Adaptive ADC Paths in Digital Microphones for Low-Power High DR
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Solution Overview
Problem
Conventional digital microphones face challenges in achieving high dynamic range (DR) while maintaining low power consumption, often requiring excessive power or introducing noise artifacts due to limitations in analog-to-digital converter (ADC) design and signal processing.
Innovation Solution
The implementation of an adaptive ADC range multipath digital microphone system, which employs multiple ADCs with different gain settings and noise profiles to cover a wide dynamic range, using capacitive feedback networks and variable sampling capacitance to adjust gain dynamically based on sound pressure levels, and incorporates glitch removal components to minimize audible artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high DR ADC is employed to achieve high dynamic range, then the dynamic range is improved, but the power consumption increases excessively
Solution Approach 1:
The dynamic range is segmented into multiple ranges, each handled by a separate ADC path with optimized gain settings. A first ADC path handles lower signal levels with higher gain, while a second ADC path handles higher signal levels with lower gain, allowing each path to operate efficiently within its optimized range without requiring excessive power for the full dynamic range
Solution Approach 2:
The system dynamically switches between different ADC paths based on the input signal level. An envelope detector monitors the signal amplitude and controls a multiplexer to select the appropriate ADC path, enabling the system to adapt its power consumption and performance characteristics to the actual operating conditions
2Measurement precision
If automatic gain control amplifier (AGC) is employed to lower ADC DR requirements, then the dynamic range is improved, but troublesome artifacts are introduced
Solution Approach 1:
Instead of using continuous AGC that can introduce artifacts, the system segments the dynamic range into discrete regions handled by separate ADC paths. Each path has fixed gain settings, avoiding the gain adjustment artifacts that occur in AGC systems while still achieving high effective dynamic range through path switching
Solution Approach 2:
The system performs preliminary signal level detection using an envelope detector before the signal enters the ADC paths. This allows the system to pre-select the appropriate ADC path based on the expected signal level, preventing the need for real-time gain adjustments that would introduce artifacts
3Measurement precision
If multipath approaches with combining algorithm are used to achieve high DR, then the dynamic range is improved, but instantaneous saturation effects occur
Solution Approach 1:
Instead of combining multiple paths and then selecting (the conventional multipath approach), the system inverts the logic by pre-selecting the appropriate path based on signal level detection. This prevents saturation effects from occurring in the first place, rather than trying to correct them after combining
Solution Approach 2:
The envelope detector performs preliminary detection of the signal amplitude and controls the multiplexer to select the appropriate ADC path before the signal is processed. This preliminary action prevents instantaneous saturation effects by ensuring the signal is routed to a path with appropriate gain settings before amplification or conversion
4Volume of moving object
If device size is reduced for mobile devices, then the portability is improved, but the ability to integrate high DR digital microphone is compromised
Solution Approach 1:
The dynamic range functionality is segmented across multiple ADC paths with different gain settings, allowing each path to be optimized for specific signal levels. This segmentation enables high effective dynamic range to be achieved through intelligent path selection rather than requiring a single high-performance ADC, reducing the overall integration requirements
Solution Approach 2:
The system changes operational parameters (gain settings, sampling capacitance) based on the input signal level. By dynamically adjusting these parameters through path selection, the system achieves high dynamic range performance without requiring all components to be optimized for the full range, enabling compact integration
Data Source
AI summary
Exemplary multipath digital microphone described herein can comprise exemplary embodiments of adaptive ADC range multipath digital microphones, which allow low power to be achieved for amplifiers or gain stages, as well as for exemplary adaptive ADCs in exemplary multipath digital microphone arrangements described herein, while still providing a high DR digital microphone systems. Further non-limiting embodiments can comprise an exemplary glitch removal component configured to minimize audible artifacts associated with the change in the gain of the exemplary adaptive ADCs.