Sim Sweep

Parameter Sweep & Corner Analysis

Parameter sweep

Sweep a design variable and collect measurements:

virtuoso sim sweep \
  --var W --from 1e-6 --to 5e-6 --step 1e-6 \
  --measure 'value(IDC("/NM0/D"))' \
  --measure 'value(getData("/NM0:gm" ?result "dcOpInfo"))' \
  --analysis dc \
  --timeout 600 \
  --format json

PVT corner analysis

Create a corners.json file:

{
  "simulator": "spectre",
  "design": {
    "lib": "FT0001A_SH",
    "cell": "gmid",
    "view": "schematic"
  },
  "model_file": "/foundry/smic/.../models/spectre/ms013_io33_v2p6_7p_spe.lib",
  "analysis": {
    "type": "dc",
    "saveOppoint": "t"
  },
  "corners": [
    {"name": "tt",      "section": "tt",  "temp": 27,   "vdd": 1.2},
    {"name": "ss_hot",  "section": "ss",  "temp": 125,  "vdd": 1.08},
    {"name": "ff_cold", "section": "ff",  "temp": -40,  "vdd": 1.32}
  ],
  "measures": [
    {"name": "Id",  "expr": "value(IDC(\"/NM0/D\"))"},
    {"name": "gm",  "expr": "value(getData(\"/NM0:gm\" ?result \"dcOpInfo\"))"}
  ]
}

Then run:

virtuoso sim corner --file corners.json --timeout 600 --format json

Tips

• Set desVar values BEFORE running sweep (sweep only varies the specified --var)
• Sweep generates all values first, then runs simulations sequentially
• For corner analysis, vars in corner entries become desVar calls (e.g., "vdd": 1.2 → desVar("vdd" 1.2))
• Use --timeout generously — each sweep/corner point runs a full simulation