Real time controller design to solve the “pull-in” instability of MEMS actuator

The purpose of this paper is to improve the performance of MEMS parallel plate actuators and RF switches systems. Electrostatic micro actuators are normally driven by static open-loop voltage control schemes. A major problem in this control strategy is that at a distance of two-thirds of the zero-bias capacitive gap, the actuator position becomes unstable and collapses. This phenomenon is known as ldquosnap-throughrdquo or ldquopull-inrdquo. In this paper a new closed-loop feedback control scheme using switching technique will be proposed to solve the problem above to provide the stable and controllable range to full gap and controlling movable plate through whole gap to achieve desired switching on-off time. The other issue to be considered is that the control strategy must be applicable for real time implementation.