Design Of SPAD Arrays And Pixel Circuit Based On CMOS Technology

With the development of society,people are increasingly in need of image detection for weak light,and single photon detection is a very effective means to solve this problem.Compared to CMOS image sensors and PMTs based on charge couplers.The device has the advantages of high detection sensitivity,strong anti-interference ability,simple structure,and ease of large-scale integration.Although widely used in aerospace,biopharmaceuticals,signal transmission,etc.,although it has broad application prospects,the difficulty in the development of this technology is how to perform monolithic integration and large-scale array applications.This article will study this.First,in traditional single-photon detection,in order to ensure the photon detection efficiency of the detector device,the device size is usually designed to be too large.However,such design is a huge challenge for reducing the array area and improving the integration of the array.Therefore,this paper will design a small-sized SPAD structure suitable for large-scale array detectors based on 0.18?m CMOS process,optimize the design,determine the device structure,draw layouts and verify the test.Secondly,aiming at the problem of no SAPD simulation model,this article will put forward a device SPICE model suitable for circuit simulation on the basis of fully researching and reading the literature,paving the way for circuit design.Secondly,two simple and reliable quenching circuits are designed for SPAD: load variable and capacitor quenching circuits.Simulation shows that the quenching time of the circuit is lower than 5 ns,the reset time is lower than 1 ns,and the overall dead time is less than 1ns,to meet the application needs of high-speed detection.The circuit reliability simulation was performed to change the temperature,bias voltage,and power supply disturbance.The simulation results still meet the design requirements.Third,this article will use a new type of analog counting circuit,using two capacitors to achieve the technical goal of mutual charge and discharge,the excellent performance of the count linearity,still good linearity in the count 200 times,and the circuit antijamming The ability is excellent and the overall goal of design is achieved.In s?mmary,the three parts of the detector,quenching circuit and counting circuit of the SPAD array pixel unit are respectively put forward their own innovative designs.Under the premise of ensuring their respective performance,the area of each module is effectively reduced,making it suitable for Large-scale SPAD detection array applications.