MEMS Gyroscope Driving Circuit Low-Pass Filter Capacitive Coupling
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Solution Overview
Problem
Microelectromechanical gyroscopes face challenges in maintaining oscillation at a precise resonance frequency due to variations caused by micromachining dispersions and temperature gradients, and electrical coupling between masses disrupts the operation, leading to ineffective stabilization and complex, costly feedback circuits.
Innovation Solution
A microelectromechanical gyroscope with a driving device forming a feedback control loop that includes a low-pass filter, ensuring the resonance frequency is within the passband while excluding disturbance frequencies from electrical coupling, thereby maintaining the driving mass in oscillation and suppressing spurious signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If feedback driving circuits are used to stabilize oscillation at resonance frequency, then oscillation stability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts and removes the problematic capacitive coupling path between the driving mass and driven mass through structural design modifications. By reconfiguring the electrode arrangements and insulation structures, the harmful capacitive coupling is eliminated while preserving the necessary electromechanical coupling for operation, thus achieving oscillation stability without complex feedback circuits
Solution Approach 2:
The patent introduces intermediate insulation structures and grounding electrodes as mediators between the driving and driven masses. These intermediary elements provide electrical isolation while maintaining mechanical coupling, allowing the system to achieve stable oscillation without requiring complex active feedback control circuits
2Object-generated harmful factors
If insulation between masses is increased to reduce electrical coupling, then spurious signal suppression is improved, but device complexity increases
Solution Approach 1:
The patent merges the insulation function with the existing structural elements by integrating ground electrodes and insulation layers into the basic mass support structure. Rather than adding separate complex insulation systems, the design combines electrical isolation requirements with the mechanical support framework, achieving spurious signal suppression through unified structural design
Solution Approach 2:
The patent applies localized insulation and grounding only in the specific regions where capacitive coupling occurs between the driving and driven masses. By concentrating the insulation measures at critical coupling points rather than providing uniform insulation throughout the structure, the design suppresses spurious signals while minimizing added complexity
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 effectively stabilizes the oscillation at the resonance frequency, reduces the complexity and cost of feedback circuits, and minimizes the impact of electrical coupling, ensuring accurate operation of the gyroscope.
Implementation Method 1
the driving device has a low-pass filter having a passband of frequencies such that the resonance frequency is in the passband and a disturbance frequency associated with disturbance signals due to electrical coupling between the first mass and the second mass is not in the passband
Implementation Method 2
The movable mass and the stator are capacitively coupled by a plurality of respective comb-fingered and mutually facing electrodes so as to form capacitors
Implementation Method 3
a driving device coupled to the microstructure so as to form a feedback control loop that includes the first mass and is configured to maintain the first mass in oscillation at the resonance frequency
Implementation Method 4
the other mass is drawn along in the oscillatory motion and, in the case of rotation of the microstructure with respect to a predetermined axis with an angular velocity, is subjected to a Coriolis force proportional to the angular velocity itself
Data Source
AI summary
A microelectromechanical gyroscope having a microstructure with a first mass, which can oscillate according to a first axis, and a second mass constrained to the first mass so as to oscillate according to a second axis in response to a rotation of the microstructure, and a driving device coupled to the microstructure to maintain the first mass in oscillation at a resonance frequency, the driving device provided with a low-pass filter having a passband such that the resonance frequency is in the passband and a disturbance frequency associated with disturbance signals due to coupling between the first mass and the second mass is not in the passband.