This article has been accepted for inclusion in a future issue of this journal. Content is final as presented, with the exception of pagination. IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS—I: REGULAR PAPERS 1 Compact Analog Temporal Edge Detector Circuit Wi

Abstract—This paper presents a low-power compact analog cir-cuit for processing time varying signals. The proposed circuit im-plements temporal differentiation, amplification and rectification, i.e., separation of outputs into on and off pathways. It is based on a hysteretic differentiator circuit, commonly used in neuromor-phic vision sensors to implement temporal edge detection. This paper presents a thorough analysis of the original circuit and iden-tifies the source of the problems and limitations it has for pro-cessing real-world sensory signals. The steps required to solve this problem are presented as well as an extended circuit with tun-able gain and adaptable threshold that allows thresholding of small temporal changes (noise) and high-pass filtering of large temporal changes. The new circuit proposed is particularly suited for focal plane implementation of both gradient based and token based mo-tion algorithms that require robust detection of temporal disconti-nuities. The circuit has been designed and successfully integrated into a 64 × 1 test prototype motion chip, fabricated in standard 350 nm CMOS technology. The paper provides extensive experi-mental characterization results. Index Terms—AER, analog VLSI, attention, hysteretic differen-tiator, motion sensors, motion circuit, subthreshold, temporal dif