JPH01220908A - Surface acoustic wave device - Google Patents

Abstract

PURPOSE:To improve the guaranteed attenuation by leading out an input/output signal line and an earth line at the transmission reception side in a direction orthogonal to each other. CONSTITUTION:Electrode pads 8b, 9b of interdigital electrodes 2b, 3b for earth potential at the transmission/reception sides are connected directly to the surface of the metallic base in a direction coincident with the propagating direction of a surface acoustic wave of earth wires 12, 13 made of thin metallic lines. That is, input/output signal lines 10, 11 and the earth wires 12, 13 are led in a direction orthogonal to each other. Since the signal lines 10, 11 and the earth wires 12, 13 are led out orthogonally in this way, even when the signal line is used as a transmission antenna and an electric signal is given for the radiation, the earth wire does not act like a reception antenna nor the guaranteed attenuation is deteriorated. Thus, the guaranteed attenuation is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention is applied to surface acoustic wave ports, and in particular to the field of application of surface acoustic wave ports. ! i
This relates to the direction in which input signal lines and ground lines are led, which can increase the amount of E-attenuation.

(Background of the Invention) A surface acoustic wave aperture is constructed by forming interdigital electrodes on the transmitting and receiving sides on a piezoelectric substrate, and has features such as being small, lightweight, and non-adjustable. In recent years, they have been used as filters, delay lines, and oscillators in various consumer electronic devices such as general communication devices and television receivers. In particular, when used as a filter, sufficient protection and xg attenuation are required due to congestion of communication lines and improvement of speech quality.

(Conventional Example) FIG. 3 is a diagram of a surface acoustic wave opening illustrating a conventional example, and FIG. 3(a) is a perspective view thereof, and FIG. 3(b) is a plan view thereof.

For example, the surface acoustic wave inlet connects the piezoelectric substrate 1 to
An interdigital electrode 2 that transmits and receives surface acoustic waves on its entire surface.
．． form 3. Interdigital electrodes 2.3 (Both form a pair on the transmitting and receiving sides, and one on the transmitting side 2 is used for input 2a,
The other side is used as the ground potential 2b, and on the receiver 48 side 3, one is used as the output 3n and the other is used as the ground potential 3b. Normally, the input/output interdigital electrodes 2a, 3n are arranged vertically upside down to prevent transmission/reception by electrical direct waves between the input/output.

A pair of input/output terminals 4 and 5 pass through insulation on the other side of the piezoelectric substrate 1, and a grounding terminal 6 is fixed to the surface of a metal base 7 which is directly connected to the main body. The electrode pad portions 8a, 9a of the input/output interdigital electrodes 2a, 3a connect input/output signal lines 10.11 made of thin metal wires to the input/output terminals 4.5, respectively. In addition, the electrode hat portions 8)) and 9b of the interdigital interdigital electrodes 2h and 3b for earth potential on the transmitting and receiving sides are ground lj%12 made of thin metal wires on the surface of the metal base 7.
．． Connect 13 directly. Generally, due to their structure, the signal line 10.11 and the ground line 12.13 are parallel to each other within approximately 30 degrees and are led out in a direction perpendicular to the propagation direction of the surface waves.

(Disadvantages of the prior art) However, in the surface acoustic wave port having such a configuration,
As shown in the transmission characteristic diagram in Figure 4, the guaranteed attenuation is 30d.
It is around B and is used for example in satellite broadcasting receivers.
There was a problem that it could not be applied to products that required a standard of 0 dB or higher. According to the present invention, the reason for this is that the signal line 10.11 and the ground line 12.13 are parallel to each other within about 30 degrees, so for example, the signal line 10.
It was thought that the guaranteed attenuation amount should be lowered as a result of the ground wire 13 acting as a receiving antenna and directly receiving the electric signal radiated as a transmitting antenna.

(Objective of the Invention) An object of the present invention is to provide a surface acoustic wave opening capable of increasing guaranteed attenuation.

(Solution Means and Effects) The present invention provides a solution in that the input/output signal line and the ground line on the transmitting/receiving side are led out in orthogonal directions. An embodiment of the present invention will be described below.

(Embodiment) FIG. 1 is a diagram of a surface acoustic wave port illustrating an embodiment of the present invention. Note that FIG. 1(a) is a perspective view, and FIG. 1(h) is a plan view, and the same parts as those of the previous embodiment are given the same numbers for explanation.

In the surface acoustic wave device, as in the previous embodiment, pairs of interdigital electrodes 2.3 on the transmitting and receiving sides are formed on the entire surface of the piezoelectric substrate 1. On the transmitting side 2, one is used for input 2a and the other is used for ground potential 2b, and on the receiving side, one is used for output 3a and the other is used for ground potential 3b. Note that the interdigital electrodes for input and output are reversely arranged above and below 2a and 3a.

