SPICE modeling of single photon avalanche diodes

In this paper we present a comprehensive circuit model for single photon avalanche diodes (SPADs), implemented into two different CAD circuit simulation environments (PSpice and Spectre), that fully describes detector behavior in the above-breakdown (Geiger-mode) operation. In particular, the SPICE modeling accurately simulates the ignition of the detector due to a photon absorption, the fast avalanche current build-up, the self-sustaining charge-multiplication process, and the self-quenching of the avalanche pulse. The model works within both passive and active quenching circuits and it deals correctly with both single-photon and photon-burst excitation. We show how to experimentally extract the required model parameters from any SPAD detector and how to input them into the circuit simulators. We discuss different operating regimes and we present various case studies that validate the modeling and quantitatively prove its accuracy.