Device Models

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Device Models

General form:

.MODEL MNAME TYPE(PNAME1=PVAL1 PNAME2=PVAL2 ... )

Examples:

.MODEL MOD1 NPN (BF=50 IS=1E-13 VBF=50)

Most simple circuit elements typically require only a few parameter values. However, some devices (semiconductor devices in particular) that are included in SPICE Simulation Program for Integrated Circuit Emulation. require many parameter values. Often, many devices in a circuit are defined by the same set of device model parameters. For these reasons, a set of device model parameters is defined on a separate .MODEL line and assigned a unique model name. The device element lines in SPICE then refer to the model name.

For these more complex device types, each device element line contains the device name, the nodes to which the device is connected, and the device model name. In addition, other optional parameters may be specified for some devices: geometric factors and an initial condition (see the following section on Transistors and Diodes for more details).

MNAME in the above is the model name, and type is one of the following fifteen types:

R

Semiconductor resistor model

C

Semiconductor capacitor model

SW

Voltage controlled switch

CSW

Current controlled switch

URC

Uniform distributed RC model

LTRA

Lossy transmission line model

D

Diode model

NPN

NPN BJT model

PNP

PNP BJT model

NJF

N-channel JFET model

PJF

P-channel JFET model

NMOS

N-channel MOSFET model

PMOS

P-channel MOSFET model

NMF

N-channel MESFET model

PMF

P-channel MESFET model

Parameter values are defined by appending the parameter name followed by an equal sign and the parameter value. Model parameters that are not given a value are assigned the default values given below for each model type. Models, model parameters, and default values are listed in the next section along with the description of device element lines.