User guide

14-22
Negative Timing Checks
Here:
• The first $setuphold timing check specifies the delay on
del_CP is more than 10 but less than 20 time units more than
the delay on del_D.
• The second $setuphold timing check specifies the delay on
del_TI is more than 10 but less than 20 time units more than the
delay on del_CP.
• The third $setuphold timing check specifies the delay on
del_CP is more than 4 but less than 8 time units more than the
delay on del_TE.
Therefore:
• The delay on del_D is 0 because its delay does not have to be
more than any other delayed signal.
• The delay on del_CP is 11 because it must be more than 10 time
units more than the 0 delay on del_D.
• The delay on del_TE is 4 because the delay on del_CP is 11.
That 11 makes the possible delay on del_TE larger than 3 but
less than 7. The delay cannot be 3 or less because the delay on
del_CP is less than 8 time units more that the delay on del_TE.
VCS makes the delay 4 because it always uses the shortest
possible delay.
• The delay on del_TI is 22 because it must be more than 10 time
units more that the 11 delay on del_CP.