An analog VLSI which emulates biological vision

A linear analog network model is proposed to describe the neural circuit of the outer retina. Using the model, we characterized the spatial filtering properties of the circuit in terms of the standard regularization theory in which the early vision problems are attributed to minimization of a cost function. Inspired by the algorithm/architecture of the circuit, a vision chip was designed using analog CMOS VLSI circuit technology. The chip fabricated is an one-dimensional 100 pixel line sensor. In the chip, sample/hold amplifier circuits are incorporated to compensate for the fixed pattern noise of photosensors as well as statistic transistor mismatch. The chip effectively extracts contour of given images by controlling the receptive field size, simulating a light-adaptive mechanism suggested in the vertebrate retinal circuit