A silicon VLSI optical sensor for pattern recognition

Abstract

We show a silicon integrated circuit optical sensor with a high degree of built-in computational power that enables the sensor to recognize specific, preset complex images projected onto its surface. The sensor consists of a multilayer feedforward network, of which the first layer detects local orientations of line and edges. The second layer of this computational sensor recognizes specific configurations of these line and edge orientations. The circuit designs have been kept simple in order to fit within the spaces between the photoreceptors. The design methodology, including that used to set the first and second layer weights, and results from test ICs are shown. The net benefit of such an approach is very high computational density of the order of 2×10 10 weights/cm 2 /s. The approach is very fault tolerant and will permit true wafer scale integration.