Electrically tunable band-pass filter on engineered substrate enabled with patterned Permalloy thin film

An electrically tunable band-pass filter based on engineered substrate with patterned Permalloy (Py) thin film has been designed and characterized. The band-pass filter is designed with metamaterial resonators to achive a compact size; the designed filter is fabricated on a multi-layered engineered substrate which composes a layer of liquid crystal polymer, a layer of patterned Py thin film, and silicon substrate. The equivalent permeability of Py thin film embedded in the engineering substrate is tunable with DC current which provides tunable inductance for the metamaterial resonators; the center frequency of the implemented band-pass filter is thus electrically tunable. The results show that the center frequency of the designed bandpass filter shifts from 2.4GHz to 2.38GHz when the applied tuning DC current is increased from 0mA to 500mA. The introduced unique concept of engineered substrate provides design feasibility of filters with continuous frequency tunability, and the implementation of substrate enabled with patterned Py thin film is suitable for the cost effective fabrication of tunable arbitrary RF devices.