Investigation of candidate topologies for 12 V VRM

With higher input voltages and lower output voltages, the most popular voltage regulator module (VRM) topology-the multiphase buck converter-operates at very small duty cycles. The influence of duty cycle on the performance of a multiphase buck converter is investigated and the results show that both the transient response and the efficiency suffer from the very small duty cycle. Alternative topologies with extended duty cycles are explored in order to improve the efficiency without comprising the transient response. The topologies under investigation are multiphase tapped-inductor buck converter, multiphase coupled-buck converter and improved multiphase coupled-buck converter with built-in filters.