Low Spurious Waveform Synthesis Based on Digital Resampling

Abstract

Arbitrary waveform generator (AWG) plays an important part in electronic measurement area. As technology continues to evolve, the need to synthesize signals with higher bandwidth and lower spurious came up. However, certain limitations exist in current digital waveform synthesis methods, which leads to high spurious in the output waveform. Direct Digital Waveform Synthesis (DDWS) method's image frequency's position isn't strictly fixed and hard to restrain due to the change of the sampling clock frequency; Direct Digital Frequency Synthesis (DDFS) method needs the phase accumulator's bits be large enough to obtain a high frequency resolution of the output waveform, which brings in the phase truncation error and adds spurious component. Therefore, in this paper we analyzed the advantages of the two methods and proposed a waveform synthesis method based on digital resampling, waveform samples are determined in variable clock domain, then use resampling filter based on Farrow structure to realize the transform from variable sample rate to fixed sample rate, achieving waveform synthesis method with low spurious. As the simulation results indicate, our new method has huge advantage over DDWS and DDFS.