传统的CMOS图像传感器一般采用基于LV-CMOS工艺的N阱/P型衬底制备的PN光电二极管或者PPD二极管作为光敏元。PIN光敏元具有结电容小、量子效率高的特点。采用HV-CMOS(高压CMOS)工艺可以实现CMOS电路与PIN光敏元的单片集成。本文研究了集成PIN光敏元的CMOS探测器的光电响应特性以及NEP随像素大小和复位电压的变化关系。研究表明，将光敏元从PN光电二极管改为PIN光电二极管后，像素电荷增益可以提高一个数量级左右; 同时，像素的瞬态电荷增益要大于传统认为的1/Cpd，并与二极管的大小以及复位电压紧密相关。研究发现，小像素因其更高的电荷增益和更低的等效噪声，更加适合弱信号下的短积分时间快速探测。若配合微透镜的使用，小像素在微光探测方面可以获得更大的优势。

Traditional CMOS image sensors generally use PN photodiodes or PPDs as the photosensitive element, which are formed based on N-well/P-type substrates using the LV-CMOS process. The PIN photosensitive element has small junction capacitance and high quantum efficiency. By using High-Voltage CMOS(HV-CMOS), monolithic integration of CMOS circuits with PIN photodiodes can be achieved. In this paper, the relationship between the photo-response characteristics, NEP of CMOS detectors and pixel size and reset voltage are studied. The results show that the pixel charge gain can be increased by about one order of magnitude when the photosensitive element is changed from PN to PIN and the transient charge gain of the pixel is larger than 1/Cpd. This is closely related to the size of the diode and reset voltage. It is found that small pixels are more suitable for fast detection of short integration time under weak signals because of their higher charge gain and lower equivalent noise. If combined with microlenses, small pixels can be further advantageous in low light detection.