A High-Frequency Model for a PCM Buck Converter

In order to analyze the high-frequency behaviors of the peak current mode (PCM) Buck converter, a small-signal multifrequency model is proposed. The multifrequency model explains the influences from the sideband frequency components generated by the nonlinear PWM comparator. It can effectively reflect some features which cannot be shown by the conventional average model, such as the phase delay. In addition, based on the proposed model, the sample-hold effect is also introduced and analyzed in this paper. Through the derivation and validation of the new model, frequency characteristics of the PCM Buck converter can be well understood, especially in the high-frequency region.