Acoustic surface wave resonator and acoustic transversely - surface acoustic wave filter

摘要

PROBLEM TO BE SOLVED: To improve the group delay time temperature characteristics by means of a surface wave consisting primarily of an SH wave and to miniaturize a device by forming an interdigital transducer consisting of one or more pairs of comb-shaped electrodes on a substrate of a langasite single crystal having a specific relation among Eulerian angles. ;SOLUTION: A piezoelectric substrate 2 uses a langasite single crystal (La3Ga5 SiO14) having Eulerian angles ϕ, θ and ψ defined as 0≤ϕ≤30 degrees, 0≤θ≤25 degrees and ψ=-1.07ϕ+90±5 degrees respectively. Then an interdigital transducer 3 consisting of an electrode material such as Al, Au, etc., is formed on the substrate 2 with the tooth parts of a pair of comb-shaped electrodes 3a and 3b placed opposite to each other. A surface wave resonator 1 with such a constitution uses a surface wave consisting primarily of an SH wave to improve the group delay time temperature characteristics(TDC). Thus, it's possible to improve the TCD and also to omit a reflector for miniaturization of a device.;COPYRIGHT: (C)2000,JPO