The Research On C-band Frequency Synthesizer With A Little Frequency Difference In Distributed Radar Systems

Frequency synthesizer always is an important part of communication and radar system, especially in the defense and military fields. The research target of the dissertation is designing a C-band frequency synthesizer, which can work in different radar system. The operating frequencies of two radars are different, and the corresponding frequencies are only several MHz apart.This paper firstly introduces the basic concept and development process of frequency synthesizer, and then analyzes the main technical indexes of frequency synthesizer.The principle and basic circuit of direct frequency synthesizer, PLL are introduced in detail. Through a comprehensive analysis of frequency synthesis methods, discuss their advantages and disadvantages and applications, combined with the development of the technical requirements of the frequency synthesizer, C band frequency synthesizer is realized by using Direct analog synthesis+DDS synthesis. After the consideration of the complexity and the generality of the application, the phase lock circuit is used to realize the most reasonable and suitable for the "small frequency difference". This synthesizer could generate the radar transmit signal, local oscillator signal, reference signal and the clock signal of AD sampling, otherwise, it can have the functions of frequency agility, frequency control and failure detection.By analyzing the main targets, the paper gives the realization processes and design of key circuits. The some photos and structure Graphing of the frequency synthesizer. The final actual test results prove the validity and feasibility of the design. Finally, analyzes the shortcomings of the system and put forward ideas to improve.