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68 2. Tutorial
In[27]:= Circuit[
Model[
Name −> NPNTransistor,
Selector −> ACgm,
Scope −> Global,
Ports −> {"B", "C", "E"},
Parameters −> {RB, beta},
Translation −> {gm −> beta / RB},
Definition −>
Netlist[
{RB, {"B", "E"}, RB},
{VC, {"B", "E", "C", "E"}, gm}
]
]
] // ExpandSubcircuits;
In[28]:= darlNumParams =
Circuit[
Netlist[
{I1, {0, 1}, 1},
{Q1, {1 −> "B", 2 −> "C", 3 −> "E"},
Model −> NPNTransistor, Selector −> ACgm,
RB −> 400.0, beta −> 150.0},
{Q2, {3 −> "B", 2 −> "C", 0 −> "E"},
Model −> NPNTransistor, Selector −> ACgm,
RB −> 100.0, beta −> 50.0},
{Load, {0, 2}, Type −> Resistor, Value −> RL,
Pattern −> Impedance}
]
];
Just before subcircuit expansion the right-hand sides of the translation rules are evaluated with
the parameter values specified in the value fields of the subcircuit references. The evaluated
parameter translation rules are then applied to all value fields in the subcircuit netlist, resulting
in the replacement of all symbols appearing on the left-hand side of the translations. Thus, gm is
automatically calculated from RB and beta.
In[29]:= ExpandSubcircuits[darlNumParams] // DisplayForm
Out[29]//DisplayForm=
Netlist Flat, 6 Entries:
I1, 0, 1, 1
RB$Q1, 1, 3, 400.
VC$Q1, 1, 3, 2, 3, 0.375
RB$Q2, 3, 0, 100.
VC$Q2, 3, 0, 2, 0, 0.5
Load, 0, 2, Type Resistor, Value RL, Pattern Impedance
Delayed Translation Rules
In this simple example, using the Translation argument is not absolutely necessary. We could have
achieved the same effect without a translation rule by writing the netlist entry for the VCCS like
this: