JPH0217709A - Surface acoustic wave resonator - Google Patents

Abstract

PURPOSE:To reduce unrequired spurious wave due to bulk oscillation other than a surface acoustic wave to be used by forming at least a pair of IDT(comb- line) electrodes and a grating reflector on the surface of a piezoelectric substrate, and cutting the corner of the end face of the substrate in a direction from where the surface acoustic wave is propagated. CONSTITUTION:Two pairs of IDT electrodes 12 and 13 and grating reflectors 14 and 15 are formed on the piezoelectric substrate 11, and the corners of the end faces 16 and 17 in the direction from which the surface acoustic wave is propagated is cut. By employing such constitution, it is possible to reduce the unrequired spurious wave due to the bulk oscillation.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a surface acoustic wave resonator that uses surface acoustic waves and functions as a filter or an oscillator in an electric circuit.

BACKGROUND OF THE INVENTION Conventionally, this type of surface acoustic wave resonator has had a configuration as shown in FIG. In FIG. 4, 1 is a piezoelectric substrate, 2 is a comb-shaped electrode (hereinafter referred to as an IDT electrode), and 3 is a grating reflector.

Normally, such an element is manufactured by forming a T electrode 2 and a grating reflector 3 on the surface of a piezoelectric substrate 1 using photolithography technology, and then cutting it. It was perpendicular to the surface of the substrate 1.

Problems to be Solved by the Invention In such a conventional configuration, bulk vibration is reflected at the end face, and unnecessary spurious waves are generated in addition to the surface acoustic wave response. For this reason, the Q of the surface acoustic wave resonator decreases,
When a bandpass filter is configured using an elastic surface resonator, there is a problem in that the attenuation characteristics outside the passband deteriorate.

Means for Solving the Problem In order to solve this problem, the present invention forms at least one set of twisted T electrodes and a grating reflector on the surface of a piezoelectric substrate, and adjusts the angle of the end surface of the substrate in the direction in which surface acoustic waves propagate. It is made by scraping away.

Effect: With this configuration, unnecessary sgelius caused by bulk vibrations other than the surface acoustic waves used can be reduced.

Embodiment FIG. 1 is a perspective view of a surface acoustic wave resonator according to an embodiment of the present invention. In FIG. Group I
DT electrode 12.13 and grating reflector 14.16
is formed using photolithography technology.

Reference numerals 16 and 17 denote end faces of the substrate in the direction in which surface acoustic waves propagate, with corners cut off. The method of shaving off the corners of these end faces 16 and 17 is to first form the IDT electrodes and grating reflector on the piezoelectric substrate and then cut them into individual elements, as shown in Figure 2a. It can be formed by making a groove halfway and then cutting it completely as shown in Figure 2.

Figure 3a shows the spurious characteristics of a conventional band-pass filter using a surface acoustic wave resonator in which the cut plane of the element is perpendicular to the surface of the piezoelectric substrate, and Figure 3b shows the spurious characteristics.
is the spurious characteristic of a surface acoustic wave resonator in which the corners of the end face in the propagation direction of the surface acoustic wave are cut off according to an embodiment of the present invention, and it can be seen that the characteristic of the present invention is superior.

Here, it is sufficient that there is at least one set of IDT electrodes.

Effects of the Invention As described above, according to the present invention, the corner of the end face of the substrate in the direction in which the surface acoustic wave propagates of a surface acoustic wave resonator having at least one pair of IDT electrodes and a grating reflector on the surface of the piezoelectric substrate is shaved off. In particular, unnecessary spurious signals due to bulk vibrations can be reduced. According to the invention,
It can be mass-produced using conventional dicing equipment without applying resin to the end face of the element, and has the effect of improving the performance of the surface acoustic wave resonator.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a surface acoustic wave resonator according to an embodiment of the present invention, FIGS. Spurious characteristic diagrams of bandpass filters using surface acoustic wave resonators according to the invention and the prior art. FIG. 4 is a perspective view showing a conventional surface acoustic wave resonator. 11...Piezoelectric substrate, 12.13...I
DT electrode (comb-shaped electrode), 14, 15... grating reflector, 16.17... end face with cut corners. Name of agent: Patent attorney Shigetaka Awano and one other personjI
2 Wards

Claims (1)

[Claims] A surface acoustic wave resonator comprising at least one set of comb-shaped electrodes and a grating reflector on a piezoelectric substrate having piezoelectric properties such as quartz, and cutting off corners of the end face of the substrate in the direction in which surface acoustic waves propagate.