Dual-Scale Inertial MEMS Accelerometers for Unified Self-Testing
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Solution Overview
Problem
Existing inertial MEMS sensors with different sensitivity scales face challenges in performing a unified sanity test due to the need for separate control units and procedures, leading to increased complexity, cost, and size.
Innovation Solution
An inertial MEMS device integrates triaxial gyroscopes and accelerometers with varying sensitivity scales on a single die, allowing a unified self-test procedure using a single control unit by optimizing the structural layout and dimensions of the high-G accelerometers to respond to a common test voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If two separate movable sensing structures (low-G and high-G) are integrated into different dice, then both low acceleration and high acceleration sensing functions are achieved, but the overall device dimensions increase and multiple dedicated circuitries are required
Solution Approach 1:
The patent merges both low-G and high-G sensing structures onto a single die, integrating multiple sensing functions into one unified device. This consolidation eliminates the need for separate dice and reduces overall device dimensions while maintaining both sensing capabilities through shared circuitry and control units.
Solution Approach 2:
The patent implements a universal control unit and shared circuitry that can operate with both low-G and high-G sensing structures. This multi-functional approach allows a single control unit to manage different sensing ranges, reducing the need for dedicated circuitries for each sensing type and simplifying the overall device architecture.
2Volume of moving object
If two separate movable sensing structures are integrated into the same die, then device dimensions are reduced, but dedicated circuitries and control units are required for each structure, increasing complexity and cost
Solution Approach 1:
The patent employs a single control unit that can operate with both low-G and high-G sensing structures, eliminating the need for separate dedicated control units. This universal control approach reduces device complexity and component count while maintaining the ability to sense across different acceleration ranges.
Solution Approach 2:
The patent combines the control circuits for both sensing structures into a unified control system, reducing the overall complexity of the device. By merging control functions and sharing circuitry between low-G and high-G structures, the patent minimizes the number of components and simplifies the control unit architecture.
3Device complexity
If a single control unit is used for both low-G and high-G inertial sensors, then complexity is reduced, but different test procedures are required due to different sensitivity levels
Solution Approach 1:
The patent adjusts test parameters such as stimulus magnitude and frequency based on the specific sensing structure being tested. By dynamically changing test parameters rather than requiring different test procedures, the patent enables a single unified test methodology to work effectively for both low-G and high-G sensors, maintaining test procedure uniformity while accommodating different sensitivity levels.
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
Enables a single self-test procedure for both low-G and high-G accelerometers, reducing complexity, cost, and size while maintaining effective operation across different acceleration ranges.
Implementation Method 1
low-G accelerometers are known, for sensing reduced accelerations... which have a lower Full Scale Range (FSR)... low-G sensors have a low full scale but high sensitivity
Implementation Method 2
the control unit applies a known electrostatic force to the respective structure under test, providing a stimulus (for example voltage steps at a predetermined frequency) of suitable value
Data Source
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AI summary
Inertial MEMS device having a plurality of inertial sensors (1-3) integrated in a die (10) of semiconductor material, the inertial sensors (1-3) being mutually arranged side by side and including a triaxial gyroscope (2), a first triaxial accelerometer (3), having a first full scale, and a second triaxial accelerometer (4), having a second full scale, greater than the first full scale. The first and the second triaxial accelerometers (3, 4) are of a capacitive type and configured to receive same self-test signals. The second triaxial accelerometer (4) is configured to allow a self-test of accelerations of at least 450 mG, in particular of approximately 500 mG.