Time-Interleaved ADC Filter Compensation for Mismatch Errors
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Solution Overview
Problem
Time-interleaved Analog-to-Digital Converter (ADC) arrays face challenges in maintaining high resolution due to frequency response mismatch errors, especially at high sampling rates, where existing compensation techniques are either suboptimal or require additional costly components like cosine and sine modulators, and often only address magnitude response mismatch errors.
Innovation Solution
A method using M time-invariant or M-periodic time-varying filters to compensate for frequency-response mismatch errors by determining filter impulse responses through separate matrix inversions, optimizing filters in the least-squares sense for better performance and handling complex-valued frequency response mismatches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If time-interleaved ADC arrays are used to increase sampling rate, then productivity is improved, but measurement precision deteriorates due to frequency response mismatch errors
Solution Approach 1:
The patent implements a feedback mechanism where the output of the time-interleaved ADC array is processed through compensation filters whose parameters are continuously adjusted based on measured frequency response mismatches. The system measures the actual frequency responses of individual ADC channels, calculates optimal filter parameters, and applies these filters to compensate for mismatches, thereby restoring measurement precision while maintaining high sampling rates.
Solution Approach 2:
The patent changes the parameters of compensation filters (specifically the impulse response parameters hr[k]) to optimize performance. By determining these parameters through separate matrix inversions in the least-squares sense, the system adapts the filter characteristics to match the specific frequency response mismatches of each ADC channel, resolving the contradiction between high sampling rate and high resolution.
2Measurement precision
If existing compensation techniques are used to correct magnitude response mismatch errors, then measurement precision is improved, but device complexity increases due to additional cosine and sine modulators
Solution Approach 1:
The patent extracts and compensates only for the frequency response mismatch errors that actually exist in the time-interleaved ADC array, rather than implementing complete compensation for all possible error types. By focusing specifically on frequency response mismatches and using simple compensation filters without additional modulators, the system improves measurement precision while avoiding unnecessary device complexity.
Solution Approach 2:
The patent uses computationally efficient separate matrix inversions to determine filter parameters, replacing complex hardware-based compensation schemes. The compensation filters are implemented in the digital domain using straightforward mathematical operations, achieving effective magnitude and phase mismatch correction without requiring expensive additional analog components like cosine and sine modulators.
3Manufacturing precision
If separate matrix inversions are used to determine filter impulse responses, then manufacturing precision is improved, but calculation time increases
Solution Approach 1:
The patent segments the determination of filter parameters into separate matrix inversions for each ADC channel rather than solving one large coupled system. This segmentation allows each channel's frequency response mismatch to be compensated independently, achieving high manufacturing precision (accurate filter parameters) while reducing computational complexity and time compared to solving a single large matrix inversion problem for all channels simultaneously.
Data Source
AI summary
A method for the compensation of frequency-response mismatch errors in M-channel time-interleaved ADCs. The compensation is done through an M-periodic time-varying filter hn(k)=hn mod M(k) (2), or, equivalently, a set of M time-invariant filters hn(k), n=0, 1, . . . , M−1. The overall compensation system is constructed by determining the M filter impulse responses hn(k) through M separate matrix inversions, where the size of the matrices equals the filter impulse response length. Also, a compensated M-channel time-interleaved ADC based on and performing the method.