Development Of Si-APD Control Circuit

Avalanche photodiode(referred to as APD),widely used in the field of science and technology such as quantum communications,lidar,imaging detection,geographic monitoring due to its feature of detecting single-photon signals in Geiger mode,has drawn more and more attention.With the increase of application scenarios,the temperature change of the APD working environment makes it unable to maintain stable performance.Aiming at the problems caused by the temperature sensitivity and avalanche self-sustaining characteristics of the APD Geiger mode,this paper has formed the related research work of the Si-APD control circuit.The specific research content is as follows:(1)In order to effectively solve the problem of unstable performance caused by the temperature sensitivity of Si-APD,this article uses MAX1978 integrated temperature control chip as the main body to develop a temperature control circuit that can directly control the working temperature in the Si-APD package.The temperature control circuit uses the STM32 microcontroller to control temperature and transmit data synchronously.(2)Based on the graphical user interface application development framework(QT),this work developed the " APD upper computer software for temperature control and counting " supporting the designed silicon APD temperature control circuit.(3)The temperature control function of the temperature control circuit was verified.The control circuit makes the temperature control fluctuation of the APD device below±0.1?,and the temperature control range is-40??0 ?.In addition,this article uses the developed temperature control circuit to test the performance parameters of a Si-APD under different temperature control conditions in a real scenario,and conducts physical analysis of the test results to explore the effect and mechanism of temperature change on the APD,which further verify reliability of the temperature control circuit and the upper computer software.As a result,this research provides a new technical solution for Si-APD temperature control.(4)In order to effectively quench the avalanche self-sustaining characteristics of the Si-APD Geiger mode,this paper designs an active quenching circuit based on the principle of the quenching circuit,and uses the APD enhanced equivalent model to simulate the designed circuit in Cadence OrCAD PSpice software.It turns out that the simulation timing diagrams are in line with the design expectations and the feasibility of the designed active quenching circuit is verified.