System Damping Ratio Analysis of a Capacitive Micromechanical Accelerometer

Abstract

In this paper, system damping ratio analysis and optimization of a capacitive MEMS accelerometer is performed. To investigate the influence of damping on the system dynamic characteristics the system dynamics equations with or without damping are solved. The results indicate that when the device works without damping it is easily damaged because of resonance. However, when it works with damping, its dynamics characteristics will improve and its bandwidth will widen. Harmonic response analysis is performed to verify the results using the FEM software ANSYS. According to the squeeze-film damping coefficient of a rectangle, the system-damping coefficient is related to the width and length of proof mass and the gap between glass and mass. The damping coefficient formula is used to optimize the system dynamic characteristics by adjusting system-damping ratio to 0.678 through changing the parameters of the proof mass