RF Electronics Chapter 2: Computer Simulation Page 33
2022, C. J. Kikkert, James Cook University, ISBN 978-0-6486803-9-0.
Figure 2.39. Buck Converter current waveforms with R
L
=120 Ω.
Observing the steady state transient output similar to figure 2.36, shows that the output
voltage has a peak of 24.3V. Extending the simulation time to 6 ms results in an output
voltage of 17.54 V at 2 ms, 17.23 V at 4 ms and 17.20 V at 6 ms. The voltage increase is
due to the discontinuous conduction mode. This voltage may cause damage to any 12 V
loads. These simulations are thus useful to design hardware that produces the correct
output voltage regardless of the output current drawn. For this application, that requires
the pulse width TW in figure 2.32 to be controlled by the output voltage.
Figure 2.40. Buck Converter voltage waveforms with R
L
=120 Ω.
Harmonic Balance Circuit Simulation
Harmonic balance (HB) is used in chapter 5, to determine the conversion loss and
waveforms of mixers, it allows the variations of gain with signal amplitude in an amplifier
to be calculated and it allows all the harmonics produced by the oscillator to be
determined. Using the appropriate non-linear amplifier models, HB allows the inter-
modulation distortion of an amplifier to be determined as a function of output power.
Because HB simulation takes significantly longer to complete, most designs are initially
RF Electronics: Design and Simulation
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