A 3.8 GHz tunable filter based on ferroelectric interdigitated capacitors

In this paper, a tunable filter using ferroelectric capacitor is described. The interdigitated capacitor (IDC) is based on Barium Strontium Titanate (BST) thin-film. After the material and capacitor characterization in microwave frequency domain, the IDC has been introduced in a hairpin filter. The characterization of the filter exhibits a center frequency shift from 3.5 GHz (under 0 kV/cm) to 3.9 GHz (under 300 kV/cm) which corresponds to a relative shift of 11.4%.