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208 3. Reference Manual
A circuit with a resistor
model.
In[6]:= resckt = Circuit[
Netlist[
{V0, {1, 0}, Symbolic −> V0, Value −> 1},
{R1, {1 −> "P", 0 −> "N"},
Model −> "RES", Selector −> "DC",
RES −> 1000., TC1 −> 10^−3}
],
Model[
Name −> "RES", Selector −> "DC",
Ports −> {"P", "N"},
Parameters −> {RES, TC1, Global[TEMP, TNOM]},
Defaults −> {TC1 −> 0, TNOM −> 300.15, TEMP −> 300.15},
Symbolic −> {RES −> R},
Variables −> {Voltage["P", "N"], Current["P", "N"]},
Definition −> Equations[
Voltage["P", "N"] ==
RES*(1 + TC1*(TEMP − TNOM))*Current["P", "N"]
]
],
GlobalParameters[TEMP −> 310.]
]
Out[6]= Circuit
Note that only R$R1 is
kept in symbolic form.
In[7]:= CircuitEquations[resckt, AnalysisMode −> DC,
ElementValues −> Symbolic] // DisplayForm
Out[7]//DisplayForm=
I$PN$R1 I$V0 ⩵⩵ 0, V$1 ⩵⩵ V0, V$1 ⩵⩵ 1.00985 I$PN$R1 R$R1,
V$1, I$V0, I$PN$R1,
DesignPoint V0 1, R$R1 1000., TEMP 310.
The following example demonstrates the use of local model parameter sets in a subcircuit definition.
The netlist shown below represents a bipolar differential pair with emitter degeneration resistors.
The Circuit object contains a local ModelParameters statement in which the values of the BJT’s
ohmic collector and emitter resistances are calculated as a function of the area factor.