Multi-point Microwave Frequency Source System Design And Production

The frequency synthesizer is the core of the electronic system, which determines the performance of it. With the development of the modern military and wireless industry, the mobile, radar, weapons of control and guide, electronic measure instruments and electronic antagonize system are all calling for better and better frequency synthesizers. Every country in the world is emphasizing the research and utility of the frequency synthesizer, the main trend for the development of frequency synthesizer is low PN, high purity of frequency spectrum, high speed of agility and high output frequency band.The frequency synthesize system which is studied in this theme is demanded to provide four frequency points having low PN , low SFDR and the ability of agility. Because the theme asked for low PN and the ability of agility, so the direct frequency synthesize is one option for the frequency synthesize scheme. At the same time, low SFDR is also important for the system. And PLL is the best choice for the scheme for low SFDR. As a result, we combine PLL and DFS(direct frequency synthesize) together, the disadvantage of low frequency change speed for PLL is also over by the ability of agility for DFS. The ultimate scheme is to use PLL to achieve each single frequency point at first, then put the four frequency points into the switch system of agility. In order to enhance the utility of the system, we choose one of the four PLLs to output the hop signals which assemble in the form of triangle when the frequency switching speed is not called for high.This paper summarized the development of frequency synthesis technology at first, then presented the design courses of PLL, assistant system, switch system, control system, practical system, the debug of the circuit and the analysis of the results of measure in detail. The design of PLL introduced the phase-lock loop with its working principle, structure and noise theory, the practical design was included, too. The design of switch system introduced the basic theory of microwave and RF switches ,and the particular design of the practical system. The design of assistant system introduced the relative theory of the high low stepped impedance low pass filter and cache amplifier which are used to enhance the behave of the whole system, and the particular design of them. The design of control system introduced the control of hardware and software for the whole system, the function description of the whole system is also more particular because of it.At last,the design of practical product and the debugging course of circuits were presented. The results of the previous experiment were given, that is : SFDR:≤-70dBc,Phase noise:≤-100 dBc@10kHz,output power:≥8dBm.As the hopping frequency function, one way is :hopping step: 10MHz,hopping points :31;The other way is :hopping step: 20MHz,hopping points :16.The results of measurement indicated that the practical system achieved the objectives which were made beforehand...