BeginnerQuestion 8 of 20Source page 5

What is a timing library, really?

From PDVerse MMMC Interview Masterclass · pdVerse Mentor Series

Direct answer

A timing library (typically in Liberty format) is the characterized model of how a specific cell behaves electrically — its pins, its logic function, and tables of delay, transition, and setup/hold behavior across a range of input slews and output loads, all captured under one PVT condition.

Mentor explanation

The netlist tells the STA engine which cells exist and how they're wired together — it says "there is a NAND2 here, and its output connects to this net." That's connectivity, not behavior. The timing library is the piece that says how that NAND2 actually responds: how much delay from input to output, how the output transition looks, what setup and hold windows its internal flops need. Without the library, the netlist is just a wiring diagram. With it, the netlist becomes something STA can actually time.

Key takeaways

  • A timing library (typically in Liberty format) is the characterized model of how a specific cell behaves electrically — its pins, its logic function, and tables of delay, transition, and setup/hold behavior across a range of input slews and output loads, all captured under one PVT condition.
Visual explanationMMMC context: What is a timing library, really?
MMMC context: What is a timing library, really?A three-step concept map summarizes the focus, core answer, and practical verification for What is a timing library, really?Question focusWhat is a timinglibrary, really?Core answerA timing library(typically in Libertyformat) is thecharacterized model of…Verify in practiceValidate the configuredview, active objects,and report context.Understand → explain the mechanism → verify the assumptions
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