Acoustic Feature Extraction Circuit With Shared Op-Amp for Low-Power VAD

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Solution Overview

Problem

Conventional voice activity detection (VAD) systems require significant circuit area and power consumption, and are susceptible to process-voltage-temperature (PVT) variations.

Innovation Solution

A VAD system with an acoustic feature extraction (AFE) circuit that uses a plurality of band-pass filters (BPFs) and a rectifier, where a single operational amplifier is shared among channels, and signals are time-division demultiplexed and multiplexed to reduce power consumption and circuit area.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional digital architecture is used for VAD, then detection accuracy is maintained, but power consumption increases and circuit area expands

Engineering Contradiction:

Improvevoice detection accuracyVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent replaces the conventional digital VAD architecture with an analog acoustic feature extraction circuit. The analog circuit processes audio signals directly in the analog domain using band-pass filters, rectifiers, and low-pass filters, eliminating the need for analog-to-digital conversion and digital signal processing. This substitution of digital processing with analog processing reduces power consumption while maintaining voice detection accuracy.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If conventional digital architecture is used for VAD, then detection accuracy is maintained, but circuit area increases

Engineering Contradiction:

Improvevoice detection accuracyVSAvoidcircuit area

Core Design Contradiction:

Measurement precisionVSArea of stationary object

Solution Approach 1:

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If multiple operational amplifiers are used for each channel, then signal processing performance is improved, but power consumption and circuit area increase

Engineering Contradiction:

Improvesignal processing performanceVSAvoidpower consumption

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent merges the signal processing functions of multiple channels into a single shared operational amplifier. The analog acoustic feature extraction circuit uses one operational amplifier that is time-division multiplexed across multiple filter channels, rather than dedicating separate operational amplifiers to each channel. This sharing of the operational amplifier reduces the total number of active components, thereby reducing power consumption and circuit area while maintaining signal processing performance through time-division multiplexing.

Inventive Principle:

Principle #5Merging (Combining)

4Productivity

If multiple operational amplifiers are used for each channel, then signal processing performance is improved, but circuit area increases

Engineering Contradiction:

Improvesignal processing performanceVSAvoidcircuit area

Core Design Contradiction:

ProductivityVSArea of stationary object

Solution Approach 1:

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS12236976B2Voice activity detection system and acoustic feature extraction circuit thereof

Publication Date: 2025.02.25 HIMAX TECH LTD

AI summary

An acoustic feature extraction (AFE) circuit includes a plurality of band-pass filters (BPFs) adaptable to a plurality of channels with different band-pass frequency ranges respectively for switchably receiving an amplified signal, thereby generating corresponding filtered signals, the plurality of BPFs including an operational amplifier that is shared among the plurality of channels; and a rectifier switchably coupled to receive the filtered signals, thereby generating a rectified signal. The amplified signal is time-division demultiplexed onto the BPFs in different phases, and the filtered signals are time-division multiplexed onto the rectifier in different phases.