Given the increasing demand to increase the switching frequency and efficiency of switched-mode power converters, pulse-width-modulated (PWM) soft-switching techniques have been proposed to combine the desirable features of PWM and resonant-mode converters. This paper presents the evolution of several soft-switching techniques, operating principles, performance characteristics, experimental results, merits and limitations are also discussed. Experimental results of three classes of zero-voltage-switched converters and one class of zerocurrent-switched converter are prototyped and presented. © 2008 IEEE.