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3.5 Setting Up and Solving Circuit Equations 245
Use the symbol p to
denote the complex
frequency.
In[21]:= CircuitEquations[rlcf,
FrequencyVariable −> p] // DisplayForm
Out[21]//DisplayForm=
1
R
1
R
0 1
1 1
R
L p V$1 0
1
R
1
L p
0 V$2 0
. ⩵⩵
0
1 1
L p
L p
C p 0 V$3 0
I$V1 V
1 0 0 0
This defines a simple
control circuit with a
signal source, a forward
signal path, and a
feedback path.
In[22]:= fbloop = Netlist[
{HS1, {in}, X[Frequency]},
{HG1, {in, out}, Hf[Frequency]},
{HG2, {out, in}, Hfb[Frequency]}
]
Out[22]= NetlistRaw, 3
By default, CircuitEquations prints a warning because the netlist does not contain a reference to
the electrical ground node 0. To turn off the warning, you must set IgnoreMissingGround −> True.
Set up modified nodal
equations for the control
circuit.
In[23]:= CircuitEquations[fbloop, NodeVoltagePrefix −> "x$"]
Netlist::gndnode: Found no connections to the ground node.
Netlist::lttc: Less than two connections at node(s) {0}.
Out[23]= DAEAC, 2 2
This tells Analog Insydes
to ignore the missing
reference to ground.
In[24]:= fbleqs = CircuitEquations[fbloop,
IgnoreMissingGround −> True, NodeVoltagePrefix −> "x$"];
fbleqs // DisplayForm
Out[25]//DisplayForm=
1 Hfbs
. x$in Xs
⩵⩵
Hfs 1 x$out 0
This defines a circuit with
two time-varying and
temperature-dependent
resistors.
In[26]:= tempckt = Netlist[
{V1, {1, 0}, V1},
{R1, {1, 2}, R1[Time]*(1 + TC11*TEMP)},
{R2, {2, 0}, R2[Time]*(1 + TC12*TEMP)},
{C1, {2, 0}, C1}
]
Out[26]= NetlistRaw, 4
By default, TEMP is simply regarded as a global parameter. Equations for transient analysis are
formulated with time as independent variable.
Set up circuit equations
for time-domain analysis.
In[27]:= CircuitEquations[tempckt,
AnalysisMode −> Transient] // DisplayForm
Out[27]//DisplayForm=
V$1t V$2t
I$V1t
⩵⩵ 0,
1 TC11 TEMP R1t
V$2t
1 TC12 TEMP R2t V$1t V$2t
1 TC11 TEMP R1t C1 V$2′ t ⩵⩵ 0,
V$1t ⩵⩵ V1, V$1t, V$2t, I$V1t, DesignPoint