Digital Sensor Assembly With Selective DELM Noise Control
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Solution Overview
Problem
Digital microphones and sensor assemblies face elevated noise levels and reduced signal-to-noise ratio (SNR) due to dynamic element matching (DELM) techniques, which are used to compensate for DAC element mismatch, leading to adverse effects on noise performance.
Innovation Solution
Implementing a control circuit to selectively enable DELM only when the benefits outweigh the noise increase, using a programmable logic control system that determines the threshold based on digital signal magnitude, thereby reducing noise and total harmonic distortion (THD) by dynamically managing DAC element selection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If dynamic element matching (DELM) is used to compensate for DAC element mismatch, then linearity is improved, but noise performance deteriorates and signal-to-noise ratio decreases
Solution Approach 1:
The patent implements a dynamic element matching (DELM) system that dynamically selects and activates specific DAC elements based on real-time signal conditions. The system transitions from static DAC element usage to dynamic selection, where elements are activated or deactivated according to signal magnitude and distortion criteria, thereby optimizing both linearity and noise performance across different operating conditions
Solution Approach 2:
The system monitors signal parameters (magnitude, distortion levels) and changes DAC element activation states accordingly. When distortion exceeds thresholds, the system modifies which DAC elements are active, changing the operational parameters of the DAC to maintain linearity while managing noise impact through selective element usage
2Manufacturing precision
If dynamic element matching (DELM) is used to compensate for DAC element mismatch, then linearity is improved, but signal-to-noise ratio deteriorates
Solution Approach 1:
The system changes operational parameters by selectively activating DAC elements based on signal magnitude and distortion measurements. This dynamic parameter adjustment allows the system to maintain accurate linearity correction while adapting noise characteristics to preserve signal-to-noise ratio under varying signal conditions
3Object-affected harmful factors
If DELM is selectively enabled based on digital signal magnitude, then noise and THD are reduced, but device complexity increases
Solution Approach 1:
The patent implements a feedback control mechanism where the system continuously monitors digital signal magnitude and distortion levels, then feeds this information back to the DELM control logic. This closed-loop feedback enables automatic, condition-based activation of DELM without requiring complex external control, reducing the perceived device complexity while maintaining noise and THD reduction benefits
Solution Approach 2:
The system performs self-monitoring and self-adjustment regarding DELM activation. By autonomously detecting when distortion thresholds are exceeded and automatically enabling DELM accordingly, the system eliminates the need for complex external control circuits, achieving noise and THD reduction through self-service operation
Data Source
AI summary
The present disclosure relates generally to digital microphone and other sensor assemblies including a transducer, a delta-sigma analog-to-digital converter (ADC), a dynamic element matching (DELM) entity configured to compensate for nonlinearity resulting from variation among digital-to-analog conversion (DAC) elements of the ADC, and a control circuit configured to enable and disable the DELM based on a magnitude of a digital signal generated by the ADC.