Author ORCID Identifier

https://orcid.org/0000-0002-5510-6721

Date of Award

8-2025

Document Type

Thesis (Ph.D.)

Department or Program

Engineering Sciences

First Advisor

Jason T. Stauth

Abstract

Applications including micro-robotics and haptics have motivated extensive exploration of dielectric actuators due to their high bandwidth and high efficiency at cm and mm scales. To maximize their benefits, dielectric actuators, including piezoelectric and electrostatic actuators, typically require high driving voltages, ranging from 100V to several kV. Generating such high driving voltages presents a challenge for drive circuits, particularly when powered by a small battery. Dielectric actuators are predominantly capacitive in most circumstances, necessitating the drive circuits to deliver and recover reactive energy for efficient operation. In some applications, such as micro-robotics, the drive circuits may need to have a weight significantly less than 1g and a volume less than 1cm3.

This dissertation explores topologies and integration strategies for drive circuits for small-scale, high-voltage dielectric actuators. Specifically, we outline a pseudo-soft switching series-parallel switched-capacitor (SC) converter that reduces hard-switching loss by stepping the load voltage with small increments and recovers the energy stored in the load to high-energy-density flying capacitors. The operation and performance benefits of the circuit are validated with several integrated circuit prototypes. A first prototype uses on-chip photovoltaic cells as a power source and achieves output voltage over 100V with up to 14x reduction in power compared to a conventional hard switching driver. A second prototype uses a decentralized daisy-chain control scheme and chip-chip stacking to extend drive voltages to the kilovolt range, beyond the buried oxide limit of conventional high-voltage SOI CMOS processes. A final prototype extends the pseudo-soft switching concept to gate drivers for silicon and GaN power semiconductor devices. This is used to show that the pseudo-soft switching concept can be extended to MHz switching regimes with sub-ns waveform tuning, while reducing gate drive power by 5x to 7x compared to conventional gate drivers.

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