本文讨论了取样保持电路设计中的一些问题,分析各元件对其特性的影响,导出了取样保持电路在环路分析中的等效电路及等效参数。根据取样保持电路的等效电路研究了在取样频率较低时锁相环设计中的一些问题,并研究了解决的途径。最后介绍了根据讨论的结论设计并研制的微波信号源锁相环的分析及主要电路。 In this paper, we discuss some problems in the design of sample-and-hold circuit, analyze the influence of each component on its characteristics, and derive the equivalent circuit and equivalent parameters of the sample-and-hold circuit in loop analysis. According to the equivalent circuit of sample-and-hold circuit, some problems in the design of PLL are studied when the sampling frequency is low, and the way to solve the problem is studied. Finally, according to the conclusion of the discussion, the design and development of the microwave signal source PLL analysis and the main circuit.