Radio Frequency Applications of Barium Strontium Titanate Thin Film Tunable Capacitors

Abstract

Properties of thin film barium strontium titanate (BST) based capacitors for RF and microwave components were studied. The capacitors were measured for their tunability, loss tangent, frequency dependence of dielectric permittivity, and behavior at large RF signal amplitudes. A nonlinear equivalent circuit model for tunable BST capacitors was developed. Analysis of a tunable low pass filter fabrication using BST capacitors along with its intermodulation distortion measurements was given. Several simulations for bandpass filters were performed. Furthermore, a periodically loaded coplanar waveguide phase shifter utilizing the BST capacitors was designed.