Time-Interleaved ADC Filtering for Frequency-Response Mismatch

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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, particularly at high sampling rates, where existing compensation techniques are suboptimal and increase implementation costs.

Innovation Solution

The method employs 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 lower filter orders, capable of handling complex-valued frequency response mismatch errors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If time-interleaved ADC arrays are used to increase sampling rate, then productivity is improved, but manufacturing precision deteriorates due to frequency response mismatch errors

Engineering Contradiction:

Improvesampling rateVSAvoidconversion resolution

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent applies parameter changes by modifying the frequency response characteristics of individual ADC channels through digital filtering. Each channel's output is processed with a compensation filter that adjusts gain, phase, and frequency response parameters to match a reference channel, thereby equalizing the overall system response and restoring conversion resolution despite the use of multiple lower-rate ADCs

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements feedback by measuring the actual frequency response of each ADC channel and using this information to compute compensation filters. The system characterizes each channel's mismatch errors and applies corrective filtering based on this feedback, enabling dynamic adjustment of channel responses to maintain high conversion resolution across the entire time-interleaved array

Inventive Principle:

Principle #23Feedback

2Manufacturing precision

If compensation filters are added to restore resolution, then manufacturing precision is improved, but device complexity increases

Engineering Contradiction:

Improveconversion resolutionVSAvoidfilter implementation complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies segmentation by dividing the compensation filtering operation into separate independent filters for each ADC channel. Instead of implementing a single complex global filter, the system creates M separate filters (where M is the number of channels), each processing its corresponding channel's output independently. This segmentation simplifies the overall implementation while achieving the desired resolution restoration

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent optimizes filter parameters by determining impulse responses through matrix inversions that minimize approximation errors in the least-squares sense. This parameter optimization reduces the filter order required to achieve a given level of compensation accuracy, thereby reducing implementation complexity while maintaining high conversion resolution

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentEP2158679B1Compensation of mismatch errors in a time-interleaved analog-to-digital converter

Publication Date: 2014.06.04 TELEDYNE SIGNAL PROCESSING DEVICES SWEDEN AB

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 h