Always-On Microphone Audio Detection With Dynamic Power Switching
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Solution Overview
Problem
Current low power operation of digital microphone sensor circuits in Low Power Mode (LPM) relies on pure current optimization techniques rather than audio activity detection, leading to inefficient power management and potential false activation or rejection of audio events.
Innovation Solution
An audio activity detector device with a closed loop feedback regulating circuit, including an automatic gain control (AGC) circuit, quantizer circuit, and signal processing to determine key statistic values and gain control values, dynamically adjusts power states based on ambient versus non-ambient audio activity, using techniques like duty cycling and reduced bias currents to minimize power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If current optimization techniques are used in Low Power Mode, then power consumption is reduced, but audio event detection accuracy deteriorates leading to false activation or rejection
Solution Approach 1:
The system dynamically adjusts the operating mode of the microphone based on detected audio activity. An audio activity detector monitors the audio signal and triggers a mode switch between low power mode and high accuracy mode, allowing the system to adapt its power consumption and detection accuracy according to real-time conditions rather than operating statically in one mode
Solution Approach 2:
The system implements a feedback mechanism where the audio activity detector continuously monitors the audio signal and provides feedback to control the mode switching. This closed-loop feedback ensures that the system transitions to high accuracy mode when audio events are detected and returns to low power mode when no significant activity is present, optimizing both power consumption and detection reliability
2Reliability
If the microphone operates in always-on state with high accuracy, then audio event detection reliability is improved, but power consumption increases
Solution Approach 1:
The system applies partial action by operating in low power mode during periods of no significant audio activity, accepting reduced detection capability in exchange for lower power consumption. Only when the audio activity detector identifies significant activity does the system transition to full high accuracy mode, applying excessive action only when necessary rather than continuously
Solution Approach 2:
The microphone operates in periodic cycles between low power mode and high accuracy mode based on audio activity detection. The system periodically monitors the audio signal and switches modes accordingly, creating a rhythmic pattern of operation that balances power consumption with detection accuracy over time rather than maintaining constant high accuracy operation
Data Source
AI summary
An audio activity detector device is disclosed. The audio activity detector device comprises a closed loop feedback regulating circuit that supplies an input signal representative of a time-varying voltage signal to a quantizer circuit, wherein the quantizer circuit, as a function of the input signal, converts the input signal to a quantizer discrete-time signal; a first circuit that, as a function of the discrete-time signal, determines a key quantizer statistic value for the quantizer discrete-time signal; and a second circuit that, as a function of the key quantizer statistic value, determines a signal statistic value for the input signal and a gain control value.