Design of high voltage tunable Shunt Interdigitated resonator based on Barium Strontium Titanate thin film

This paper reports a design methodology of tunable Coplanar Waveguide Shunt Interdigitated Capacitor (IDC) which is fabricated on a Barium Strontium Titanate (BST) thin film deposited on a sapphire substrate. The Shunt IDC can be utilized to develop a microwave resonator, a tunable notch filter or other promising applications. The designed resonant frequencies of resonators are in the range from 11.53GHz to 17.51GHz with a notch depth of -27.72dB (S21). The measured bandwidth is around 2GHz at -10dB. The tunable range of center frequency under bias voltage is 0.3GHz for bias voltage change from 0V to 50V. The EM structure and equivalent circuit model were developed for comparison with experimental data to find out the relationship of the capacitance, and parasitic inductance and resistance.