MEMS Gyroscope Self-Test Using Integrated Sensing Capacitors
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Solution Overview
Problem
Existing MEMS gyroscope sensors require additional capacitors and electrical contacts for testing, which complicates their design and manufacturing process.
Innovation Solution
Utilizing the sensing capacitors themselves for testing by electrically decoupling and applying test signals to them, eliminating the need for additional test capacitors and contacts, and employing a switch circuit and capacitance measurement circuit to measure capacitance changes without rotational force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional capacitors and electrical contacts are added for testing, then testing capability is improved, but device complexity increases
Solution Approach 1:
The sensing capacitors are designed to serve dual purposes: they function as sensing elements during normal gyroscope operation and as test capacitors during self-testing mode. This multi-functionality eliminates the need for separate dedicated test capacitors and reduces the number of electrical contacts required, directly resolving the contradiction between testing capability and device complexity
Solution Approach 2:
The gyroscope sensor performs self-testing by utilizing its own sensing capacitors as test elements. The sensor applies test signals to itself and measures the responses through its existing electrical contacts, eliminating the need for external test equipment and additional dedicated test components, thereby maintaining testing capability while minimizing device complexity
2Device complexity
If sensing capacitors are used for both sensing and testing, then device complexity is reduced, but measurement precision may be affected
Solution Approach 1:
The electrical contacts are segmented into functional groups that can be selectively activated: sensing contacts for normal operation and test contacts for self-testing mode. This segmentation allows the sensing capacitors to be electrically isolated and dedicated to testing during self-test mode, preventing interference from sensing operations and maintaining measurement precision
Solution Approach 2:
The electrical contacts are designed to be dynamically reconfigurable, switching between sensing mode and test mode as needed. During self-testing, the contacts are configured to apply test signals and measure capacitance without rotational forces, while during normal operation, they function for sensing. This dynamic reconfiguration ensures measurement precision is maintained in both modes while using the same physical components
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
Simplifies the design of MEMS gyroscope sensors by reducing the number of components and contacts required, enabling effective self-testing without additional test capacitors, and ensuring accurate capacitance measurement during normal and test modes.
Implementation Method 1
A capacitive MEMS gyroscope undergoes a change in capacitance in response to a change in angular rate
Data Source
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AI summary
An apparatus includes a MEMS gyroscope sensor including a first sensing capacitor and a second sensing capacitor and an IC. The IC includes a switch circuit configured to electrically decouple the first sensing capacitor from a first input of the IC and electrically couple the second sensing capacitor to a second input of the IC, and a capacitance measurement circuit configured to measure capacitance of the second sensing capacitor of the MEMS gyroscope sensor during application of a first electrical signal to the decoupled first capacitive element.