宽带锁相扫频源设计

Design of Broadband Phase Locked Sweep Frequency Source

根据给出的扫频源设计指标,对PLL+DDS常用组合方式DDS激励PLL和PLL内插DDS进行了分析比较,确定了一种将两种组合方式的优点充分结合起来新的组合设计方案,并对这种方案进行了可行性分析。分析表明,这种组合方式有效地减小了倍频次数N,实现了宽带低相位噪声,同时利用DDS的超高频率分辨率、高频率精确度、容易实现程控等优点与锁相环良好的窄带跟踪滤波特性相结合,实现了细步长、可程控的宽带扫频功能。实验结果证明了方案的正确性。

According to design goals of sweep frequency source,a new scheme is presented by making the best of advantages of DDS -driven PLL and DDS -generated frequency offset, which are firstly analyzed and compared. And its feasibility is shown. It indicates that this scheme can get low phase noise for wideband frequency source by effectively reduced multiple N. At the same time, the merits of DDS such as super fine frequency resolution,high frequency accuracy,easy programmed and in combination with the excellent character of narrow -band tracing filter merits of PLL make the little step and process control sweep function easily achieved. At last ,the experimental result proved the rationality of this method.