Based On Dds And Pll Frequency Synthesizer

Frequency synthesizer is used as core components of electronic devices, radar, electronic warfare, communications, measurement, instrumentation, and other fields widely used. The rapid development of modern electronic technology requires a lower frequency synthesizer phase noise, clutter suppression stronger, faster frequency conversion.This paper describes the background of the topic, the practical value and the domestic and international research, and introduced the basic principles of PLL and direct digital frequency synthesizer principle, analyzes the advantages and disadvantages of PLL and DDS, according to the subject asked to select a kinds of requirements for the design of the project.The traditional single frequency synthesis technology has advantages and disadvantages, DDS frequency conversion speed and high frequency resolution, low phase noise, stray, but a rich, PLL spur suppression ability, but the low frequency resolution, frequency conversion is slow. Single frequency synthesis technology is difficult to meet the modern electronic technology to a higher frequency synthesizer requires more comprehensive, mixed-frequency synthesizer technology will combine the traditional frequency synthesis, and avoid weaknesses, give full play to their strengths, to achieve better frequency synthesis device. DDS and PLL combination is currently the most widely used mode hybrid synthesizer.The subject used a combination of DDS and PLL frequency synthesizer hybrid frequency synthesizer frequency hopping technology, the use of PLL to achieve a fixed frequency synthesizer. After testing, phase noise, stray, frequency conversion time to meet the design requirements, tests show that the frequency synthesizer used to meet project needs.