In this paper, a detailed analytical analysis of a passive resonant snubber cell that is perfectly constructed for a pulse width modulated (PWM) d.c.-d.c. buck converter is proposed. This snubber cell provides a larger overall efficiency and a wider load range than most of the active snubber cells presented previously, and has a simple structure and low cost. The operation principles and a detailed steady-state analysis of a PWM buck converter implemented with this snubber cell are presented. The theoretical analysis is verified with a prototype of a 5-kW and 50-kHz insulated gate bipolar transistor-(IGBT)-PWM buck converter. All of the semiconductor devices in the converter operate under soft switching conditions. Additionally, at 80% output power, the overall efficiency of the proposed soft switching converter is increased to about 98% from the value of 91% in its counterpart hard switching version.