JPS59117310A - Elastic surface wave resonator - Google Patents

Abstract

PURPOSE:To obtain an elastic surface wave resonator with small size and low cost without adhering especially an absorbing band by forming a drawing-out electrode pad of an interdigitating electrode to both ends in the propagating direction of an elastic surface wave on a piezoelectric substrate. CONSTITUTION:Each electrode finger of the interdigitating electrode 12 is connected alternately to conductors 21, 22 and the leads 21, 22 pass respectively through both sides of the elastic surface wave propagating path and are connected to the drawing-out electrode pads 25, 26 formed at both ends of the elastic surface wave propagating path on the piezoelectric substrate 11. Electrodes 13, 14 are grating electrodes arranged at an equal interval on the elastic surface wave propagating path. Thus, it is not necessary to widen the width of the piezoelectric substrate 11 to form the electrode pads 25, 26, and since an unnecessary elastic surface wave is absorbed by the electrode pads 25, 26 and lead wires connected thereto, no special absorbing band is required. Thus, miniaturization and low cost are realized.

Description

[Detailed description of the invention] The present invention relates to the structure of a surface acoustic wave resonator.

For example, as shown in FIG. 1, a conventional surface acoustic wave resonator has an interdigital electrode 12 approximately in the longitudinal center of a piezoelectric substrate 11.
, and grade ink electrodes 13 and 14 are arranged at regular intervals on both sides, and each electrode finger of the interdigital electrode 12 is connected to a lead-out pad 15 or 16 every other group. The lead-out electrode pads 15 and 16 are provided on both sides of the surface acoustic wave propagation path (in the direction perpendicular to the electrode fingers of the interdigital electrode 120') as shown in the figure. Absorption bands 17 and 18 are attached to both ends of the surface acoustic wave propagation path to attenuate unnecessary surface acoustic waves. Therefore, the above-mentioned conventional resonator requires labor and extra length to attach the absorption bands 17, 18, and also requires widening the piezoelectric substrate 110 to form the lead-out electrode pads 15, 16. Therefore, the cost of the conventional ridge resonator increases.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional drawbacks, reduce the area of a piezoelectric substrate, and provide a small and low-cost surface acoustic wave resonator in which no absorption band is specifically attached.

The resonator of the present invention is a surface acoustic wave resonator in which interdigital electrodes are formed on a piezoelectric substrate, in which electrode pads for leading out the interdigital electrodes are formed at both ends of the piezoelectric substrate in the surface acoustic wave propagation direction. It is characterized by what it did.

Next, the present invention will be explained in detail with reference to the drawings.

FIG. 2 is a plan view showing one embodiment of the present invention;
This resonator has characteristics equivalent to the conventional example shown in the figure.

That is, each electrode finger of the interdigital electrode 12 is connected to the conducting wire 21.22 every other time, and the four fingers 21.22 are connected to the lead-out electrode pad 25. 26. Extraction electrode pad 25.2
6 are formed at both ends of the surface acoustic wave propagation path on the piezoelectric substrate 11. Of course, the cladding electrodes 13 and 14 are
Conventionally, the co-rotating index finger's straight poles 12 are arranged at equal intervals on both sides of the straight pole 12. Therefore, in this embodiment, the width of the pressure α substrate 110 is widened in order to form the electrode pads 25, 26. There is no need to do this, and the board area can be reduced.In addition, the unstable surface acoustic waves are absorbed by the electrode pads 25 and 26 and the lead wires connected to these, as shown in Figure 1. It has the same characteristics as the conventional example.

The third section is a plan view showing another embodiment of the present invention, and shows the case of "□" suitable for a resonator without a cladding electrode. In this case as well, the electrode pad 25.2 for extraction
6 are arranged at both ends of the surface acoustic wave propagation path, and every other electrode finger of the interdigital electrode 12 is connected to it@! via conductive wires on both sides of the surface acoustic wave propagation path. , connected to pads 25, 26. The electrode pads 25, 26 and the lead wires connected thereto also serve to absorb unnecessary Z+i surface waves.

Therefore, there is no need to provide a special absorption band. Further, the piezoelectric substrate 110 has the effect of being narrow.

As described above, in the present invention, electrode pads for electrically drawing out the interdigital electrodes are formed at both ends of the surface acoustic wave propagation direction on the piezoelectric substrate, and the electrode pads and the leads connected thereto are formed at both ends of the piezoelectric substrate in the surface acoustic wave propagation direction. Since the structure is configured so that unnecessary surface acoustic waves are absorbed by the wire, the same characteristics as conventional ones can be obtained without providing a special absorption band. According to the invention t
Since there is no need to increase the width of the piezoelectric substrate to form the f&pad, a piezoelectric substrate with a small area is sufficient. Further, there is no need to attach an absorption band, and the device can be provided in a small size and at low cost.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an example of a conventional surface acoustic wave resonator.
FIG. 2 is a plan view showing one practical example of the present invention, and FIG. 3 is a plan view showing another embodiment of the present invention. In the figure, 11... piezoelectric substrate, 12... interdigital electrode, 13.14... grading electrode, 15.16
゜25.26...'magnetic pole pad, 17.18...absorption band, 21.22...conductor wire. Agent: Patent attorney Toshimune Sumita

Claims (1)

[Claims] In a surface acoustic wave resonator in which interdigital electrodes are formed on a piezoelectric substrate, both sides of the surface acoustic wave propagation direction on the piezoelectric substrate,
A surface acoustic wave resonator characterized in that an electrode pad for leading out the interdigital electrodes is formed at an end portion.