Tunable RF Filters Fabricated Using MOCVD Deposited Graded Composition BST Films

Abstract

Compositionally graded Barium Strontium Titanate (BST) thin films were deposited by MOCVD on r-plane sapphire substrates with patterned platinum electrodes. Tunable parallel plate capacitors were fabricated using these films by ion-milling and photolithography. The capacitors show a tunability of 36% for an electric field of + 13V at a measurement frequency of 1 MHz. These tunable capacitors were integrated with resonators fabricated on FR-4 substrates to form tunable RF filters. Characterization of the filters shows that the center frequency can be tuned from 3.710 GHz to 4.062 GHz by applying a tunable bias of 12 volts.