Intrinsically switchable frequency reconfigurable barium strontium titanate resonators and filters

Abstract

Multimode transceivers for the next generation of wireless devices require new and innovative frequency-agile microwave circuit designs to reduce their complexity, size, and cost. Intrinsically switchable frequency reconfigurable thin-film bulk acoustic resonators (FBARs) and filters that utilize these resonators are presented here for the very first time. Barium strontium titanate (BST) is a ferroelectric material that exhibits electric-field-induced piezoelectricity, which allows for the design of voltage controlled bulk acoustic wave devices. In this paper, a frequency reconfigurable resonator consisting of two series connected BST-based FBARs and a reconfigurable dual-band filter consisting of two 1.5 stage ladder-type bandpass filters are discussed. Their small size, simple design, and zero static power consumption make multifunctional ferroelectric thin-film devices attractive for use in adaptive and reconfigurable radios.