A JAX-compatible circuit simulator with automatic differentiation support.
Intended for work on piezo transformers, and more widely, for identification of equivalent circuit parameters out of measurable quantities like impedance.
Applications:
- Equivalent circuit parameter recovery (from measurements)
- Control strategy development and numerical optimisation
- In-depth understanding of effects in circuits
pyvibrate/
timedomain/ # Time-domain transient simulation (MNA + trapezoidal)
R, C, L # Passive components
VSource # Voltage source
Switch # Controllable switch
VoltageSwitch # Voltage-controlled switch
VCVS # Voltage-controlled voltage source
VCR # Voltage-controlled resistor
DelayLine # Pure voltage delay
HBridge # H-bridge subcircuit
frequencydomain/ # Steady-state AC analysis with complex phasors
R, C, L # Passive components
ACSource # AC voltage source with phase
ConstantTimeDelayVCVS # Time delay element (active/energy source)
VCVS # Voltage-controlled voltage source
TLine # Transmission line (Z0, tau)
from pyvibrate.timedomain import Network, R, C, VSource
# Build circuit (functional style)
net = Network()
net, n1 = net.node("n1")
net, n2 = net.node("n2")
net, vs = VSource(net, n1, net.gnd, name="vs", value=5.0)
net, r1 = R(net, n1, n2, name="R1", value=1000.0)
net, c1 = C(net, n2, net.gnd, name="C1", value=1e-6)
# Compile and simulate
sim = net.compile(dt=1e-6)
state = sim.init({})
for _ in range(1000):
state = sim.step({}, state, {})
v_out = sim.v(state, n2)PyVibrate supports reusable subcircuits that don't require ground connection. These floating building blocks can be composed to create complex circuits.
The Series and Parallel functions accept arbitrary two-port elements via factory functions:
from pyvibrate.timedomain import Network, R, C, L
from pyvibrate.timedomain.subcircuits import Series, Parallel
net = Network()
net, n_in = net.node("in")
net, n_out = net.node("out")
# Series RC low-pass filter (floating, no ground reference yet)
net, (r_ref, c_ref, rc_mid) = Series(
net, n_in, n_out,
lambda net, a, b: R(net, a, b, name="r1", value=1000.0),
lambda net, a, b: C(net, a, b, name="c1", value=1e-6),
prefix="rc_lpf"
)
# Parallel RL impedance
net, (r_ref, l_ref) = Parallel(
net, n_in, n_out,
lambda net, a, b: R(net, a, b, name="r2", value=100.0),
lambda net, a, b: L(net, a, b, name="l1", value=1e-3),
prefix="rl_par"
)
# Complete circuit by connecting to voltage source and ground
net, vs = VSource(net, n_in, net.gnd, name="vs", value=5.0)
net, load = R(net, n_out, net.gnd, name="load", value=1000.0)Subcircuits can be nested to create complex structures:
# Nested series-parallel combination
# Structure: n1 ──[R1-R2 series]──[C1||R3 parallel]── n2
net, nested = Series(
net, n1, n2,
# First element: R1 and R2 in series
lambda net, a, b: Series(
net, a, b,
lambda n, x, y: R(n, x, y, name="r1", value=100.0),
lambda n, x, y: R(n, x, y, name="r2", value=200.0),
prefix="r_ser"
),
# Second element: C1 and R3 in parallel
lambda net, a, b: Parallel(
net, a, b,
lambda n, x, y: C(n, x, y, name="c1", value=1e-6),
lambda n, x, y: R(n, x, y, name="r3", value=1000.0),
prefix="rc_par"
),
prefix="nested"
)The same operations work in frequency domain for impedance analysis:
from pyvibrate.frequencydomain import Network, R, C, L, ACSource, Series, Parallel
import math
net = Network()
net, n_in = net.node("in")
net, n_out = net.node("out")
# Series RLC resonator (floating)
net, (r_ref, lc_refs) = Series(
net, n_in, n_out,
lambda net, a, b: R(net, a, b, name="r_esr", value=10.0),
lambda net, a, b: Parallel(
net, a, b,
lambda n, x, y: L(n, x, y, name="l1", value=1e-3),
lambda n, x, y: C(n, x, y, name="c1", value=1e-6),
prefix="lc_tank"
),
prefix="rlc_res"
)
# Complete circuit
net, vs = ACSource(net, n_in, net.gnd, name="vs", value=1.0, phase=0.0)
net, r_load = R(net, n_out, net.gnd, name="load", value=50.0)
# Frequency sweep to find resonance
solver = net.compile()
freqs = [100, 1000, 5033, 10000] # 5033 Hz ≈ 1/(2π√LC)
for f in freqs:
sol = solver.solve_at(omega=2*math.pi*f)
z_in = solver.z_in(sol, vs)
print(f"{f} Hz: |Z| = {abs(z_in):.1f} Ω, ∠{math.degrees(math.atan2(z_in.imag, z_in.real)):.1f}°")You can create your own subcircuits following the pattern in pyvibrate/timedomain/subcircuits.py or pyvibrate/frequencydomain/subcircuits.py:
def MySubcircuit(net, terminal_a, terminal_b, prefix="mysub"):
"""Create custom subcircuit between two terminals."""
# Create internal nodes if needed
net, n_internal = net.node(f"{prefix}_int")
# Add components
net, r1 = R(net, terminal_a, n_internal, name=f"{prefix}_r1", value=100.0)
net, c1 = C(net, n_internal, terminal_b, name=f"{prefix}_c1", value=1e-6)
# Return network and references
return net, (r1, c1, n_internal)- Step-by-step simulation with Modified Nodal Analysis (MNA)
- Trapezoidal integration for reactive components
- JAX-compatible for autodiff optimization (sensitivity analysis, gradient descent)
- Functional/immutable API
- Primary application: detailed study of circuit behaviour
- Steady-state AC analysis at a single frequency
- Complex phasors for voltages and currents
- Components: R, C, L, ACSource, PhaseShift, VCVS, TLine
- JAX-compatible for autodiff optimization (sensitivity analysis, parameter fitting)
- Primary application: equivalent circuit discovery by fitting parameters to data obtained from VNA
from pyvibrate.frequencydomain import Network, R, C, ACSource
import math
# Build RC low-pass filter
net = Network()
net, n1 = net.node("n1")
net, vs = ACSource(net, n1, net.gnd, name="vs", value=1.0)
net, r1 = R(net, n1, net.gnd, name="R1", value=100.0)
net, c1 = C(net, n1, net.gnd, name="C1", value=1e-6)
# Solve at 1 kHz
solver = net.compile()
omega = 2 * math.pi * 1000.0
sol = solver.solve_at(omega)
# Get input impedance
z_in = solver.z_in(sol, vs)
print(f"|Z| = {abs(z_in):.1f} ohm, phase = {math.degrees(phase(z_in)):.1f} deg")
- actively developed as of December 2025
- 159 tests passing
- 6+ examples ported from the famous, brilliant Falstad Circuit Simulator (sourced from: https://github.com/hausen/circuit-simulator )
- work ongoing to add more worked examples and real-world data
If you spot any bugs, please let me know by opening an issue here! https://github.com/jerzydziewierz/pyvibrate/issues