Small-Signal Analysis and Design of Constant On-Time Controlled Buck Converters With Duty-Cycle-Independent Quality Factors

This article presents a frequency-domain analysis that models the behavior of Constant-on-Time (COT)-controlled buck converters in wide-input-output-range scenarios. Based on this analysis, a design strategy is proposed to enable robust control with a duty-cycle-independent quality factor, also known as a constant Q-value. A constant Q-value circuit based on the proposed strategy is then constructed and incorporated with a baseline ultrafast transient COT control scheme to experimentally verify the system stability and optimal load transient response under wide input-output range scenarios. In addition, the design strategy is extended to otherCOTbuck control schemes with simulation and calculation verifications.