A New Verilog-A SPAD Circuit Model Integrating Crosstalk for Large-Scale Array

Single Photon Avalanche Diode (SPAD) is an optoelectronic conversion device with excellent detection sensitivity and extremely high gain. With the increase of SPAD array scale, crosstalk has become an urgent problem to improve the signal-to-noise ratio in SPAD circuit design. However, there is still a lack of SPAD array circuit models that can be used for circuit simulators and describe crosstalk to optimize circuits. To this end, this paper proposed a new structure of single pixel SPAD model, which responds to interference from surrounding pixels using current controlled switch and current controlled current source. Based on the single pixel model and theoretical analysis, a SPAD array circuit model that can describe crosstalk is established, successfully expanding the SPAD circuit model from single pixel to array. This model is described by Verilog-A and can be directly implemented in commercial circuit simulators. The developed model was simulated and validated using a gate controlled mode active quenching circuit. The experimental results show that the simulation results are in good agreement with theoretical and measured data, and have excellent adaptability to SPAD arrays with different structures. In most cases, the simulation error does not exceed 10%, which verifies the accuracy of the established SPAD array circuit model. This model is helpful for achieving collaborative design of circuits and large-scale SPAD array.