We present a novel analog VLSI implementation of visual motion computation based on the lateral inhibition and positive feedback mechanisms that are inherent in the hysteretic winner-take-all circuit. By use of an input-dependent bias current and threshold mechanism, the circuit resets itself to prepare for another motion computation. This implementation was inspired by the Barlow-Levick model of direction selectivity in the rabbit retina. Each pixel uses 33 transistors and two small capacitors to detect the direction of motion and can be altered with the addition of six more transistors to measure the interpixel transit time. Simulation results and measurements from fabricated VLSI designs are presented to show the operation of the circuits.
Erhan Ozalevli, Paul Hasler, and Charles M. Higgins, "Winner-Take-All-Based Visual Motion Sensors," IEEE Transactions on Circuits and Systems II, vol. 53, no. 8, pp. 717-721, August 2006.