Finding return current paths via synchronized measurements in a multiphase DCDC buck converters

Abstract

Evaluation of a product in terms of radiated emissions involves identifying the current return path. In a complex system multiple sources can contribute to the current at one place and frequency. Identifying the source of the current can be achieved by correlating the current to different sources. A multiphase buck converter uses multiple parallel buck converters having different switching times to source a large mount of current. In a multiphase buck converter currents in the capacitors are caused by all phases of the converter, however, the phases do not switch at the same time. Thus, synchronizing to a specific phase allows evaluating how the current of this specific phase spreads throughout the board. With the objective of localizing current one can evaluate if the capacitor placement is optimal and find improved layout and placement solution for a multi-phase buck converter.