JPS6324583B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ternary logic device and a ternary communication system using the device.

The present applicant previously proposed a ternary transmission system as a method that adds another degree of freedom in logic to binary transmission (Japanese Patent Application No. 54-068999). This converts a three-value logic signal consisting of a combination of pulses of positive polarity, zero amplitude, and negative polarity into a signal S of a predetermined frequency, a signal _S0 of zero amplitude, and a signal with the same frequency that has a phase shift of 180° with respect to the signal S. This signal is output as a signal consisting of a combination of the above signals, and the signal is detected as a difference in amplitude level via a ternary logic device. The ternary logic device consists of a piezoelectric substrate, two interdigital interdigital electrodes provided on one surface of the substrate, and two flat electrodes provided on the other surface of the substrate opposite to each interdigital electrode. , the Lamb wave is excited by the signal to obtain good operating characteristics in the ternary mode. Therefore, the thickness of the piezoelectric substrate must be less than the wavelength of the Lamb wave in the substrate, and as the frequency increases, the thickness of the piezoelectric substrate must be made thinner. As a result, the aforementioned ternary logic devices have the drawback of being limited to use in a relatively low frequency range, for example, limited to about 20 to 30 MHz.

Therefore, the present invention aims to improve the above-mentioned drawbacks of the conventional technology, and its purpose is to provide a ternary logic device having good ternary mode characteristics even in a high frequency range of several hundred MHz or more, and to The purpose of the present invention is to provide a three-level communication system using the following.

A feature of the present invention for achieving the above object is that input and output interdigital electrodes consisting of a pair of comb-like electrodes having an interdigital configuration are connected to a piezoelectric substrate having a thickness sufficient to excite surface acoustic waves. 1 arranged spaced apart from each other on the top and forming each interdigital electrode.
One of the pair of comb tooth-shaped electrodes is grounded and the other is divided into two to form first and second divided electrodes at least on the input comb-shaped electrode, and a signal of a predetermined frequency is sent to the first divided electrode. At the same time, the above signal S and a signal with zero amplitude are applied to the second divided electrode.
S ₀ and a signal with the same frequency and a phase shift of 180° with respect to the signal S are applied, and each of the signals S and S ₀ is detected as a difference in amplitude level through an output interdigital electrode. Located in a ternary logic device.

Another feature of the present invention is that a three-value logic signal constituted by a combination of pulses of positive polarity, zero amplitude, and negative polarity is divided into a signal S of a predetermined frequency, a signal S ₀ of zero amplitude,
A transmitting means for outputting a signal consisting of a combination of a signal having the same frequency and a phase shift of 180° with respect to the signal S, a transmission line for transmitting the signal, and a piezoelectric substrate having a thickness that excites surface acoustic waves. and input and output interdigital transducer electrodes comprising a pair of interdigital comb-like electrodes arranged spaced apart from each other on the substrate, each interdigital transducer comprising a pair of interdigital interdigital transducer electrodes. One of the tooth-shaped electrodes is grounded and the other is divided into two, thereby providing a receiving means equipped with a ternary logic device in which first and second divided electrodes are formed on at least the interdigital interdigital electrode for input. By applying the signal S to the first divided electrode of the input interdigital electrode in the logic device and applying S, S ₀ to the second divided electrode, and detecting each signal as a difference in amplitude level, 3. This is in a three-value communication system that transmits and receives value logic signals.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of a ternary logic device according to the present invention. The piezoelectric substrate 1 has a thickness of, for example, about 5 wavelengths for the excited sound waves, which is sufficient to excite surface acoustic waves. The piezoelectric substrate 1 has an input interdigital electrode 2 and an output interdigital electrode 4.
can be received at a distance from each other. The input interdigital electrode 2 is constructed by interdigitally combining a pair of comb tooth electrodes 3a and 3b, one of the comb tooth electrodes 3b is grounded via the terminal O, while the other comb tooth electrode 3b is grounded via the terminal O. Comb tooth electrode 3a
As shown in the figure, it is divided into two to form first and second divided electrodes 3a-1 and 3a-2. A terminal A is provided on the first divided electrode 3a-1, and a terminal B is provided on the second divided electrode 3a-2. The output interdigital electrode 4 is constructed by interdigitally combining a pair of comb tooth electrodes 4a and 4b, and one comb tooth electrode 4b is a terminal.
It is grounded via O′ as before.
A terminal A' is provided on the other comb-tooth electrode 4a. The output interdigital electrode can also have the same configuration as the input interdigital electrode 2, that is, the comb tooth electrode 4a can be configured as a divided electrode.
According to this, output signals of equal amplitude and having a phase difference of 180° from each other can be obtained for each divided electrode. Therefore, it has the advantage that it can be directly input to the differential amplifier, which is preferable when used in cascade connection.

Under the above configuration, a signal S having a carrier of frequency _c is applied as a reference signal between the A and O terminals, and a signal S having a carrier with a frequency of c is applied between the B and O terminals as an input signal with a phase deviation of 180° with respect to the signal S. A signal S having the same frequency as the shifted signal S, and a signal S ₀ having zero amplitude are applied. If the input signal between B and O terminals is A
- Since a signal S with the same frequency and a 180° phase shift is applied between the -O terminals, considering the 180° phase difference from the electrode structure, the output interdigital electrode 4
The output obtained between the A' and O' terminals is the maximum, and its amplitude is S-, which is larger than S or S-. Next, when the input signal between the B and O terminals is S, the same signal S is applied between the A and O terminals, so almost no surface acoustic waves are excited.
The output obtained between A′ and O′ terminals is a signal with zero amplitude S ₀
becomes. Furthermore, when the input signal between the BO terminals is S ₀ , the sound wave is excited by the reference signal S.
The output between A' and O' terminals becomes S. Therefore, input signals can be determined based on differences in amplitude levels, and each signal can be easily identified.

