In this paper

we report a high-precision intermediate-frequency digital phase detector.Suitable parameters for digital filter and other modules in the digital phase detector are chosen via careful analysis.The digital phase detector uses I/Q technology

and is achieved on FPGA chip

working as a part of experimental setup to detect the phase of intermediate-frequency signal.The results show that precision of the digital phase detector is 0.029°.The phase discrimination for one 3.71875 MHz signal is better than 0.05°

with a root mean square phase value of 0.0076°;while it is better than 0.1° with a root mean square phase value of 0.0287° for two 3.71875 MHz signals.