sim-run

name	sim-run
description	Run circuit simulation (DC, tran, AC) on Virtuoso. Use when executing Spectre simulation, running analysis, or checking simulation results.
argument-hint	["analysis","e.g. \"tran 10us\" or \"ac 1Hz-1GHz\" or \"dc\""]
allowed-tools	Bash(virtuoso *)

Run Simulation

Execute Spectre simulation via virtuoso sim run.

Prerequisites

Simulation must be set up first (see /sim-setup):

• simulator('spectre) configured
• design(lib cell view) set
• modelFile(...) configured
• desVar(...) set for any parameterized variables
• resultsDir(...) set

Run analysis

# DC operating point
virtuoso sim run --analysis dc --param saveOppoint=t --timeout 120 --format json

# Transient
virtuoso sim run --analysis tran --stop 10u --timeout 300 --format json

# AC
virtuoso sim run --analysis ac --start 1 --stop 1e9 --dec 10 --timeout 300 --format json

Important: resultsDir — DO NOT CHANGE

⚠️ The ADE session binds run() to the resultsDir established when the GUI session was first created. Changing it to any other path silently breaks run() (returns nil).

# ✅ Find the canonical path from the runSimulation script
cat <netlist_dir>/runSimulation | grep "\-raw"
# → -raw ../../../../tmp/opt_5t_ota/psf  →  canonical = /tmp/opt_5t_ota

# ✅ If resultsDir is nil, restore to canonical path
virtuoso skill exec 'resultsDir("/tmp/opt_5t_ota")'

# ❌ Never do this before a run — it will break run()
virtuoso skill exec 'resultsDir("/tmp/some_new_path")'

sim run now returns a clear error if resultsDir is nil instead of auto-setting it to a temp path (which would break the ADE session binding).

Also: do not call sim setup again once a working ADE session exists — it resets the Ocean session state and can cause run() to return nil.

Verify success

After run(), check spectre.out for errors:

# Check the log
virtuoso skill exec 'resultsDir()' --format json
# Then read the spectre.out file at <resultsDir>/psf/spectre.out

# A successful run has PSF data files (dcOp.dc, tran.tran, etc.)
# A failed run only has artistLogFile, simRunData, variables_file

Key indicators

run() output	Meaning
Returns resultsDir path AND PSF data files exist	Simulation completed ✓
Returns resultsDir path BUT only artistLogFile/simRunData/spectre.out	Spectre failed — run() does NOT check spectre's exit code
Returns nil, takes <0.01s	Analysis not configured or session lost
Returns nil, takes >0.1s	Netlisting ran but spectre may have failed

⚠️ run() returning a non-nil path is not sufficient proof of success. Spectre can terminate with fatal errors (e.g., SFE-868) and run() still returns the resultsDir. Always verify PSF data files exist:

tail -2 <resultsDir>/psf/spectre.out
# ✓ "spectre completes with 0 errors"
# ✗ "spectre terminated prematurely due to fatal error"

Common errors in spectre.out

Error	Fix
SFE-868: ADE-generated path .../oa/lib/../models/...	Patch input.scs: replace with direct absolute model path + section=tt — see /spectre-netlist-gotchas §8
SFE-868: Cannot open input file (other)	Model path wrong — verify file exists
SFE-675: no valid section name	Empty section "" in modelFile for .lib — remove it
SFE-1997: parameter not assigned	Set desVar() for the missing parameter
OSSHNL-116: Cannot descend into views	Subcell missing spectre view — remove instance or add view