Fast and accurate current sensing in a multiphase buck converter

Abstract

Voltage Regulator Modules (VRM), which are used to power advanced microprocessors, have stringent efficiency and transient response requirements. A multiphase buck converter scheme with inner current loop control is one of the candidates for use in this application because of its ability to achieve fast dynamic current response under step-load conditions. In order to realize the full potential of the scheme, a small, efficient and accurate current sensor with high bandwidth is essential. The paper proposes a current sensing technique capable of high performance based on current transformers. The requirements and the design of the current transformer to be used in the scheme are presented. Finally, experimental results on a step down buck converter, controlled in peak current mode using such a sensor, are provided to confirm its performance. The proposed technique can also be applied to several other types of power converters besides the multiphase buck converter. © 2005 IEEE.