Analysis of the spurious spectrums in direct digital frequency synthesizers

The basic principle of Direct Digital Frequency Synthesizers(DDS) is introduced and the ideal frequency spectrum of DDS is analyzed in this paper.On the basis of signal analysis methods,the regularity and performance of the DDS output spectrum lines of the spurious signals due to the phase accumulator truncation and amplitude quantization are investigated in detail.The spurious response due to DAC’s non-idealization is discussed qualitatively.The conclusions are finally proved by computer simulations.All the obtained conclusions provide important theoretical bases and experience references for selecting the parameters,evaluating and suppressing the spurs in DDS designs and engineering application developments.