The multi-frequency small-signal model for buck and multiphase interleaving buck converters

This paper introduces a multi-frequency small-signal model for buck and multiphase interleaving buck converters. Including the influences from the sideband-frequency components generated by the pulse-width modulation (PWM), this model is applicable beyond half of the switching frequency. In voltage-mode-controlled buck converters, the proposed model predicts the measured phase delay, while the conventional average model fails to explain this phenomenon. With this new model, frequency-domain characteristics are clearly explained for buck and multiphase buck converters. Furthermore, the aliasing effect at half of the switching frequency is examined. Simulation and experimental results are presented to verify the proposed multi-frequency model.