Digital controller design for point-of-load DC-DC converters with variable switching frequency

Presented is a digital controller to regulate a point-of-load Buck converter. The regulator varies both the duty cycle, as well as the switching frequency, by controlling not only the on-time, but also the off-time of the switching period. The multi-loop digital controller, which achieves a tight voltage regulation and an excellent dynamic performance, is presented and its effectiveness is proven by means of experimental results. The controller architecture, together with an analogue-to-digital converter, has been integrated in a 0.13 μm CMOS technology.