By cascading two different converters being a quadratic step-up converter and adopting voltage multiplier achieve extra ratio of voltage conversion with appropriated duty ratio and low turn ratio of the coupled inductor. However, the energy stored in the leakage inductor of the coupled inductor can be recycled to the output capacitor. The operating principles and steady-state analyses of continuous conduction mode are discussed. A 200-W/ 400-V prototype sample is implemented with input voltage 20-V. The maximum efficiency of 93.2 % is reached; the full load efficiency remains at 89.5 %.