Mitigation and utilization of the inductor coupling effect in interleaved multiphase DC/DC converters

Interleaved multiphase synchronous buck converters have been used in powering CPU, GPU and memory due to ever increasing load current and fast load slew-rate requirements of the processors. The unwanted inductor coupling exists between adjacent phases but has not been studied systematically and has been ignored in multiphase converter designs. In some cases, the unwanted inductor coupling increases the current ripple and affects the inductor current sensing accuracy and therefore should be minimized. In other cases, the inductor coupling effect can be utilized to improve load transient response and/or converter efficiency. This paper presents magnetic simulation on three different types of inductors commonly used in multiphase converters to demonstrate the coupling effect and its influence on inductor current. The simulation results of the inductor coupling effect have been verified by experiments. Recommendations are provided to minimize the unwanted coupling effect in some designs or utilize the coupling effect in others.