Physical Model of Current-Assisted Photonic Demodulator (CAPD) for Time-of-Flight CMOS Image Sensor

This article presents a physical model of the current-assisted photonic demodulator (CAPD) for the time-of-flight (TOF) CMOS image sensor. An analytical expression relating the optical photogenerated current to the input bias and incident light intensity is derived by solving the continuity and drift-diffusion equations along the optical window of the CAPD. The model has been extensively verified with numerical simulations, as well as with published experimental data. Based on the developed model, the CAPD efficiency with respect to peak modulation voltage is discussed.