This proposed boost converter utilizes active-clamp circuit to achieve zero-voltage-switched (ZVS) transition in a full-wave zero-current-switched quasi-resonant (ZCS-QR) converter. The ZCS-ZVS switching transition results in higher efficiency, better output voltage regulation, opens possibility to incorporate higher switching frequency, and has some potency to reduce converter's conducted EMI. It is important to note that the active-clamp circuit works under ZVS condition. Therefore, this switch will not cause excessive losses and extra EMI. In this paper, the working principle and steady state performance of the proposed boost converter are presented. A 100 V dc input, 300 W maximum output, and 430 kHz resonant frequency experimental circuit has been built. Maximum efficiency of 95.6% has been confirmed by experiment.