Is a delay corner the same thing as a setup view or a hold view?
From PDVerse MMMC Interview Masterclass, part of the pdVerse Mentor Series
Direct answer
No. A delay corner is purely physical data (library set + RC corner). It only becomes a setup view or a hold view when paired with a constraint mode and explicitly activated for that check type via tool commands.
Mentor explanation
Delay corners are passive physical data containers; check types are determined by view activation.
Key terms
- Delay corner — purely physical; calculates propagation delays without knowing the check type.
- Analysis view — delay corner + constraint mode.
- Activation [Innovus:
set_analysis_view -setup {...} -hold {...}] — explicitly assigns views to the active setup list or hold list.
Naming a delay corner dc_setup does not make the tool check setup on it. The tool only performs setup analysis on views explicitly declared in the -setup view list.
Practical example
Activation Syntax in Innovus:
# Building the view (combining intent + physics)
create_analysis_view -name view_func_ss -constraint_mode cm_func -delay_corner dc_ss_rcmax
create_analysis_view -name view_func_ff -constraint_mode cm_func -delay_corner dc_ff_rcmin
# Explicitly assigning setup and hold roles
set_analysis_view \
-setup [list view_func_ss] \
-hold [list view_func_ff]Interview trap
Assuming that naming a view func_setup automatically causes the tool to check setup on it. If not included in set_analysis_view -setup, the tool ignores it entirely during setup optimization.
Key takeaways
- Delay corners describe physical delay; they do not dictate whether setup or hold is tested.
- The Analysis View binds the delay corner to an SDC constraint mode.
- The tool's activation command [Innovus:
set_analysis_view] explicitly designates the setup and hold roles.
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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