A Resonant Switched-Capacitor Parallel Inductor Hybrid Buck Converter

This article presents a resonant switched-capacitor (SC) parallel inductor (ReSC-PL) hybrid buck converter with reduced inductor current for high and wide voltage conversion ratio (VCR). The proposed ReSC-PL buck converter lowers down the switching node voltage with V_IN-related flying capacitors and reduces the inductor current I_L with V_OUT-related flying capacitors. Therefore, it can always effectively reduce I_L to a value below 0.5~0.67 of the output current I_O for high VCRs ranging from 10 to 20. In addition, by utilizing the parasitic inductor, this design effectively reduces the glitches on the output and forms a resonant SC operation to further improve the conversion efficiency. This work, fabricated in 180-nm Bipolar-CMOS-DMOS (BCD), occupies an area of 8.88 mm². Measurement results show that the proposed ReSC-PL buck obtains a peak efficiency of 91.8% and a peak current density of 350 A/cm³ with a power inductor as small as 2.5 × 2 × 1.2 mm³, with 12-V input and 0.6-V to 1.2-V output, and 5-A maximum output current.