SYCAN

SYCAN (SYmbolic Circuit ANalysis) is a Python package for symbolic circuit simulation built on SymPy. It provides closed-form DC, AC, transient, noise, transfer-function, pole–zero, and sensitivity analyses, plus automatic schematic drawing and an in-browser REPL.

Install

Requires Python ≥ 3.11.

pip install sycan

Or with uv:

uv add sycan

For a faster CAS backend (optional):

pip install "sycan[symengine]"

Then opt in by setting SYCAN_CAS_BACKEND=symengine before importing sycan. The symengine backend covers ~95 % of the test suite (10 tests skipped on representation / API divergences) and is 7–8× faster than SymPy on AC and noise solves and ~30 % faster on headroom analysis — see docs/BE_BENCHMARK.md and docs/BE_PORT_STATUS.md.

Quick start

from sycan import cas, Circuit, solve_ac
from sycan.components.basic import Resistor, Capacitor, VoltageSource

R, C = cas.symbols("R C", positive=True)
Vin  = cas.Symbol("Vin")

c = Circuit("RC low-pass")
c.add(VoltageSource("V1", "in", "0", value=0, ac_value=Vin))
c.add(Resistor("R1", "in", "out", R))
c.add(Capacitor("C1", "out", "0", C))

sol = solve_ac(c)
H = sol[cas.Symbol("V(out)")] / Vin
print(cas.simplify(H))   # 1 / (C*R*s + 1)

Try it without installing

The live REPL runs SYCAN entirely in the browser via Pyodide — no install needed. The page ships preset examples for filters, amplifiers, voltage references, and S-parameter transmission lines.

Documentation

Full docs (API reference, tutorial, autodraw pipeline) live at https://al-255.github.io/sycan/.

Analysis modes

Solver	Purpose
solve_dc / solve_dc_sweep	DC operating point, parameter sweeps
solve_ac	Small-signal frequency response
solve_tf	Transfer functions between arbitrary nodes
solve_impedance	Port impedance with auto termination
solve_noise	Output-referred noise PSD with per-source breakdown
solve_pz	Pole–zero extraction
solve_sensitivity	Component-level sensitivity analysis
solve_headroom	DC headroom analysis
autodraw	Automatic schematic SVG rendering

Development

git clone https://github.com/AL-255/sycan
cd sycan
uv sync --dev
./run_tests.sh

License

GPL v2 — see LICENSE.

Credits

The project heavily references the work of ahkab and ngSpice. Kudos to them for their contributions.