Sub-nanosecond synchronization implementation in pure Xilinx Kintex-7 FPGA

White Rabbit (WR) provides high-performance synchronization with sub-nanosecond accuracy and picoseconds precision, and it has been included in the new High Accuracy Default PTP Profile in the IEEE 1588-2019. As an open-source project, WR Precision Time Protocol (WR-PTP) core has been implemented in different FPGA platforms with dedicated clock circuits. This paper presents a novel approach to achieve the WR function in Xilinx Kintex-7 FPGA depending on the on-chip resource. This approach could achieve sub-nanosecond accuracy and tens of picoseconds precision, simplifying WR devices' hardware design and making it possible to port the WR PTP core to many mature hardware platforms.