Undersampling Observation Receiver for Multi-Band PA DPD
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Solution Overview
Problem
Power amplifier systems in wireless communication face challenges in achieving high efficiency and linearity due to high peak-to-average ratios of signals and strict out-of-band emission requirements, leading to bandwidth expansion issues in digital predistortion, which exceeds the sampling rate limits of current IC technology.
Innovation Solution
An undersampling observation receiver is used in a power amplifier digital predistortion system to process concurrent multi-band signals by selecting a sampling rate that allows frequency-flipped images of original frequency bands to fall within a frequency range of zero to half of the sampling rate, without overlapping, thereby reducing the required sampling rate and aliasing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If digital predistortion is applied to compensate for power amplifier non-linearity, then linearity is improved, but bandwidth expansion occurs causing sampling rate to exceed IC technology limits
Solution Approach 1:
The patent segments the multi-band signal into separate frequency bands, processing each band independently through separate observation receivers. This segmentation allows each receiver to operate at a lower sampling rate appropriate for its specific bandwidth requirements, rather than requiring a single high sampling rate to handle the entire aggregated bandwidth of all bands combined.
Solution Approach 2:
The patent transforms the time-domain sampling problem into a frequency-domain solution by using frequency-selective filtering and band-specific observation receivers. Instead of sampling the entire wideband signal at a high rate in the time domain, the system processes different frequency bands separately, effectively moving the problem from a time-domain sampling constraint to a frequency-domain resource allocation approach.
2Measurement precision
If higher sampling rate is used to process predistorted signal, then signal processing accuracy is improved, but hardware cost and power consumption increase
Solution Approach 1:
The patent applies local quality by assigning different sampling rates to different frequency bands based on their specific bandwidth requirements. Each observation receiver is configured with a sampling rate optimized for its assigned band, rather than using a uniformly high sampling rate across all bands. This localized optimization maintains signal processing accuracy where needed while reducing power consumption in bands with lower bandwidth requirements.
3Manufacturing precision
If bandwidth of predistorted signal increases to counteract higher order distortion, then linearity performance is improved, but sampling rate requirement exceeds IC technology limits
Solution Approach 1:
The patent divides the wideband signal into multiple narrower frequency bands, each processed by a separate observation receiver. This segmentation allows the system to achieve the necessary linearity performance for each band without requiring a single receiver to handle the entire aggregated bandwidth, thereby avoiding the need for excessively high sampling rates that would exceed IC technology capabilities.
Data Source
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AI summary
The present disclosure relates to an undersampling observation receiver (22) for use in a power amplifier digital predistortion system (10) for concurrent multi-band signals. In one embodiment, an undersampling observation receiver (22) receives a concurrent multi-band signal output by a power amplifier (18). The concurrent multi-band output signal includes multiple original frequency bands. The undersampling observation receiver (22) undersamples the concurrent multi-band signal at a select sampling rate to provide an undersampled multi-band signal. The select sampling rate is such that a frequency-flipped image of at least one of the original frequency bands and images of any remaining original frequency bands fall within a frequency range of zero to half of the select sampling rate and do not overlap one another.