A Modular Switched-Capacitor Chip-Stacking Drive Platform for kV-Level Electrostatic Actuators

This work presents a switched-capacitor (SC) actuator driver implemented in 180-nm silicon-on-insulator (SOI) CMOS that uses multi-chip stacking to extend drive voltages beyond the process limits of a single chip. Building on past work, the SC stage uses a modified series–parallel architecture to step the actuator drive voltage sequentially, reducing hard-charging losses and recovering energy stored in the bulk dielectric of representative piezoelectric and other electrostatic transducers. The design uses an auxiliary (inductor-based) boost converter in the first chip to interface with low-voltage primary battery inputs while providing regulation. Multi-chip stacking allows modularity and scalability to kV-level drive voltages with low-voltage control signals relayed through a floating daisy-chain network. With a single chip using $\mathrm { < }5$ - $\mathrm {\mu }\text{A}$ quiescent current, the design provides voltage conversion ratios (VCRs) $\mathrm {>} 100$ , converting 3.7-V inputs to over 400 Vpp. In a demonstration with eight chips stacked in a miniaturized interposer platform, the design can convert 2.5–5-V inputs to 3 kVpp (VCR > 1000), delivering 1-W reactive power with over 97% efficiency.