Sensor Control Circuit With Buffering For Full Sampling

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Solution Overview

Problem

Conventional sensor control circuits face challenges such as non-sufficient sampling, large circuit area, high power consumption, and weak noise suppression due to the low signal amplitude and noise amplification issues in piezo-resistive acceleration sensors, particularly with continuous passive RC filters and active filter circuits.

Innovation Solution

A sensor control circuit comprising a piezo-resistive acceleration sensor, an anti-aliasing filter, a differential buffer circuit with auto-zero structure, and a gain controllable switched capacitor integrator amplifier, which includes a pulse modulation switch for intermittent operation and chopping technology to reduce noise and offset voltages, enhancing signal sampling and noise suppression.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a continuous passive RC filter circuit is used to filter low frequency noise, then noise suppression capability is improved, but circuit area and power consumption increase

Engineering Contradiction:

Improvenoise suppression capabilityVSAvoidcircuit area

Core Design Contradiction:

Object-affected harmful factorsVSArea of stationary object

Solution Approach 1:

The patent employs periodic sampling action where the sensor and filter circuit operate intermittently rather than continuously. A sampling switch periodically connects the sensor output to the filter circuit only during active sampling periods, reducing power consumption and allowing smaller filter components while maintaining noise suppression effectiveness during the sampling window.

Inventive Principle:

Principle #19Periodic action

2Object-affected harmful factors

If a continuous passive RC filter circuit is used to filter low frequency noise, then noise suppression capability is improved, but power consumption increases

Engineering Contradiction:

Improvenoise suppression capabilityVSAvoidpower consumption

Core Design Contradiction:

Object-affected harmful factorsVSUse of energy by stationary object

Solution Approach 1:

Inventive Principle:

Principle #19Periodic action

3Quantity of substance

If traditional amplifier circuits are used to amplify the sensor signal, then signal amplitude is increased, but noise is also amplified reducing SNR

Engineering Contradiction:

Improvesignal amplitudeVSAvoidsignal to noise ratio

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary filtering action by placing the RC filter circuit before the amplifier in the signal path. Low frequency noise is filtered out before the signal reaches the amplifier, so when the amplifier boosts the signal amplitude, it amplifies both the signal and remaining high-frequency noise but not the low-frequency noise that has already been removed, thereby preserving or improving the signal-to-noise ratio.

Inventive Principle:

Principle #10Preliminary action

4Object-affected harmful factors

If passive RC filter circuit is used, then noise filtering is achieved, but driving capability is insufficient for proper sampling

Engineering Contradiction:

Improvenoise filteringVSAvoiddriving capability

Core Design Contradiction:

Object-affected harmful factorsVSPower

Solution Approach 1:

The patent introduces a buffer amplifier as an intermediary component between the passive RC filter circuit and the main amplifier. The buffer amplifier has high input impedance that does not load down the filter circuit (preserving its noise filtering characteristics) while providing low output impedance that can drive the subsequent stages properly, thus solving the driving capability deficiency of the passive filter.

Inventive Principle:

Principle #24Intermediary (Mediator)

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

The proposed solution improves signal sampling, reduces circuit area and power consumption, and enhances noise suppression capabilities, leading to better signal recovery and improved signal-to-noise ratio.

Implementation Method 1

the piezo-resistive acceleration sensor is extensively applied to many fields

Methodology Applied

Scientific EffectPiezo-resistive effect: Piezoresistive Effect

Implementation Method 2

For the low frequency noise in the signal outputted by the sensor, it is generally removed by adopting a passive RC low-pass filter to filter

Methodology Applied

Scientific EffectRC filtering: Filter (electronic)

Data Source

PatentEP3079133B1Sensor control circuit and electronic apparatus

Publication Date: 2018.10.17 CSMC TECH FAB1

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AI summary

A sensor control circuit comprises a sensor (201), a filtering circuit (202), a buffering circuit (203), and an amplifying circuit (204). An output end of the sensor (201) is connected to an input end of the filtering circuit (202), an output end of the filtering circuit (202) is connected to an input end of the buffering circuit (203), and an output end of the buffering circuit (203) is connected to an input end of the amplifying circuit (204). Because the buffering circuit (203) is disposed between the filtering circuit (202) and the amplifying circuit (204), the sensor circuit has an advantage of full sampling. Further provided is an electronic apparatus using the sensor control circuit.