Electro-Thermal Scaling Constraints in Chip-Scale Power Inductors

Abstract

Two-dimensional (2-D) full-wave finite-element (FE) solution ofMaxwell's equations including thermal heating and heat diffusion in micro-fabricated power inductors suggests significant increase in AC resistance and eddy current losses, especially at increased power switching frequencies when conducting large currents. The simulation results indicate that severe thermal constraints arise when sourcing currents in excess of 5 amps in DC-DC power converters switching at frequencies in excess of 5 MHz. A simple circuit model is presented to evaluate the high-frequency characteristics of power inductors on efficiency and load regulation of point-of-load (POL) DC-DC power converters that utilize advanced silicon power MOSFETs and Gallium Nitride (GaN) power transistors.