CMOS photoelectric image sensor

CMOS (Complementary-Oxide-Semiconductor) image sensor appeared in 1969, it is a traditional chip process method photosensitive components, amplifiers, A / D converters, digital signal processors and computer interface circuits integrated on a silicon chip image sensor device, this device has a simple structure, many processing functions, high yield and low price, has a wide range of application prospects.

Although the CMOS image sensor appeared a year earlier than the CCD, for a long time, due to its poor imaging quality, small image sensitive unit size, low filling rate (effective cell to total area) (10%-20%), slow response speed and other shortcomings, so it can only be used in digital cameras with low image quality requirements and small size, such as robot vision applications. Early CMOS devices adopted a "passive cell" (passive) structure, each image-sensitive unit was mainly composed of a photosensitive component and a pixel addressing switch, no signal amplification and processing circuit, poor performance. After 1989, "active cell" (active) structures appeared. It not only has photosensitive elements and pixel addressing switches, but also has signal amplification, digital-to-analog conversion and digital processing circuits, which improve photoelectric sensitivity, reduce noise, expand dynamic range, and make some of its performance parameters close to CCD image sensors, and in terms of function, power consumption, size and price are superior to CCD image sensors, so the application is more and more extensive.

CMOSImage sensingThe device is mainly composed of photodiode, MOS field effect transistor, amplifier and switch and other circuits. Therefore, the basic principle and main performance parameters of MOS field effect transistors are first introduced, and then the structure and working principle of CMOS image sensors are described, and the main performance parameters of CMOS image sensors and their improvement methods are discussed. Finally, some typical CMOS image sensors and typical ones are introducedCMOSDigital cameras and other products