T09.3 - A Series-Capacitor Based Zero-Bias Trans-Inductor Voltage Regulator

In data-center applications, the trans-inductor voltage regulator (TLVR) has emerged as a favorable Point-of- Load (PoL) converter due to its superior transient response. However, conventional trans-inductor (TL) suffers from high DC bias current, which limits magnetic saturation margins and hinders power density improvement—a critical bottleneck for Vertical Power Delivery (VPD) scenarios. To address this, this paper presents a multi-phase Series-Capacitor Zero-Bias Trans-Inductor Voltage Regulator (SC-ZBTLVR). The proposed topology utilizes a series-capacitor network to extend the voltage step-down ratio and inherently resolve the current-balancing challenges typical of zero-bias configurations. A 24V-to-1V, 8-phase SC-ZBTLVR prototype is built and tested, featuring compact 3-in-1 integrated TL modules. Leveraging the zero-bias mechanism, the converter achieves a peak efficiency of 90.5% and delivers 47.5A per phase at full load, realizing a power density of 1617W/in3, a current density of 0.523A/mm2 at 380A output.