A 2-D velocity- and direction-selective sensor with BJT-based silicon retina and temporal zero-crossing detector

In this paper, a 2-D velocity- and direction-selective visual motion sensor with a bipolar junction transistor (BJT)-based silicon retina and temporal zero-crossing detector is proposed and implemented. In the proposed sensor, a token-based delay-and-correlate computational algorithm is adopted to detect the selected speed and direction of moving object images. Moreover, binary pulsed signals are used as correlative signals to increase the velocity and direction selectivities. Each basic detection cell in the sensor has a compact architecture, which consists of one BJT-based silicon retina cell, one current-input edge extractor, two delay paths, and four correlators. Using the proposed architecture, an experimental 32/spl times/32 visual motion sensor chip with a cell size of 100/spl times/100 /spl mu/m/sup 2/ has been designed and fabricated by using 0.6-/spl mu/m CMOS technology. The correct operations of the fabricated sensor chip have been verified through measurements. The measured ranges of selectively detected velocity and direction in the fabricated sensor chip are 56 mm/s-5 m/s and 0-360/spl deg/, respectively. The complete sensor system consumes 20 mW at 5 V.