Design of A DDS based frequency synthesizer

In this paper, we will present a design of a DDS based frequency synthesizer whose output is 67-83MHz, and which will be used in an X band sweep frequency source as the phase detect frequency of PLL. According to the analysis of DDS structure and operating principle, we can get the output with excellent frequency switching time, low phase noise and extremely tiny resolution. And we can use some methods to make the spurs as small as possible.