Non-synchronous resonators on leaky substrates

Meltaus, J.; Plessky, V.P.; Hong, Seong Su

doi:10.1109/ultsym.2005.1603308

Cited by 3 publications

(1 citation statement)

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“…Based on these characterizations, a quasisynchronous, optimized design is then proposed for higher quality factors and wireless sensing compliance. Nonsynchronous designs have been previously presented in the Literature for various resonator structures [13,14]. The slight detuning that results from non-synchronicity between the IDTs and reflectors, allows to reshape the resonance spectrum of the devices, and thus offers larger quality factors which is an essential parameter for the remote interrogation of SAW resonators.…”

Section: Considerations On Resonator Designmentioning

confidence: 99%

Design and Characterization of High-Q SAW Resonators Based on the AlN/Sapphire Structure Intended for High-Temperature Wireless Sensor Applications

et al. 2020

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Aluminium nitride piezoelectric thin films grown on sapphire are strong candidates for high-temperature surface acoustic wave (SAW) sensors, due to their thermal stability, large bandgap, high acoustic velocity and suitable electromechanical coupling. However, thin-film resonators need more design efforts than those based on bulk crystals, due to the usually limited thickness of the piezoelectric films, and to acoustic properties disparities between the latters and their host substrate. This work presents an optimization of AlN/Sapphire-based SAW resonators with high quality factors for high-temperature applications. It combines specifically grown, 3 µm-thick aluminium nitride films, with the use of aluminium electrodes for their low density and resistivity, as an alternative to heavier electrodes like Pt. These electrodes allow for much lower mechanical losses and higher quality factors, in spite of needing passivation for increased lifetime. A standard resonator design is first presented and used for preliminary tests, in order to monitor the AlN/Sapphire structure with unprotected aluminium electrodes, for temperatures up to 600°C. A quasi-synchronous, optimized design is then proposed for higher quality factors and wireless sensing compliance. The high temperature characterizations confirmed that much larger quality factors can be retrieved from this optimized design. The quasi-synchronous resonators proposed in this study remain well-tuned for temperatures up to 400°C, and show high quality factors, as high as 3400 at 400°C.

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Section: Considerations On Resonator Designmentioning

confidence: 99%

Design and Characterization of High-Q SAW Resonators Based on the AlN/Sapphire Structure Intended for High-Temperature Wireless Sensor Applications

et al. 2020

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Double-resonance SAW filters

Meltaus¹,

Hong

Holmgren³

et al. 2007

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

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A novel surface acoustic wave filter on a leakywave substrate is studied. It features a hiccup-type resonance occurring around a distributed gap between two long interdigital transducers. Compared to a classical coupled resonator filter, it enables a relatively narrow passband (1% to 2% of center frequency) with low insertion loss, steep skirts, and improved suppression levels. The structure consists of long transducers having the number of fingers greater than 1=K 2 and 1= , where K 2 is the coupling coefficient of the substrate material and is the reflectivity per wavelength, separated with short transducer sections constituting a distributed gap. A strong, localized resonance is formed in the gap region, in addition to the resonance arising in the long structures-hence, the name doubleresonance filter. The substrate studied here is 42 -rotated lithium tantalite. We show experimental results for both single-ended and unbalanced-to-balanced filters at 1.6 GHz, having a minimum insertion loss of 1.07 dB, suppressions of 30 dB, and absolute ;3-dB bandwidth of 29 MHz (1.9% of the center frequency). For the balanced device, the amplitude imbalance over the passband ranges from ;0.6 dB to 2 dB and the phase imbalance from 1 to 4.5 . Furthermore, we have measured the acoustical power distributions using a scanning laser interferometer, and we compare these results with the profiles simulated using a coupling-of-modes model.

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