Multi-phase buck converter design with two-phase coupled inductors

Ever increasing demand for higher current, lower voltage and faster dynamic response imposes a challenge for multi-phase buck converter designs. Coupling the output inductors of multi-phase buck has the potential to reduce steady-state power losses while maintaining or even improving dynamic performance. Two-phase coupled inductors take advantage of magnetic coupling, have a physically symmetrical structure and with identical magnetic characteristics, and avoid the sub-harmonic output ripple current inherent in coupled inductor designs where the number of phases is larger than two. This paper presents the configuration and design methodology of implementing two-phase coupled inductor in multi-phase buck converters. Although the number of phases is preferred to be even, the design procedure has been extended to converters with any number of phases.