Design of CMOS Image Sensor Dynamic Pixel Structure by Utilizing Pulse Width Modulation

A typical CMOS image sensor (CIS) amplifiers voltage or current through source follow to read the value of the pixel. However, the source-follower used in a CMOS active pixel sensor (APS) suffers from degraded SNR due to its gain being less than unity. In this paper Pulse Width Modulation (PWM) of the structure of a common-gate-amplifier has proposed a new pixel structure. A PWM pixel can convert light intensity to a digital pulse width by using an in-pixel comparator with a low power-supply voltage without any degradation of signal-to-noise ratio (SNR). To reduce the size of these pixels, with a comparison of the transistor through the commongate-amplifier structure to a 4-transistor pixel structure was proposed. proposed pixel has Larger signal range, low voltage leakage current and low power consumption than the conventional structure of the pixel