Control-loop bandwidth limitations for multiphase interleaving buck converters

To investigate the relationship between the control-loop bandwidth and the switching frequency, this paper introduces a multi-frequency small-signal model for multiphase interleaving buck converters. Including the influences from the frequency components generated by the pulse-width modulation schemes, this model is applicable beyond half the switching frequency, which is where the average model loses its validity. For voltage-mode control, both cases of trailing-edge modulation and of double-edge modulation are analyzed. Control-loop bandwidth limitations are clearly illustrated. In addition, peak current-mode control is discussed. Simulation and experimental results prove the analysis.