This paper addresses the modulation, design, and ZVS range extension of a single-stage current-fed fullbridge AC-DC converter with an active clamp circuit. A modulation scheme is proposed to achieve zero voltage turn-ON and zero current turn-OFF with reduced current stress as compared to the traditional phase-shifted modulation scheme. The impact of converter parameters, parasitic elements, and loading is considered while analyzing the switching transitions to understand the ZVS bounds of the converter. It is demonstrated that the ZVS range can be extended by a suitable choice of the dead time. The analysis is validated using switching circuit simulations that incorporate semiconductor models. Furthermore, experimental results from a 1.2 kW hardware prototype operating at 94.5 % efficiency at full load are presented to validate the findings.