JPS61136314A - Surface acoustic wave signal processor - Google Patents

Abstract

PURPOSE:To place compactly transmitting and receiving electrodes by providing a transmitting electrode circular in shape and directional property, and placing plural pieces of receiving side electrodes in its periphery. CONSTITUTION:On a silicon substrate 11, a 120 deg. phase type one directional electrode is placed as an only transmitting electrode 21, and plural receiving electrodes 22-28 are provided on its periphery. Each of these receiving electrodes 22-28 are different in shape, outputs of these receiving electrodes 22-28 are synthesized by an output signal circuit 33, and outputted as a signal which has encoded or decoded a signal received by an input signal circuit 32. In such a way, one piece of transmitting electrode will suffice, therefore, the device becomes compact.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a signal encoding and decoding device using a tapped delay line using a single surface acoustic wave.

[Technical background of the invention and its problems]

In a conventional signal encoding/decoding device using a single surface acoustic wave tapped delay line, transmitting side electrodes and receiving side electrodes are parallel and correspond to each other on a one-to-one basis. and.

The number of signals that can be encoded or decoded is
It is fixed depending on the electrode shape of the receiving side electrode.

Therefore, the encoding of several types of signal patterns.

If decoding is desired, the number of transmitting electrodes and receiving electrodes must be formed in pairs.

[Purpose of the invention]

This invention improves the above-mentioned drawbacks of the conventional device.The present invention uses one circular and unidirectional transmitting electrode, and has one fan-out from the input signal to the transmitting electrode, thereby increasing the input signal level. It is an object of the present invention to provide a signal processing device in which transmission and reception electrodes can be arranged in a compact manner.

[Summary of the invention]

Interdigital transducers (interdigital transducers) are formed on a piezoelectric wafer by metal vapor deposition, etching, or the like. Alternatively, by similarly forming an interdigital ta on a non-piezoelectric wafer and growing a piezoelectric thin film on it, surface acoustic waves are generated when a signal voltage is applied to the transmitting electrode of the obtained transmitting and receiving electrode. The surface acoustic wave propagates to the receiving electrode, where the surface acoustic wave is converted into an electrical signal.

〔Effect of the invention〕

When encoding or decoding a signal, the response signal pattern is determined by the shape of the receiver electrode, so when handling multiple signal patterns, it is necessary to provide a receiver electrode with a shape that responds to each.

In this case, by placing a circular, unidirectional transmitting electrode in the center and arranging a plurality of receiving electrodes around it, the degree of integration of the transmitting and receiving electrodes can be increased.

[Embodiments of the invention]

An embodiment of this invention is shown in FIG. In Fig. 1, an aluminum conductor ff1 (21) for transmitting and receiving is placed on a silicon substrate (11).
22, . . , 28), and a ZnO piezoelectric thin film 03 is formed thereon. Here, 1 for transmission is pole Qj
is a 120° phase type unidirectional electrode, and when an input signal is applied as shown in Fig. 1 using a 1200 phase shifter 0υ, the surface acoustic wave propagates radially and reaches the transmitting electrode c! It is not transmitted to the inside of D. 22, 23, 24, 25, 26°27.2
8 are receiving electrodes, each having a different electrode shape. 32 is an input signal peripheral circuit, and 33 is an output signal peripheral circuit.

Figure 2 shows one of the principles of decoding a 7-bit Parker code.
Give an example. (a) The receiving electrode is 1 such that the transmitting electrode is 11.
When it has the shape (b) like 2.

When a signal as shown in (C) enters the transmitting electrode, a signal as shown in (d) is obtained at the receiving electrode.

Furthermore, in the electrode shape shown in FIG. 3, the transmitting electrode Q11 (a
) When a signal as shown in (C) is inputted to the receiving electrode, an encoded signal as shown in (b) and FIG. 2 (C) is obtained at the receiving electrode.

[Other embodiments of the invention]

In the embodiment shown in FIG. 4, a 90' phase type unidirectional electrode is used as the transmitting electrode QD, and the receiving electrode (22°23) is 2
It heavily surrounds the transmitting electrodes. Inner receiving electrode (c)
By providing a depression (to) as shown in the figure between the front and outer receiving electrodes (to), the radially spreading surface acoustic waves are made into waves with parallel wavefronts.

Further, the width of the outer receiving electrode is wider than that of the inner electrode in consideration of scattering and attenuation during the transmission of surface acoustic waves to the electrode. 13 in the figure is a surface acoustic wave absorbing material.

With this structure, the number of receiving electrodes can be reduced to 2.
Can be doubled. If there is a large difference in the distance between the transmitting electrode and the inner receiving electrode and the distance between the outer receiving electrode and the delay difference in the received signal becomes a problem, insert a delay element between the inner receiving electrode and the output signal circuit. do it.

Agent: Patent Attorney Noriyuki Chika (and 1 other person) No. 1
Figure 2

Claims (1)

[Claims] A surface acoustic wave signal processing device characterized in that a transmitter electrode for surface acoustic wave excitation is a circular, unidirectional electrode, and a plurality of receiver electrodes are arranged around the transmitter electrode.