A thin-film bulk acoustic resonator and filter with optimal edge shapes for mass production

Hara, Motoaki; Ueda, Masahiko; Satoh, Y.

doi:10.1016/j.ultras.2012.04.003

Cited by 4 publications

(1 citation statement)

References 9 publications

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“…Hence, they will have lower Qvalues compared to those of Air-FBARs. For the FBAR resonator, there are several elements that will affect the Q factor, such as the Ohmic loss and acoustic loss induced by the selection of electrode material [37,38], the spurious wave mode that leads to energy loss [39,40], and the effect of the electrode shape [41]. The detailed analysis of the Q factor is beyond the scope of this work.…”

Section: Analysis and Discussion Of Phc-fbarsmentioning

confidence: 99%

Numerical Investigation of Phononic Crystal Based Film Bulk Acoustic Wave Resonators

et al. 2021

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Film bulk acoustic resonator (FBAR)-based filters have attracted great attention because they can be used to build high-performance RF filters with low cost and small device size. Generally, FBARs employ the air cavity and Bragg mirror to confine the acoustic energy within the piezoelectric layer, so as to achieve high quality factors and low insertion loss. Here, two-dimensional (2D) phononic crystals (PhCs) are proposed to be the acoustic energy reflection layer for an FBAR (PhC-FBAR). Four kinds of PhC structures are investigated, and their bandgap diagrams and acoustic wave reflection coefficients are analyzed using the finite element method (FEM). Then, the PhCs are used as the acoustic wave reflectors at the bottom of the piezoelectric stack, with high reflectivity for elastic waves in the specific frequency range. The results show that the specific PhC possesses a wide bandgap, which enables the PhC-FBAR to work at a broad frequency range. Furthermore, the impedance spectra of PhC-FBARs are very smooth with few spurious modes, and the quality factors are close to those of traditional FBARs with air cavities, showing the application potential of the PhC-FBAR filters with wide bandwidth and high power capability.

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