This paper presents some novel circuits of soft-switched quasi-resonant DC/DC boost and flyback converters. These topologies use coupled inductors with capacitor for resonating circuit to achieve zero voltage switching of the converters. The circuits have minimum voltage stress across the switches. Moreover, they have reduced commutation losses and increased switching frequency. The paper explains the principle of operation and describes the analysis of both boost as well as flyback converters. It also gives design criteria, derived from the mathematical analysis carried out, for achieving zero voltage switching under all loading conditions from no load to full load. The feasibility of the proposed circuits has been verified by PSPICE simulation.