HIGH FREQUENCY SAW FILTER AND SURFACE ACOUSTIC WAVE FUNCTION ELEMENT USING HIGH-STABILITY HIGH COUPLING SAW SUBSTRATE

摘要

PURPOSE: To provide a surface acoustic wave(SAW) filter and SAW function element with the low insertion loss of a superhigh frequency band using the substrate of thin film structure which reduces the change of a central frequency caused by temperatures. ;CONSTITUTION: The SAW filter and SAW function element are provided with one directivity of superhigh frequencies or the reduced insertion loss of resonator structure or IIDT structure by providing an SiO₂/128°Y-X LiNbO₃ substrate, SiO₂/36°Y-X LiTaO₃ substrate, SiO₂/41°Y-X LiNbO₃ substrate, SiO₂/64°Y-X LiNbO₃ substrate, SiO₂/128°Y-X LiTaO₃ substrate as structure provided with opposite temperature characteristics on a LiNbO and LiTaO substrate 1 provided with a large electric/mechanical coupling coefficient and using a SAW substrate for which the value of H/λ₀ is within a range from 0.03 to 0.5 when those cut angles are settled within the range of ±20° from those values concerning 128°, 36°, 41° and 64°, the film thickness of SiO₂ is defined as H and the operational central frequency is defined as),.;COPYRIGHT: (C)1995,JPO