在航天技术和锁相接收机中,为了快速捕捉和提取噪声中的有用信号以及提高信噪比,希望锁相环宽带能在一定范围内根据信号的情况而变化,本文提出了一种变带宽数字锁相环的基本原理和环路结构。对变带宽数字锁相环进行了数学建模与Matlab仿真。通过建模、仿真和合理设置参数,证明该数字锁相环结构可以在一定范围内变化其带宽,并能有效提取和跟踪淹没在噪声中的微弱信号。 In space technology and phase-locked receiver, in order to quickly capture and extract the useful signal in the noise and improve the signal-to-noise ratio, it is hoped that the phase-locked loop wideband can vary with the signal within a certain range. In this paper, The basic principles of digital phase-locked loop and loop structure. The mathematical model and Matlab simulation of variable bandwidth digital PLL are given. Through modeling, simulation and reasonable parameter setting, it is proved that the digital phase-locked loop structure can change its bandwidth within a certain range, and can effectively extract and track the weak signals submerged in the noise.