Dual-ADC Microphone Switching for Low-Power Wake-Word Capture
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Solution Overview
Problem
Existing acoustic-activated devices face challenges in reducing power consumption due to the need for significant data capture before wake-word utterance detection, which prevents the use of power-saving techniques and necessitates high-power components like ADCs and audio buffers.
Innovation Solution
A threshold detector circuit with a switch and dual analog-to-digital converters (SAR and Sigma-Delta ADCs) that dynamically adjusts power consumption based on signal quality, switching between low-power, low-quality and high-power modes to capture necessary data efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a threshold-based or voice-detection-based wake-up system is used to turn on the ADC and DSP, then power consumption is reduced, but the system cannot provide the necessary amount of data (500 msec.) when the wake-word causes the system to wake up
Solution Approach 1:
The patent divides the data capture system into multiple parallel channels with different quality levels. A first channel captures low-quality data at low power consumption, while a second channel captures high-quality data at higher power consumption. This segmentation allows the system to provide sufficient data when needed without continuously consuming high power.
Solution Approach 2:
The patent implements dynamic switching between different data capture modes based on system state. The controller dynamically selects which channel to activate (first channel for low power/low quality, second channel for high power/high quality) based on whether the system is in a dormant state or needs to wake up, enabling adaptive power consumption.
2Measurement precision
If high-quality ADC and audio buffer are used continuously to capture necessary data, then data quality is improved, but power consumption increases significantly
Solution Approach 1:
The patent applies different quality levels to different parts of the system at different times. The first channel provides sufficient quality for wake-up detection at low power, while the second channel provides high quality for full audio processing when needed. This local quality approach ensures data quality is adequate when required without continuous high power consumption.
Solution Approach 2:
The patent changes the operating parameters of the ADC system dynamically. The controller switches between first and second channels, which have different sampling rates, resolutions, and power consumption characteristics. This parameter change allows the system to optimize between data quality and power consumption based on operational requirements.
3Productivity
If the ADC and audio buffer remain in active state to capture data, then data capture capability is maintained, but power consumption cannot be reduced
Solution Approach 1:
The patent implements periodic activation of different channels based on system state. The first channel is activated during dormant periods for low-power data capture, while the second channel is activated during wake-up events for high-quality data capture. This periodic action maintains data capture capability when needed while allowing power reduction during quiet periods.
Solution Approach 2:
The system uses its own output signals to control its own operation. The controller monitors the output of the first channel and automatically determines when to switch to the second channel based on detected audio characteristics, enabling self-regulating power consumption without external intervention.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces power consumption by using low-power modes for quiet periods and high-power modes for voice detection, enabling efficient data capture and reducing overall energy usage in acoustic-activated devices.
Implementation Method 1
a first analog-to-digital converter having an input coupled to the first output port of the switch and having an output to convert the output signal from the acoustic sensor element into a first digitized output signal
Implementation Method 2
a second analog-to-digital converter having an input coupled to the second output port of the switch and having an output to convert the output signal from the acoustic sensor element into a second digitized output signal
Implementation Method 3
an acoustic sensor element configured to sense acoustic energy and produce an output signal
Data Source
AI summary
An acoustic device is described and includes an acoustic sensor element configured to sense acoustic energy and produce an output signal and a threshold detector circuit including a switch having an input coupled to the output of the acoustic sensor element to receive the output signal, a control port that receives a control signal, and first and second output ports, a first channel including an analog-to-digital converter that operates at a first power level a second analog-to-digital converter that operates at a second higher power level, relative to the first power level and a threshold level detector that receives an output from the first analog-to-digital converter to produce the control signal having a first state that causes the switch feed the output signal from the acoustic sensor element to the second analog-to-digital converter when the first digitized output signal meets a threshold criteria.