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2.7 Time-Domain Analysis of Nonlinear Dynamic Circuits 125
Note that the initial condition for the capacitor C1 is given by the node voltage difference
V$1[0] V$2[0] and is included in the set of time-domain equations. Applying NDAESolve yields
the following DC operating-point values for the node voltages and the initial inductor current I$L1:
In[27]:= NDAESolve[oscillatorMNA1, {t, 0.}]
Out[27]= V$1 0., V$2 0.002, I$L1 0.002
For the DC analysis the inductor was replaced by a short circuit, therefore V$1 is zero. I$L1 has
the same numerical value as V$2 because the resistor has the unit value . Now, we compute the
transient response:
In[28]:= transient1 = NDAESolve[oscillatorMNA1, {t, 0., 10^−4}]
Out[28]=
V$1 InterpolatingFunction0., 0.0001, ,
V$2 InterpolatingFunction0., 0.0001, ,
I$L1 InterpolatingFunction0., 0.0001,
Finally, we plot the transient waveform of the output current I out (given by the inductor current I$L1)
in the simulated time interval.
In[29]:= TransientPlot[transient1, {I$L1[t]}, {t, 0., 10^−4},
PlotRange −> All]
0.0015
0.001
0.0005
-0.0005
-0.001
-0.0015
-0.002
0.00002 0.00004 0.00006 0.00008 0.0001 t
I$L1[t]
Out[29]= Graphics
Initial Conditions for all Dynamic Elements
Alternatively, the function CircuitEquations can be instructed to use initial conditions for all
dynamic elements by applying the option setting InitialConditions −> All. Initial conditions
which are not explicitly specified in the netlist are then assumed to be zero. For our example, we
again set up a system of modified nodal equations from the circuit configuration at the time t ⩵ .