A 16-24V to 1-1.8V 1.187W/mm3-Power-Density Hybrid DC-DC Converter Featuring Inductor Current in $\Sigma$-Fibonacci Region for Unmanned Aerial Vehicle Applications

This paper presents a $16-24 ~\mathrm{V}$-input $1-1.8 ~\mathrm{V}$-output $3 / 2$-phase hybrid DC-DC converter for powering point-of-load systems in unmanned aerial vehicles. The converter minimizes inductor DC resistance and AC resistance losses by reducing inductor current into the $\Sigma$-Fibonacci region, enabling the use of a compact inductor. This region corresponds to the minimum achievable inductor current with flying capacitors fully utilized. Fabricated in a $0.18 \mu ~\mathrm{m}$ BCD process, the converter achieves a 93.9 % peak efficiency and a $1.187 ~\mathrm{W} / \text{mm}^{3}$ power density.