If I change my speed grade option from a faster speed grade to a slower speed grade, the net delays are as I expect. If I change back from the slower speed grade to the faster speed grade, I still see the slower speed grade net delays. How do I get the net delays back to the original faster speed grade?
If the speed grade move from the slower speed grade to the faster speed grade is not made incrementally, Timing Analyzer will report the net delays as the slower speed grade. For example, if you begin with a -4 speed grade and change to a -6 speed grade, the net delay after analysis will still show the -4 net delay.
To work around this issue, increment from a -4 to a -5 speed grade, run the analyzer, then increment from a -5 to a -6 speed grade, and run the analyzer again. Timing Analyzer will report the expected net delays in all cases.