A Linear-Logarithmic CMOS-Memristor Vision Sensor

Abstract

Nowadays, the variety of CMOS image sensors with wide dynamic range is expanding at an undoubtedly fast rate. The primary goal in image sensors design is to maintain small pixel size and high sensitivity at low light illumination. Existing image sensors with mixed log-linear output characteristics, produce linear output at dark conditions whereas high-intensity zones provide the capability of logarithmic response. However, the change in the light intensity is not easy to be detected considering the alternation in time and the number of pixels to work with. Besides, the recording of the variation should be made when pixel changes due to its previous history. As a result, in order to track and simultaneously notify about the changes in the behavior, a memory device called memristor, also known as a time-varying resistor, should be implemented. This paper propounds an original design of CMOS vision sensor based on the five-transistor (5T) active pixel sensor (APS) and memristorintegrated APS with a lin-log response. The proposed model was constructed with TSMC 0.18-μm standard CMOS process.