Research of high precision time interval measurement base on carry chain

The time interval measurement system with an average resolution of 65ps has been designed in an FPGA chip. The system combines direct pulse counting with digital interpolation using dedicated carry chain inside FPGA. In order to calibrate the time-to-digital converter (TDC), a statistics code density method is adopted. The paper particularly introduces the architecture of the system and the calibration of TDC. Experimental results show that the whole system can be operated simply and functions well.