Intrinsically switchable thin film bulk acoustic wave resonators

Abstract

The concept of the frequency switching in the composite bulk acoustic wave (BAW) resonators based on the thin films of paraelectric phase ferroelectrics is demonstrated experimentally. The composite BAW resonators based on the Ba 0.25 Sr 0.75 TiO 3 /SrRuO 3 /Ba 0.25 Sr 0.75 TiO 3 multilayer structure are fabricated and characterized. It is shown that the resonance frequency of the BAW resonators can be switched more than two times (from 3.6 GHz to 7.7 GHz) by changing polarity of the 5 V dc bias voltage at one of the ferroelectric layers. The composite BAW resonators performance is analyzed using the theory of the dc field induced piezoelectric effect in the paraelectric phase ferroelectrics. V

Ferroelectric thin film acoustic devices with electrical multiband switching ability

“…As an example, the expected multiband switching ability of a FBAR with four active FE layers is considered. We validated the proposed modelby comparisonof the results of our calculationwith the data from previousexperimental works 15–17 . Finally, the possible applications of two layer structures for switchable MW high overtone bulk acoustic resonator (HBAR), binary and quadrature phase-shift keying (BPSK, QPSK) modulators are suggested.…”

“…The possibility to provide the frequency switching of two FE layer BAR due to the application of the control voltages of different polarities to layers has been earlier experimentally demonstrated for RF 16 and MW 15 frequency ranges. The mathematical approach considered below models the acoustic MW response of thin film structures with an arbitrary number of ferroelectric layers with induced piezoelectric effect when electric fields E dc with different magnitudes and polarities are applied to each FE layer or to a group of FE layers.…”

“…The theoretical approach, considered above and in 18–20 , wasverified for devices with fundamentally different operating frequencies (MHz and GHz scales) 15–17 . Theultrasound transducer (operating at MHz frequencies) reported in ref.…”

“…15 , Gevorgian and Vorobiev have reported the firstFBARwith frequency switching ability operating at microwaves. In their work, a composite thin film BAW resonator based on a Ba 0.25 Sr 0.75 TiO 3 /SrRuO 3 /Ba 0.25 Sr 0.75 TiO 3 (180/50/180 nm) multilayer structure was considered.…”

Tunable and switchable resonators and filters based on ferroelectric BST thin films for wireless communications

“…This theoretical concept was experimentally verified by Vorobiev et. al [12]. They fabricated BAW resonators based on Ba0.25Sr0.75TiO3/SrRuO3/Ba0.25Sr0.75TiO3 multilayer structure.…”