Transversely coupled resonator filters utilizing reflection of Bleustein-Gulyaev-Shimizu wave at free edges of substrate

Michio Kadota, Junya Ago, Hideya Horiuchi, Haruo Morii

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

Smaller-sized and lower insertion loss surface acoustic wave (SAW) filters are urgently required for mobile telecommunications. We describe here that miniature, low-loss transversely coupled resonator filters without reflector electrodes could be realized and commercialized by utilizing the edge reflection of a Bleustein-Gulyaev-Shimizu (BGS) wave for the first time. The transversely coupled resonator filter has a narrower bandwidth than a longitudinally coupled one. A small, low-loss resonator filter for a first intermediate-frequency stage (first IF) of a spread spectrum (SS) codeless telephone system could be realized using a piezoelectric ceramic substrate with a coupling factor (k) of 0.20 and the transversely coupled resonator filter consisting of single finger electrodes. A filter for the first IF of the global system for mobile communication (GSM) requires a narrower bandwidth than SS codeless telephone, but a suitable substrate with a small coupling factor is not available. However, we could realize the small transversely coupled filter for GSM using split finger electrodes.

Original languageEnglish
Pages (from-to)3045-3048
Number of pages4
JournalJapanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers
Volume39
Issue number5 B
DOIs
Publication statusPublished - 2000

Keywords

  • BGS wave
  • Ceramic substrate
  • Edge reflection
  • Split finger electrode
  • Transversely coupled resonator filter

ASJC Scopus subject areas

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

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