Multipath Digital Microphone AGC for High Dynamic Range
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Solution Overview
Problem
Conventional digital microphones face challenges in achieving high dynamic range (DR) while maintaining low power consumption and compact size, particularly in mobile devices exposed to varying sound pressure levels, with existing solutions often requiring excessive power, die area, and introducing artifacts.
Innovation Solution
A multipath digital microphone system employing automatic gain control (AGC) and multipath digital signal processing chains, which adjusts gain based on audio signal characteristics, switches between signal paths in the digital domain, and corrects for gain and offset differences to minimize audible artifacts, thereby optimizing power and die area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional high DR solutions (high DR ADC or AGC) are employed, then dynamic range is improved, but power consumption and die area increase excessively
Solution Approach 1:
The patent divides the audio signal processing into multiple paths (e.g., high-gain path and low-gain path) that operate simultaneously. Each path processes signals within its optimal dynamic range, and the results are combined digitally. This segmentation allows the system to achieve high overall dynamic range without requiring any single component to handle the entire range, thereby reducing power consumption and die area compared to conventional single-path solutions.
2Measurement precision
If conventional high DR solutions (high DR ADC or AGC) are employed, then dynamic range is improved, but die area increases excessively
Solution Approach 1:
The patent divides the audio signal processing into multiple paths (e.g., high-gain path and low-gain path) that operate simultaneously. Each path processes signals within its optimal dynamic range, and the results are combined digitally. This segmentation allows the system to achieve high overall dynamic range without requiring any single component to handle the entire range, thereby reducing power consumption and die area compared to conventional single-path solutions.
3Measurement precision
If gain switching is performed to extend dynamic range, then dynamic range is improved, but audible artifacts are introduced
Solution Approach 1:
The patent maintains continuous operation of multiple signal paths simultaneously, with each path actively processing the audio signal. The high-gain path and low-gain path operate in parallel without interruption, and their outputs are combined through digital signal processing. This continuous multi-path operation eliminates the discontinuities and switching transients that cause audible artifacts in conventional gain-switching systems.
Solution Approach 2:
The patent introduces digital signal processing as an intermediary between the multiple analog signal paths. The digital domain performs gain adjustment, noise shaping, and signal combination, acting as a mediator that smoothly integrates the outputs of different paths without introducing audible artifacts. This digital intermediary enables artifact-free dynamic range extension by avoiding direct analog switching.
Data Source
AI summary
Exemplary multipath digital microphones described herein can comprise exemplary embodiments of automatic gain control and multipath digital audio signal digital signal processing chains, which allow low power and die size to be achieved as described herein, while still providing a high DR digital microphone systems. Further non-limiting embodiments can facilitate switching between multipath digital audio signal digital signal processing chains while minimizing audible artifacts associated with either the change in the gain automatic gain control amplifiers switching between multipath digital audio signal digital signal processing chains.