STA interview question: about GBA_mode VS PBA_mode timing

[WatchFish]

Hi All,

I have 2 questions got from an interview. I did not find any answers online and hope you could help.

1. After the timing is fixed in PBA mode, can it be tapeout then? Or it needs some extra step?
2. If using GBA mode to do timing closure, it is pessimistic. Is there any negative impact?

Any thoughts are welcome. Thank you very much!:smile:

 

[skrishneogg]

1. Once timing is fixed, we need to verify formality, DRC caused due to new routing patterns, Signal EM and also IR drop. If all the verifications are through, then we can tape out. If your design has different power domains, we might have to a special MVRC (Multi Voltage Rule Check) check as well.

2. Only negative impact is increased number of violations to be fixed.

 

[WatchFish]

Thank you very much! But is it any other concern about timing? Since the timing is fixed in PBA mode.