Digital MEMS Microphone SoC for Noise-Robust Headset Voice Processing
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Solution Overview
Problem
Traditional electret condenser microphones (ECMs) in handheld consumer electronics have reached technological limits, failing to meet the needs of the mobile consumer electronics market in terms of size, vibration/temperature performance, and stability, and require additional components for signal processing.
Innovation Solution
A digital MEMS microphone integrated with an analog-to-digital converter (ADC) on the same substrate, which simplifies design, enhances signal quality, and eliminates the need for separate pre-amplifier, voice CODEC, ADC, and digital-to-analog converter chips, enabling robust digital output and integrated noise/echo cancellation, speech compression, and lossless speech transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If ECMs are used in handheld consumer electronics, then the design is simple and cost-effective, but the device size cannot be reduced further and vibration/temperature performance deteriorates
Solution Approach 1:
The patent combines the microphone sensing element with integrated amplification and A/D conversion functions into a single MEMS device. This integration allows the microphone to achieve smaller size while maintaining reliable performance by consolidating multiple functions that were previously separate components into one unified MEMS structure.
Solution Approach 2:
The patent replaces traditional electromagnetic ECM technology with MEMS (micro-electromechanical systems) technology. This substitution enables miniaturization while improving vibration and temperature performance through the inherent properties of MEMS construction, which is more resilient to mechanical stress and thermal variations.
2Device complexity
If analog microphones with separate pre-amplifier and codec chips are used, then the signal processing chain is complex, but the design and implementation time increases
Solution Approach 1:
The patent merges the microphone, pre-amplifier, and A/D converter into a single integrated MEMS device with built-in digital output. This consolidation eliminates the need for separate analog signal processing components, significantly reducing device complexity and accelerating time-to-market by removing multiple discrete components and their interconnections.
Solution Approach 2:
The integrated MEMS microphone performs multiple functions within a single component: acoustic sensing, signal amplification, and digital conversion. This multi-functionality reduces the overall system complexity by replacing what would traditionally require three separate components (microphone, pre-amp, codec) with one universal device.
3Reliability
If digital MEMS microphones with integrated ADC are used, then signal quality and immunity to interference improve, but the manufacturing complexity increases
Solution Approach 1:
The patent replaces analog signal processing with digital signal processing by integrating an A/D converter directly into the MEMS microphone. This conversion to digital domain provides inherent immunity to RF and EMI interference, as digital signals are less susceptible to electromagnetic noise compared to analog signals, while the CMOS-based integration keeps manufacturing feasible.
Solution Approach 2:
The patent changes the signal domain parameter from analog to digital by integrating an ADC into the MEMS microphone. This parameter change fundamentally improves immunity to RF and EMI interference, as digital signals operate at higher frequencies and voltage levels that are less affected by electromagnetic noise, while the transformation is achieved through standard CMOS fabrication processes.
Data Source
AI summary
The invention is a multi-microphone voice processing SoC primarily for head worn applications. It bypasses the use of conventional pre-amp voice CODEC (ADC/DAC) chips all together by replacing their functionality with digital MEMS microphone(s) and digital speaker driver (DSD). Functionality necessary for speech recognition such as noise/echo cancellation, speech compression, speech feature extraction and lossless speech transmission are also integrated into the SoC. One embodiment is a noise cancellation chip for wired, battery powered headsets and earphones, as smart-phone accessory. Another embodiment is as a wireless Bluetooth noise cancellation companion chip. The invention can be used in headwear, eyewear glass, mobile wearable computing, heavy duty military, aviation and industrial headsets and other speech recognition applications in noisy environments.