MEMS Sensor Adjustable Amplifier Circuit Design

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Solution Overview

Problem

Conventional digital microphones with MEMS sensors consume high current and occupy significant space due to the inclusion of components like source followers, Programmable Gain Amplifiers (PGA), and Analog-to-Digital converters (ADC), which hinder their efficiency and compactness.

Innovation Solution

A sensing device incorporating a MEMS sensor directly coupled with an adjustable amplifier having high impedance input terminals, eliminating the need for a source follower and reducing current consumption, while maintaining a high signal-to-noise ratio (SNR) through a compact circuit design.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If source follower, PGA and ADC are used to process the electric signal, then the signal-to-noise ratio is improved, but the current consumption increases and the circuit size increases

Engineering Contradiction:

Improvesignal-to-noise ratioVSAvoidcurrent consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent removes the source follower component from the signal processing chain. By directly coupling the MEMS sensor to the amplifier input terminal, the unnecessary buffering stage is eliminated, reducing current consumption while maintaining signal integrity through the high impedance input of the amplifier.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent integrates the MEMS sensor directly with the amplifier input terminal, eliminating intermediate components. This merging of functions reduces the overall circuit complexity and current consumption while achieving the required signal-to-noise ratio through the amplifier's high impedance input characteristics.

Inventive Principle:

Principle #5Merging (Combining)

2Measurement precision

If source follower, PGA and ADC are used to process the electric signal, then the signal-to-noise ratio is improved, but the circuit size increases

Engineering Contradiction:

Improvesignal-to-noise ratioVSAvoidcircuit size

Core Design Contradiction:

Measurement precisionVSArea of stationary object

Solution Approach 1:

The source follower component is extracted and removed from the circuit. The direct coupling of the MEMS sensor to the amplifier input terminal eliminates the need for this intermediate buffering stage, reducing circuit area while maintaining signal-to-noise ratio through the amplifier's high impedance input.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The circuit architecture merges the MEMS sensor output directly with the amplifier input, eliminating intermediate components and reducing overall circuit footprint. This integration achieves compact design without sacrificing signal quality.

Inventive Principle:

Principle #5Merging (Combining)

3Ease of operation

If source follower is used for buffering the electric signal, then the signal processing is improved, but the current consumption increases

Engineering Contradiction:

Improvesignal processingVSAvoidcurrent consumption

Core Design Contradiction:

Ease of operationVSUse of energy by moving object

Solution Approach 1:

The source follower buffering stage is extracted and removed. The high impedance input terminal of the amplifier provides sufficient buffering capability on its own, eliminating the need for the additional source follower component and its associated current consumption.

Inventive Principle:

Principle #2Taking out (Extraction)

4Adaptability or versatility

If conventional circuit components are used, then the signal processing capability is improved, but the device complexity increases

Engineering Contradiction:

Improvesignal processing capabilityVSAvoidcircuit complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The source follower component is extracted from the signal processing chain. The amplifier's high impedance input terminal provides the necessary buffering function without requiring the additional source follower stage, simplifying the overall circuit architecture.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The circuit design merges the MEMS sensor directly with the amplifier input, consolidating functions and reducing component count. This integration maintains signal processing capability while reducing device complexity.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS10273151B2Sensing device including a MEMS sensor and an adjustable amplifier

Publication Date: 2019.04.30 SILICON INTEGRATED SYSTEMS CORP

AI summary

A sensing device includes a MEMS sensor and an adjustable amplifier. The MEMS sensor is configured to generate an input signal according to environmental changes. The adjustable amplifier has a first input terminal, a second input terminal, a third input terminal, a fourth input terminal and a first output terminal. The first input terminal is electrically connected to the MEMS sensor for receiving the input signal. The second input terminal is electrically connected to a first signal terminal for receiving a first common-mode signal. The third input terminal is electrically connected to the first output terminal. The fourth input terminal is electrically connected to a second signal terminal. An electric potential of a first output signal output by the first output terminal of the adjustable amplifier is related to electric potentials of the input signal, the first signal terminal and the second signal terminal.