Spectre Skill

How it works

SpectreSimulator uploads a .scs netlist to a remote machine via SSH, runs Spectre there, downloads the PSF results, and parses them into Python dicts. You write the netlist locally, the simulation runs remotely — no Virtuoso GUI needed. SSH is managed automatically by SpectreSimulator.from_env() — just configure .env with the remote host and Cadence environment path.

SpectreSimulator is independent of VirtuosoClient (see the virtuoso skill). You can run standalone Spectre simulations without a Virtuoso GUI session.

The typical workflow:
1. Write or prepare a .scs netlist (see references/netlist_syntax.md for syntax)
2. Create a SpectreSimulator instance
3. Call sim.run_simulation(netlist, options) — returns a result object with parsed waveforms
4. Analyze result.data (dict of signal name → list of float)

Before you start

1. Check connection: virtuoso-bridge status — shows Spectre path, version, and license info.
2. Check examples first: look at examples/02_spectre/ below — if similar functionality exists, use it as a basis.
3. Env requirement: VB_CADENCE_CSHRC must be set in .env to source the Cadence environment on the remote machine.

Core pattern

from virtuoso_bridge.spectre.runner import SpectreSimulator, spectre_mode_args

sim = SpectreSimulator.from_env(
    spectre_args=spectre_mode_args("ax"),  # APS extended (recommended)
    work_dir="./output",
    output_format="psfascii",
)
result = sim.run_simulation("my_netlist.scs", {})

# Check status
if result.ok:
    time = result.data["time"]
    vout = result.data["VOUT"]
else:
    print(result.errors)

With Verilog-A include files

result = sim.run_simulation("tb_adc.scs", {
    "include_files": ["adc_ideal.va", "dac_ideal.va"],
})

Result object

Parsing PSF files directly

When you have raw PSF files without going through run_simulation:

from virtuoso_bridge.spectre.parsers import parse_psf_ascii_directory
data = parse_psf_ascii_directory("output/tb.raw")
# data = {"time": [...], "VOUT": [...], "VIN": [...]}

# Or a single PSF file (e.g. PSS results)
from virtuoso_bridge.spectre.parsers import parse_spectre_psf_ascii
result = parse_spectre_psf_ascii("output/tb.raw/pss.td.pss")

Simulation modes

Choose based on license availability and performance needs:

spectre_mode_args("spectre")  # basic Spectre (least license demand)
spectre_mode_args("aps")      # APS
spectre_mode_args("ax")       # APS extended (recommended)
spectre_mode_args("cx")       # Spectre X custom

License check

info = sim.check_license()
print(info["spectre_path"])  # which spectre binary
print(info["version"])       # version string
print(info["licenses"])      # license feature availability

References

Load only when needed:

• references/netlist_syntax.md — Spectre netlist format, analysis statements, instance syntax, parameterization

Existing examples

Always check these before writing new code.

• examples/02_spectre/01_inverter_tran.py — basic inverter transient simulation
• examples/02_spectre/01_veriloga_adc_dac.py — 4-bit ADC/DAC transient with Verilog-A
• examples/02_spectre/02_cap_dc_ac.py — capacitor DC + AC analysis
• examples/02_spectre/04_strongarm_pss_pnoise.py — StrongArm comparator PSS + Pnoise
• Netlists in examples/02_spectre/assets/

Related skills

• virtuoso — GUI-based Virtuoso workflow (schematic/layout editing, ADE Maestro simulation). Use when the user is working inside the Virtuoso GUI.