RF Electronics Chapter 2: Computer Simulation Page 32
2022, C. J. Kikkert, James Cook University, ISBN 978-0-6486803-9-0.
Figure 2.37. Buck Converter current waveforms with R
L
=2.4 Ω.
Figure 2.38. Buck Converter, expanded time current waveforms with R
L
=2.4 Ω.
Changing the load resistor from 2.4 Ω to 120 Ω causes a larger transient output voltage
overshoot and results in the converter operating in a discontinuous conduction mode as
shown in figure 2.39. The plot of voltage waveforms similar to figure 2.35, show some
damped high frequency oscillations, when the transistor switches OFF, as shown in figure
2.40, with the expanded time waveforms on the right. This figure also shows that the
output voltage has an overshoot to 10.8V, which may be too high for safe operation of
any hardware connected to the DC-DC converter. This simulation is done with the time
and step settings of figure 2.34 (L). Using the Use HB settings produces slightly different
results and may not clearly show the oscillations.
RF Electronics: Design and Simulation
32 www.cadence.com/go/awr
