MEMS Microphone with Acoustic Activity Detector for Low-Power Voice Detection
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Solution Overview
Problem
Existing voice activity detection (VAD) approaches in mobile devices consume significant power, leading to battery life issues and user dissatisfaction, as they require constant scanning and are often enabled only after device activation.
Innovation Solution
Integration of VAD or acoustic activity detection (AAD) modules into microphones on application-specific circuits (ASICs) with standardized interfaces, allowing operation in multiple modes, including a low-power mode that detects voice signals, and switching between internal and external clock modes to optimize power usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If voice activity detection algorithms are constantly running to detect voice signals, then voice detection capability is improved, but power consumption increases significantly
Solution Approach 1:
The system dynamically switches between two operational modes: a low-power mode where the microphone operates without an external clock signal, and a full-performance mode where the microphone processes audio continuously. This dynamic operation allows the system to adapt power consumption to actual voice activity levels, resolving the contradiction between constant detection capability and power consumption.
Solution Approach 2:
The patent changes the operational parameters of the microphone by introducing an optional external clock signal. When the clock signal is present, the microphone operates at full performance; when absent, it operates in low-power mode. This parameter change enables the system to achieve both low power consumption during idle periods and reliable voice detection when needed.
2Ease of operation
If speech recognition is enabled at all times to improve user experience, then ease of operation is improved, but battery life decreases due to high power consumption
Solution Approach 1:
The system uses periodic clock signals to control the operation of the microphone. The external clock signal enables the microphone to operate only during periods when speech recognition is actually needed, rather than continuously. This periodic operation maintains ease of use when required while significantly extending battery life during normal operation.
3Adaptability or versatility
If microphones use internal clocks for operation, then device compatibility is improved, but power consumption increases compared to external clock operation
Solution Approach 1:
The microphone is designed with multi-functionality to operate in two clocking modes: internal clock mode for standalone operation and external clock mode for integrated operation with host devices. This universal design allows the microphone to adapt to different device requirements while optimizing power consumption by using the external clock when available, thereby reducing its own power consumption.
Data Source
AI summary
A microphone apparatus including a MEMS transducer, an acoustic activity detector, a local oscillator, and an external-device interface standardized for compatibility with devices from different manufacturers is disclosed. The microphone apparatus has a first mode of operation during which the apparatus is clocked by the internal clock signal when the acoustic activity detector processes digital data for acoustic activity, and a second mode of operation during which the microphone apparatus is clocked by an external clock signal received at the external-device interface after voice activity is detected by the acoustic activity detector.