ANALYSIS OF PARASITIC CAPACITANCE EFFECT IN A DRIVE-MODE OF MICROELECTROMECHANICAL GYROSCOPE
The most effective method for the identification of the dynamic characteristics of the resonant structure of a microelectromechanical gyroscope (MMG) is the experimental determination of its frequency characteristics in two modes: a drive-mode and a sense-mode. In a drive-mode, resonant mechanical structure gyro is driven electrostatic force by applying a harmonic signal to the excitation electrodes by the method of frequency sweeping and output is determined by information capacitive response. However, the output signal is usually distorted by the passage of the excitation signal to the information signal through parasitic electrical components that parallel to the ideal structure of the electromechanical resonator. Because of this, an accurate estimate of the parameters of the dynamic system MMG is difficult. In this case there is a resonance frequency. The most actual task is to search for the parameters of parasitic components and method to reduce their negative effects, which affects the characteristics of the MMG. This article presents the internal design, theoretical analysis and results in the experiment with MMG. The main influence on the dynamic characteristic of the MMG is parasitic capacitance. Based on the mathematical model of the movable structure of MMG, a comprehensive theoretical analysis has been carried out, as a result of which two methods have been derived that allow reducing the influence of parasitic capacitance. The first method is realized by increasing the supplied DC voltage. And the second method is to increase the quality factor. The effectiveness of the first method is confirmed by practical tests. The parasitic capacitance value, equal to 0.16 pF, was determined from the test results. The phenomenon of displacement of the resonance frequency was also discovered and clarified in the work with the use of two proposed methods.