Dds And The Dpll-based Agile Source Design

The Direct Digital Frequency Synthesizer is a kind of fully digitized frequency synthesizer, which consists of the phase accumulator, the sine look-up table, the digital to analog converter and the low band filter. It is of high frequency resolution, fast frequency switching speed, low phase noise, the ability to switch frequencies while maintaining constant phase, and the ability to producing arbitrary waveforms. Because of above features, DDS can be used in such fields as radar, communications, electronic warfare and electronic measurement instruments.The Chapter 2 and 3 emphasizes on DDS. First synthesizes the Direct Digital Frequency Synthesizer in mathematics. Analysis the spectrum characteristic of DDS output in ideal case. The bad spurious performance is the major problem that restricts the applications of DDS, so the theoretical and practical analysis attaches importance to the spectrum performance of DDS.For the speed limitation of digital hardware, the output frequency of DDS cannot get a high level yet. By combining the DDS and PLL technology, we can get high frequence, high frequency resolution and excellent frequency agility. Two methods of DDS hybrid PLL technology are discussed. In this dissertation, a new methods of DDS hybrid PLL technology are analyzed detailedly. The results of simulation and the measured by spectrum analyzer are given.