Design and analysis of four-phase synchronous buck converter for VRM applications

A four-phase synchronous buck converter is designed and analyzed with an emphasis on the variation of R/sub DS/-on and C/sub GS/ of the power MOSFET, and the ESR of the filter inductor. As the R/sub DS/-on of the device decides the voltage drop across the device, and C/sub GS/ of the device decides the switching transients, both of these play a role in the efficiency of the multiphase converter. It is shown that, devices of same rating and make may have different performance characteristics, which do affect the efficiency of the converter. Even the inductors of the same rating though expected to behave in the same way, may not literally have the same effect when connected in different phases. In this paper a four-phase buck converter and its performance with and without variation of R/sub DS/-on, C/sub GS/ and ESR of the filter inductors are analyzed and presented.