A self-powered asynchronous image sensor with independent in-pixel harvesting and sensing operations

Abstract

A self-powered asynchronous sensor with a novel pixel architecture is presented. Pixels are autonomous and can harvest or sense energy independently. During the image acquisition, pixels toggle to a harvesting operation mode once they have sensed their local illumination level. With the proposed pixel architecture, most illuminated pixels provide an early contribution to power the sensor, while low-illuminated ones spend more time sensing their local illumination. Thus, the equivalent frame rate is higher than the one offered by conventional self-powered sensors that harvest and sense illumination in independent phases. The proposed sensor uses a Time-to-First-Spike readout that allows trading between image quality and data and bandwidth consumption. The device has HDR operation with a dynamic range of 80 dB. Pixel power consumption is only 70 pW. The article describes the sensor’s and pixel’s architectures in detail. Experimental results are provided and discussed. Sensor specifications are benchmarked against the art.