Dynamic Element Matching with Reduced Switching Noise in Converters
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Solution Overview
Problem
Existing analog-to-digital and digital-to-analog converters face issues with mismatch errors due to fabrication process variations, temperature gradients, and component noise, leading to undesirable artifacts like non-linearity and harmonic distortion, which are not adequately addressed by current dynamic element matching techniques.
Innovation Solution
The proposed solution involves a reduced-switching dynamic element matching apparatus that tracks the usage of unit elements and limits their maximum usage spread, disallows switching in certain instances, and introduces dither to spectrally distribute quantizer noise, thereby reducing noise and distortion caused by timing mismatches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dynamic element matching is used to randomize mismatched elements, then mismatch errors are reduced, but additional UE switching transitions occur causing output noise and distortion
Solution Approach 1:
The patent implements dynamic element matching that adapts the switching behavior of unit elements based on their usage history. The system dynamically adjusts which UEs are selected and when they switch states, using usage counters to track and balance the activation patterns of individual UEs, thereby reducing systematic mismatch errors while controlling switching noise
Solution Approach 2:
The patent changes the operational parameters of unit elements by varying their selection and switching patterns based on usage counters. By modifying which UEs are activated in each conversion cycle and controlling the timing of switching transitions, the system transforms the static mismatch problem into a dynamically managed process that reduces both mismatch errors and switching noise
2Reliability
If unit elements are switched frequently to randomize mapping, then static mismatch artifacts are decreased, but timing mismatches between switching transitions increase causing distortion
Solution Approach 1:
The patent employs usage counters that track the number of times each unit element has been selected or switched. This feedback mechanism allows the system to monitor and balance the usage patterns of individual UEs, adjusting future selections to achieve more uniform usage distribution across all UEs, thereby reducing static mismatch artifacts while controlling switching frequency
Solution Approach 2:
The patent implements periodic switching patterns for unit elements based on their usage counter values. By systematically cycling through UEs in a controlled sequence and using the usage counters to modulate the periodicity of switching for each UE, the system achieves randomization of mismatch effects while maintaining regular switching intervals that minimize timing mismatches
Data Source
AI summary
Apparatus and methods disclosed herein operate to reducing switching artifacts associated with dynamic element matching by sorting a set of unit elements to establish a priority order of selection of a subset of the set of unit elements to use in a next single-sample integration operation. Sorting is achieved by demoting unit elements during the sorting if a usage value associated with the unit element is greater than or equal to a maximum allowable usage spread parameter value. A unit element is promoted during the sorting if a usage value associated with the unit element is less than the maximum allowable usage spread parameter value and the unit element was used in an immediately previous single-sample integration operation.