Study Of FPGA Time-to-digital Converter Based On Channel-interpolation

High-precision TDC(Time to Digital Converter) is used for measuring the time interval between two physical events. It is widely used in the field of nuclear physics experiments, space science, power transmission, timing and synchronization, aerospace, chip design, satellite navigation and digital communication.Single photon detection is a very weak light signal detection technology, if the detection diodes are integrated in an array, single photon three-dimensional imaging function can be realized by obtaining signal intensity as well as time information of each pixel at the same time. This technique can be implemented in robots vision, autonomous vehicle navigation, manufacturing process control, industrial safety, as well as military uses such as finding and locating camouflage or hidden targets.This thesis will focus on the study, design and realization of FPGA TDC based on channel-interpolation method mainly for the application of single photon detector with following four tasks:(1) The fully analysis of single photon imaging technique, time-to-digital converter technology and its application in single photon detector array; Choosing tapped delay line based method after considering the feasibility of system realization;(2) The realization of the system based on Xilinx’s XC5VLX30 T FPGA chip by utilizing its internal fast carry chain, advanced first out module, phase locked loop and other resources;(3) Using code density test method in the measurement circuit to eliminate delay cell non-linearity problem. Proposing a channel-interpolation scheme to improve the measurement accuracy for multi-channel measurement, and make a comparison with the channel-averaging method;(4) Analyzing the code density test results in Matlab; Processing the experiment data and estimate the performance of the system; Designing the software based on C# in the workstation, which can communicate with the hardware circuit such as sending instructions to the system and receiving experiment data and display results in real time.In this thesis, the tapped delay line based system can offer an improvement from 63 ps to 21 ps in resolution and 66 ps to 34 ps in RMSE after implementing channel-interpolation method.