Tunable band-pass filter using interdigital capacitor by barium strontium titanate (BST) thin films

Abstract

In this paper, new design method of a bandpass filter (BPF) using tapped-line structure is suggested on BST/MgO substrate. A tunable BPF with interdigital capacitor (IDC) using BST thin film is successfully demonstrated for the improved tunability characteristic. The center frequency of the tunable hair-pin BPF with IDC is moved from 6.08 GHz to 6.30 GHz at 50 V bias with 2% bandwidth.