Characterization-Based Modeling of Retriggering and Afterpulsing for Passively Quenched CMOS SPADs

Abstract

The current trend in the design of systems based on CMOS SPADs is to adopt smaller technological nodes, allowing the co-integration of additional electronics for the implementation of complex digital systems on chip. Due to their simplicity, a way to reduce the area occupied by the integrated electronics is the use of passive quenching circuits (PQCs) instead of active (AQCs) or mixed (MQCs) ones. However, the recharge phase in PQCs is slower, so the device can be retriggered before this phase ends. This paper studies the phenomena of afterpulsing and retriggering, depending on the characteristics of the SPADs and the working conditions. In order to do that, a test chip containing SPADs of different size has been characterized in several operating environments. A mathematical model has been proposed for fitting afterpulsing phenomenon. It is shown that retriggering can be also described in terms of this model, suggesting that it is linked to carriers trapped in the shallow levels of the semiconductor and that should be taken into account when considering the total amount of afterpulsing events.

Numerical Model of SPAD-Based Direct Time-of-Flight Flash LIDAR CMOS Image Sensors

“…From a statistical point of view, crosstalk and afterpulsing effects create correlated events that are non-trivial to be efficiently modeled. Regarding afterpulsing in particular, probabilistic models and characterization techniques which may be employed in the simulation process have been proposed [ 35 , 36 ], even though the universality of other approaches is questioned in the work from Ziarkash et al [ 37 ]. Therefore, our strategy will be toward the investigation of the most suited approach which provides statistically reliable results with a computationally efficient implementation.…”

High-resolution single-photon imaging with physics-informed deep learning

“…In such a case, the saturation current is relayed, and the detector will count an additional detection event with a certain probability, denoted as afterpulsing noise . The existing studies of afterpulsing noise 51 , 52 consider its probability to be a power function or exponential decay with time. Since we only consider its statistical effect related to the manufacture of each pixel unit, we simplify the model to be a fixed probability distribution map, and assume that its effect of the previous frame may only apply to the current frame.…”

Low‐power compact tunable quenching configuration for minimizing afterpulsing in single‐photon avalanche diodes

“…Since most SPAD front-ends with active or mixed passive-active approach suffer from high power and area consumption, PQ is preferred due to its simplicity and low area consumption. 22 The schematic representation of first proposed circuit is illustrated in Figure 1. The proposed circuit consists of two inverters, two transistors, a Schmitt trigger and a MOSCAP.…”