RMS Output Accelerometer Integrating MEMS and ASIC

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Solution Overview

Problem

Conventional acceleration detection systems require separate processors for calculating acceleration, leading to increased power consumption and space usage, as they cannot function without an external processor and often require complex computations and data processing.

Innovation Solution

Integration of a microelectromechanical systems (MEMS) device with an application-specific integrated circuit (ASIC) that includes analog circuitry, an analog-to-digital converter (ADC), and root-mean-square (RMS) firmware, allowing for direct calculation and filtering of acceleration data within a single chip, reducing the need for external processing and minimizing power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a separate processor is used to calculate acceleration from accelerometer data, then measurement precision can be improved through complex computations, but power consumption and device space increase substantially

Engineering Contradiction:
Improveacceleration calculation precisionVSAvoidpower consumption
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent combines the accelerometer sensor and processing circuitry into a single integrated device. The processing circuitry is directly coupled to the accelerometer, allowing acceleration calculations to be performed internally without requiring a separate external processor, thus reducing power consumption while maintaining measurement precision.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The accelerometer device is designed to be self-sufficient by incorporating the processing circuitry within the same device. The device can independently calculate acceleration from raw sensor data using internal computational resources, eliminating the need for external processing and reducing overall system power consumption.

Inventive Principle:
Principle #25Self-service

2Measurement precision

If a separate processor is used to process accelerometer data, then measurement precision can be improved through complex computations, but the device space occupied increases substantially

Engineering Contradiction:
Improveacceleration calculation precisionVSAvoiddevice space
Core Design Contradiction:
Measurement precisionVSArea of stationary object

Solution Approach 1:

The patent integrates the processing circuitry and accelerometer into a single compact device, merging functions that were previously distributed across separate components. This consolidation reduces the total device space required while maintaining the computational precision needed for accurate acceleration measurement.

Inventive Principle:
Principle #5Merging (Combining)

3Measurement precision

If complex computations are performed externally to determine acceleration, then measurement precision is improved, but the device complexity increases

Engineering Contradiction:
Improveacceleration determination accuracyVSAvoidsystem complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent merges the accelerometer and processing circuitry into a single integrated device, simplifying the overall system architecture. By incorporating the computational functions within the accelerometer itself, the system requires fewer external components and interconnections, reducing system complexity while maintaining measurement precision.

Inventive Principle:
Principle #5Merging (Combining)

4Measurement precision

If raw data signals are processed externally, then measurement precision can be improved, but the quantity of data transmission and processing increases power consumption

Engineering Contradiction:
Improveacceleration measurement accuracyVSAvoidpower consumption
Core Design Contradiction:
Measurement precisionVSLoss of energy

Solution Approach 1:

The accelerometer device processes raw data signals internally using integrated processing circuitry, eliminating the need to transmit large amounts of raw data externally for processing. This self-processing approach reduces data transmission requirements and associated power consumption while maintaining measurement accuracy.

Inventive Principle:
Principle #25Self-service

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 solution enables more efficient and compact acceleration detection, reducing power consumption and space requirements while providing higher resolution and precision in acceleration measurements by performing calculations directly on the chip, with the ability to output a single RMS value representing acceleration.

Implementation Method 1

The MEMS device includes a capacitive structure having a capacitance that is configured to change in response to acceleration of an object

Methodology Applied
Scientific EffectCapacitance: Capacitance

Data Source

PatentEP3874278B1Accelerometer having a root-mean-square (RMS) output
Publication Date: 2025.01.08 ROHM CO LTD
  • EP3874278B1 patent drawingFigure 1
  • EP3874278B1 patent drawingFigure 2
  • EP3874278B1 patent drawingFigure 3

AI summary

Accelerometers are described herein that have RMS outputs. For instance, an example accelerometer may include a MEMS device and an ASIC. The MEMS device includes a structure having an attribute that changes in response to acceleration of an object. The ASIC determines acceleration of the object based at least in part on changes in the attribute. The ASIC includes analog circuitry, an ADC, and firmware. The analog circuitry measures the changes in the attribute and generates analog signals that represent the changes. The ADC converts the analog signals to digital signals. The firmware includes RMS firmware. The RMS firmware performs an RMS calculation on a representation of the digital signals to provide an RMS value that represents an amount of the acceleration of the object.