Time-Interleaved ADC Compensation Using Fixed Differentiator Filters
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Solution Overview
Problem
Existing methods for compensating frequency response mismatch errors in M-channel time-interleaved Analog-to-Digital Converter (ADC) arrays are cumbersome and costly, particularly for high-resolution, high-speed applications, as they often require online filter design and additional components like cosine and sine modulators.
Innovation Solution
A compensation method using fixed filters that approximate differentiators of various orders and a few variable multipliers, directly corresponding to parameters in polynomial models of the M channel frequency responses, allowing for economical implementation and adjustment of multipliers as channel frequency responses change.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If online filter design is used to compensate frequency response mismatch errors, then compensation accuracy is improved, but device complexity and implementation cost increase
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing compensation filter coefficients offline before the ADC system operates. The complex filter design process is performed in advance using polynomial models of channel frequency responses, and the resulting coefficients are stored in memory for direct use during operation. This eliminates the need for real-time filter design while maintaining high compensation accuracy.
Solution Approach 2:
The patent replaces the mechanical/computational process of online filter design with a stored lookup table approach. Instead of performing complex filter design calculations in real-time, the system substitutes this with pre-computed coefficient tables that are simply retrieved and applied during operation, significantly reducing implementation complexity.
2Reliability
If additional components like cosine and sine modulators are added to compensate frequency response mismatch errors, then compensation effectiveness is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the need for additional cosine and sine modulator components by using an alternative approach based on pre-calculated compensation coefficients. The complex modulation hardware is removed entirely, replacing it with a simpler system that uses polynomial models and stored coefficients to achieve the same compensation effectiveness.
Solution Approach 2:
The patent uses polynomial models as simplified copies or representations of the actual channel frequency responses. Instead of using complex physical modulators, the system creates mathematical models of the channel characteristics and uses these models to generate compensation coefficients, achieving the same effect with simpler means.
3Device complexity
If fixed filters approximating differentiators are used instead of online filter design, then device complexity is reduced, but adaptability to frequency response changes decreases
Solution Approach 1:
The patent introduces dynamics by making the compensation system adaptable to changing frequency responses through adjustable coefficient tables. While the filter structure itself is fixed and simple, the system can dynamically update the compensation coefficients stored in memory when channel frequency responses change, maintaining adaptability without increasing structural complexity.
Solution Approach 2:
The patent changes parameters by allowing the compensation coefficients to be adjusted based on measured channel frequency responses. When frequency responses drift or change, the system re-calculates and updates the polynomial coefficients and stored tables, maintaining compensation effectiveness without requiring complex re-design of the filter structure.
Data Source
AI summary
A method for the compensation of frequency-response mismatch errors in M-channel time-interleaved ADCs. The compensation is done utilizing a technique that makes use of a number of fixed filters, that approximate differentiators of different orders, and a few variable multipliers that directly correspond to parameters in polynomial models of the M channel frequency responses. A compensated M-channel time-interleaved ADC is based on and can perform the method.