Time-Interleaved ADC Path Randomization for Aperture Delay Mismatch
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Solution Overview
Problem
Multi-ADC systems face challenges with aperture delay mismatch, leading to systematic errors in digital codewords due to timing discrepancies among ADCs, for which existing solutions either introduce additional distortion or are costly and inefficient.
Innovation Solution
A system with selection switch stages and additional conductive paths between ADCs and a voltage source is implemented to randomize aperture delay, using a switch array that provides multiple conductive paths to each sampling capacitor, allowing for random selection and thereby converting systematic noise into white noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple ADCs are used in a time-interleaved system to increase conversion rate, then productivity is improved, but aperture delay mismatch causes systematic errors that worsen measurement precision
Solution Approach 1:
The patent applies dynamics by making the conductive path selection variable and time-varying. Instead of fixed connections between ADCs and voltage sources, the system dynamically selects different conductive paths from a pool of N+1 paths for each sampling operation. This dynamic path selection randomizes the aperture delay characteristics, preventing consistent systematic errors while maintaining high conversion rates through parallel ADC operation.
Solution Approach 2:
The patent implements preliminary action by pre-establishing N+1 conductive paths before the actual sampling process. These additional paths are prepared in advance and can be selectively activated. By having these paths ready beforehand, the system can randomize aperture delay without adding delay during the critical sampling moment, thus maintaining timing precision while eliminating systematic errors.
2Measurement precision
If calibration techniques are used to address offset, gain, and linearity errors, then measurement precision is improved, but aperture delay mismatch remains unresolved and continues to cause systematic errors
Solution Approach 1:
The patent introduces conductive paths as an intermediary element between the ADCs and voltage sources. These intermediate paths serve as a mechanism to randomize aperture delay without directly modifying the ADCs themselves. By placing this intermediary layer, the system can address aperture delay mismatch independently of other calibration processes, complementing existing offset, gain, and linearity corrections while providing specific protection against timing-related systematic errors.
3Measurement precision
If prior attempts to solve systematic aperture delay artifacts are implemented, then measurement precision may be improved, but device complexity increases significantly due to additional circuit components
Solution Approach 1:
The patent applies parameter changes by modifying the conductive path configuration parameter. Instead of changing the fundamental architecture or adding complex circuitry, the system changes the selection of conductive paths from fixed to variable. By having N+1 available paths and selecting different ones for different ADCs or different time intervals, the system achieves error reduction through parameter variation rather than structural complexity. This approach minimizes additional components while effectively randomizing aperture delay.
Data Source
AI summary
A system for randomizing aperture delay in a time interleaved ADC system that includes a plurality of selection switch stages corresponding to each of the ADCs in the system and a second selection switch stage coupled to a voltage source. A plurality of conductors extend between the second selection switch stage and each of the selection switch stages, in excess of the number of ADCs in the system. For each of N ADCs in the system, the selection switch stages and the second selection switch stage support at least N+1 selectable conductive paths extending from each of the sampling capacitors of the ADCs to the voltage source. Random selection of the N+1 paths can randomize aperture delay.