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56 2. Tutorial
In[5]:= flatAmpDyn = ExpandSubcircuits[
commonEmitterAmplifier /.
{supplyVoltage −> 0, inputVoltage −> 1,
BJTModel −> ACdynamic}];
DisplayForm[flatAmpDyn]
Out[6]//DisplayForm=
Netlist Flat, 10 Entries:
V1, 1, 0, 1
VCC, 2, 0, Type VoltageSource, Value 0
R1, 2, 1, R1
R2, 1, 0, R2
RC, 2, 3, RC
RE, 4, 0, RE
RB$Q1, X$Q1, 4, RB
CM$Q1, 1, 3, CM
CC$Q1, 1, X$Q1, 3, 4, beta
RO$Q1, 3, 4, RO
As we can see from the flattened netlists, ExpandSubcircuits has not simply replaced the subcircuit
references by the original netlists from the Model definitions. The function has also generated
unique symbols for all internal reference designators and node identifiers in the subcircuit netlists by
appending a separator character ($) and the subcircuit instance name (Q1) to the original identifiers.
This eliminates possible name conflicts with reference designators from the top-level netlist and
allows for using multiple instances of a subcircuit definition.
Analysis of the Common-Emitter Amplifier
Now we can analyze the circuit by means of the functions CircuitEquations (Section 3.5.1) and
Solve (Section 3.5.4). We start by setting up the modified nodal equations for the simple AC model
from the flattened netlist. Note that we could call CircuitEquations on the Circuit object equally
well. We used ExpandSubcircuits for demonstrating the subcircuit expansion mechanism.