Very small-sized resonator filter using shear horizontal wave on quartz

M. Kadota, T. Yoneda, K. Fujimoto, T. Nakao, E. Takata

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)

Abstract

By composing interdigital transducers (IDTs) and reflectors consisting of films made of a heavy metal such as Au, Ta or W on an ST cut 90°X propagation (direction perpendicular to X-axis) quartz substrate, the authors realized a new type of shear horizontal (SH) wave. This wave has an excellent temperature characteristic, a large electromechanical coupling factor (k), and a large reflection coefficient at reflector electrodes. The square of this electromechanical coupling factor (k2 = 0.28 ∼ 0.34%) and the reflection coefficient at reflector electrodes are 2.2 ∼ 2.6 times and 30 ∼ 35 times, respectively, as large as those of a Rayleigh wave on an ST cut X propagation quartz substrate. The authors applied this technology to filters for the first intermediate frequency (first IF) stage of a global system for mobile communications (GSM) in the nominal center frequency from 200 to 400 MHz. As a result, we succeeded in developing the first IF filter having a low insertion loss, an excellent temperature characteristic (frequency shift: 1 ppm/°C) and a small package size (3 × 3 mm2), which is as small as a radio frequency (RF) surface acoustic wave (SAW) filter, for the first time.

Original languageEnglish
Pages (from-to)3718-3721
Number of pages4
JournalJapanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers
Volume40
Issue number5 B
Publication statusPublished - 2001 May 1

Keywords

  • Heavy metal film
  • Intermediate frequency filter
  • Longitudinally coupled
  • Quartz
  • Resonator filter
  • Shear horizontal wave
  • Small size

ASJC Scopus subject areas

  • Engineering(all)
  • Physics and Astronomy(all)

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