A new interleaved buck converter (IBC) having low switching losses and improved step-down conversion ratio is proposed in this paper. It is similar to a conventional IBC, but two active switches are connected in series, and a coupling capacitor is employed in the power path, like Cuk, Sepic, and Zeta converters. The proposed IBC shows that since the voltage stress across all active switches is half of the input voltage before turn-on or after turn-off, the capacitive discharging and switching losses can be reduced considerably. This allows the proposed IBC to have higher efficiency and be operated at higher switching frequency. In addition, the proposed IBC has higher step-down conversion ratio and smaller output current ripple than a conventional IBC. The features, operation principles, and relevant analysis results of the proposed IBC are presented in this paper. The validity of this study is confirmed by the experimental results of prototype converters with 150-200V input, 24V/10A output.