Development Of The L-band Digital Sweep Source

It is the research focuses to design frequency synthesizers with high frequency resolution, low phase noise and immediate settling to frequency hop. This dissertation focuses on the realization of L-band sweep signal source based on Direct Digital Synthesis (DDS) and Phase Locked Loop (PLL).Firstly, the structure and output spectrum of DDS is analyzed. The problems of practical design are also discussed in detail.Secondly, the phase noise and spurs of PLL are analyzed and the formulae for calculating them are given. The method of designing the loop filter with the phase margin and loop bandwidth is displayed.At last, several plans of sweep signal source with DDS and PLL together are discussed, based on one of them, the L-band sweep signal source is designed successfully.