Design And Implementation Of High Precision Time Base Calibrator Based On Digital Phase Locked Loop

Time base source,also known as clock source,is the core component of electronic system.It provides a unified and accurate time-frequency reference for the sequential circuit of application equipment to ensure the orderly work of various functional circuits.It is widely used in many national defense industries and related civil fields,such as frequency synthesis,navigation control,computer network and data communication.Time base source calibration and phase control synchronization technology is the key way to achieve high-precision time base calibration.Therefore,the research on time base calibration and phase control synchronization technology has important practical significance.This paper focuses on the research of time-base signal correction,synchronous phase-locked loop and phase-locked loop technology,introduces the research status of the two technologies,and proposes a new method based on second-order generalized integrator(SOGI)as the data preprocessing unit,park transform as the digital phase detector A high-precision time base calibration method of digital phase-locked loop based on IIR digital filter and DDS phase control frequency synthesis technology is proposed.The high-precision time base calibrator includes time base signal sampling,time base signal orthogonalization,phase detector based on Park transform,loop filter,PI regulator and DDS frequency synthesis.The functional circuit involved in the scheme and the FPGA design and implementation of closed-loop phase-locked control algorithm are analyzed and discussed in detail.Through the design of the principle prototype,the frequency of the time base calibrator,the synchronization state of the digital phase locked loop and the output characteristics of the10MHz time base are tested.The test results show that the output signal frequency after frequency calibration can realize the high-precision traceability of the reference source,and the time base calibration accuracy reaches 1.9×10^-8,which verifies the feasibility of the time base calibrator scheme and the correctness of the design.