Surface Acoustic Wave Resonators with Hetero Acoustic Layer (HAL) Structure Using Lithium Tantalate and Quartz

Michio Kadota, Yoshimi Ishii, Shuji Tanaka

Research output: Contribution to journalArticlepeer-review

46 Citations (Scopus)

Abstract

This article reports a new concept of surface-acoustic-wave (SAW) resonator, which uses shear horizontal (SH) wave confined in a thin LiTaO3 (LT) layer supported by a quartz (Qz) substrate. The LT layer is 35-50°YX LT, and the quartz substrate is 35-60°Y90°X Qz. A negative temperature coefficient of frequency (TCF) of the SH SAW in the LT layer is compensated by the quartz substrate, which shows a wide range of positive TCF depending on the crystalline orientation. Excellent TCFs of 2 and -10 ppm/°C were measured for the series and parallel resonance frequencies, respectively. The strong confinement of the SH SAW in the LT layer results in the best level of resonance characteristics ever reported. The measured impedance ratio reached 84 dB. On the other hand, spurious waves other than the SH SAW are not confined in the LT layer due to the unique properties of quartz, which results in spurious-free characteristics throughout a wide frequency range.

Original languageEnglish
Article number9265194
Pages (from-to)1955-1964
Number of pages10
JournalIEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Volume68
Issue number5
DOIs
Publication statusPublished - 2021 May

Keywords

  • Impedance ratio
  • lithium tantalate
  • quartz
  • spurious response
  • surface acoustic wave (SAW)
  • temperature coefficient of frequency (TCF)

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