A miniaturized UMTS band II duplexer employing piezoelectric boundary acoustic wave.

This paper describes the characteristics of boundary acoustic wave employing novel multi-layer metal electrode structure and a miniaturized UMTS Band II duplexer using this structure. For the electrode, Pt/Al/Pt is adopted and k2 and TCF dependency on the position of the total electrode gravity center is investigated, both theoretically and experimentally. It was found that selecting the contents of metal material is very effective to control k2 and TCF. Small sized and low profile UMTS Band II duplexer has been developed. Its size is 2.0×1.6×0.4 mm3 and good temperature characteristics are obtained, which is almost zero TCF. [ABSTRACT FROM PUBLISHER]