VHF频段DDS频率合成器的杂散抑制策略

摘要

介绍了频率合成技术中三个重要的方法，比较分析直接频率合成技术、锁相环频率合成技术(PLL技术)以及直接数字频率合成技术(DDS技术)的优缺点。着重探讨了DDS频率合成技术杂散噪声来源，比如：幅度量化噪声、相位舍位噪声以及DAC的非理想性引起的噪声等。以相位舍位噪声尤为突出，通过分析DDS产生的噪声来源，提出了一种合理规避DDS舍位噪声引起的杂散信号的方法，并且在实际工程中得以验证。%The paper introduced three important frequency synthesis technologies,discussed direct frequency synthesis technology,phase lock loop frequency synthesis technology(PLL)and direct digita frequency synthesis technology(DDS),com⁃pared the merit and demerit of these three methods,and emphasizes the sources of spurious signal in direct digita frequency syn⁃thesis technology,such as the amplitude quantization noise,the phase truncation noise and the noise resulting from non⁃ideality of the DAC. Through the analysis of the noise source in DDS,the paper puts forward a reasonable method to avoid stray signal caused by phase truncation noise,and it is verified in the actual project.