VERTICAL JFET SOURCE FOLLOWER FOR SMALL PIXEL CMOS IMAGE SENSORS

摘要

An image sensor pixel (200) suitable for use in a back-side-illuminated or a front-side-illuminated sensor arrangement is provided. The image sensor pixel may be a small size pixel that includes a source fol¬ lower (300) implemented using a vertical junction field effect (JFET) transistor. The vertical JFET source follower may be integrated directly into the floating diffusion node (302), thereby eliminating excess metal routing and pixel area typically allocated for the source follower in conventional pixel configurations. Pixel area may instead be al¬ located for increasing the charge storage capacity of the photodiode (207) or can be used to reduce pixel size while maintaining pixel performance. Using a vertical junction field effect transistor in this way simplifies pixel addressing operations and minimizes random telegraph signal (RTS) noise associated with small size metal-oxide-semiconductor (MOS) transistors.