Investigation of Suppression of the Insertion Loss of a CoFeB/Polyimide Hybrid Thin-Film Coplanar Line for Impedance Matching in a Mobile Phone Power Amplifier Module

Suppression of the insertion loss of a CoFeB/polyimide hybrid thin-film coplanar line for impedance matching in a mobile phone power amplifier module was investigated. To suppress the insertion loss of the CoFeB/polyimide hybrid coplanar line, various techniques were investigated on the basis of device simulations and fabrication. As a result, it was found that the introduction of a thick copper signal line, a multilayer magnetic film structure and optimum width of the magnetic film were effective for lowering insertion loss. Insertion loss per quarter wavelength of the fabricated devices was below 0.5 dB in the frequency range from 1 to 1.5 GHz.