Struct OtaModel 

pub struct OtaModel {
    pub iabc_max: f64,
    pub vt: f64,
    pub r_load: f64,
}

CA3080 OTA model parameters.

Unlike voltage-mode op-amps, an OTA’s output is a current proportional to the differential input voltage, controlled by a bias current (Iabc).

The key equation: Iout = gm * (V+ - V-) where gm = Iabc / (2 * Vt) and Vt is the thermal voltage (~26mV at room temperature).

The CA3080 has a tanh-like transfer characteristic: Iout = Iabc * tanh(Vdiff / (2 * Vt))

This means:

• For small signals: linear gain proportional to Iabc
• For large signals: soft clipping at ±Iabc
• The gain is controlled by current, not voltage — perfect for VCA/compressor

Fields

iabc_max: f64

Maximum bias current (A). CA3080 typical: 0.5mA.

vt: f64

Thermal voltage (V). ≈25.86mV at the ngspice default 27°C.

r_load: f64

Output load resistance (Ω). Determines voltage gain from current output.

Implementations

impl OtaModel

pub fn ca3080() -> OtaModel

CA3080 with typical bias point.

The CA3080 is the classic OTA used in:

• MXR Dyna Comp (compressor)
• Ross Compressor
• EHX Doctor Q (envelope filter)
• Boss CE-1 (chorus VCA section)

Trait Implementations

impl Clone for OtaModel

fn clone(&self) -> OtaModel

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for OtaModel

impl Debug for OtaModel

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

Formats the value using the given formatter.