Study Of Ultra-wideband Microwave Frequency Source

This paper introduces the realization scheme and key technology of 2~12GHz ultra-wideband microwave frequency synthesizer.It adopts DDS + PLL frequency synthesizer scheme to realize low end frequency 2~4GHz output,then through segment amplifying multiplying chain realize from 2~4GHz expand to 2~12GHz,and the output frequency is selected by microwave switch. The whole system adopts one PLL only to control VCO to output the ultra wideband frequency of 2~12GHz,and realizes small volume , low cost microwave frequency source.The main content of this paper:Firstly,the basic theory and characteristics of various frequency synthetic technologies and the mixed frequency synthetic technology of DDS+PLL have been introduced,and the method to expand frequency bandwide has been analyzed and compared. Secondly,the system has been demonstrated in detail,and every part of systems has been done feasible analysis. According to the requirement of system,it chooses the device suitable to put up the systematic circuit, carrys on the rational circuit overall arrangement and design EMC. Finally, through debugging procedure and circuit repeatedly, the request of the system is achieved basically.Its specifications show that the system have basically realized within the range of 2~12GHz: the phase noise is superior to -72dBc/Hz@10kHz ,spurious is superior to -55dBc, harmonic restrain is superior to 30dBc, step is 10MHz, hopping time is 14μs. So the feasibility has been verified.