Parallel Dds Incentive Pll Microwave Frequency Agile Comprehensive Research

From the early 70s, when direct digital frequency synthesizer (DDS) technology was proposed, it beacame the focus. Its high frequency switching speed and the excellent frequency resolution attracted many scientists to do further research on DDS. And the DDS has got considerable progress. But with its digital system, it has the shortage of too narrow bandwith and bad spurs level. Meanwhile, PLL technology also has the contradiction between the frequency switching speed and frequency resolution. Just for the aboving reason, many people use the method of DDS+PLL to improve the performance of the system. But in some rada and communication systems, they require higher speed and more excellent spurs level. Only by the method of DDS+PLL, it can't satisfy these requires.So we propose a method by using double DDS+PLL to improve the performance of the system.The following are the structure of this paper:Chapter 1, the development of the frequency synthesizers are analyzed, which give the base of frequency synthersizer methods and their futures.Chapter 2, the basic theory of DDS and PLL are introduced, which lay the theoretical base for the frequency synthesizer.Chapter 3, the methods of the frequency synthesizer in commom use are analyzed and compared, and the advantages and disadvantages of each technique was also introduced.Base on this analysis, a novel frequency syntesizer method is given.Chapter 4, an experiment on the technology is operated in order to verify the new method of frequency synthesizer proposed in the previous chapter.Chapter 5, the results of the previous experiment are given, that is , the output frequency range: 655～675MHz , SFDR: -70dBc , phase noise: ≤ -99dBc/Hz@10kHz, hopping time: 0.06 μs, hopping step 0.15625MHz.