An interface circuit for time-multiplexed electrostatic drive and sample of electrostatic mems mirror

This paper reports on an interface circuit for microelectromechanical systems (MEMS) electrostatic actuators by reading the stored electrical charge to speculate the mechanical displacement in a time-multiplexing manner. A pass transistor is inserted between the drive source and the actuator to intermittently apply the pulse-width modulated (PWD) voltage at a given voltage height to control the analog displacement of the actuator, while the stored charge is sampled at a fast speed higher than the electromechanical resonance of the actuator so that its displacement is not affected by reading. We developed an integrated circuit (IC) based on the switched capacitor model by using the 0.35-micron CMOS technology. The read/drive circuit is universally used for two-port electrostatic actuators without changing the micromechanical structures.