Multi-Path Digital Predistortion for Multi-Band PA Linearity
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Solution Overview
Problem
Conventional digital predistortion systems for power amplifiers face challenges in efficiently processing multiple bands with high sampling rates, leading to increased complexity and cost, while failing to correct out-of-band intermodulation distortion effectively.
Innovation Solution
The implementation of a digital predistorter engine with multiple paths and linear transformation blocks that separate and process input samples into distinct bands, allowing for cross-coupling and interpolation to generate a composite predistorted signal, thereby reducing sample rates and processing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional digital predistortion systems process multiple bands with high sampling rates, then transmission quality is maintained, but processing complexity and cost increase
Solution Approach 1:
The patent divides the digital predistortion processing into multiple independent paths, each handling a specific band. The input signal is separated into first and second samples corresponding to different bands, and each path processes its band independently with dedicated digital predistorters. This segmentation reduces the sampling rate requirement for each path while maintaining overall transmission quality.
2Device complexity
If conventional systems use a single power amplifier for multiple bands, then cost is reduced, but out-of-band intermodulation distortion increases
Solution Approach 1:
The patent applies different predistortion characteristics to different bands by providing separate digital predistorter sets for first and second samples. Each path can be optimized with specific predistortion coefficients and characteristics tailored to its band's requirements, enabling effective correction of out-of-band intermodulation distortion while using a single power amplifier.
Data Source
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AI summary
An apparatus relates generally to multi-band digital predistortion. In this apparatus, a single-band digital predistorter engine (400) has first and second sample paths (481, 482). An input stage (491 ) is coupled to receive input samples and configured to separate them into first samples and second samples. The input stage (491 ) provides first and second magnitudes for the first and second samples, respectively. A first set of digital predistorters (441, 443) receives the first samples, the first magnitudes and the second magnitudes. A second set of digital predistorters (445, 447) receives the second samples, the second magnitudes and the first magnitudes. An output stage (492) is coupled to receive predistorted outputs from the first set of digital predistorters (441, 443) and the second set of digital predistorters (445, 447) and is configured to provide a digital predistorted composite signal from the first set of digital predistorters (441, 443) and the second set of digital predistorters (445, 447).