A new photodiode model for SPICE simulation of complementary metal-oxide-semiconductor image sensors

In this paper, a novel photodiode model that better describes the electro optical behavior of a complementary metal-oxide-semiconductor (CMOS) image sensor has been developed. The conventional diode model adopted by Berkeley short-channel insulated-gate field-effect transistor model 3 (BSIM3) suffers from a large discrepancy between simulation and measurement results for CMOS image sensors (CISs). The simulated response exceedingly overestimates the dark signal and is unable to provide the optical response of a CIS pixel circuit. A closed-form photodiode model is proposed in our work. The experimental results demonstrate that this photodiode model can accurately predict the relationship between the diode current and the operation voltage, temperature, incident light intensity and wavelength. Using the novel photodiode model, a more precise environment can be established for performance optimization and system-on-chip simulations in various CIS applications.