2004 Volume 28 Issue 2 Pages 157-163
A hybrid thin-film coplanar transmission line with a CoFeB metallic magnetic film was fabricated and studied. The fabricated devices consisted of top and bottom 3-μm-thick aluminum conductor layers and an inner (0.5-μm-thick polyimide)/(0.5-μm- thick CoFeB)/(0.5-μm-thick polyimide) trilayer. The top conductor layer consisted of a signal line and ground planes on the same plane. The CoFeB metallic magnetic film, exposed to the same thermal process as for the device fabrication, had a static relative permeability of about 180 and an FMR frequency of about 3.7 GHz. The polyimide had a relative permittivity of about 3.5.
As a result, the wavelength shortening ratio of the fabricated device was about 0.19 at a frequency of a few gigahertz. The line length and the insertion loss of a quarter-wavelength device were estimated to be about 7 mm and about 2.9 dB at 2 GHz.
