直接数字频率合成技术杂散信号频谱性能分析

Analysis of the spurious spectrums in direct digital frequency synthesizers

本文介绍了直接数字频率合成技术DDS(Direct Digital Frequency Synthesizers)工作原理,分析了其理想频谱;采用信号分析的方法深入研究了DDS存在相位截断和幅度量化时引入的杂散信号频谱分布的规律和性能;定性讨论了DAC非理想性对DDS输出杂散谱的影响。最后进行计算机仿真分析并验证了结论。所得规律性结论为DDS设计和工程应用开发中的参数选取、杂散评估和杂散抑制提供重要的理论依据和经验参考。

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.