Studies On Fast Tuning Frequency Synthesis Based On AD9858

Direct Digital Frequency Synthesis(DDS),as a new kind of frequency synthesis method, is a revolution of frequency synthesis technology. With the development of digital integrated circuits and microelectronic techniques, DDS exhibits its superiorities day by day. It has been more recognized as the best method to generate sine wave, LFM and other complex signals, and has been used widely in radar system. Modern radar not only gains the information of position and speed of the objects, but also analyses and distinguishes the objects, which requires the signal with a wide band emitted by radar to gain the high resolution of distance and other characteristics of objects. So it has become an important requirement in designing a radar signal generator that generating radar signal with wide band even ultra wide band. AD9858 is an extraordinary powerful DDS chip, which not only has all the advantages of general DDS, also has broad-band and low-spur, bringing more conveniences in the processing of the design. This design is mostly utilizing its advantages and decreasing its demerits influence.The first chapter introduces the development of frequency synthesis technology and DDS(Direct Digital Synthesizer) technology. The principle,configuration and the spur distribution of DDS are introduced in the second chapter. The third chapter introduces the principle of PLL. The forth chapter mostly introduces the chips - AD9858 and C8051F020. in the fifth chapter, it demonstrates the design of the whole system, including bandwidth and spur. The sixth chapter introduce the hardware and software problems which met in the debug and test. at the same time, the author also puts forward some own opinions in this design. and all the parameters of the result attain the demands.