基于DSP控制的直接数字频率合成器的实现

系统地介绍了一种低杂散、低相位噪声、快速捷变频频率合成器的实现途径。提出了使用TMS320VC5409高速DSP作为控制电路，由DDS芯片AD9858构成宽带、低相噪、低功耗数字频率合成器的方案。详细阐述了AD公司最新的内部时钟可达1GHz的高性能DDS芯片AD9858的主要性能及其在快速捷变频频率合成器设计中的应用方法。给出了具体的超宽带应用电路和最终的测试结果，并对如何提高DDS频谱纯度进行了探讨。该数字频率合成器通过编程可方便地实现单点频、线性调频和调相功能，经过实际应用达到了比较满意的效果。

Application of Direct Digital Frequency Synthesizer Based on DSP

The paper presents a fast agile frequency synthesizer of low spurious,low phase noise.A method that uses AD9858 based on TMS320VC5409 is presented to access a wideband,low phase noise and low power frequency source.The main performance of AD9858 chip and its application in frequency synthesizer with frequency hopping fast is mainly introduced in this paper.AD9858 is produced by Analog Device latterly and its internal clock speed is up to 1 GHz.And the paper also including the discussion on DDS spectrum purity improvement,and gives the circuit scheme and the measurement data.this DDS can easily achieve single-tone mode,frequency-sweeping mode and phase modulation.The practical application achieves preferable effect.