Since the three-value logic device according to the present invention excites surface acoustic waves, there is no need to consider the thickness of the piezoelectric substrate with respect to frequency, unlike in the case of Lamb waves, and therefore the device can perform well even in the high frequency range of several hundred MHz or more. Three-value operating modes can be obtained.

Figures 2a and 2b show an example of a ternary communication system using the above device, in which Figure 2a is an example of the configuration of the transmitting side of the ternary communication system, and Figure 2b is an example of the configuration of the receiving side. shows.

In FIG. 2a, 10 is a photocoupler composed of, for example, a photodiode and a phototransistor, 11 is an electronic switch controlled by the photocoupler 10, and 12 is an electronic switch 1.
An operational amplifier whose input is the output of
R ₁ to _{R 6} are resistors, C ₁ and C ₂ are capacitors, C and D are input terminals, and E is an output terminal. If a three-value logic signal consisting of a combination of pulses of positive polarity, zero amplitude, and negative polarity is applied to the input terminal C, and a sine wave alternating current (frequency _c ) is applied to the terminal D, positive polarity, zero amplitude, and negative polarity will be generated. The opening and closing of the electronic switch 11 is controlled according to each pulse of the frequency, and a signal S having a carrier of frequency _c , an output signal S ₀ of zero amplitude, and the above S are sent to the output side terminal E via the operational amplifier 12. An output signal composed of a combination of signals having a phase shift of 180° is obtained. The transmitting side sends out this signal to the transmission path as a transmission output.

In Figure 2b, 13 is 3 explained in Figure 1.
In the value logic device, the transmitted signals S and _S0 are applied to the input signal terminal B of the input interdigital electrode 2, and the signal S is applied to the reference signal terminal A. Therefore, the terminal A' of the output interdigital electrode 4 receives output signals S-, S-, S-, S-, S-, S-, S-, S-, S-, S-, S-, S-, S-, S-, _S-- , S--, S--, S--, S--, S--, S--, S--, S--, S--, S--, S--, S--, S--, S--, S--, S--, S--, S--,
It is obtained as S ₀ ,S. This output signal is amplified by the amplifier circuit 14, then subjected to envelope detection via the detection circuit 15, and is supplied to the output terminal OUT as signals with different amplitude levels.

FIG. 3 shows an embodiment of the ternary communication system according to the present invention, in which FIG. 3a shows the transmitting side, FIG. 3b shows the receiving side, and A in the figure shows the voltage applied to the terminal C (FIG. 2a). coded ternary signal, B is terminal E (Figure 2a)
C shows the transmission signal obtained at , C shows the timing pulse, and D shows the demodulated signal obtained at the output terminal OUT of the receiving system (FIG. 2b). As is clear from d, 3
It can be seen that signals consisting of various amplitude levels are obtained, and that the ternary logic device is operating effectively.

As explained above, according to the present invention, it is possible to provide a ternary logic device using surface acoustic waves, obtain good ternary mode characteristics even in a high frequency region, and use the device to obtain a ternary logic device using a binary logic device. A ternary communication system can be provided that adds another logical degree of freedom to transmission. Moreover, since the transmission signals in this system use signals (S) with opposite phases to each other, a relatively narrow frequency band is required, and since the interdigital electrode structure is used, it is resistant to noise and can obtain a high S/N ratio. .

[Brief explanation of drawings]

FIG. 1 shows an embodiment of a ternary logic device according to the present invention, FIGS. 2a and 2b show an embodiment of a ternary communication system according to the present invention, and FIGS. 3a and 3b
is an embodiment of a ternary communication system according to the present invention. 1; piezoelectric substrate, 2, 4; interdigital electrode, 3a,
3b, 4a, 4b; comb tooth electrode, 3a-1,
3a-2; Divided electrode, 10; Photo coupling, 1
1; electronic switch, 12; operational amplifier, 13; ternary logic device, 14; amplifier circuit,
15; Detection circuit.

Claims (1)

[Claims] 1. Input and output interdigital electrodes consisting of a pair of interdigital comb-like electrodes are spaced apart from each other on a piezoelectric substrate having a thickness that excites surface acoustic waves. A pair of comb-shaped electrodes constituting each interdigital electrode are arranged, one of which is grounded, and the other is divided into two, thereby forming first and second divided electrodes at least on the input interdigital electrode. , a signal S of a predetermined frequency is applied to the first divided electrode, and a signal _S0 with zero amplitude is applied to the second divided electrode, and a signal with the same frequency and a phase shift of 180° with respect to the signal S is applied to the second divided electrode. A ternary logic device characterized in that the signals S and S ₀ are detected as a difference in amplitude level through output interdigital electrodes. 2 A ternary logic signal composed of a combination of pulses of positive polarity, zero amplitude, and negative polarity is divided into a signal S of a predetermined frequency, a signal S ₀ of zero amplitude, and a signal S of the same frequency with a phase shift of 180° with respect to the above signal S. a transmission means for outputting a signal consisting of a combination of signals, a transmission path for transmitting the signal, a piezoelectric substrate having a thickness such that it excites surface acoustic waves, and interdigital signals arranged spaced apart from each other on the substrate. An input and output interdigital electrode consisting of a pair of comb-like electrodes, one of which is grounded and the other divided into two. By doing so, there is provided a receiving means comprising a ternary logic device in which first and second divided electrodes are formed on at least the input interdigital electrode, and the first division of the input interdigital electrode in the ternary logic device is provided. A ternary logic signal is transmitted and received by applying a signal S to the electrode and applying S, S ₀ , to the second divided electrode, and detecting each signal as a difference in amplitude level. Communications system.