Random-switching control in DC-to-DC converters

The authors discuss the properties of switching noise in power converters from the viewpoint of the frequency domain. They also discuss the concept of random-switching control, by which the switching-noise spectrum is smoothed and its level is reduced. Two types of control circuits realizing the random switching are introduced for a buck converter, and their basic operations are explained and experimentally examined. Finally, the authors report experimental switching-noise spectra for two kinds of control, namely, random-switching control and conventional PWM (pulse-width-modulated) control. A comparison of these control schemes confirms that random-switching control is effective for suppressing the peak level of the switching-noise spectrum