Current‐balance method for multi‐phase DC–DC buck converters with wide duty ratio applications in both CCM and DCM

Abstract

To cope with the current imbalance situation of multi-phase buck converters with wide duty ratio range applications in continuous conduction mode (CCM) and discontinuous conduction mode (DCM), a current-balance method is proposed. In CCM, with small power loss, current balance can be achieved by comparing the replica currents flowing through the sensing transistors. In DCM, an additional offset cancellation circuit is designed to eliminate the intrinsic offset voltage mismatch existing in main-loop comparators. Then each phase sequentially performs a switching operation to share the switching stress. Experimental results show that the current imbalance is decreased to 0.15% under duty ratio from 0.1 to 0.75. Load current is well distributed between phases in both the CCM and DCM without tricky implement.