An Optically Powered, High-Voltage, Switched- Capacitor Drive Circuit for Microrobotics

This work presents an efficient high-voltage (HV) drive circuit for mmand cm-scale electrostatic and piezoelectric microrobotic transducers. Designed in a 650-V SOI CMOS process, a reconfigurable series-parallel switched-capacitor (SC) converter interfaces between either on-chip photovoltaic (PV) cells or a single off-chip battery, and an HV MEMs actuator. The SC converter boosts a nominal ~3.7-7.4-V input by ~16× to 60-117 V. By using a pseudo-adiabatic drive process, the converter charges the output sequentially and recovers energy in discharge cycles to reduce power consumption by over 10× compared with a conventional hard-switching driver. On-chip PV cells use deep-trench isolation such that they can be stacked and reconfigured in arbitrary series and parallel voltage domains. Measured results show effective operation with reactive loads up to 20 nF, operating frequencies over 50 kHz, and delivered power levels up to 95 mW.