Design and Implementation of LLC-DCX With 1A/mm2 Current Density for High-Current XPU Power Systems

In modern data centers utilizing a 48 V intermediate DC bus, voltage regulator modules (VRMs) are critical for supplying low-voltage, high-current terminal loads, which impose stringent demands on both efficiency and power density. To overcome these challenges, this paper introduces a heterogeneously integrated design for high-current windings employing a high-frequency transformer. The proposed method substantially reduces winding length, area, and associated losses by leveraging current cancellation and an integrated magnetic core. A vertical power delivery architecture is adopted and functionally verified, which enables lossless current scaling through modular parallel integration. Experimental results demonstrate a power density of 1.05 A/mm² in the high frequency transformer and a final output current of 450 A in the prototype. This design significantly reduces dependency on conventional PCB windings, particularly on the high-current secondary side, and markedly improves overall power density and system efficiency.