A Time Error Correction Method Applied to High-Precision AER Asynchronous CMOS Image Sensor

A time error correction method for improving the accuracy of asynchronous CMOS (Complementary Metal Oxide Semiconductor) imager sensor (CIS) is proposed. By adding a time error measurement unit in each pixel, the time error can be recorded, and then is sent out together with the address-events. Besides, in the external processing circuit, the correction will be accomplished before making time-stamping. For the sake of clarifying the influences on the image accuracy, different scale of the pixel array, event collisions, accuracy of time-stamping and illumination are adopted in the simulation. The simulation results of the Matlab Simulink show that, in an 8 × 8 asynchronous CIS without time error correction, when the illumination is 103 ~ 105 lx, the error of the image accuracy is from 0.4 % to 28 %. With the decrease of the time-stamping accuracy, the expansion of pixel array, the increase of event collisions and the strengthening of illumination, the error would deteriorate further. As to the model of asynchronous CIS with time error correction, when the accuracy of the time-stamping is 10 ns, the time error can be controlled within 20 ns. For the same illumination, the maximal error of image is 0.31 %.