Novel Coupled-Inductor Multi-phase VRs

Coupling the output inductors of the multi-phase Buck can reduce the steady-state current ripple while maintaining the same transient response. The conduction losses in the switches can thus be reduced. Furthermore, using coupled inductor can greatly improve the dynamic performance with smaller inductance during the transient. Magnetic fundamentals of the existing coupled inductor multi-phase Buck converters will be revealed in this paper firstly. With the insight gained, novel coupled inductor circuitries will be disclosed. They feature flexibility, symmetric magnetic path, short winding length, and light load efficiency enhancement. Finally, theoretical analysis, design guideline and experimental verification are included.