Tunable Bulk Acoustic Wave Resonators Based on BaxSr1-xTiO3 Thin Films

Licentiate thesis, 2009

The main focus of this thesis is the study of a novel component based on ferroelectric BaxSr1−xTiO3 thin films – the tunable thin film bulk acoustic resonator (TFBAR). The tunable TFBAR utilizes a dc field induced piezoelectric effect in the ferroelectric film, in contrast to conventional fixed frequency TFBARs, widely used for filtering applications in wireless communication systems, which are based on ordinary piezoelectric materials. This allows dc field tuning of the resonance frequency as well as switching between resonator and capacitor response.