Modeling and Analysis of Conductive Voltage Noise for a DC-DC Buck Converter

Voltage noise from a synchronised buck converter is known to causes various problems in electronic system design. The power supply noise is generally related to the switching activity of the converters. Voltage noise from switching dc/dc converter shows different behaviours at switching and ringing frequencies. In this paper, we first proposal analytical expressions to evaluate voltage ripples at switching frequency with considerations of complex decoupling structures with parasitics. We also developed an equivalent RC circuit model with step sources to represent ringing noise in the switching waveform at input side of buck converter. Passive parasitics from layout are extracted from electromagnetic models of print circuit boards. Based on analysis of our proposal model, novel design methods are given to mitigate supply noise. Our analytical expressions and models have been verified with measurements on a buck converter design in a high-speed system. System performance has been improved after applying optimization techniques from buck converter design and layout suggested from our models.