دانلود A Retinomorphic Chip with Parallel Pathways: Encoding INCREASING, ON, DECREASING, and OFF Visual Signals

Abstract

Retinomorphic chips may improve their spike-coding efficiency by emulating the primate retina’s parallel pathways. To model the four predominant ganglion-cell types in the cat retina, I morphed outer and inner retina microcircuits into a silicon chip, Visio1. It has 104 ×96 photoreceptors, 4 ×52 ×48 ganglion-cells, a die size of 9.25×9.67 mm² in 1.2 μm 5 V CMOS, and consumes 11.5 mW at 5 spikes/second/ganglion-cell. Visio1includes novel subthreshold current-mode circuits that model horizontal-cell autofeedback, to decouple spatial filtering from local gain control, and model amacrine-cell loop-gain modulation, to adapt temporal filtering to motion. Different ganglion cells respond to motion in a quadrature sequence, making it possible to detect edges of one contrast or the other moving in one direction or the other. I present results from a multichip 2-D motion system, which implements Watson and Ahumada’s model of human visual-motion sensing.