A 1500-A/48-V-to-1-V Switching Bus Converter for Next-Generation Ultra-High-Power Processors

This article proposes an ultra-high-current 48-V-to-1-V hybrid switched-capacitor (SC) voltage regulator, named the switching bus converter, with a single-stage vertical power delivery architecture for next-generation ultra-high-power processors (e.g., graphics processing units, central processing units, application-specific integrated circuits, etc.). The proposed topology consists of two 2-to-1 SC front-ends and four 10-branch series-capacitor-buck modules, merged through four switching buses. Compared to the existing dc-bus-based architecture, the proposed switching-bus-based architecture eliminates the need for dc bus capacitors, reduces the switch count, and guarantees complete soft-charging operation. Through a topological comparison, this article reveals that the proposed topology achieves the lowest normalized switch stress and the smallest normalized passive component volume among existing 48-V-to-1-V hybrid SC demonstrations, showing great potential for both higher efficiency and higher power density than prior hybrid SC solutions. A hardware prototype was designed and built with custom four-phase coupled inductors and gate drive daughterboards to validate the functionality and performance of the proposed switching bus converter. It was tested up to 1500-A output current and achieved 92.7% peak system efficiency, 85.7% full-load system efficiency (including gate drive loss), and 759 W/in^{3} power density (by box volume), pushing the performance limit of the state-of-the-art 48-V-to-1-V solutions toward higher efficiency and higher power density.