The other side of the piezoelectric substrate 1 is fixed onto a metal base 7. The electrode pads Flu, 9a of the input/output interdigitated ftS poles 2m, 3a and the input/output terminals 4.5 of the metal pad 7 connect the signal lines 10.11 made of thin metal wires in the propagation direction of the surface wave. Connect in orthogonal direction. In addition, the electrode pad part 8b of the interdigital Ti electrode 2) 1.313 for earth potential on the transmitting and receiving side
, 9b directly connects ground wires 12 and 13 made of thin metal wires to the surface of the metal base in alignment with the propagation direction of the surface waves.

That is, the input/output signal lines 10.11 and the ground line 12.
13 and are derived in directions perpendicular to each other.

As shown in the transmission characteristic diagram of Fig. 2, the passband characteristics of the surface acoustic wave aperture with this configuration have a guaranteed attenuation of 40 dB or more, and are about 10 dB compared to the characteristics of the previous embodiment (Fig. 2).
We were able to obtain a guaranteed attenuation of R or higher. In other words, since the signal line and the ground line are drawn out in orthogonal directions, even if the signal line is used as a transmitting antenna to radiate an electrical signal, the ground line will not act as a receiving antenna and the guaranteed attenuation will not decrease. It is thought that this is because of this. In this embodiment, ripples and the like within the band were also improved compared to the characteristics of the previous embodiment.

(Other Matters) In the above embodiment, the ground wires 12.13 are made perpendicular to the ground return wires 10, 11 in the propagation direction of the surface waves, but for example, the signal wires 10.11 are made in the propagation direction of the surface waves. direction, earth 1s
Of course, the directions 12 and 13 may be orthogonal to the direction of propagation of the surface waves so that the two directions are orthogonal to each other. and,
Based on this consideration, the present invention can be expected to have the same effect even if the angle between the signal line and the ground line is, for example, 45 degrees, and the orthogonal direction herein refers to an angle of approximately 45 degrees or more. In addition, the input signal PJ, 10 and the ground wire 13 on the receiving side are orthogonal to each other, and the output signal line 11 and the ground wire on the sending side are orthogonal to each other. Alternatively, the effect can be expected even if the power signal line 11 and the ground wire on the transmission line 3 side are led out in a direction perpendicular to each other.

In addition, although it is possible to obtain a guaranteed attenuation of 40 dR or more, it is possible to increase the guaranteed attenuation by leading the input/output signal line and the ground line in orthogonal directions, regardless of the value. It belongs to the technical scope of the invention and can be modified as appropriate without departing from the spirit thereof.

(Effects of the Invention) The present invention can provide a surface acoustic wave opening that can increase guaranteed attenuation because the input/output signal line and the transmission/reception (Z side ground line) are led out in orthogonal directions. Its practical value is great.

[Brief explanation of the drawing]

FIG. 1 is an elastic surface diagram illustrating an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Piezoelectric substrate, 2... Transmission side interdigital electrode, 3. Receiving side interdigital electrode, 2a... Input electrode, 3n... Output electrode, 2b, 3b... Earth electrode, 4 .5.6 Terminal, 7... Metal base, 8.9... Electrode pad part, 10
．． 11...Signal line, 12.13...Earth line. 3rd horse 2nd frequency Hz

Claims (3)

[Claims] (1) A pair of transmitting and receiving interdigital electrodes is formed on the surface of the piezoelectric substrate, one of the transmitting interdigital electrodes is used for input, the other is used for ground potential, and one of the receiving interdigital electrodes is used for output; In a surface acoustic wave mount in which an input/output signal line and a ground line are connected with the other end being for ground potential, the input/output signal line and the ground line on the transmitting/receiving side are led out in directions orthogonal to each other. surface wave device (2) A pair of transmitting and receiving interdigital electrodes is formed on the surface of the piezoelectric substrate, one of the transmitting interdigital electrodes is used for input, the other is used for ground potential, and one of the receiving interdigital electrodes is used for output; A surface acoustic wave device in which an input/output signal line and a ground line are connected, the other being for ground potential, characterized in that the input signal line and the ground line on the receiving side are led out in directions perpendicular to each other. Device. (3) A pair of transmitting and receiving interdigital electrodes is formed on the surface of the piezoelectric substrate, one of the transmitting interdigital electrodes is used for input, the other is used for ground potential, and one of the receiving interdigital electrodes is used for output; An elastic surface in which an input/output signal line and a ground line are connected, the other being for ground potential, and the output signal line and the ground line on the transmitting side are led out in directions orthogonal to each other. wave device.