A view exists in the database but isn't active for setup or hold. What does that actually mean for signoff?
From PDVerse MMMC Interview Masterclass, part of the pdVerse Mentor Series
Direct answer
An unactivated view is completely ignored by the timing engine — no slack is calculated, no paths are checked, and no violations are reported. It creates a dangerous silent escape because summary reports show zero violations, mimicking a clean signoff.
Mentor explanation
Unactivated views create silent tapeout escapes by reporting zero violations.
Key terms
- Silent zero — an unactivated view reports 0 violating paths and WNS = 0.000 ps because it was never timed.
all_analysis_viewsvsall_setup_analysis_views— commands to audit declared views versus actually active views.report_analysis_coverage— tool check confirming that all required design views are actively evaluated.
If a hold view for scan-shift mode is accidentally left unactivated, real hold violations escape to silicon, resulting in un-testable chips upon fab return.
Practical example
Verifying Active Analysis Views:
# In Cadence Innovus / Tempus:
all_analysis_views ;# Returns all created views
all_setup_analysis_views ;# Returns actively enabled setup views
all_hold_analysis_views ;# Returns actively enabled hold views
# Diagnostic Audit Script:
set inactive_views [lminus [all_analysis_views] [concat [all_setup_analysis_views] [all_hold_analysis_views]]]
if {[llength inactive_views] > 0} {
puts "[ERROR] INACTIVE VIEWS DETECTED: inactive_views - SIGNOFF INVALID!"
}Interview trap
Trusting a clean report_timing summary without verifying that all project-required views are present in all_setup_analysis_views and all_hold_analysis_views.
Key takeaways
- Inactive views are not analyzed or optimized by the tool.
- An unactivated view reports zero violations, creating a false illusion of clean timing.
- Signoff leads must audit active view coverage [Innovus:
all_setup_analysis_views, all_hold_analysis_views] before tapeout.
Self-check: can you answer this aloud?
Try a 45-second answer using this structure:
- State the direct answer.
- Explain the timing or physical reason.
- Name one caveat.
- Say how you would verify it in a real flow.
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