부산대학교 도서관

This article presents a monolithic hybrid boost converter suitable for a high conversion ratio (CR). It uses two inductors, two cross-connected flying capacitors ( $C_{F}\text{s}$ ), and six power switches, allowing a two-phase operation and $C_{F}\text{s}$ near-soft charging. With the internal voltages halved by the $C_{F}\text{s}$ , the inductor current ripple and voltage stress of the switches decrease, thus allowing a reduction in both power loss and silicon area. In addition, the cross-connected $C_{F}\text{s}$ double the pulsewidth of the control signals, thereby allowing a higher switching frequency even under a very high CR. Moreover, this design shares the large bootstrap capacitors of the high-side NMOS switches and also eliminates the need for an additional bootstrap voltage generation for the stacked NMOS switches, enabling an area-efficient full integration of the bootstrap capacitors. The converter, fabricated in 0.35- $\mu \text{m}$ CMOS, occupies a core area of 0.86 mm 2 . It achieves a 93.5% peak efficiency when the CR is 4.5, with two 3.3- $\mu \text{H}$ inductors (3010 package), two 0.47- $\mu \text{F}~C_{F}\text{s}$ , and a 2-MHz switching frequency.