一种用于自由运转SPAD的高速淬灭电路设计

A High-Speed Quenching Circuit for Free-Running Single Photon Avalanche Detector

摘要:

针对标准CMOS工艺的单光子雪崩探测器 (Single Photon Avalanche Detector,SPAD),设计了一种可用于自由运转模式的高速淬灭电路。为了实现淬灭电路的功能设计与精准仿真,根据实测的SPAD电流-电压曲线拟合得到了电流与电压间的多段式函数解析式,进一步建立了SPAD器件的Verilog-A行为级模型并与淬灭电路进行集成仿真与验证。淬灭电路采用基于电容感应的主被动淬灭结构,利用可变MOS电容的延迟电路实现了关断时间 (Hold-off Time) 的灵活调节。仿真结果表明,所设计淬灭电路的淬灭时间和恢复时间分别为1.0和1.2ns,关断时间调节范围为1.02~3.55μs,可以满足自由运转CMOS SPAD的应用需求。

Abstract:

In this paper, a fast quenching circuit is designed and simulated for free-running CMOS single photon avalanche diode (SPAD). In order to obtain more accurate simulation results, an enhanced SPAD simulation model is compiled using Verilog-A language, and I-V characteristic is expressed by three segmented functions. The fast quenching circuit is based on mixed passive-active quenching and capacitive sensing. A timing control circuit composed of the variable MOS capacitor is used to achieve hold-off time regulation. The simulation results show that the quenching time and reset time of the quenching circuit are 1.0 and 1.2ns, respectively. The hold-off time can be varied in the range of 1.02~3.55μs, which can meet the requirements of free-running CMOS SPAD detectors.