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Default Models

Some simple devices support a ``default model'' in WRspice, meaning that if no model name is given in an instance line, an internally provided default model will be used. Internally, all devices have a model structure, which is a container for the instances of that device type. It is possible to access the default model used for various devices with .defmod lines. This will affect all devices of the corresponding type that are not explicitly given a model in the instantiation line.

General Form:
.defmod type (pname1=pval1 pname2=pval2 ... )
Examples:
.defmod r (m=1.2)
.model v (temp=300 tc1=.001

The type is the name of the device model (the second name that would be provided on a .model line) such as R (for resistors), C (for capacitors), and L (for inductors).

The type name is followed by a list of parameter assignments, optionally enclosed in parentheses. These are precisely the same as would appear in a .model line for the device. These provide the values for the parameters to be used in the default model.

Not all devices support default models, meaning that lack of a model name in an instance line is an error. In particular devices that have a variable terminal count (optional nodes) require a model name and therefor don't support a default model.

It is probably also not possible to use a level parameter in a default model, and binning parameters will be ignored at best. Anything too fancy should be done through a normal model, or there may be trouble.

The capability is very powerful, but might cause headaches, too, so the user should beware. For example, if the following line is added to an existing deck

.defmod R(M=1.2)
all ``standard'' resistors in the deck will have their values reduced by about twenty percent. This can be useful for corner analysis, but don't let the line get ``lost'' in a big file.


next up previous contents index
Next: Analysis at Different Temperatures Up: Device Models Previous: Device Models   Contents   Index
Stephen R. Whiteley 2018-10-10