Struct EbersMollTwoPort 

pub struct EbersMollTwoPort {
    pub is: f64,
    pub bf: f64,
    pub br: f64,
    pub nf_vt: f64,
    pub nr_vt: f64,
    pub is_pnp: bool,
    /* private fields */
}

Simplified Ebers-Moll BJT model for deterministic-cost NR evaluation.

This model is Gummel-Poon with all advanced effects disabled:

• No Early effect (Qb = 1, no base-width modulation via VAF/VAR)
• No high-injection (no IKF/IKR knee currents)
• No leakage (no ISE/ISC terms)
• No parasitic resistances (RB/RE/RC are zero)
• No junction/diffusion capacitances

The simplified IV equations are:

Ic = IS * (exp(Vbe / NF*VT) - 1) - (IS/BR) * (exp(Vbc / NR*VT) - 1)
Ib = (IS/BF) * (exp(Vbe / NF*VT) - 1) + (IS/BR) * (exp(Vbc / NR*VT) - 1)

The Jacobian requires only 2 exp() calls and 4 multiplications (vs 10+ exp() calls and full Qb chain-rule for Gummel-Poon).

When to use

Suitable for clean amplifier stages where GP advanced effects are negligible at the operating point (Vbe near turn-on, Vce >> Vce_sat, small-signal regime). Enable via --features ebers-moll.

Fields

is: f64

Saturation current (A). Typically 1e-15 to 1e-12.

bf: f64

Forward current gain (beta_F, hFE). Typically 100-500.

br: f64

Reverse current gain (beta_R). Typically 1-20.

nf_vt: f64

NF * VT — forward thermal voltage denominator.

nr_vt: f64

NR * VT — reverse thermal voltage denominator.

is_pnp: bool

Whether this is a PNP (vs NPN) transistor.

Implementations

impl EbersMollTwoPort

pub fn from_gp(gp: &GummelPoonModel) -> EbersMollTwoPort

Create an EbersMollTwoPort from a GummelPoonModel (NPN polarity).

Only IS, BF, BR, NF, NR, and VT are used; all advanced parameters are discarded.

pub fn from_gp_pnp(gp: &GummelPoonModel) -> EbersMollTwoPort

Create an EbersMollTwoPort from a GummelPoonModel (PNP polarity).

pub fn set_v_max(&mut self, v_max: f64)

Set the maximum Vce (supply voltage).

pub fn is_pnp(&self) -> bool

true if this is a PNP device.

Trait Implementations

impl Clone for EbersMollTwoPort

fn clone(&self) -> EbersMollTwoPort

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for EbersMollTwoPort

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl NlDeviceGroupIv for EbersMollTwoPort

fn eval(&self, v: &[f64], currents: &mut [f64], jacobian: &mut [f64])

Evaluate Ebers-Moll currents and 2×2 Jacobian.

Port ordering matches BjtTwoPort:

• Port 0: Vbe (base-emitter) → Ib
• Port 1: Vce (collector-emitter) → Ic

PNP devices negate all voltages before evaluation and negate currents before writing back.

fn n_ports(&self) -> usize

Number of ports in this device group.

fn v_clamp_port(&self, port: usize) -> (f64, f64)

Voltage clamp bounds for a specific port.

fn limit_port_voltage(&self, port: usize, v_new: f64, v_old: f64) -> f64

SPICE-style junction voltage limiting (pnjlim) hook.