Behavioral modeling

Gnucap behavioral modeling is in a state of transition, so this is subject to change in a future release.

Basically, all simple components can have a behavioral description, with syntax designed as an extension of the Spice time dependent sources. They are not necessarily physically realizeable. Some only work on particular types of analysis, or over a small range of values. Some can be used together, some cannot.

In general, all simple components are considered to have simple transformations. A function returns one parameter as a function of one other, as an extension of their linear behavior.

Linear behavior:

Capacitor

$q = C v$

Inductor

$\phi = L i$

Resistor

$v = I r$

Admittance

$i = Y v$

VCVS

$v_o = E v_i$

VCCS

$i_o = G v_i$

CCVS

$v_o = E i_i$

CCCS

$i_o = G i_i$

Sources are defined as functions of time:

Voltage source

$v = f(t)$

Current source

$i = f(t)$

For behavioral modeling / nonlinear values, replace the constant times input by an arbitrary function:

Capacitor

$q = f(v)$

Inductor

$\phi = f(i)$

Resistor

$v = f(r)$

Admittance

$i = f(v)$

VCVS

$v_o = f(v_i)$

VCCS

$i_o = f(v_i)$

CCVS

$v_o = f(i_i)$

CCCS

$i_o = f(i_i)$

Conditionals

AC

AC analysis only.

DC

DC (steady state) value.

OP

OP analysis.

TRAN

Transient analysis.

FOUR

Fourier analysis only.

ELSE

Anything not listed.

ALL

All modes.

Functions

COMPLEX

Complex (re, im) value.

EXP

Spice Exp source. (time dependent value).

FIT

Fit a curve with splines.

GENERATOR

Value from Generator command.

POLY

Polynomial (Spice style).

POSY

Posynomial (Like poly, non-integer powers).

PULSE

Spice Pulse source. (time dependent value).

PWL

Piece-wise linear.

SFFM

Spice Frequency Modulation (time dependent value).

SIN

Spice Sin source. (time dependent value).

TANH

Hyperbolic tangent xfer function.

Model Functions

TABLE

Fit a curve with splines.

Cap

Spice semiconductor ``capacitor'' model.

Res

Spice semiconductor ``resistor'' model.