback signal (Yin) to generate a targeted filtered signal (Yout), a digital pre-distortion (DPD) coefficient estimation module configured to update signal generation coefficients based on comparing an input signal (Sin) with the targeted filtered signal (Yout), and a distortion compensation processing module configured to generate a pre-distorted signal (Uout) based on the input signal (Sin) using the updated signal generation coefficients.