A 640×640 Fully Dynamic CMOS Image Sensor for Always-On Object Recognition

Abstract

This paper presents a $640\times 640$ fully dynamic CMOS image sensor for always-on object recognition. A pixel output is sampled with a dynamic source follower (SF) into a parasitic column capacitor, which is readout by a dynamic single-slope (SS) ADC based on a dynamic bias comparator and an energy-efficient two-step counter. The sensor, implemented in a 0.11μm CMOS, achieves 0.3% peak non-linearity, 6.8$e_{rms}^{-}$ RN and 67dB DR. Its power consumption is only 2.1mW at 44fps and is further reduced to 260μW at 15fps with sub-sampled 320 × 320 mode. This work achieves the state-of-the-art energy-efficiency FoM of 0.7$e^{-}\cdot$ nJ.