A Multimodal Impedance and Optical CMOS Sensor with Integrated On-Chip Energy Harvesting

This work develops an on chip solar energy harvester for an impedance and optical detector sensing system. The optical detector is used as a single photon avalanche diode (SPAD) based silicon photomulitplier (SiPM) by operating the diode in reverse breakdown. The same SiPM is also used in photovoltaic mode when arranged as a stacked set of SPADs. The battery charging circuit is comprised of a charge pump assisted by a non overlapping clock circuit and a ring oscillator.