Multi-Band Predistortion for PA Linearity at Lower Sampling Rates
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current power amplifier systems in transmitters face challenges in achieving high efficiency and linearity, especially with advanced modulation schemes, due to high peak-to-average ratios and strict out-of-band emission requirements, which lead to increased bandwidth of predistorted signals exceeding the limits of current IC technology.
Innovation Solution
A predistortion sub-system for concurrent multi-band signals uses separate predistorters for each frequency band, leveraging carrier frequency information to reduce the sampling rate and compensate for power amplifier non-linearity, thereby reducing the bandwidth requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If adaptive digital predistortion is applied to compensate for power amplifier non-linearity, then linearity is improved, but bandwidth of the predistorted signal increases
Solution Approach 1:
The patent divides the predistortion process into multiple parallel branches, each handling a specific frequency band or distortion order. By segmenting the overall predistortion function into separate processing paths, the bandwidth requirement for each individual branch is reduced while maintaining overall linearity compensation effectiveness.
2Manufacturing precision
If higher order intermodulation distortion is counteracted, then linearity is improved, but sampling rate requirement increases
Solution Approach 1:
The patent separates the predistortion processing into parallel branches that handle different distortion orders independently. This segmentation allows each branch to process at a lower effective sampling rate while collectively addressing higher order intermodulation distortion, thus reducing the overall sampling rate requirement.
Solution Approach 2:
The patent implements predistortion branches that selectively address specific distortion orders rather than attempting to compensate for all possible distortion components. By focusing on the most significant distortion orders and using parallel processing, the system achieves adequate linearity compensation without requiring excessive sampling rates for complete spectral coverage.
Data Source
AI summary
Systems and methods are disclosed for effecting predistortion of a concurrent multi-band signal to compensate for power amplifier non-linearity. In general, the concurrent multi-band signal contains frequency components occupying multiple frequency bands with no frequency components between adjacent frequency bands. In one embodiment, a transmitter includes a power amplifier that amplifies a modulated concurrent multi-band signal to provide an amplified concurrent multi-band signal. A predistortion sub-system effects predistortion of the modulated concurrent multi-band signal prior to amplification in order to compensate for non-linearity of the power amplifier. The predistortion sub-system includes a number of predistorters each providing predistortion for a different one of the frequency bands of the modulated concurrent multi-band signal. At least one of the predistorters provides predistortion for the corresponding frequency band of the modulated concurrent multi-band signal based on carrier frequency information for the modulated concurrent multi-band signal.