If saw filters without love wave's spurious consisting of ZnO film and specific cut angle quartz substrate

Michio Kadota, Hajime Kando

Research output: Contribution to journalConference articlepeer-review

Abstract

The substrate with large electromechanical coupling factor and excellent temperature coefficient of frequency (TCF) is required to realize surface acoustic wave filters for the first intermediate frequency stage (1st IF). One of the authors (M. Kadota) realized a Rayleigh wave substrate with an excellent TCF and a large electromechanical coupling factor by a combination of a specific quartz substrate (ST-cut 35°X propagation: ST- 35°X) having a positive TCF with a ZnO film having a negative TCF. But, it has been clarified that the SAW filter having of a single electrode (strip) or single-phase unidirectional transducer (SPUDT) on the ZnO/ST-35°X-quartz substrates, often had a large spurious response due to the Love wave which was a higher-order-mode of the Rayleigh wave. The new cutting angle and the propagating direction (26-27°Y-X) on quartz has been developed in order to suppress the spurious response. The IF SAW filters for the Wide-band and the Narrow-band Code Division Multiple Access (W-CDMA: 380MHz and N-CDMA: 183.6MHz) have been developed by combining this 26-27°YX quartz with the ZnO film. The IF filters which have a small-size, an excellent TCF, a low insertion loss, a cost advantage in their applications, and no spurious responses due to the Love wave have been realized. Their frequency shift per 1°C from -20°C to 80°C was less than 0.37 ppm/°C, which was better than a Rayleigh SAW on an ST-cut X propagation quartz.

Original languageEnglish
Pages (from-to)888-892
Number of pages5
JournalProceedings of the Annual IEEE International Frequency Control Symposium
Publication statusPublished - 2003 Dec 1
EventProceedings of the 2003 IEEE International Frequency Control Symposium and PDA Exhibition Jointly with the 17th European Frequency and Time Forum - Tampa, FL., United States
Duration: 2003 May 42003 May 8

Keywords

  • Excellent TCF
  • Large coupling factor
  • Quartz
  • ZnO film

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Electrical and Electronic Engineering

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