Front-end Readout Integrated Circuit Design Of Geiger-mode Focal Plane Array

Single-photon detection technology can detect extremely weak optical signals and is widely used in the fields of physics,chemistry,biomedicine,astronomy,and information science to provide the ultimate sensitive detection method.The avalanche photodiode is a photoelectric device based on avalanche multiplication.It is a good candidate for single-photon detectors due to its sensitivity,easy integration,and moderate requirements on the refrigeration systems.Plenty of studies have been focused on InGaAs Geiger mode avalanche photodiodes(GmAPDs)because they have a response in shortwave infrared wavelength,which is safe for human eyes and has mature laser sources.Readout integrated circuit(ROIC)is one of the essential components of the GmAPD infrared focal plane detectors.It is used for operation states switching,high precision timing,and high-speed timing data output.The front-end readout integrated circuit is responsible for quenching,resetting and protecting the ROIC from breakdown due to unexpectedly high voltage.It has a significant impact on the detector performance such as dark count rate(DCR),photon detection efficiency(PDE),and reliability.Due to the restrictions of the low area and power consumption,the design of high-performance quenching circuits for large-format GmAPD focal plane are facing great difficulties and challenges.This paper presents a study and design of the front-end ROIC of the GmAPD detectors,and the researches focus on the fast quenching circuit design and high voltage protection methods.The main research contents and achievements are as follows:(1)In order to obtain more accurate simulation results,an enhanced GmAPD simulation model is compiled using Verilog-A language,and I-V characteristic is expressed by three segmented functions with the 93 % fitting precision.(2)Two kinds of quenching circuit are designed for gated and free-running GmAPD based on the study of front-end ROIC transfer function.The simulation results show that the quenching time of the proposed circuits is 1.75 ns and 1.8 ns,and the reset time is 3.8 ns and 1.5 ns,respectively.The hold-off time variable range of the free-funning quenching circuit is 0.854 μs～3.697 μs.The test results show that the chip meets the basic functional requirements(3)A quenching circuit with a meander metal fuse is fabricated in 0.18 μm standard CMOS process,which aims to protect ROIC from breakdown due to unexpectedly high voltage.Fuse resistances in states of pre-burnout and post-burnout are investigated to satisfy requirements of rapid quenching and high voltage protection,respectively.Several fuse options using commercial mixed-signal CMOS processes,such as metal and polysilicon,are compared in detail.Meander metal fuse is the most suitable candidate according to measurement results.A rapidly quenching circuit integrated with a metal fuse is developed using a 0.18 μm CMOS process.After being bonding with GmAPDs and resistors,test results show that this circuit could endure a high voltage of 75 V,demonstrating that this innovative design can contribute in a low-cost and high-reliable way to high-yield large-format GmAPD arrays.