Compact Numerical Modeling of Indirect Time-of-Flight CMOS Image Sensors

A pixel-level compact numerical model, including input optical, pixel parameter, modulation gate clock, and readout noise for indirect time-of-flight (i-ToF) sensor, is proposed. The modulation contrast (Cmod) of the pixel and the depth characteristics, including depth accuracy and depth noise, are obtained with the iterative and Monte Carlo methods. The rationality of the demodulation process is verified through the pixel parameter Cmod with technology computer-aided design (TCAD) simulation and test. Then, the prediction results of the depth accuracy under nonideal conditions are obtained, which is consistent with the theoretical analysis and measurements. Finally, the depth noise is characterized. The model results give an excellent agreement with the measurement results. The proposed development of such a compact model presents an essential convenience toward for the design and circuit-level simulation and can provide the prediction of i-ToF sensor characteristics.