This paper presents a step-up hybrid series-parallel DC-DC converter with high voltage conversion ratio for soft-charging dominantly capacitive dielectric actuators such as piezoelectric actuators, dielectric elastomer actuators, and ultrasound transducers. The hybrid switched capacitor (SC) converter includes a buck-boost stage which soft charges (and discharges) both the SC network and the capacitive load. The multi-level series-parallel SC stage uses all low voltage-rated devices while efficiently stepping up the output voltage. The prototype is based on a high-voltage 180nm SOI CMOS integrated circuit (IC) that achieves 200V output voltage from a 3.3V input voltage supply with 94.2\% peak reactive power efficiency and delivers up to 250mW peak reactive power. This is the first dielectric actuator driver IC to demonstrate full hybrid soft charging, enabling higher efficiency for a given passive component area, weight, and cost.
