An Inductance-Variation-Insensitive Buck Converter Using a Dynamic Ramp Compensation With Slope Sensing Technique

This brief introduces a current-mode DC-DC buck converter that operates without performance degradations, even when the inductance value changes. The proposed circuit can be widely utilized to ensure the stable operation of various systems, as inductor values in PMICs may fluctuate despite being identical components. The proposed Inductance-Variation-Insensitive (IVI) buck converter directly senses the rate of change of inductor current and transmits information about the output voltage and inductance to a dynamic ramp generator. The dynamic ramp generator produces a ramp signal proportionate to the sensed inductor current slope, thereby maintaining a deadbeat state and preventing subharmonic oscillations. This innovative approach enables the converter to function seamlessly across a wide range of output values while maintaining overall stability. The proposed buck converter is fabricated using a 0.18 m 1P6M CMOS process, occupying an active area of 0.82 mm2. Experimental results demonstrate its stable operation over a broad range of output voltages, even in the presence of inductance variations, when compared to conventional fixed-ramp approaches. It exhibits a transient response recovery time of 3.9 s for a load change from 50 mA to 350 mA and 4.7 s for the reverse change, from 350 mA to 50 mA. Furthermore, this work achieves a maximum power efficiency of 90.5%, accompanied by an output ripple of less than 30 mV.