A primitive device is the lowest level model that can be used in a circuit and is a building block for macromodels and entire circuits. Multisim supports many such devices.

This section looks at how a primitive device is declared and used in a circuit.

Primitive devices are comprised of either just an instance declaration or an instance declaration with an associated model definition.

Instance Declaration

The instance declaration places a primitive device between circuit nodes, specifies device parameters, and links the instance to a model definition (where needed). The instance declaration has the following general format:

PREFIX_ anyname node1 < node2 < … >> my_ModelNAME Instance_line_parameters

Identifier Description
PREFIX Device specific character.
_anyname Arbitrary instance name suffix.


nodeN
where N=1,2,3…

 The name of the Nth node that the device is connected to. Node names may contain any characters except for white space and the following: \ {} () [] : # " ' ; , % < > ` & = *
my_ModelNAME Arbitrary name that links the instance declaration to a model definition. It is optional for some devices is and mandatory for others.
Instance_line_parameters A list of device specific instance parameters, some of which are mandatory and some optional.

Model Definition

Required for some primitive devices and optional for others, the model line allows users to specify additional parameters for a device. The model line has the following format:

.model my_ModelNAME <AKO:akomodelname>devicename(<Model_Parameters>)

Identifier Description
my_ModelNAME Arbitrary model identifier that links the model definition to one or more instance declarations.
akomodelname Model identifier from which specified model parameters will be inherited.
devicename Device-specific identifier.
Model_Parameters List of device-specific model parameter assignments. Note that every model parameter of every device has a default value. Assignments made in the Model_Parameters block overwrite these defaults.

Examples


*Resistor device without its optional model line
R88 1 0 10k tc1=0.1 tc2=5


*Resistor device with its optional model line
R15 in8 out myResmodel 10k
.model myResmodel res(rmult=5)


*A BJT with area factor of 8
*and BJT with an area factor 4
Q54 99 b 0 BJTer area=8
Q55 e b 0 BJTer area=4
.model BJTer npn(is=1e-12 bf=140 rc=3 tf=3n)


*MOSFET M1 will inherit
*kp=1e-3 phi=0.76 mj=0.44 ld=0.1u
M1 1 4 9 9 myMOS1
.model myMOS1 AKO:myMOS2 nmos(vto=1.4)
.model myMOS2 nmos(kp=1e-3 phi=0.76 mj=0.44 ld=0.1u)