Multiphase Lateral Flux Indirect Coupled Inductor for Vertical Power Delivery Voltage Regulator Module

The rising trend of artificial intelligence (AI) usage in many applications requires high-performance processors, demanding power to an unprecedented level. Recently, in the 48 V two-stage conversion system, the vertical power delivery (VPD) solution is sought, where the second stage is placed directly underneath the processor to remove the "last inch" power loss found in the lateral power delivery (LPD) architecture. However, the VPD solution gives a strict size requirement for the voltage regulator module (VRM), where the bottleneck is usually the magnetic component. In addition, high-performance processors require a fast transient response. This article proposed a new air gap-less powder-core-based multiphase integrated lateral flux negative coupled inductor structure with a footprint of only 100 mm² and a height of 2.9 mm, enabling a high-density and fast-transient VRM solution. The negative coupling is achieved electrically through the coupled winding, which enables symmetrical N-phase coupling and straight-phase winding, resulting in an extremely small DCR. The proposed inductor is experimentally tested at up to 300 A (75 A/phase) to prove its high current handling capability, achieving a high 3 A/mm² current density.