The low-frequency output noise that is caused by introducing random-switching control into DC-to-DC converters with output regulation, is discussed quantitatively. A modified converter model involving the unintended effect of random switching is derived from the consideration of noise-generation mechanism. After the theoretical analysis based on the model, it is clarified that the magnitude of output noise is in proportion to the variance of switching interval. The experimental results of a buck-type converter are compared with those obtained theoretically, so that the validity of the theoretical results is confirmed experimentally.

A family of single-switch ZVS-CV (Zero-voltage switchingclamped voltage) dc-to-dc converters is presented. This class of converter is realized by employing a commutation inductor circuit which is connected in parallel with either the transistor or the freewheeling diode in a conventional PWM converter. The technique described here is simple and output-voltage control is easy. The converters that comprise this family are derived form Buck, Boost, Buck/Boost, Cuk, Sepic and Zeta PWM converters. The steady-state characteristics of these converters such as the voltage conversion ratio, the ZVS conditions, and the input and output current ripples are analyzed. The analysis is confirmed by experiment.