DPD Feedback Filtering for Targeted Spectrum Emission Control
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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, due to high processing loads associated with 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 gain masks and signal filters based on transmission measurements and standards, such as 5G New Radio (NR) specifications, to reduce distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If frequent updating of distortion compensation characteristics is performed to follow instantaneous changes in distortion, then the accuracy of distortion compensation is improved, but the processing load increases making frequent updates difficult
Solution Approach 1:
The patent extracts and removes unnecessary frequency components from the feedback signal through filtering. By eliminating out-of-band signals and intermodulation distortion products that fall outside the desired transmission band, the system reduces the amount of data requiring processing while maintaining accuracy for the relevant frequency components, thus resolving the contradiction between compensation accuracy and processing speed
Solution Approach 2:
The patent applies selective filtering to different frequency components of the feedback signal. Rather than processing the entire spectrum uniformly, the system focuses computational resources on the specific frequency bands of interest (the transmission band), applying appropriate filtering and compensation only where needed. This localized approach improves processing efficiency while maintaining accuracy for the critical frequency components
2Reliability
If the entire feedback signal is processed for distortion compensation, then comprehensive distortion correction is achieved, but the processing load and complexity increase
Solution Approach 1:
The patent extracts only the necessary frequency components from the full feedback signal for processing. By using filters to remove out-of-band signals and unwanted intermodulation products, the system processes a reduced subset of the feedback signal that contains the essential distortion information for the transmission band, thereby reducing processing complexity while maintaining compensation reliability
Solution Approach 2:
The patent applies partial processing by focusing computational effort only on the relevant frequency components within the transmission band. Rather than attempting to compensate for all frequency components equally, the system performs targeted compensation on the partial set of frequencies that matter for the application, reducing overall processing complexity while maintaining effective distortion correction
Data Source
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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.