How do you detect the wrong same-named library cell?
From PDVerse PnR Interview Handbook · pdVerse Mentor Guide
Short Answer
Correlate reference-library order, cell view identity, PVT assignment, pin interface, and handoff version rather than trusting the instance reference text.
Technical Explanation
Treat this as a readiness check. It should produce named objects and a result that another engineer can repeat from the same handoff.
What To Check
• Warning sign: Linking succeeds against an unintended library containing the same cell name. • Inspect: Compare one named object across the related reports; the same object should tell a consistent story. • Correct: Correct reference setup, relink deliberately, and compare representative resolved cells and timing models.
Command Checks & Actions
• report_ref_libs: shows the reference libraries used for linking
• report_pvt: shows process, voltage, and temperature assignments
Run the commands in order. Each line answers a separate part of the check.Healthy, Suspicious & Hard-stop Results
• Expected: Correlate reference-library order, cell view identity, PVT assignment, pin interface, and handoff version rather than trusting the instance reference text. • Investigate: Linking succeeds against an unintended library containing the same cell name. • Stop before floorplanning when required logic or timing coverage is missing or unexplained. Correct reference setup, relink deliberately, and compare representative resolved cells and timing models.
Common Mistake
Do not assume the check passed just because ICC2 continued: Linking succeeds against an unintended library containing the same cell name. Fix or narrowly justify the named objects, then rerun the same command.
What The Interviewer Is Testing
Be ready to explain why this matters before floorplanning: Linking succeeds against an unintended library containing the same cell name.
Follow-up Question & Model Response
Model response: “I would save the report, inspect one affected object in the correct block and scenario, and make or request this correction: Correct reference setup, relink deliberately, and compare representative resolved cells and timing models. Then I would reopen the clean checkpoint and rerun the same evidence.”
Practical Example
Symptom: Linking succeeds against an unintended library containing the same cell name. Corrective path: Correct reference setup, relink deliberately, and compare representative resolved cells and timing models.
Continue practising