.MODEL — Define a SPICE Model

Defines a model for a diode, transistor, switch, lossy transmission line or uniform RC line.

Some circuit elements, for example transistors, have many parameters. Instead of defining every transistor parameter for every instance of a transistor, transistors are grouped by model name and have parameters in common. The transistors of the same model can have different sizes and the electrical behavior is scaled to the size of the instance.

Syntax:

.model <modname>|<string expression> <type>[(<parameter list>)]

It is allowed to define multiple models with the same name as long as they have different types. However, this is not recommended.

The parameter list depends on the type of model. Below is a list of model types:

Type	Associated Circuit Element
SW	Voltage Controlled Switch
CSW	Current Controlled Switch
URC	Uniform Distributed RC Line
LTRA	Lossy Transmission Line
D	Diode
NPN	NPN Bipolar Transistor
PNP	PNP Bipolar Transistor
NJF	N-channel JFET model
PJF	P-channel JFET model
NMOS	N-channel MOSFET
PMOS	P-channel MOSFET
NMF	N-channel MESFET
PMF	P-channel MESFET
NIGBT	N-channel IGBT
PIGBT	P-channel IGBT
VDMOS	Vertical Double Diffused Power MOSFET

See the description of the circuit element for a list of which parameters are instance specific and which are common to a model.

You can also define a model that is based on another model:

.model <modname>|<string expression> ako: <modname>|<string expression> [<type>] [(<parameter list>)]

For instance, this line:

.model SLOW ako:NORMAL D(tt=10n)

defines a diode model "SLOW" which is identical to the diode model "NORMAL" except for the "tt" parameter. Although the type specification is optional, it must match the type of the source model if present.