Digital Microphone ADC Mismatch Shaping with Randomized DWA
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Solution Overview
Problem
Digital microphones and sensor assemblies face issues with dynamic range and distortion due to mismatch among digital-to-analog converter (DAC) elements, which classic mismatch shaping algorithms like data weighted averaging (DWA) fail to address effectively, resulting in undesirable spectral anomalies.
Innovation Solution
Implementing a dynamic element matching (DELM) entity that selects DAC elements using a modified DWA algorithm combined with a randomized shift in successive sample periods to reduce spectral artifacts, thereby improving mismatch shaping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If classic mismatch shaping algorithms like data weighted averaging (DWA) are used to address DAC element mismatch, then distortion is reduced, but spectral anomalies are introduced that adversely impact sensor performance
Solution Approach 1:
The patent converts the harmful spectral anomalies generated by classic DWA algorithms into beneficial noise shaping. By modifying the DWA algorithm to include randomized element selection and noise shaping filters, the previously harmful spectral artifacts are transformed into shaped noise that can be filtered out, thereby improving overall sensor performance while maintaining distortion reduction.
Solution Approach 2:
The patent changes the parameters of the mismatch shaping algorithm by introducing randomized DAC element selection and modifying the weighting factors in the DWA algorithm. These parameter changes allow the system to reduce spectral anomalies while maintaining effective mismatch compensation, resolving the contradiction between distortion reduction and spectral purity.
2Reliability
If the number of DAC elements is increased to improve dynamic range, then processing capability is enhanced, but mismatch among DAC elements increases due to PVT variation
Solution Approach 1:
The patent implements a feedback mechanism where the modified DWA algorithm continuously monitors and compensates for DAC element mismatch. By using the output of the ADC to adjust the selection and weighting of DAC elements in real-time, the system maintains accurate mismatch compensation even as PVT variations cause drifting in element characteristics, thereby preserving both dynamic range and matching precision.
Solution Approach 2:
The patent introduces dynamic element selection where the weighting factors and element choices in the DWA algorithm are continuously adjusted based on current operating conditions. This dynamic adaptation allows the system to compensate for PVT variations and maintain precise mismatch shaping across changing temperature, voltage, and frequency conditions, resolving the contradiction between increased element count and matching precision.
Data Source
AI summary
The present disclosure relates generally to digital microphone and other sensor assemblies including a transducer and a delta-sigma analog-to-digital converter (ADC) with digital-to-analog converter (DAC) element mismatch shaping and more particularly to sensor assemblies and electrical circuits therefor including a dynamic element matching (DELM) entity configured to select DAC elements based on data weighted averaging (DWA) and a randomized non-negative shift.