A dual threshold adaptation method to dynamic vision sensor pixel

Abstract

This paper introduces a method for the dynamic vision sensor (DVS) pixel that achieves dual-threshold adaptation based on the interval between adjacent event spikes. The Time-to-Amplitude Converter (TAC) measures the adjacent spike interval per pixel. Based on the output of the TAC and two predefined time limit, the threshold selection circuit automatically chooses between the low threshold ΘL or the high threshold ΘH. The proposed pixel pitch is 33.2μm×34.2μm with 8.1% fill factor in a 0.11μm 1P4M CMOS process. Compared to traditional pixel with fixed threshold temporal contrast Θ = 15%, the behavior model indicates that the proposed structure maintains almost equivalent detection ability while reducing event output by 30% when ΘH = 45% and ΘL = 15%. Compared to the traditional pixel with fixed Θ = 45%, the behavior model indicates that the average gradient of the proposed structure is improved by at least 3 times with ΘH = 45% and ΘL = 15%. This enables the detection of low temporal contrast signals while minimizing the quantity of output events.