1. Lunch edge与Capture edge
   

   Luanch edge：源端Reg发送数据的时钟边沿（参考点）

   Capture edge：目的端Reg捕获数据的边沿(Next launch edge)。

2. 4种时序路径

   1）Input delay：外部Device port到内部Sequential cell路径延时；

   2）Data path delay：内部两个Sequential cell之间的路径延时；

   3）Output delay：内部Sequential到外部Device port路径的延时；

   4）Pin data path delay：Pin之间的延时；

3. 公式计算

   Data arrival time = Launch edge + Tclka + Tco + Tdata

   Clock arrival time = Capture edge + Tclkb

   Data require time(setup) = Clock arrival time - Tsu - Setup uncentainly

   Data require time(hold) = Clock arrival time(Next）+ Th  + Hold uncentainly

                       (Data的最小有效采样窗口：起点（Tsu) -> 终点(Th))

       Setup slack = Data required time(setup) - Data arrival time

       Hold slack = Data arrival time - Data require time{hold)

                       Setup slack为负数：说明Data path delay太大

                       Hold slack为负数：说明clock的延时太大

4. System

     Tdata = Tlogical + Tnet

     Tsys >= Tco +Tdata + Tsu