Control-Oriented Modeling of Comparator Overdrive Delay for Stabilizing High-Frequency Current-Mode DC–DC Converters

The comparator is one of the most intensively used yet often inadequately modeled components in power electronics. This paper presents a control-oriented behavioral model of the comparator overdrive delay (COD) and leverages it to address the stability issues of high-frequency current-mode DC-DC converters caused by current-sensing interference. This model links the comparator's intrinsic dynamics to its nonlinear filtering behavior, matching closely the experimental delay-overdrive characteristics while maintaining analytical simplicity and design intuitions. Building on this model, aCOD conditioningapproach is proposed, which exploits the intrinsic comparator dynamics to reshape sensor interference and thereby stabilize current-mode converters. An analytical stability condition is then derived through a Lur'e system representation. This theory is validated on a 2.3 MHz buck converter prototype, where commercial off-the-shelf comparators are leveraged to eliminate the instability, manifested as inductor current subharmonic oscillations. The results confirm the practicality of the COD conditioning method, highlighting its advantages over conventional linear filtering techniques, and reveal a new design insight: a properly engineered comparator delay can enhance the resilience of current-mode power converters without sacrificing transient speed.