Universal Compensation Ramp Auto-Tuning Technique for Current Mode Controls of Switching Converters

The conventional slope compensations for current mode controls do not take all the parameters' changes into account, so the variations on small-signal transfer functions limit the voltage loop bandwidth (BW). In order to optimize the dynamic performance of current-mode control, this letter proposes a universal auto-tuning technique for external ramp slope based on the sensed slope of current feedback signal. The tuning mechanism keeps the quality factor of the double poles unchanged over the duty cycle variation, inductor tolerance, sensing element variation, and topology change, thus a consistent wide BW control is achieved without the limitation from the corner cases. Simple digital and analog implementations are proposed to realize the auto-tuning concept. This method is applicable to digital and analog current-mode controllers with peak current mode, valley current mode, and average current mode operations. The effectiveness of the proposed method is verified by simulation and experimental results.