Multi-channel high precision time digital converter system based on equivalent pulse counting

Time-to-digital converter (TDC) implemented in Field Programmable Gate Array (FPGA) has been developed for years and obtained superior performance. In an application with a large amount of channels, trade-off must be weighed between performance and complexity if TDC is implemented in FPGA. In this paper, a TDC prototype with equivalent pulse counting structure implemented in low-cost FPGA is presented. It contains 64 time measurement channels and can be applied in laser three-dimensional(3D) imaging systems. Preliminary tests show the resolution after calibration can reach 72.1ps and the standard deviation can reach 0.501LSB.