The Research Of Temperature Control System Of APD Arrays Based On FPGA

The Avalanche Photo diode(APD)is the main receiver of the Lidar.With the development of the APD device in the direction of miniaturization,modularization,and integration,the influence between the APDs in the array becomes large,and due to the severe influence of temperature on the APD,which places a very high requirement on the gain stability of the APD.Therefore,in order to obtain stable gain,this paper designs a real-time temperature control system to ensure APD gain stability,which is the focus of this study.The main research contents of this article include:(1)Introduce the research of APD temperature control system at home and abroad.Through analyzing the influence of temperature,optical power and other factors on the work performance of APD,we choose to use the method of constant temperature control to obtain a stable gain.(2)Design the temperature measurement system based on FPGA,use the digital temperature sensor chip TCN75 A to design the temperature measurement module,and create an IP core with the temperature measurement module in the VIVADO and SDK software environment to measure the temperature,and work on different bias voltages,different frequencies,and different pulses.The temperature of a single-point APD device and an area array APD device under wide conditions is detected,and the influence of temperature on the received signal of the APD device is also studied.(3)FPGA-based array APD temperature control system is designed,combined with the temperature measurement point on the array APD chip,a DC voltage readout circuit is designed to obtain the APD temperature in real time,and the semiconductor refrigeration chip is used as a refrigeration device,and design the circuit of switching to control the semiconductor refrigeration chip,design low ripple power to supply the APD,design thermostat device.The temperature measurement module and on-chip DC voltage readout circuit were used to collect the ambient temperature and on-chip temperature of the APD array.The FPGA control program was written using Verilog HDL language and C language.The Zed Board development board was used to control the semiconductor refrigeration chip to real-time cool the APD.(4)The MIO control method was designed to discover the problems in the MIO control mode through experiments,and the control mode was improved.A PWM control method that can change the output power according to the temperature change amplitude was designed,and the PWM control method was tested experimentally.