Virtuoso

Virtuoso Skill

How it works

You control a remote Cadence Virtuoso instance through virtuoso-bridge — a Python client that sends SKILL commands to the running Virtuoso CIW over a persistent connection. You write Python locally; Virtuoso executes SKILL remotely. SSH tunneling and daemon management are handled automatically by VirtuosoClient.from_env() — just configure .env with the remote host info and it works.

VirtuosoClient and SpectreSimulator (see the spectre skill) are independent clients. You don't need one to use the other.

The bridge supports three levels of abstraction (highest to lowest):

Use the highest level that covers your need. Drop to a lower level only when the higher one doesn't have the method.

Before you start

1. Check connection: run virtuoso-bridge status. If unhealthy: virtuoso-bridge restart.
2. Check examples first: look at examples/01_virtuoso/ below — if similar functionality exists, use it as a basis rather than writing from scratch.
3. Open the window: call client.open_window(lib, cell, view="layout") so the user can see what you're doing in the GUI.

Core patterns

Client setup

from virtuoso_bridge import VirtuosoClient
client = VirtuosoClient.from_env()

Schematic editing

with client.schematic.edit(lib, cell) as sch:
    sch.add_instance("analogLib", "vdc", (0, 0), "V0", params={"vdc": "0.9"})
    sch.add_instance("analogLib", "gnd", (0, -0.5), "GND0")
    sch.add_wire_between_instance_terms("V0", "MINUS", "GND0", "gnd!")
    sch.add_pin("VDD", "inputOutput", (0, 1.0))

Use terminal-aware helpers (add_wire_between_instance_terms, add_net_label_to_instance_term) instead of guessing pin coordinates — they resolve positions from the database. See references/schematic.md for full API.

Layout editing

with client.layout.edit(lib, cell) as layout:
    layout.add_rect("M1", "drawing", (0, 0, 1, 0.5))
    layout.add_path("M2", "drawing", [(0, 0), (1, 0)], width=0.1)
    layout.add_instance("tsmcN28", "nch_ulvt_mac", (0, 0), "M0")
    layout.add_via("M1_M2", (0.5, 0.25))

For large edits: split into chunks — first call with mode="w" (create), then mode="a" (append). Screenshot after layout work to verify visually. See references/layout.md for full API.

Inline SKILL (for anything beyond the Python API)

client.execute_skill('dbOpenCellViewByType("myLib" "myCell" "layout")')

SKILL file (for bulk / complex operations)

client.load_il("my_script.il")
client.execute_skill('myCustomFunction("arg1" "arg2")')

Put loops in .il files rather than sending giant SKILL strings — keeps each request payload small while the heavy loop runs inside Virtuoso.

File transfer and other operations

VirtuosoClient is the only client that exposes file transfer to the user. SpectreSimulator handles its own file transfer internally during run_simulation().

client.upload_file(local_path, remote_path)    # local → remote
client.download_file(remote_path, local_path)  # remote → local
client.open_window(lib, cell, view="layout")
client.get_current_design()
client.save_current_cellview()
client.close_current_cellview()
client.run_shell_command("ls /tmp/")

ADE control (Maestro)

Quick pattern — open session, configure, run, read results:

ses = client.execute_skill(f'maeOpenSetup("{lib}" "{cell}" "maestro")').output.strip('"')
client.execute_skill(f'maeCreateTest("AC" ?lib "{lib}" ?cell "{cell}" ?view "schematic" ?simulator "spectre" ?session "{ses}")')
client.execute_skill(f'maeSetAnalysis("AC" "ac" ?enable t ?options `(("start" "1") ("stop" "10G") ("dec" "20")) ?session "{ses}")')
client.execute_skill(f'maeSaveSetup(?lib "{lib}" ?cell "{cell}" ?view "maestro" ?session "{ses}")')
client.execute_skill('maeRunSimulation()')
client.execute_skill("maeWaitUntilDone('All)")

For the full API (variables, outputs, specs, corners, OCEAN results, history display), read references/ade.md. See examples/01_virtuoso/ade/01_rc_filter_sweep.py for the complete workflow.

References

Load only when needed — these contain detailed API docs and edge-case guidance:

• references/schematic.md — schematic API, terminal-aware helpers, CDF parameter setting
• references/layout.md — layout API, read/query, mosaic, layer control
• references/ade.md — ADE Maestro mae* API, OCEAN results, corners, simulation control
• references/netlist.md — CDL/Spectre netlist formats, spiceIn import, netlist export

Existing examples

Always check these before writing new code. If similar functionality exists, use it as a basis.

examples/01_virtuoso/basic/

• 01_execute_skill.py — run arbitrary SKILL expressions
• 02_load_il.py — upload and load .il files
• 03_list_library_cells.py — list libraries and cells
• 04_screenshot.py — capture layout/schematic screenshots

examples/01_virtuoso/schematic/

• 01a_create_rc_stepwise.py — create RC schematic via operations
• 01b_create_rc_load_skill.py — create RC schematic via .il script
• 02_read_connectivity.py — read instance connections and nets
• 03_read_instance_params.py — read CDF instance parameters
• 05_rename_instance.py — rename schematic instances
• 06_delete_instance.py — delete instances
• 07_delete_cell.py — delete cells from library
• 08_import_cdl_cap_array.py — import CDL netlist via spiceIn (SSH)

examples/01_virtuoso/layout/

• 01_create_layout.py — create layout with rects, paths, instances
• 02_add_polygon.py — add polygons
• 03_add_via.py — add vias
• 04_multilayer_routing.py — multi-layer routing
• 05_bus_routing.py — bus routing
• 06_read_layout.py — read layout shapes
• 07–10 — delete/clear operations

examples/01_virtuoso/ade/

• 01_rc_filter_sweep.py — full Maestro workflow: create schematic, AC analysis, parametric sweep, bandwidth spec, display results

Related skills

• spectre — standalone netlist-driven Spectre simulation (no Virtuoso GUI). Use when the user has a .scs netlist and wants to run it directly.