A micro-inductor with thin film magnetic core for a 20 MHz buck converter

摘要

A micro-inductor has been fabricated on silicon substrate using a Micro-Electromechanical Systems (MEMS) process. The micro-inductor has a single layer copper winding sandwiched between two layers of electroplated NiFe core. It has a footprint area of 2.9 mm~2, an inductance of 204 nH at 21.7 MHz, a DC resistance of 470 mil, and a peak quality factor of 9.23 at 9.2 MHz. The micro-inductor has been applied in a buck converter and achieved a maximum converter efficiency of 81.74% at 20 MHz. The performance of the micro-inductor has also been compared with an air-core inductor embedded in PCB. The air core inductor has a similar inductance of 220 nH, but with a large footprint area of 32 mm2. The maximum buck converter efficiency is 85.47% when the air core inductor is applied.