Modeling the Photovoltaic Diode Region for High Dynamic Range Image Sensor Design

This work presents an analytical model for the dependence of the open-circuit voltage of CMOS diodes operating in the photovoltaic (PV) regime versus illuminance and temperature. The model is targeted for image sensor design and provides insights into key behavioral features relevant to high dynamic range (HDR) image acquisition, including the steady-state response, sensitivity, bandwidth, noise, and signal-to-noise ratio (SNR) under varying illuminance and temperature conditions. The article also includes experimental data to confirm the adequacy of the proposed model in predicting the behavior of practical photodiodes. These findings highlight the suitability of a PV diode as the photoreceptor stage for HDR imaging applications, offering improved compactness and noise performance over conventional logarithmic photoreceptors while operating without static power consumption as a result of its self-biased nature.