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

Basic Terminology

Setup Time:

It is time required for data to be available at input of sequence device before clock edge captures the data in device.

Hold Time:

It is time required for data to be available at input of sequence device after the clock edge captures the data in device.

• For better understanding of Setup and Hold Time here an example of  D-FF is presented. As shown in figure, red box shows the  data which must be stable in those areas i.e before and after the active edge of clock respectively for setup and hold time. If data input doesn't remain constant (in this period of time) the setup and hold violation occurs in the circuits. 

Figure: Understanding of  Setup & hold time.