Optimization of acoustic dispersion for high performance thin film BAW resonators

Fattinger, Gernot; Marksteiner, S.; Kaitila, J.; Aigner, Robert

doi:10.1109/ultsym.2005.1603060

Cited by 72 publications

(34 citation statements)

References 3 publications

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“…Though the dependence of dispersion types on the stack was investigated before [9,11], the quantitative relations between them are not clarified yet. In this paper, we theoretically analyze the device stack through the computational modeling.…”

Section: Introductionmentioning

confidence: 99%

A Novel Bulk Acoustic Wave Resonator for Filters and Sensors Applications

et al. 2015

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Bulk acoustic wave (BAW) resonators are widely applied in filters and gravimetric sensors for physical or biochemical sensing. In this work, a new architecture of BAW resonator is demonstrated, which introduces a pair of reflection layers onto the top of a thin film bulk acoustic resonator (FBAR) device. The new device can be transformed between type I and type II dispersions by varying the thicknesses of the reflection layers. A computational modeling is developed to fully investigate the acoustic waves and the dispersion types of the device theoretically. The novel structure makes it feasible to fabricate both type resonators in one filter, which offers an effective alternative to improve the pass band flatness in the filter. Additionally, this new device exhibits a high quality factor (Q) in the liquid, which opens a possibility for real time measurement in solutions with a superior limitation of detection (LOD) in sensor applications.

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Section: Introductionmentioning

confidence: 99%

A Novel Bulk Acoustic Wave Resonator for Filters and Sensors Applications

et al. 2015

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“…The basic reflector design method gives best results if K l and K H are close to 2, which is true for most of the materials [9]. However, in some cases in which the velocity ratio deviates from 2, the basic stopband design approach becomes less accurate.…”

Section: ) a Novel Optimization Schemementioning

confidence: 99%

“…This can be explained by the fact that the shear wave velocity is typically about half of the longitudinal wave velocity [9]. by implementing a transmission line model, and with the approach of mirror reflectivity [13] but with the top-most mirror layer as the reference point, the transmission curve as a function of frequency of such a mirror is computed in mathcad (Parametric Technology corp., needham, ma) for the mirror stack.…”

Section: Introductionmentioning

confidence: 99%

“…The quality factor (Q) of traditional solidly mounted bulk acoustic wave resonators (smrs) is traditionally limited by substrate losses [9]- [13], because the conventional quarter-wave acoustic mirror employed in smrs reflects only the longitudinal acoustic waves and not the shear waves. To obtain high-Q smrs, the mirror should effectively reflect both of the waves.…”

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confidence: 99%

“…Therefore, the influence of shear waves on Q was reviewed earlier [11]. some optimized stacks have been reported for specific material combinations [9], [10] based on numerical calculations.…”

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confidence: 99%

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Optimized reflector stacks for solidly mounted bulk acoustic wave resonators

Jose

Jansman

Hueting

et al. 2010

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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Abstract-The quality factor (Q) of a solidly mounted bulk acoustic wave resonator (SMR) is limited by substrate losses, because the acoustic mirror is traditionally optimized to reflect longitudinal waves only. We propose two different design approaches derived from optics to tailor the acoustic mirror for effective reflection of both longitudinal and shear waves. The first one employs the stopband theory in optics; the second one takes advantage of the periodic nature of reflection spectra in a Bragg reflector: the diffraction grating design approach. The optimized design using stopband theory reaches a calculated minimum transmission of −25 dB and −20 dB at resonance frequency for longitudinal and shear waves, respectively, for various practical reflector material combinations. Using the diffraction grating approach, a near quarter-wave performance is maintained for longitudinal waves, whereas shear waves reach minimum transmission below −26 dB. However, this design does necessitate relatively thick layers. The experimental results show good agreement with finite element models (FEM). The extracted 1-D Q for the realized shear optimized devices was increased to around 3300.I. Introduction b ulk-acoustic-wave (baW) devices are receiving great interest for rF selectivity in mobile communication systems and other wireless applications. Thinfilm baW devices have several advantages compared with saW resonators because they are remarkably small in size, and have better power handling abilities and better temperature coefficients, leading to more stable operation [1]. From a practical point of view, saW filters have considerable drawbacks at frequencies beyond 2 GHz, whereas baW devices up to 20 GHz have been demonstrated [2]. baW is expected to supersede saW as the technology of choice in many applications over the next few years as they have now evolved in performance beyond saW and can be manufactured in a very cost-competitive way using standard Ic technology. baW technology is commercially available for applications using the U.s. Personal communication service (UsPcs) (1.85 to 1.91 GHz) standard. Transmit and receive bands of the Us-Pcs standard are close in frequency [3]. This demands that the baW resonators which constitute the narrow band filters must be nearly loss-free. Hence, one of the important goals of baW community is to come up with high-Q resonators for rF filters by minimizing the losses [4]- [8].The quality factor (Q) of traditional solidly mounted bulk acoustic wave resonators (smrs) is traditionally limited by substrate losses [9]- [13], because the conventional quarter-wave acoustic mirror employed in smrs reflects only the longitudinal acoustic waves and not the shear waves. To obtain high-Q smrs, the mirror should effectively reflect both of the waves. Therefore, the influence of shear waves on Q was reviewed earlier [11]. some optimized stacks have been reported for specific material combinations [9], [10] based on numerical calculations.recently [12], we reported a systematic design procedu...

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Properties of Coaxial Cables and Transmission Lines, Directional Couplers and RF Filters

Rudolph

2023

Fundamentals of RF and Microwave Techniques and Technologies

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Optimization of acoustic dispersion for high performance thin film BAW resonators

Cited by 72 publications

References 3 publications

A Novel Bulk Acoustic Wave Resonator for Filters and Sensors Applications

A Novel Bulk Acoustic Wave Resonator for Filters and Sensors Applications

Optimized reflector stacks for solidly mounted bulk acoustic wave resonators

Properties of Coaxial Cables and Transmission Lines, Directional Couplers and RF Filters

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