A constant on-time current-mode (COTCM) control features inherent phase-current balancing, good stability margin and improved light-load efficiency which is a new mandate for many CPU power applications nowadays.For a delicate application such as adaptive voltage positioning (A VP) application, however, the output voltage regulation of a COTCM converter is often inadequate when constant converter output impedance feature is also required.In this paper, a modified converter with a DC-offset correction circuit is presented. A small-signal model is also developed based on describing-function approach which is complicated but necessary to uncover the inherent nature of this control scheme. Experimental results will be shown. A comparison with a ripple-based constant on-time (RBCOT) control scheme will also be given.
A new multi-frequency small-signal control model for high-bandwidth DC buck regulator is proposed. Describing function approach is taken to model the duty-cycle modulator, incorporating the effects of not only the modulating frequency fm, the switching frequency fs, and the two sideband frequencies fs-fm and fs+fm. This model is significantly more accurate than the conventional average model and the recently proposed two-frequency model for applications with high control bandwidth-to-switching frequency ratio and high input-to-output voltage step down ratio, such as the v-core voltage regulators. The model is verified by simulations and experiments.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.