A time-domain gradient-detection architecture for VLSI analog motion sensors

A time-domain gradient-detection architecture of analog motion sensors has been developed for high-speed-execution of motion related image processing algorithms. In this architecture, a compact gradient detector circuit calculates temporal and spatial gradients of photodiode signals at each pixel location, converting the gradients to pulse widths, i.e. to time-domain signals. The time-domain signals are then converted to digital format using on-chip binary counters, thus allowing us to carry out various algorithms by external general-purpose processors. A proof-of-concept chip of 31times31 pixels was designed and fabricated using 0.35mum CMOS technology, and the optical flow estimation at the rate of 400 frames/sec has been experimentally demonstrated