A Highly Integrated Hybrid DC-DC Converter With nH-Scale IPD Inductors

Abstract

This article presents a new integrated step-down dc-dc hybrid converter that uses only nano-Henry scale inductors at 2-5-MHz switching frequency. Since it is derived from a Dickson-star switched capacitor (SC) converter, the proposed converter inherits the benefit of low voltage stress on switches while enjoying an efficient fine regulation by phase shift, similar to a dual active bridge (DAB) converter. The converter is optimized, designed, and fabricated in 1.7 × 1.9 mm area of a 130-nm bipolar-CMOS-DMOS (BCD) process. The active die is flip-chipped on a 6.5 × 6.5 mm package substrate together with power capacitors and two 10-nH integrated passive device (IPD) inductors for demonstration, illustrating the feasibility of passive components' integration, resulting in a peak efficiency of 91.2% and a peak power density of 1.36 W/mm3 from 9.6-12-V input to 2.15-3.3-V output. Another demonstration is constructed on the same package substrate but with discrete air-core inductors. It achieves a peak efficiency of 92.4% and a peak power density of 0.62 W/mm3, while delivering a max power of 7.5 W. To achieve the performance, a detailed loss analysis and a unique optimization methodology for the converter, together with the design of key sub-blocks, including gate drivers (GDs), phase shift modulator (PSM), and ramp generator (RG), are provided in this article.