A systematic frequency planning method in Direct Digital Synthesizer (DDS) design

Direct Digital Synthesizer (DDS) based frequency synthesizer is important to the performance of radar. Effective DDS frequency planning is a problem still untouched in DDS design. Traditional software based method in DDS design can only get one frequency point spur performance at each run. A new DDS frequency planning method is proposed in the paper, this method can indicate DDS´s output ¿clean¿ frequency band with a graphic method. This simple and useful method can tell the designer the usable DDS´s output frequency band in the early stage of the overall frequency synthesizer design. As a result, it is of great significance in realizing a high performance synthesizer. Finally, a real S band frequency synthesizer was developed for a stepped frequency radar, the frequency synthesizer works well and its test results prove the effectiveness of the frequency planning method.