Acceleration Sensor Input Protection for Low-Offset Detection

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Solution Overview

Problem

Existing acceleration sensors face challenges in maintaining detection precision due to electrostatic discharge risks and temperature-induced input offsets, which affect the accuracy of acceleration measurements, especially in high-temperature environments.

Innovation Solution

The acceleration sensor incorporates electrostatic protection diodes with a PN structure, ensuring identical leakage current characteristics and minimizing error currents, and includes an offset correction and adjustment unit to reduce temperature gradients, thereby enhancing detection precision and robustness against electrostatic discharge.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If electrostatic protection diodes are added to protect against electrostatic discharge, then reliability is improved, but device complexity increases

Engineering Contradiction:

Improveprotection against electrostatic dischargeVSAvoidnumber of protection components

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines multiple electrostatic protection diodes (first and second diodes) into a single integrated protection circuit within the signal processing device. This merging approach provides comprehensive electrostatic discharge protection while minimizing the increase in device complexity by integrating the protection function into the existing sensor structure rather than adding separate discrete components.

Inventive Principle:

Principle #5Merging (Combining)

2Measurement precision

If offset correction and adjustment units are added to reduce temperature-induced offsets, then measurement precision is improved, but device complexity increases

Engineering Contradiction:

Improveacceleration measurement accuracyVSAvoidcomplexity of signal processing circuit

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent implements offset correction and adjustment units that proactively compensate for temperature-induced input offsets before they affect measurement accuracy. The system performs preliminary calibration and continuous temperature compensation, adjusting offset values in advance based on predicted temperature variations. This preliminary action maintains high measurement precision without requiring complex real-time correction mechanisms during operation.

Inventive Principle:

Principle #10Preliminary action

3Measurement precision

If multiple electrostatic protection diodes with identical leakage current characteristics are used, then measurement precision is maintained, but manufacturing precision requirements increase

Engineering Contradiction:

Improveminimization of error currentsVSAvoidmatching leakage current characteristics

Core Design Contradiction:

Measurement precisionVSManufacturing precision

Solution Approach 1:

The patent employs parameter changes by selecting diodes with specifically matched leakage current characteristics and implementing circuit design adjustments that compensate for manufacturing variations. The system uses temperature-dependent parameter adjustment and calibration routines to ensure that the combined effect of multiple diodes maintains precise measurement performance, thereby reducing the stringency of initial manufacturing precision requirements through post-fabrication parameter optimization.

Inventive Principle:

Principle #35Parameter changes

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 configuration significantly reduces input offsets and improves detection precision, ensuring accurate acceleration measurement across varying temperatures, suitable for applications in in-vehicle and industrial machines.

Implementation Method 1

electrostatic protection diodes with a PN structure, ensuring identical leakage current characteristics and minimizing error currents

Methodology Applied

Scientific EffectElectrostatic discharge: Electrostatic Discharge

Implementation Method 2

first electrostatic protection diode and a second electrostatic protection diode having same structure and same leakage current characteristic

Methodology Applied

Scientific EffectDiode conduction: Diode

Implementation Method 3

includes an offset correction and adjustment unit to reduce temperature gradients

Methodology Applied

Scientific EffectTemperature gradient: Temperature Gradient

Data Source

PatentUS20240162219A1Acceleration sensor

Publication Date: 2024.05.16 ROHM CO LTD

AI summary

The present disclosure provides an acceleration sensor including a sensor device and a signal processing device sealed in a single package. The sensor device is configured to generate an acceleration signal, and the signal processing device is configured to process the acceleration signal. The signal processing device includes a signal input terminal, a first electrostatic protection element and a second electrostatic protection element. The signal input terminal is configured to receive an external input of the acceleration signal. The first electrostatic protection element is configured to be connected between the signal input terminal and a first node to which a first voltage is applied. The second electrostatic protection element is configured to be connected between the signal input terminal and a second node to which a second voltage is applied. The first electrostatic protection element and the second electrostatic protection element have the same structure and leakage current characteristic.