Delta-Sigma ADC Feedback Circuit With Adaptive Current Segments
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Solution Overview
Problem
Digital microphone assemblies face challenges in reducing power consumption while maintaining high dynamic range, as the digital-to-analog converter (DAC) requires significant feedback current, leading to increased power usage.
Innovation Solution
A multibit delta-sigma analog-to-digital converter (ADC) with a DAC having selectively enabled current elements, where only active segments contribute to the feedback signal during sampling periods, reducing power consumption without compromising dynamic range by adaptively activating fewer current elements based on signal magnitude.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the DAC provides high feedback current to the ADC input to achieve high dynamic range, then the dynamic range is improved, but the power consumption increases significantly
Solution Approach 1:
The patent applies dynamics by making the feedback current adaptive rather than fixed. The DAC adjusts its feedback current level dynamically based on the actual signal characteristics and noise floor conditions, enabling the system to maintain high dynamic range when needed while reducing power consumption during normal operation. This is achieved through control circuits that modulate the feedback current in response to signal conditions.
Solution Approach 2:
The patent changes the parameter of feedback current from a fixed high value to a variable value that adapts to signal conditions. By modifying the feedback current parameter dynamically based on measured noise floors and signal levels, the system achieves high dynamic range performance only when necessary, thereby reducing overall power consumption while maintaining measurement precision.
2Reliability
If the DAC provides high feedback current to maintain signal quality, then the audio quality is preserved, but the power consumption increases
Solution Approach 1:
The system dynamically adjusts feedback current based on actual audio signal conditions rather than maintaining a fixed high current. The control circuits monitor signal levels and noise floors, activating high feedback current only when signal quality would otherwise degrade, thus preserving audio quality reliability while minimizing power consumption during normal operation.
Solution Approach 2:
The patent implements periodic measurement of noise floors and signal characteristics, using these periodic assessments to adjust feedback current levels. This periodic action ensures audio quality is maintained through regular quality checks and adjustments while avoiding continuous high power consumption, as the system only activates full feedback current when measurement indicates quality degradation.
Data Source
AI summary
A sensor signal processing circuit including a delta-sigma analog-to-digital converter (ADC) and a control circuit is disclosed. The circuit is configured to adaptively activate one or more segments of current elements for sequential sampling periods based on a digital signal input to a DAC, wherein less than N current elements are allocated to each segment, each current element in an active segment is enabled and either contributes to a feedback signal of the DAC or does not contribute to the feedback signal, and current elements not in an active segment are disabled. The circuit can be integrated with an acoustic or other sensor as part of a sensor assembly.