Miniature surface acoustic wave devices with excellent temperature stability using high density metal electrodes and SiO2 film

Currently, miniature surface acoustic wave (SAW) devices (filters and duplexers) with a good temperature stability are strongly required. In order to realize its requirement, various SAW substrates combining a high density metal electrode, a SiO₂ film, and LiTaO₃ or LiNbO₃ substrate were researched. Their combinations offer excellent properties such as large electrode reflection coefficient, large mechanical coupling factor, low velocity, and good temperature stability. This paper reviews realization of miniature SAW devices with low insertion loss and good temperature stability, such as SAW duplexers for personal communication service system in the United States (US-PCS) and wide band code division multiple access system (W-CDMA) using their combinations.