A foveated silicon retina for two-dimensional tracking

A silicon retina chip with a central foveal region for smooth-pursuit track ing and a peripheral region for saccadic target acquisition is presented. T he foveal region contains a 9 x 9 dense array of large dynamic range photor eceptors and edge detectors. Two-dimensional direction of foveal motion is computed outside the imaging array. The peripheral region contains a sparse array of 19 x 17 similar, but larger, photoreceptors with in-pixel edge an d temporal ON-set detection. The coordinates of moving or flashing targets are computed with two one-dimensional centroid localization circuits locate d on the outskirts of the peripheral region. The chip is operational for am bient intensities ranging over six orders of magnitude, targets contrast as low as 10%, foveal speed ranging from 1.5 to 10K pixels/s, and peripheral ON-set frequencies from <0.1 to 800 kHz. The chip is implemented in 2-mu m N well CMOS process and consumes 15 mW (V dd = 4 V) in normal indoor light (25 mu W/cm(2)). It has been used as a person tracker in a smart surveillan ce system and a road follower in an autonomous navigation system.