Setup & Hold Slack Check

Setup Check:

To meet the setup requirements the following equation must be satisfied.

• Setup slack check=>  Reqiured time > Arrival Time

 Tcapture + Tcycle - Tsetup - Uncertainty > Tlaunch + Tck2q + Tcombo +Twire

• Uncertainty includes skew, jitter & slack margin.

Figure1: Understanding about capture and launch clock

With OCV:

Tcap-(Tcap*derating factor/100)+ T-Tsetup-Tuncertainity>Tcomb+Tcq +Tlaunch+                                                                                                      (Tlaunch*derating factor/100)

Early the capture clock & late the launch clock.

Figure2: Setup & hold Check basic understanding

Hold Check:

To meet the hold requirements the following equation must be satisfied.

• Setup slack check=>  Reqiured time < Arrival Time

       Tcap+ Thold<Tcomb+Tcq+Tlaunch+Twire+Uncertainty

With OCV:

 Tcap+(Tcap*derating factor/100)+ Thold+Tuncertainity<Tcomb+Tcq+Tlaunch-                                                                            (Tlaunch*derating factor/100)

 Late the capture clock & Early the launch clock.

•      The negative value of hold slack means signal value propagates from one register to next, too fast that it overrides the old value before that can be detected by the corresponding active clock edge.
•      The clock frequency variation doesn't effects the hold time or the hold slack, so it is critical to fix the hold time violation in a design prior to the setup violation if both exists simultaneously.