Compact High-Voltage Switched-Capacitor Driver for MEMS Actuators

This paper presents a compact high-voltage switched-capacitor (SC) MEMS actuator driver. Specifically, an exponential SC boost stage provides a high step-up voltage conversion ratio (VCR), followed by a series-parallel (SP) SC stage to sequentially drive the load step by step for efficient reactive power delivery while complying with the voltage rating of passive components. With a reduced number of operating steps as well as passive components, the proposed SC driver can effectively enable a high MEMS driving efficiency with a smaller volume, lighter weight, and lower cost. The reduced number of steps also ensures a higher driving frequency, improving the maximum reactive output power. Fabricated in a standard 180nm BCD process, the chip prototype can efficiently transfer reactive power up to 683mW, while achieving a ~3× power density improvement when compared with similar prior arts.