公开(公告)号：US6150892A

公开(公告)日：2000-11-21

申请号：US182236

申请日：1998-10-30

申请人： Chen-Yi Lee ,  Terng-Yin Hsu ,  Bai-Jue Shieh ,  Chung Cheng Wang

发明人： Chen-Yi Lee ,  Terng-Yin Hsu ,  Bai-Jue Shieh ,  Chung Cheng Wang

IPC分类号： H03L7/085 ,  H03L7/095 ,  H03L7/099 ,  H03L7/18 ,  H03L7/00

CPC分类号： H03L7/0805 ,  H03L7/085 ,  H03L7/0997 ,  H03L7/18 ,  H03L2207/50 ,  H03L7/095

摘要： A method and device for frequency synthesizing, in which the digital frequency synthesizer includes a clock pair having two similar ring-oscillators to separately generate a search frequency and an output frequency, a frequency tracking unit, and a clock controlling unit. The frequency-search method includes two stages: one stage is the coarse search stage based on the "Prune-and-Search", and other stage is the fine search stage based on the "fixed-step" algorithm. In order to determine which search scheme is used to search the target frequency and to determine the lock status, two cost functions for search and lock-in are derived. These two cost functions define the search threshold and the lock threshold, and these thresholds define the cost window and the lock window. If the frequency error is higher than both the search and lock thresholds, a coarse search is activated to estimate the correct frequency. And only when the frequency error falls between the search and the lock thresholds, should the fine search be activated. By properly assigning these two thresholds, the search performance, such as tinting and frequency error, and the output resolution can be improved. The digital frequency synthesizer which can be designed at HDL level and synthesized as part of a target cell library.

摘要翻译： 一种用于频率合成的方法和装置，其中数字频率合成器包括具有两个类似的环形振荡器以分别产生搜索频率和输出频率的时钟对，频率跟踪单元和时钟控制单元。 频率搜索方法包括两个阶段：一阶段是基于“剪枝搜索”的粗搜索阶段，其他阶段是基于“固定步长”算法的精细搜索阶段。 为了确定哪个搜索方案用于搜索目标频率并确定锁定状态，导出用于搜索和锁定的两个成本函数。 这两个成本函数定义搜索阈值和锁定阈值，并且这些阈值定义了成本窗口和锁定窗口。 如果频率误差高于搜索和锁定阈值，则会激活粗略搜索以估计正确的频率。 只有当频率误差落在搜索和锁定阈值之间时，才能激活精细搜索。 通过适当地分配这两个阈值，可以提高诸如着色和频率误差之类的搜索性能以及输出分辨率。 数字频率合成器，可以在HDL级别设计，并作为目标单元库的一部分合成。