Self-dependent Equivalent Circuit Modeling of Electrostatic Comb Transducers for Integrated MEMS

Overview & Synopsis

The article presents a new equivalent circuit model of electrostatic comb transducers for an integration of MEMS into LSI. The model detects the displacement using a dummy spring to express the current induced by the movement, and the model parameters can be derived from only its dimensions not from external parameters, such as acting force and applied voltage. In addition, being composed from basic circuit components, the model is easily utilized in conventional circuit simulation software. The in-plane two-degree-of-freedom comb model was applied to a simple SOI coupled resonator and the measured and simulated electrical and mechanical properties showed good agreement with each other. The model was also applied to a decoupled two-axis resonator for a vibrating gyroscope made on silicon-on-glass substrate. Frequency tuning and oscillating circuit with constant amplitude control have been tested and the tuning results and transient responses showed good agreement as well.