The Dds-based Frequency Sweep Signal Source Design And Realization

This paper first introduced the concept and development of frequency synthesis, as well as the present situation and the trend of development of the direct digital frequency synthesis technology (DDS).It has analyzed the principle and the basic structure of DDS, it also has carried on the theoretical analysis to the ideal DDS frequency spectrum characteristic. For the effective suppression of DDS spur, the paper has discussed three main origins of DDS spur and analyzed influence of the spur to the DDS output frequency spectrum. Then narrated using phase-locked loop chip ADF4360-2 to realize the 1GHz reference clock and using AD9858 to realize the 20-320MHz wide band frequency sweeping source, as well as their hardware realization process, it also has given the picture of the hardware circuit and the test result. For suppressing the DDS spur better, the paper has introduced the design and the realization of synchronization multi-channel filter group, and has given the simulation result and the test result of each filter, it also has analyzed the group delay of each filter through the simulation. The experiment indicated that the filter design has achieved the anticipated effect.