The Study On C Band Fine Resolution Low Phase Noise And Spur Frequency Synthesizer

The technique of frequency synthesize is one of the key techniques to achieve good performance in radar and communication systems. With the development of modern communication, the performance of the frequency synthesizer will directly influence the application of the equipment. So, in modern communication techniques, it is an important research aspect to design a high performance frequency synthesizer.In this paper, we introduced the common kinds of the frequency synthesizer, and analyzed the advantages and disadvantages of whom full and clear firstly. Then we discussed the phase noise and the generation of spur in the frequency synthesizer, especially analyzed the widely used Digital Phase-Locked-Loop (DPLL) frequency synthesizer in engineering, and introduced the mainly application of the frequency synthesizer. Thirdly, we analyzed the phase noise of Digital Phase-Lock-Loop (DPLL) frequency synthesizer, the operating principle of DDS and Fractional-N Phase-Locked Loop (FNPLL) in detail. On the base of studying the fundamentals of PLL, it is on the side of innovation that we studied the multi-loop frequency synthesizer spur, and we analyzed and derived the tracking band of the frequency shift loop detailedly. According to the conclusion above and the require of one program, we used a new method to initialize the frequency and designed a2.275GHz～4.625GHz frequency synthesizer with low phase noise, low spurious and fine frequency resolution (1Hz). Multi loops were applied in this synthesizer, by the application of some RF simulation tools to analyze and calculate, we selected appropriate components and integrated design scheme to accomplish this synthesizer.At last, comparing the simulating result with the testing result, we analyzed the difference of which deeply and gave some ameliorative advice to the future circuit design. This paper offers some technical references to the latter design of the frequency synthesizer.