A 90 µW at 1 fps and 1.33 mW at 30 fps 120-dB Intrascene Dynamic Range 640 × 480 Stacked Image Sensor for Autonomous Vision Systems

Abstract

We present an ultralow-power high dynamic range (DR) image sensor dedicated to autonomous vision systems, produced in a back illuminated 65 nm/40 nm stacked process and based on a time-to-digital pixel with in-pixel A/D conversion and data memory. Key to the low-power consumption is a new in-pixel comparator without dc current consumption. The 120-dB intrascene DR of the sensor, encoded on 10 bits, makes use of a logarithmic data representation. Thanks to the high intrascene DR, no adaptation to the local illumination is necessary. The sensor has a sensitivity of 6.4 V/lux/s, an FPN of 0.6%, and a temporal noise of 11 e−, with a pixel pitch of $6.3 \, \mu \text{m}$ and a fill factor of 86%.