A Photovoltaic Energy Harvester/Image Sensor Platform With Event Detection Capability in 180 nm

Abstract

Photodiodes can be utilized for both image sensing and energy harvesting, but at opposite polarity. There have been numerous research works which have attempted a self-powered imager, by flipping the diodes and harvesting. However, the integration cycle in the image sensing(IS) process is very long and the chip cannot harvest while in this mode. In this letter, an event detector (ED) function is demonstrated in 180 nm, whereby the voltage across the photodiode is monitored during harvesting. If there is a significant change in this voltage, then an event is detected, and the chip can take a picture. Two types of EDs are proposed, which can function at average power as low as 0.2– $1 ~\mu \text{W}$ .