Integrated Tunable Bandstop Filter Using Self-Biased FeGaB/Al 2 O 3 Multilayer Thin Film

In this paper, we report an integrated bandstop filter (BSF) with magnetic multilayer films on silicon substrate. The device performs a self-biasing resonance at the ${C}$ -band by taking the advantage from the shape anisotropy of a long iron–gallium–boron (FeGaB)/Al 2 O 3 multilayer ribbon. The self-resonance of the BSF appears at 5 GHz with an attenuation of over 20 dB. The device can also be magnetically tuned up to over 8.5 GHz (70% tunability) with an attenuation of over 45 dB by applying an external magnetic field of less than 400 Oe. The power handling capability under various magnetic biases is measured, where a maximum of 3.7 dBm IP 1dB power capability is exhibited under zero bias field.