基于DDS内插PLL的设计分析

对目前常用的几种频率合成方式进行了简单介绍,阐述了直接频率合成、间接锁相环合成(PLL)以及DDS与PLL相结合的多种频率合成方式的优缺点,并着重讨论了DDS内插PLL的频率合成方法。详细阐述和分析了DDS内插PLL频率合成方式的实现方案及关键技术。针对DDS固有杂散讨论了DDS滤波器的设计并得出指导性结论。给出应用于实际电路的测试结果,证实了文中分析的正确性和实用性。

Analysis on Using DDS as a Digitally Programmable Fractional N Divider in PLL

Some commonly used frequency synthesis methods are introduced first, and then the characteristics of direct frequency synthesis, indirect Phase Locked Loop （PLL） synthesis and DDS ＋ PLL synthesis are described. The method with DDS working as a digitally programmable fractional N divider in PLL is discussed particularly. Its operation principle and critical technologies are analyzed in detail. After analyzing the causes of spurious of DDS, the design method of DDS filters is discussed and a directive conclusion is drawn. The experimental result which proves the validity of this method is presented in the end of this paper.