本文介绍了７４ＨＣ４０４６的工作原理以及采用７４ＨＣ４０４６锁相环芯片组成的图象数字化电路中的行锁相象素时钟（采样时钟）发生器，该发生器的过渡过程快，捕获时间短，跟踪精度高，本文给出了实用电路。 This article describes the working principle of the 74HC4046 and the line-locked pixel clock (sampling clock) generator in an image digital circuit composed of 74HC4046 phase-locked loop chips. The generator has a fast transition process, a short acquisition time and a high tracking accuracy This article gives a practical circuit.