Intrinsically switchable, BST-on-silicon composite FBARs

This paper presents a DC voltage dependent switchable, composite thin film bulk acoustic wave (FBAR) resonator at 1.82 GHz. The resonator consists of barium stronium titanate-on-silicon in which barium stronium titanate (BST) is primarily used for transduction. The electrostrictive property of BST is exploited to turn the resonator on and off by applying a DC voltage. The device exhibits a quality factor of 157 and 301 at its series and parallel resonance frequencies, respectively. The preliminary result of an acoustically coupled thickness mode filter based on BST-on-Silicon structure is also presented. The insertion loss of the filter is 15 dB at 2.03 GHz. When the resonator is turned off (no DC bias), it behaves like a capacitor. This is the first demonstration of a BST-on-Silicon FBAR resonator.