A non-isolated high step-up DC-DC converter with coupled inductor is developed for large voltage gain applications such as electric mobility and renewable energies. This converter combines the concepts of magnetic integration and interleaving phases that are effective for downsizing of power converters. The developed converter offers a good performance of voltage gain vs. converter size, because, compared with the conventional two-phase interleaved boost converter, it only needs the addition of two diodes and one winding. Nevertheless, in order to describe the design method of the developed high step-up converter, the coupled inductor characterization is required. Therefore, the current ripple characterization of the coupled inductor is analyzed and evaluated in this paper. A 100W prototype is constructed and experimental results are provided to verify the characterization analysis.