Rf Front-end Technology. Ku-band Linear Fm Detector

On the basis of principle of linear frequency modulated continuous wave (LFMCW) detection system, this thesis designs the radio frequency (RF) front-end of detection system's structure and accomplishes the circuit design.In the first part of this thesis, the principle of LFMCW ranging system has been introduced, the modulation parameters of the system launch signal, and system indicators have been discussed. Then, Direct Digital Synthesizer (DDS) and Phase Lock Loop (PLL) phase noise characteristics are analyzed, the advantage and disadvantage of common frequency synthetic technologies are compared from two point of view, one spurs, the other phase noise. Combining of system indicators, this thesis decided to use the PLL plus DDS program to design the signal source. This program combines the advantages of DDS, such as high frequency resolution, fast frequency switching speed, and the advantages of PLL, such as high frequency output, and good quality of frequency spectrum, and can be implemented relatively simple. By analyzing the advantages and disadvantages of the common receiver program, this thesis select a program combined with the superheterodyne structure and digital IF receiver. In order to determine the entire system solutions, indexes of the various components have been distributed.Base on the above analysis, this thesis accomplishes the development of the RF front-end of LFMCW detection system, includes DDS, PLL, mixer and divider. On the basis of analysis of each component, the selection of chip and the design method of each component have been discussed. Finally, the problems during testing and solutions are proposed, and some suggestions for improvement have been offered.