sindr-devices

Pure electronics device physics companion models for MNA circuit simulation.

sindr-devices is a standalone workspace crate that implements the nonlinear device models used by the sindr solver. It has no dependency on the solver — pure physics math, independently testable.

Devices

Usage

Add to your Cargo.toml:

[dependencies]
sindr-devices = { workspace = true }

Diode companion model

use sindr_devices::diode::{DiodeParams, diode_companion, temperature_scale_is};

let params = DiodeParams::silicon(); // IS=1e-14, N=1.0, rs=0.0, temperature=300.15 K
let (g_eq, i_eq) = diode_companion(0.65, &params);
// g_eq — linearised conductance (S)
// i_eq — Norton current source (A)

// Temperature-dependent IS (SPICE formula)
let is_at_125c = temperature_scale_is(1e-14, 398.15, 300.15, 1.11, 3.0);

DiodeParams fields:

• is: f64 — saturation current (A)
• n: f64 — ideality factor
• rs: f64 — series resistance (Ω), default 0.0; single-step Newton correction applied internally
• temperature: f64 — junction temperature (K), default 300.15 K

BJT companion model

use sindr_devices::bjt::{BjtParams, BjtKind, bjt_companion};

let params = BjtParams::default(); // IS=1e-15, BF=100, BR=1, vaf=0.0 (no Early effect)
let companion = bjt_companion(0.65, -5.0, &params);
// companion.g_ce — Early output conductance (A/V); 0.0 when vaf=0
// companion.{gbe, gbc, ice, ibc, ibe, ...}

BjtParams fields:

• is, bf, br — Ebers-Moll parameters
• vaf: f64 — forward Early voltage (V); 0.0 = infinite (no Early effect)
• var: f64 — reverse Early voltage (V); 0.0 = infinite
• temperature: f64 — junction temperature (K), default 300.15 K

MOSFET companion model

use sindr_devices::mosfet::{MosfetParams, MosfetKind, mosfet_companion};

let params = MosfetParams::default(); // Vto=0.7, Kp=2e-4, Lambda=0.01
let companion = mosfet_companion(2.0, 3.0, MosfetKind::Nmos, &params);
// companion.gds, companion.ids, companion.region (Cutoff/Triode/Saturation)

Varactor junction capacitance

use sindr_devices::varactor::{VaractorParams, junction_capacitance, varactor_companion};

let params = VaractorParams { cj0: 10e-12, phi: 0.7, m: 0.5 };
let c_j = junction_capacitance(-2.0, &params); // reverse-biased capacitance

// Transient companion (dt=0.0 → DC open circuit)
let (g_eq, i_eq) = varactor_companion(v_prev, dt, &params);

VaractorParams fields: cj0 (zero-bias cap, F), phi (built-in potential, V), m (grading coefficient).

IGBT companion model

use sindr_devices::igbt::{IgbtParams, igbt_companion};

let params = IgbtParams::default(); // vth=5.0, k=5.0, vce_sat=2.0
let companion = igbt_companion(vge, vce, &params);
// companion.gm    — transconductance (A/V)
// companion.ids   — collector current (A)
// companion.g_ce  — output conductance = ids / vce_sat (A/V)
// companion.region — "cutoff" | "triode" | "saturation"

Schottky diode

use sindr_devices::schottky::{SchottkyParams, schottky_companion};

let params = SchottkyParams::default(); // IS=1e-8, N=1.05 → ~0.3 V forward
let companion = schottky_companion(0.3, &params);

NTC thermistor

use sindr_devices::thermistor::{ThermistorParams, thermistor_resistance};

let params = ThermistorParams::ntc_10k(); // R0=10 kΩ, beta=3950 K, T0=298.15 K
let r_at_85c = thermistor_resistance(358.15, &params); // ~2.5 kΩ

Photodiode

use sindr_devices::photodiode::{PhotodiodeParams, photodiode_companion};

let params = PhotodiodeParams::default(); // responsivity=0.5 A/W, IS=1e-11
let companion = photodiode_companion(vd, 0.1 /* W irradiance */, &params);
// i_ph = responsivity * irradiance flows as reverse photocurrent

Optional features

sindr-devices = { workspace = true, features = ["serde"] }