The Development Of Wideband Fast Hopping Frequency Synthesizer

Frequency Synthesizer is one of the most important parts in the modern electronic systems, and it can be widely used in the such fields as the military communication, radar and guidance system. With the development of modern electronic technology, frequency synthesizers are required to have wider band, higher resolution, faster frequency switching speed and lower spurious lever. This thesis focuses on the realization of signal source based on DDS and PLL, proposes a design plan of the S-band high-switch-speed frequency synthesizer.At first, this paper described the basic structure ,phase model, frequency response and performance analysis for noise and spur, of phase locked loop( PLL),then presented the basic structure, working principle, sources of spurious signals and characteristics of output spectrum, of direct digital frequency synthesizer(DDS).After that, some hybrid frequency synthesis methods for DDS +PLL which used usually are presented in the following section, and the analysis of different methods, for phase noise, spur, and frequency switch speed, was also introduced. According to the technical specifications of the project, this paper picked out excellent DDS and PLL chips, and developed a wideband, low noise, high resolution and high-switch-speed frequency synthesizer by adopted the integrative frequency synthesis technology of DDS+ PLL + Mixer + Doubler.The processes of design and production of main configuration components were presented, and the test results of those were illustrated. The test results of the project prove that our method is feasible and valid, the performance index of our product has reached the design requirement. The frequency step is 500kHz, the output phase noise is - 90 dBc/Hz@1kHz and - 100dBc/Hz@1MHz, the spurs level is below- 60 dBc, and hopping time is 20μs.