CMOS image sensor 3T Nwell photodiode pixel SPICE model

CMOS image sensor pixel design requires accurate SPICE modeling to determine pixel performance. In this work, a standard Nwell/Psub photodiode with a 3 transistor pixel has been modeled using Cadence SPECTRE SPICE simulator fabricated using a conventional 0.18 /spl mu/m CMOS process technology. Pixel parameters such as voltage swing, clock feedthrough and pixel capacitance have been modeled using silicon based measurements of individual components. These components include reset source region, Nwell photodiode and source follower gate capacitances. In addition, nonlinear effects of the photodiode and source follower are included in the model. The accuracy of the model agrees well with measured pixel transient response.