What is a false path?
From PDVerse STA Mentor Guide · pdVerse Mentor Guide
Short Answer
A false path is a path through the netlist that STA is able to trace topologically (structurally, following the logic connections) but that can never actually be exercised during real functional operation of the chip.
Example
You exclude a false path from timing analysis using the set_false_path command, which tells STA to leave that path out of its checks entirely.
Why It Matters
STA by itself only looks at structure and doesn't understand functional intent, so it will flag paths as needing to be checked even if, in practice, the real logic behavior of the design would never actually let data race down that path in a way that matters.
Command
set_false_pathMentor Note — Common Mistake
Declaring a false path is essentially a promise to the tool that the path truly cannot matter. If that promise turns out to be wrong, you've silently removed a real, necessary check from analysis, and that is exactly the kind of mistake that causes real chips to fail in silicon.
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