thevenin

A SPICE circuit simulator written in Rust, targeting both native and WebAssembly.

Thevenin is a from-scratch rewrite of ngspice in idiomatic Rust. It parses standard SPICE netlists and runs simulations with the same algorithms — Modified Nodal Analysis, Newton-Raphson iteration, sparse direct solvers — but with Rust's type safety and wasm32 support.

Crates

Crate	Description
thevenin	Simulation engine — MNA assembly, Newton-Raphson solver, analysis drivers
thevenin-types	Netlist parser and IR types for the ngspice SPICE dialect

Supported analyses

• DC operating point (.op)
• DC sweep (.dc)
• AC small-signal (.ac)
• Transient (.tran)
• Noise (.noise)
• Sensitivity (.sens)
• Transfer function (.tf)
• Pole-zero (.pz)

Device models

• Resistors, capacitors, inductors
• Independent voltage/current sources (DC, AC, pulse, sin, PWL, exp, AM, SFFM)
• Dependent sources (VCVS, VCCS, CCVS, CCCS)
• Diodes
• BJTs (Gummel-Poon)
• MOSFETs (level 1-3)
• JFETs
• BSIM3v3, BSIM4
• BSIM3SOI (FD, PD, DD)
• VBIC

Quick start

use thevenin::simulate_op;
use thevenin_types::Netlist;

let netlist = Netlist::parse("
Voltage Divider
V1 in 0 1.0
R1 in mid 1k
R2 mid 0 2k
.op
.end
").unwrap();

let result = simulate_op(&netlist).unwrap();
for plot in &result.plots {
    for vec in &plot.vecs {
        if let Some(&val) = vec.real.first() {
            println!("{}: {:.6}", vec.name, val);
        }
    }
}

Building

# native
cargo build
cargo nextest run --workspace

# wasm32
cargo test --workspace --target wasm32-unknown-unknown

License

BSD-3-Clause