NSPUDT orientations in new materials

Abstract

This paper reports an investigation on Natural Single Phase Unidirectional Transducer (NSPUDT) orientations in new materials and along new orientations, namely for gallium phosphate (GaPO/sub 4/) and langasite (LGS, La/sub 3/Ga/sub 5/SiO/sub 14/). The NSPUDT orientations explore a non-symmetric characteristic of transducers and reflectors along these directions for the excitation and propagation of Surface Acoustic Wave (SAW). Devices built along such orientations present directivity, allowing power to be directed preferably in one orientation with respect to the other. In reflector structures the phase in one direction with respect to the reverse direction are also non-symmetric, thus allowing easier placement of the reflector structure with respect to the interdigital transducer structure, lowering costs, increasing performance, and yield in low loss resonator based SAW devices. The new materials referred to in this work offer the opportunity to design higher bandwidth devices due to the increased electromechanical coupling coefficient, with low loss, and with the equivalent excellent characteristics quartz present, as far as the temperature behavior is concerned. The designing of new devices along the orientation mentioned in this paper is thus very promising for the next generation of NSPUDT SAW devices for low loss, high performance consumer and communication filters required in wireless communication and remote control equipment.