MEMS Gyroscope Band-Pass Filter Phase Control
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Solution Overview
Problem
Current photolithography and microfabrication techniques are inadequate for producing high-performance MEMS inertial sensors, leading to manufacturing imperfections that limit the performance and robustness of MEMS gyroscopes due to tight tolerance requirements.
Innovation Solution
A micro-gyro device with a motor rotor and motor assembly that oscillates at a frequency determined by a driving signal, utilizing band-pass filter circuitry to maintain oscillation amplitude and suppress harmonics, thereby reducing phase shift and improving signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If current photolithography and microfabrication techniques are used, then manufacturing cost and ease of production are improved, but manufacturing precision and performance are insufficient due to inadequate process capabilities
Solution Approach 1:
The patent changes the operational parameters of the MEMS gyroscope by implementing a specific oscillation frequency range (1 kHz to 10 kHz) and controlling phase shift characteristics (not exceeding 0.1°/Hz). This parameter optimization compensates for manufacturing imperfections and achieves high performance despite limitations in current photolithography and microfabrication processes.
2Measurement precision
If tight tolerances are required for reliable MEMS gyroscopes, then measurement precision is improved, but device complexity and difficulty of fabrication increase significantly
Solution Approach 1:
The patent implements feedback control by monitoring the phase shift characteristics of the oscillating structure and adjusting operating parameters accordingly. The system maintains phase shift not exceeding 0.1°/Hz through active control, achieving high measurement precision without requiring extremely tight manufacturing tolerances.
Solution Approach 2:
The patent employs dynamic oscillation at controlled frequencies (1 kHz to 10 kHz) to achieve precise measurement. By operating in the dynamic regime and optimizing oscillation characteristics, the system attains high measurement precision while avoiding the need for static tight tolerances that would increase fabrication complexity.
3Ease of manufacture
If manufacturing imperfections are present, then ease of manufacture is improved, but reliability and robustness of the MEMS gyroscope deteriorate
Solution Approach 1:
The patent optimizes operational parameters including oscillation frequency (1 kHz to 10 kHz) and phase shift characteristics (≤0.1°/Hz) to compensate for manufacturing imperfections. This parameter tuning enhances reliability and robustness despite the presence of manufacturing variations inherent in current fabrication processes.
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
The solution enhances the yield and accuracy of MEMS gyroscopes by reducing errors caused by manufacturing imperfections and temperature variations, achieving effective suppression of harmonics and maintaining phase characteristics within a narrow range, resulting in improved performance and robustness.
Implementation Method 1
The motor rotor receives the driving signal and oscillates about a motor axis at a frequency determined as a function of the driving signal
Implementation Method 2
The motor assembly oscillates around a rate axis, which is orthogonal to the motor axis, as a function of the frequency of the motor rotor oscillation
Implementation Method 3
A capacitance of the motor assembly changes as a function of the oscillation of the motor assembly
Data Source
AI summary
In one embodiment, a micro-gyro device for measuring rotational movement about an input axis includes a driving element generating a driving signal. A MEMS gyro includes a motor rotor and a motor assembly. The motor rotor receives the driving signal and oscillates about a motor axis at a frequency determined as a function of the driving signal. The motor assembly oscillates around a rate axis, which is orthogonal to the motor axis, as a function of the frequency of the motor rotor oscillation. A capacitance of the motor assembly changes as a function of the oscillation of the motor assembly. Driving element feedback circuitry, including a first band-pass filter, is between the motor rotor and the driving element. The driving element feedback circuitry causes the driving element to generate the driving signal as a function of an amplitude of the motor rotor oscillation for maintaining the amplitude of the motor rotor oscillation within a predetermined range. Output circuitry, including a second band-pass filter, produces an output signal as a function of the changing capacitance of the motor assembly. The first and second band-pass filters have central frequency phase characteristics not exceeding about 0.1°/Hz.