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52 2. Tutorial
Connections to subcircuits can only be made through designated port nodes. Any attempt to interface
directly with an internal node will cause the generation of an error message when the netlist hierarchy
is flattened. However, there is one exception: since the ground node (0) is considered to be global,
elements in subcircuit definitions may be connected directly with global ground without the need
to specify 0 as a port node. In fact, 0 cannot be used as port node identifier in Analog Insydes.
Finally, all which remains to do is to write the netlists of the two subcircuits and set up the Model
definitions as follows:
Model[
Name −> NPNTransistor,
Selector −> ACsimple,
Ports −> {"B", "C", "E"},
Definition −>
Netlist[
{RB, {"X", "E"}, RB},
{CC, {"B", "X", "C", "E"}, beta}
]
]
Model[
Name −> NPNTransistor,
Selector −> ACdynamic,
Ports −> {"B", "C", "E"},
Definition −>
Netlist[
{RB, {"X", "E"}, RB},
{CM, {"B", "C"}, CM},
{CC, {"B", "X", "C", "E"}, beta},
{RO, {"C", "E"}, RO}
]
]
In this example, we used node names for all subcircuit nodes given by strings ("B", "C", "E", "X") but
we could have used positive integers just as well. However, using symbolic names is usually preferable. The
reason is that during subcircuit expansion all internal nodes of subcircuit objects will be instantiated and
labeled with unique identifiers such as X$Q1, which are automatically generated from the node names and the
reference designator of the subcircuit instance. If an internal node identifier is an integer, e.g. 2, the generated
instance identifier 2$Q1 could be confused easily with the product 2*$Q1.
2.3.3 Referencing Subcircuits
The Netlist Entry Format for Subcircuit References
Subcircuits or device models defined with the Model command can be referenced from a netlist on a
higher hierarchy level by a netlist entry whose value field contains the options Model and Selector: