Analysis of Double Step-Down Two-Phase Buck Converter for VRM

A novel two-phase buck converter suitable to apply the power supplies for MPU is proposed. Compared to conventional two-phase buck converter, the proposed converter essentially has double step-down ratio as Eo/Ei = D/2 and high efficiency is realized by reducing the switching loss of the switching elements. In addition the current ripple of the output smoothing capacitor is improved to the same value as that of conventional four-phase buck converter. Moreover the current unbalance between two inductors in each phase is removed automatically without any current sensing means. The above fine characteristics are simply achieved an additional capacitor