Professor Nagi Krishnapura's Links

https://www.ee.iitm.ac.in/~nagendra/cadinfo.html

If You Want to Add Value to Open EDA - chatGPT's Advice

Analog · Automation · Open Flow

EDA Automation for Analog — a 90-Day MVP You Can Start Today

Build the missing glue: auto testbenches, corner/MC orchestration, lint, and clean HTML reports — open-source first, portable to Virtuoso/Spectre later.

xschem ngspice/Xyce Magic KLayout netgen Python · Jinja2 · YAML · pandas

Strategy in One Paragraph

Use free/open tools to prove value on Sky130/GF180: generate testbenches from a small YAML “design contract,” run corners & Monte Carlo with reproducible seeds, lint schematic/layout for analog foot-guns, and publish a one-page HTML dashboard leadership can skim. Keep clean adapters so you can swap ngspice→Spectre and xschem→Virtuoso later with minimal rework.

Tool Stack (Free)

Schematic

xschem

Simulation

ngspice or Xyce

Layout

Magic + KLayout

LVS/DRC

netgen (LVS), Magic/KLayout (DRC)

PDKs

SkyWater 130, GF180 (open)

Glue

Python 3.11+, Jinja2, YAML, pandas, HTML

Milestones & Deliverables

Weeks 1–2 v0.1

• Repo layout: tools/, examples/, reports/, docs/
• gen_tb.py — Jinja SPICE TB generator
• run_corners.py — PVT runner (real if ngspice found; mock otherwise)
• report_html.py — JSON → HTML report
• schematic_lint.py — basic xschem lint (stub)

Success: An inverter example renders a shareable HTML report.

Weeks 3–4 v0.2

• YAML-driven corners (VDD, temp, tt/ss/ff when available)
• Parameter sweeps: cload, W/L, bias current
• Measurements: tpHL/tpLH, tr/tf, static current
• Artifacts: summary.json, results.csv, sortable HTML

Success: 6+ corners with one command, neat table output.

Weeks 5–6 MC

• Monte Carlo with deterministic seeds
• Stats & yield: mean/σ/min/max, pass/fail vs. spec
• HTML distributions + yield bar

Success: 200-run MC of comparator delay across 3 corners.

Weeks 7–8 Lint

• Schematic lint: unlabeled nets, P/G rails, floating nodes, naming consistency
• Layout lint (KLayout): symmetry pairs, matched areas, orientation checks
• Checklist emitted into HTML

Success: Actionable lint before LVS/DRC, fewer late surprises.

Weeks 9–10 LVS/DRC

• Wrap netgen (LVS): device/net mismatches, pin naming
• Wrap Magic/KLayout (DRC): total errors, top rules, coordinates
• One-page sign-off snapshot

Success: PVT + MC + LVS/DRC summary on one screen.

Weeks 11–12 v0.4

• Cell pack: Inverter, Comparator, Two-stage Op-Amp (or simple LDO stage)
• Each with ready configs, corners, MC, lint, LVS/DRC
• One-Click: run_all.py examples/opamp/config.yaml

Success: A non-expert can clone & run and get a professional report.

Example: Minimal Workflow

# 1) Generate a testbench from YAML
python tools/gen_tb.py examples/inverter/config.yaml

# 2) Run corners (uses ngspice if present; otherwise mock)
python tools/run_corners.py examples/inverter/config.yaml --out reports/inverter

# 3) Build a shareable HTML report
python tools/report_html.py reports/inverter/summary.json --out reports/inverter/report.html

What to Automate (High Value)

• Auto Testbench Generation: from a small YAML “design contract” (pins, supplies, stimulus recipe) → SPICE with measures.
• Corner/MC Orchestration: reproducible seeds, resumable runs, cache, CSV+JSON artifacts, CI-friendly.
• Lint: schematic (nets, names, floating nodes) and layout (symmetry/matching heuristics) for early catches.
• HTML Reports: specs vs targets, pass/fail heatmap, MC yield, LVS/DRC counts, links to artifacts.

Porting to Cadence/Synopsys Later

Design with adapters so swapping tools is trivial:

• Simulator: NgspiceAdapter ⇄ SpectreAdapter (CLI args, netlist dialect, measures/Ocean)
• Schematic: xschem parse ⇄ Virtuoso via SKILL/Ocean or exported netlists
• Layout Checks: KLayout scripts stay useful even in Virtuoso flows; later swap to Calibre/PVS wrappers

The value isn’t replacing Virtuoso — it’s automating everything around it.

Validation & First “Customers”

• Who first: small analog consultancies & university labs (hate manual PVT/MC + reporting).
• Pilot: offer your stack free to 1–2 teams for feedback and anonymized screenshots.
• Measure: time saved/iteration, bugs caught by lint pre-LVS/DRC, earlier MC yield visibility.

Risks & Mitigations

• Open PDK limits: use Sky130/GF180 to prove flow; keep adapters ready for proprietary PDKs.
• Layout heuristics: start with simple symmetry checks; evolve toward device-graph matching.
• Vendor lock-in: strict adapter boundaries to avoid rewrites when adding Spectre/Calibre.

Quick Start Checklist

• Python 3.11+, optional ngspice on PATH
• YAML config describing pins, supplies, stimulus, corners, MC
• Run: generate TB → run corners/MC → build HTML
• Iterate: add lint and LVS/DRC wrappers, then ship one-click reports

Want an expanded YAML schema, a first KLayout symmetry macro, or a SKILL/Ocean mapping sheet to Virtuoso? Say the word and I’ll include them in a follow-up post.