Analysis and dynamic simulation of the synthetic voltage division controller for extending the parallel plate actuator stable range of motion

Abstract

Parallel-plate actuators (PPAs) are useful in micro-electro-mechanical systems (MEMS) devices. The main drawback of a PPA is that it has limited stable motion range. The series capacitor method (SCM) is a common way to solve this issue. However, the SCM requires a much higher voltage input to drive the PPA and series capacitor, and it is deleteriously affected by parasitic capacitance in parallel with the PPA. Additionally, it is usually difficult to obtain a sufficiently small series capacitor, which has to be no greater than half of the minimum capacitance of the PPA. In this work, a synthetic voltage division (SVD) controller is proposed to solve these problems. Firstly, this paper reviews the system dynamics of PPAs and the SCM. The effects of parasitic capacitance are also explored. Then, the SVD controller is presented in detail. It is demonstrated through simulation that the SVD controller can increase the stable range of motion while reducing the required input voltage and cancelling the effect of the parasitic capacitance.