Model Equations

Product Documentation

Spectre Circuit Simulator Components and Device Models Reference
Product Version 23.1, June 2023

Model Equations

The charge model in GaAs is a charge-conserving model. The capacitances are nonreciprocal.

(-1)

(-2)

Drain Current for the Subthreshold Region

This equation applies when V_GST ≤ 0.

(-3)

Drain Current for the Triode Region

These equations apply when V_GST ≥ 0, V_DS ≤ 3/alpha.

(-4)

where

(-5)

Drain Current for the Saturation Region

This equation applies when V_GST ≥ 0 and V_DS ≥ 3/alpha.

(-6)

Gate Junction Currents

(-7)

where V_t is the thermal voltage given by

(-8)

,

(-9)

is the forward explosion voltage,

(-10)

is the conductance at V_Expl, and

(-11)

is the current linearly extrapolated to V = 0 from V_Expl.

Gate Junction Capacitance

(-12)

(-13)

where

(-14)

(-15)

(-16)

(-17)

(-18)

(-19)

Temperature Effect

Junction Potential

(-20)

Gate Junction Current

(-21)

where, if SPICE compatibility is required (set by the options),

(-22)

(-23)

otherwise,

(-24)

(-25)

Noise Model

Source Series Resistance Thermal Noise

(-26)

Drain Series Resistance Thermal Noise

(-27)

Channel Conductance Thermal and Flicker Noise

(-28)

where

(-29)

g_m is the transconductance, g_ds is the channel conductance, and kf and af are constants for a given device. The Spectre^® circuit simulator defaults for kf and af are 0.0 and 1.0, respectively.

Related Topics

GaAs Model (gaas)

Scaling Effects

Component Statements

⠀ X