Title :
Characteristics of a thin film microtransformer with circular spiral coils
Author :
Yamaguchi, Kazuyuki ; Ohnuma, Shigehiro ; Imagawa, Takao ; Toriu, Jirou ; Matsuki, Hidetoshi ; Murakami, Koichi
Author_Institution :
Amorphous Magnetic Device Lab., Sendai, Japan
fDate :
9/1/1993 12:00:00 AM
Abstract :
A thin-film 3.14-mm×3.88-mm microtransformer has been fabricated, using photolithography technology, to support high-frequency switching regulators. The microtransformer is composed of sputtered amorphous magnetic layers, electroplated copper windings with 20-μm width, and insulator layers. The coupling factor between the primary and secondary windings of the microtransformer is 0.97 for f=3 MHz. An input-output voltage ratio of 0.95 at 15 MHz is obtained at no-load. Observation of the domain images under high-frequency excitation indicates that the magnetic anisotropy of the microtransformer films is induced by rotating magnetic field annealing so as to increase the output voltage
Keywords :
coils; induced anisotropy (magnetic); magnetic annealing; magnetic domains; magnetic properties of amorphous substances; magnetic thin film devices; photolithography; transformer cores; transformer windings; transformers; 15 MHz; 3 MHz; 3.14 mm; 3.88 mm; CoFeSiB; CoNbZr; circular spiral coils; coupling factor; domain images; electroplated Cu windings; high-frequency excitation; high-frequency switching regulators; input-output voltage ratio; insulator layers; magnetic anisotropy; photolithography technology; primary windings; rotating magnetic field annealing; secondary windings; sputtered amorphous magnetic layers; thin film microtransformer; Amorphous magnetic materials; Amorphous materials; Lithography; Magnetic anisotropy; Magnetic domains; Perpendicular magnetic anisotropy; Regulators; Sputtering; Transistors; Voltage;
Journal_Title :
Magnetics, IEEE Transactions on
