A CMOS Image Sensor With In-Pixel Buried-Channel Source Follower and Optimized Row Selector

This paper presents a CMOS imager sensor with pinned-photodiode 4T active pixels which use in-pixel buried-channel source followers (SFs) and optimized row selectors. The test sensor has been fabricated in a 0.18-mum CMOS process. The sensor characterization was carried out successfully, and the results show that, compared with a regular imager with the standard nMOS transistor surface-mode SF, the new pixel structure reduces dark random noise by 50% and improves the output swing by almost 100% without any conflicts to the signal readout operation of the pixels. Furthermore, the new pixel structure is able to drastically minimize in-pixel random-telegraph-signal noise.