Vector synthesis algorithm for spur reduction in direct digital synthesis

This paper introduces a novel algorithm based on the vector synthesis to reduce the spurs. The vector synthesis algorithm is based on the idea that the spurs can be reduced when the angle between the spurs is obtuse and that between the signals is sharp by utilizing the different initial phase. Spurious spectrum of the signal with initial phase in a DDS system is analyzed and we get the conclusion that the phase delay will change the phase spectrum. Thus, it is reasonable to add the signals together, between which there is a small phase offset, to reduce the spurs caused by the phase truncation error. Meanwhile, the algorithm will not level up the noise floor. Simulation results are also exhibited to show feasibility and advantages of the technique compared with the traditional algorithms.