Fabrication and characterization of a Ni-Fe-W core microtransformer for high-Frequency power applications

This paper presents the fabrication and characterization of a microtransformer device for high-frequency power applications using electroplating and photolithography techniques. These devices are realized on an oxidized silicon wafer. They have the identical geometry on the primary and the secondary side combined with a core thickness value of 6 μm. The device consists of six coils (three coils on the primary side and three coils on the secondary side) and each coil has nine numbers of turns. The copper coil winding and the Ni-Fe-W alloy magnetic core are fabricated by electroplating. The fabricated microtransformer has an inductance ranging from 25 nH to 74 nH. An optimum quality factor of 4.5 is obtained at 70 MHz.