DDS频率合成器由于其固有的数字特征,使得输出信号中存在大量的杂散,杂散的抑制一般通过输出端的低通或带通滤波器来进行,但效果较差。PLL具有良好的窄带和跟踪特性,文中提出了基于PLL的窄带滤波器杂散抑制方法。利用ALTERA公司Dspbuilder工具箱实现的DDS进行仿真,通过输出信噪比的比较,验证了该法的正确性。

Because of DDS's inherent digital characteristic,there are many spuriousness presences in its output.In general,the spuriousness restraining is implemented by low-pass or band-pass filter,but the result is always not ideal.For the PLL has better performances in narrowband filtering and frequency tracking,the paper presents a new method which based on PLL accomplish the spuriousness restrained.In the end,using dspbuilder toolbox of Altera corp.we verify the validity of the method by simulation.

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