Effect of Parasitics and Process Variations in Buck Converters Operated in Voltage-Mode

In this work, the components affecting regulation performance in voltage-mode buck-converters exploiting Pulse Width Modulation are identified and the effects of uncontrolled variations in their values is discussed. For this analysis, a multi-phase buck converter has been considered, operated at 2-MHz switching frequency, supplied by a 5-V input and generating a 1-V regulated output. A model for the output filter has been developed, including parasitics, while the regulation is performed by a Type-III compensator. An average model of buck converter has been developed in MATLAB and Monte Carlo analysis have been performed, showing how component variations affect loop speed and stability. Moreover, a switching model of the regulator has been used and the effect of uncontrolled variations in the component values has been investigated in the time domain.