Microwave Acoustic Wave Devices: Recent Advances on Architectures, Modeling, Materials, and Packaging

Hagelauer, Amelie; Fattinger, Gernot; Ruppel, C.C.W.; Ueda, Masahiko; Hashimoto, Ken–ya; Tag, Andreas

doi:10.1109/tmtt.2018.2854160

Cited by 110 publications

(46 citation statements)

References 72 publications

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“…One proposed path for 5G RF acoustic devices is to scale down the critical dimensions directly (e.g., film thickness and electrode feature size) of the conventional RF acoustic platforms, such as surface acoustic wave (SAW) [6]- [8], and film bulk acoustic resonators (FBAR) [9]- [11], to operate at the sub-6 GHz bands. However, three significant challenges prohibit such an approach to meet the 5G NR requirements.…”

Section: Introductionmentioning

confidence: 99%

Enabling Higher Order Lamb Wave Acoustic Devices With Complementarily Oriented Piezoelectric Thin Films

Yang

Link

et al. 2020

J. Microelectromech. Syst.

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In this work, we present a new paradigm for enabling gigahertz higher-order Lamb wave acoustic devices using complementarily oriented piezoelectric (COP) thin films. Acoustic characteristics are first theoretically explored with COP lithium niobate (LiNbO 3) thin films, showing their excellent frequency scalability, low loss, and high electromechanical coupling (k 2). Acoustic resonators and delay lines are then designed and implemented, targeting efficient excitation of higher-order Lamb waves with record-breaking low loss. The fabricated resonator shows a 2 nd-order symmetric (S2) resonance at 3.05 GHz with a high quality factor (Q) of 657, and a large k 2 of 21.5% and a 6 th-order symmetric (S6) resonance at 9.05 GHz with a high Q of 636 and a k 2 of 3.71%, both among the highest demonstrated for higher-order Lamb wave devices. The delay lines show an average insertion loss (IL) of 7.5 dB and the lowest reported propagation loss of 0.014 dB/µm at 4.4 GHz for S2. Notable acoustic passbands up to 15.1 GHz are identified. Upon further optimizations, the proposed COP platform can lead to gigahertz low-loss wideband acoustic components.

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Section: Introductionmentioning

confidence: 99%

Enabling Higher Order Lamb Wave Acoustic Devices With Complementarily Oriented Piezoelectric Thin Films

Yang

Link

et al. 2020

J. Microelectromech. Syst.

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“…Particularly, the enhanced mobile broadband (eMBB) [3] require new components at higher frequencies for the recently released bands [4], [5]. RF acoustic elements, leveraging the technical benefits of the acoustic domain [6], hold great potentials for chip-scale and low-loss signal processing [7], [8]. The shorter acoustic wavelengths [6] lead to orders of magnitude smaller resonant structures than their EM counterparts, while the low damping of acoustic waves enables efficient passives.…”

Section: Introductionmentioning

confidence: 99%

Low-Loss 5-GHz First-Order Antisymmetric Mode Acoustic Delay Lines in Thin-Film Lithium Niobate

Yang

Link

et al. 2021

IEEE Trans. Microwave Theory Techn.

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In this work, we present the low-loss acoustic delay lines (ADLs) at 5 GHz, using the first-order antisymmetric (A1) mode in 128 • Y-cut lithium niobate thin films. The ADLs use a single-phase unidirectional transducer (SPUDT) design with a feature size of quarter acoustic wavelength. The design space is analytically explored and experimentally validated. The fabricated miniature A1 ADLs with a feature size of 0.45 µm show a high operating frequency at 5.4 GHz, a minimum insertion loss (IL) of 3 dB, a fractional bandwidth (FBW) of 1.6%, and a small footprint of 0.0074 mm 2. The low IL and high operating frequency have significantly surpassed the state-of-theart performance of ADLs. The propagation characteristics of A1 acoustic waves have also been extracted. The demonstrated designs can lead to low-loss and high-frequency transversal filters for future 5G applications in the sub-6-GHz bands.

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“…Moreover, the trend to densify the integration of RF components and in particular in communication systems, coupled with the increase in operating frequencies to allow for wide bandwidths, imply an extreme miniaturization of SAW devices and therefore a very localized concentration of power. This generates an intense heating of the substrate in the vicinity of the electrodes and thus requires the use of suitable materials [ 21 ].…”

Section: Introductionmentioning

confidence: 99%

Langasite as Piezoelectric Substrate for Sensors in Harsh Environments: Investigation of Surface Degradation under High-Temperature Air Atmosphere

Aubert

Kokanyan

Elmazria

2021

Sensors

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Langasite crystals (LGS) are known for their exceptional piezoelectric properties at high temperatures up to 1000 °C and more. In this respect, many studies have been conducted in order to achieve surface acoustic wave (SAW) sensors based on LGS crystals dedicated to high-temperature operations. Operating temperatures of more than 1000 °C and 600 °C for wired and wireless sensors, respectively, have been reached. These outstanding performances have been obtained under an air atmosphere since LGS crystals are not stable in high-temperature conditions under a low-oxygen atmosphere due to their oxide nature. However, if the stability of bulk LGS crystals under a high-temperature air atmosphere is well established, the surface deterioration under such conditions has been hardly investigated, as most of the papers dedicated to LGS-based SAW sensors are essentially focused on the development of thin film electrodes that are able to withstand very elevated temperatures to be combined with LGS crystals. Yet, any surface modification of the substrate can dramatically change the performance of SAW sensors. Consequently, the aim of this paper is to study the stability of the LGS surface under a high-temperature air environment. To do so, LGS substrates have been annealed in an air atmosphere at temperatures between 800 and 1200 °C and for durations between one week and one month. The morphology, microstructure, and chemical composition of the LGS surface was examined before and after annealing treatments by numerous and complementary methods, while the surface acoustic properties have been probed by SAW measurements. These investigations reveal that depending on both the temperature and the annealing duration, many defects with a corolla-like shape appear at the surface of LGS crystals in high-temperature prolonged exposure in an air atmosphere. These defects are related to the formation of a new phase, likely an oxiapatite ternary compound, the chemical formula of which is La14GaxSi9−xO39−x/2. These defects are located on the surface and penetrate into the depth of the sample by no more than 1–2 microns. However, SAW measurements show that the surface acoustic properties are modified by the high-temperature exposure at a larger deepness of at least several tens of microns. These perturbations of the LGS surface acoustic properties could induce, in the case of LGS-based SAW sensors operating in the 434 MHz ISM band, temperature measurement errors around 10 °C.

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Microwave Acoustic Wave Devices: Recent Advances on Architectures, Modeling, Materials, and Packaging

Cited by 110 publications

References 72 publications

Enabling Higher Order Lamb Wave Acoustic Devices With Complementarily Oriented Piezoelectric Thin Films

Enabling Higher Order Lamb Wave Acoustic Devices With Complementarily Oriented Piezoelectric Thin Films

Low-Loss 5-GHz First-Order Antisymmetric Mode Acoustic Delay Lines in Thin-Film Lithium Niobate

Langasite as Piezoelectric Substrate for Sensors in Harsh Environments: Investigation of Surface Degradation under High-Temperature Air Atmosphere

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