JPH10173469A - Surface acoustic wave element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce noise components with a simple structure by connecting a wire for ground with a shield pattern electrodes provided between an input electrode and an output electrode, and grounding it. SOLUTION: Two pairs of comb-shaped electrode 11 and 12 are provided so as to be mutually faced to each other on the surface of a substrate having piezoelectricity, and reflectors 13 and 14 in which a pattern is formed with equal pitches are arranged at the side parts of the comb-shaped electrodes 11 and 12. An input electrode 16 is connected to the side part of the comb-like electrode 11, and the top end part of a wire 18 is connected, and the wire 18 for ground is connected to a ground electrode 20 of the reflector 13. Moreover, the wire 18 is connected to an output electrode 22 of the comb-shaped electrode 12 at the opposite side, the wire 18 for ground is connected to a ground electrode 24 of the reflector 14. The reflectors 13 and 14 are respectively connected to shield pattern electrodes 28 and 30 provided between the input electrode 16 and the output electrode 22, and the wire 18 for ground is also connected to each shield pattern electrode 28 and 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface acoustic wave element using a surface acoustic wave, which is a frequency filter for extracting electromagnetic waves in a specific frequency band.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 3, a surface acoustic wave element 10 has two pairs of comb electrodes 1 on a piezoelectric substrate such as quartz.
1 and 12 are provided alternately facing each other.
Reflectors 13 and 14 in which patterns are formed at an equal pitch are arranged on the sides of 1 and 12. This pitch corresponds to the wavelength synchronized at the desired center frequency.
One of the outer sides of the comb-shaped electrode 11 is connected to the input electrode 16,
The distal end of the wire 18 is connected. Reflector 13
The ground wire 18 is also connected to the ground electrode 20. Further, a wire 18 is connected to the output electrode 22 of the outer comb electrode 12 on the opposite side, and a ground wire 18 is also connected to the ground electrode 24 of the reflector 14.

[0003]

In the above-mentioned prior art, the grounding wires 18 are connected to the grounding electrodes 20 and 24 of the reflectors 13 and 14 of the surface acoustic wave element 10, however, the output signal of the output signal is not changed. It is difficult to sufficiently reduce the noise component, and if a new shield is provided, the structure becomes large, which is against the demand for miniaturization.

[0004] The present invention has been made in view of the above-mentioned problems of the conventional art, and has as its object to provide a surface acoustic wave device having a simple structure and a small noise component.

[0005]

According to the present invention, there is provided a surface acoustic wave device in which a comb-shaped electrode and a reflector are arranged on a piezoelectric substrate, wherein an input electrode, an output electrode,
And a ground electrode, and a ground wire is also connected to the shield pattern electrode provided between the input electrode and the output electrode.

In the surface acoustic wave device according to the present invention, the shield pattern electrode is also grounded, so that L
It is the one with reduced ingredients.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a surface acoustic wave device 10 according to one embodiment of the present invention. Two pairs of comb-shaped electrodes 11 and 12 are alternately provided on the surface of a substrate having a piezoelectric property such as quartz or lithium tantalate. Are formed. This pitch corresponds to the wavelength synchronized at the desired center frequency.

The input electrode 16 is connected to the side of the comb-shaped electrode 11, and the tip of a wire 18 is connected to the input electrode 16. A ground wire 18 is also connected to a ground electrode 20 of the reflector 13. Further, the opposite comb electrode 12 has
The wire 18 is connected to the output electrode 22, and the ground wire 18 is also connected to the ground electrode 24 of the reflector 14.

The comb electrodes on the side opposite to the comb electrodes 11 and 12 are connected to each other via a conductor 26, and the reflector 13 includes a shield pattern electrode 28 provided between the input electrode 16 and the output electrode 18. It is connected to the. Reflector 1
4 is connected to a shield pattern electrode 30 provided between the input electrode 16 and the output electrode 18. The shield pattern electrodes 28 and 30 are also connected to the ground wire 18 respectively.

In manufacturing the surface acoustic wave device 10 of this embodiment, each electrode is formed on a substrate by using a photolithography technique, and an electrode interval is appropriately formed to be several μm to several tens μm. The substrate is a large-sized multi-piece substrate. After forming an electrode pattern, the substrate is divided into individual elements, and the elements are fixed to a sealing base.
The wire 18 is bonded to 24 and housed in a predetermined case to complete the element.

In the surface acoustic wave device of this embodiment, the grounding wires 18 are also provided on the shield pattern electrodes 28 and 30 respectively.
Are connected, and the L component due to the loop effect of the shield pattern electrodes 28 and 30 is suppressed. A comparison between FIG. 2 showing the data of the frequency characteristics according to the embodiment of the present invention and FIG. 4 showing the data of the prior art shows that the noise component near the center frequency could be reduced by 5 to 10 dB.

[0012]

According to the surface acoustic wave element of the present invention, the shield pattern electrode connected to the reflector is grounded, the noise component is effectively suppressed, and a high quality filter can be formed.

[Brief description of the drawings]

FIG. 1 is a front view of an embodiment of a surface acoustic wave device according to the present invention.

FIG. 2 is a graph showing measurement data of one embodiment of the surface acoustic wave device according to the present invention.

FIG. 3 is a front view of a conventional surface acoustic wave device.

FIG. 4 is a graph showing measured data of a conventional surface acoustic wave device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Surface acoustic wave element 11, 12 Comb-shaped electrode 13, 14 Reflector 16 Input electrode 18 Wire 20, 24 Earth electrode 22 Output electrode 28, 30 Shield pattern electrode

Claims (2)

[Claims] 1. A surface acoustic wave device in which a plurality of comb-shaped electrodes are formed on a piezoelectric substrate, and a reflector is arranged on a side of the comb-shaped electrodes. A ground electrode connected to the reflector is formed, the input electrode and the output electrode are connected to the corresponding separate comb electrodes, respectively, the reflector is connected to the ground electrode, and the input electrode and the output electrode are connected to the ground electrode. A surface acoustic wave element wherein a ground wire is connected to a shield pattern electrode provided therebetween and grounded. 2. A plurality of shield pattern electrodes are connected between the input electrode and the output electrode, and each shield pattern electrode is connected to a reflector on the input electrode side and on the output electrode side, respectively. The surface acoustic wave device as described in the above.