说明：  一种全数字时钟数据恢复电路的设计与实现，提出一种改进型超前滞后锁相环法的全数字时钟恢复算法，与同类电路比较，具有数据码率捕获范围宽、捕获时间短的优点。
(Clock Date Recovery(CDR)circuit is a important part of data transmission equipment．For the burst data transmission，the traditional phase—lock loop can hardly achieve the requirement of fast synchronization． Whereof，this essay is trying to put forward an improved Lead and Lag Control a11-numeric CDR calculation，which is characterized with wide frequency capture range and rapid capture time．)