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MachAI Lens Help

Corners and scenarios

Tell me

In Lens a scenario is one PVT corner and mode combination in a PrimeTime report set, and Scan / Detect Scenarios finds the scenarios under your report folder. You run one scenario or all of them, see them side by side in Scenario Analyzer, and use Corner Sensitivity to see how sensitive a clock group's WNS is to voltage and temperature across corners.

Show me

  • Timing Review tab, top bar: Scan / Detect Scenarios, which becomes Rescan once scenarios exist, then Run Scenario or Run All Scenarios.
  • Timing Review tab, scenario bar: the Scenario: dropdown, with ◀ Prev and Next ▸ to step through the list. Lens remembers your selection.
  • Timing Explorer: the Summary Information strip and the context line above Top Net Segments both name the Corner.
  • Compare Runs opens Lens Compare on Scenario Analyzer: the Scenario Stress Overview (setup and hold WNS, TNS and violations for each scenario), the Clock × Scenario Stress Matrix, Derived Insights and Most Sensitive Clocks.
  • Scenario Analyzer > Corner Sensitivity…: the WNS vs Rail Voltage and WNS vs Temperature plots, and the MODE pill at the top of the left panel.
  • Lens Compare > Build Compare: a coverage strip showing how many scenarios matched between the two builds. See Compare two runs.

Teach me

A PVT corner is one combination of process (how fast or slow the silicon came out), voltage and temperature at which timing is checked. A mode is one way the chip can be configured to operate, such as functional, scan or test, each with its own constraints. A scenario is one corner checked in one mode.

Scenarios and stages. PrimeTime results are organised by scenario. Fusion Compiler results are organised by stage, one run per stage, and you name each stage's files yourself, so Scan / Detect Scenarios is not offered for Fusion Compiler. A run is one analysis of one scenario or one stage. A PrimeTime scenario normally needs both its setup and its hold report; see Setup and hold.

Scenario Analyzer shows absolute margins for a single database, not deltas, and a banner says so. It looks for patterns across scenarios and clocks, such as a specific clock domain failing across all hold corners, rather than going path by path.

  • The Scenario Stress Overview needs only each scenario's summary WNS. The matrix, Derived Insights and Most Sensitive Clocks need each scenario's per-clock setup and hold WNS, so the overview can fill in while those three stay empty.
  • If a saved run has no per-clock records, Lens rebuilds them from that run's own report file when it loads. Only if that fails do the three sections show one "unavailable" message, which names the missing evidence. Lens never builds them from summary WNS or from the clock inventory.

Corner Sensitivity works on PrimeTime builds only. It joins two reports by scenario name: a Fusion Compiler report_pvt gives each scenario's voltage per rail, temperature and process label, and the PrimeTime constraint PBA report gives per-clock WNS and a status. To use it, set the build's Constraint PBA pattern, for example *_constraint_PBA.rpt*.

The report_pvt comes from the Report : pvt field of the Fusion Compiler inputs in the configuration dialog; Lens saves that path on the build and uses it when you open Corner Sensitivity for the PrimeTime build in the same project, falling back to whatever file the field currently holds in Timing Review. The field is optional, and without it Corner Sensitivity has no PVT axis to plot against.

Status Meaning Plotted
VIOLATION The constraint PBA report has an explicit violating block Yes, coloured by WNS
PASS_INFERRED The report says "No paths to recalculate". This is not real slack Only if you turn on Plot PASS_INFERRED at WNS=0.000, as a hollow green circle at 0.000
UNKNOWN No evidence either way. It is not assumed to pass Never; it appears in the table only
  • MODE: Clean slice (green) means temperature and process are held, so the sweep compares like with like. MODE: Mixed corners (amber) means temperature or process may vary between points. In Mixed mode the primary driver reads n/a (mixed) and boundary details are suppressed.
  • Choose the Rail that actually varies between your corners. "No VDD sweep" means the selected rail has the same voltage in every scenario of the active slice; try another rail.

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Updated 19 October 2026