Abstract: A DC-DC converter includes a first transformer connected between a first node and a ground, the first node being located between an input terminal and an output terminal, and the first transformer comprising a first inductor and a second inductor magnetically coupled to each other, a first switch serially connected to the first inductor, between the first node and the ground, a second switch serially connected to the second inductor, between the first node and the ground, a third switch connected between a second node and the output terminal, the second node being located between the second inductor and the second switch, and a fourth switch connected between a third node and the output terminal, the third node being located between the first inductor and the first switch, and the third and fourth switch being controlled in a same manner as the first and second switch, respectively.