Small-sized resonator if filter using shear horizontal wave on heavy metal film/quartz substrate

Michio Kadota, Toshimaro Yoneda, Koji Fujimoto, Takeshi Nakao, Eiichi Takata

Research output: Contribution to journalConference article

5 Citations (Scopus)

Abstract

By composing interdigital transducers (IDTs) and reflectors made of a heavy metal film such as Au, Ta, or W on an ST cut 90°X propagation (direction perpendicular to X-axis) quartz substrate, authors succeeded in exciting a new type of shear horizontal (SH) wave. This wave has a large electromechanical coupling factor, a very large reflection coefficient and an excellent temperature characteristics. Though a conventional longitudinally-coupled resonator filter using Rayleigh wave on an ST cut X propagation quartz substrate requires more than 300 fingers of Al grating reflector on each side of the Al-IDTs, our newly developed resonator filter utilizing this SH wave requires only about 10 grating fingers for the reflector at most due to the large reflection coefficient. The authors applied this SH wave to filters for the first intermediate frequency (IF) stage of global system for mobile communications (GSM), personal handy phone system (PHS) and personal digital cellular (PDC in Japan). As a result, we succeeded in developing low loss and small-sized IF filters (3×3×1.03 mm3) having a high stop band rejection, a sufficient bandwidth without expansion coil, and an excellent temperature property for the first time.

Original languageEnglish
Pages (from-to)50-54
Number of pages5
JournalProceedings of the Annual IEEE International Frequency Control Symposium
Publication statusPublished - 2002 Jan 1
EventProceedings of the 2002 IEEE International Frequency Control Symposium and PDA Exhibition - New Orleans, LA, United States
Duration: 2002 May 292002 May 31

Keywords

  • Heavy metal IDTs
  • Longitudinally-coupled resonator filter
  • SH wave
  • ST-90°X quartz

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Electrical and Electronic Engineering

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