STA Mastery · All levels

Delay Graph & Path Analysis

Cell delay, net delay, parasitics, graph traversal, slack, path groups, and deep reading of timing reports.

Section goal

Cell delay, net delay, parasitics, graph traversal, slack, path groups, and deep reading of timing reports.

How to study this section

Start with the topic hub to learn the contract.
Use mechanism and reports pages to connect rules to metrics.
Use debug and worked-example pages for interview and on-call practice.
Close with checklist and PPA impact before signing any change.

Topics

graph-traversal-and-slack/ — Graph Traversal & Slack
cell-vs-net-delay-budgets/ — Cell vs Net Delay Budgets
path-group-prioritization/ — Path Group Prioritization
report-timing-deep-read/ — Report Timing Deep Read

Related topics

STA course hub

STA deep dive

Slack is a path story — read the graph, not just the number.

Concept diagram

diagram

TIMING GRAPH

FF --cell-- logic --net-- logic --cell-- FF
launch                              capture

Metric graph

diagram

SLACK TAIL

paths |    ***
      |  *******
      |*********  <- fix WNS first

Reports and artifacts

WNS/TNS
path slack histogram
cell vs net %
path group summary

Mini case study

WNS -90ps but 80% net delay on one congested route — PD route fix beat upsizing three cells.

Debug branches

Cell-heavy -> sizing/VT
Net-heavy -> route/layer
Check launch/capture clocks

Senior review question

Ask: what corner/mode/view proves this topic is closed or failing?

Practice this lesson