Analysis and design of a CMOS angular velocity- and direction-selective rotation sensor with a retinal Processing circuit

This paper implements and analyzes a CMOS angular velocity- and direction-selective rotation sensor with a retinal processing circuit. The proposed rotation sensor has a polar structure and is selective of the angular velocity and direction (clockwise and counterclockwise) of the rotation of images. The correlation-based algorithm is adopted and each pixel in the rotation sensor is correlated with the pixel that is 45° apart. The angular velocity selectivity is enhanced by placing more than one pixel between two correlated pixels. The angular velocity selectivity is related to both the number and the positions of the edges in an image. Detailed analysis characterizes angular velocity selectivity for different edges. An experimental chip consisting 104 pixels, which form five concentric circles, is fabricated. The single pixel has an area of 91×84μm² and a fill factor of 20%, whereas the area of the chip is 1812×1825μm². The experimental results concerning the fabricated chip successfully verified the analyzed characteristics of angular velocity and direction selectivity. They showed that the detectable angular velocity and range of illumination of this rotation sensor are from 2.5×10^-3 π/s to 40 π/s and from 0.91 lux to 366 lux, respectively.