JPH09199982A - Surface acoustic wave device and communication system using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface acoustic wave device by which a convolution output signal is easily detected. SOLUTION: At least part of input side external circuits 10a, 12a or an output side external circuit 11 is arranged in a package containing a surface acoustic wave convolver element in input side external circuits 10a, 10b consisting of at least part or all of an impedance matching circuit, a filter and an amplifier and an output side external circuit 11 consisting part or all of an impedance matching circuit, a filter and an amplifier.

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 device that utilizes the characteristics of a piezoelectric element and a communication system using the same.

[0002]

2. Description of the Related Art A surface acoustic wave device using a surface acoustic wave convolver for extracting convolution outputs of two input signals by using a surface acoustic wave is known as spread spectrum communication (Spread).
In recent years, its importance has been increasing as a device for establishing synchronization in performing Spectrum Communication), and is being actively researched.

FIG. 8 is a schematic plan view showing a conventional surface acoustic wave device using a surface acoustic wave convolver. In the figure, 1 is a piezoelectric substrate such as Y-cut Z-propagation lithium niobate, 2,
3 is a comb-shaped input electrode formed on the surface of the piezoelectric substrate 1, 4
Reference numerals a and 4b are input bonding wires for transmitting signals to the comb-shaped input electrodes 2 and 5, reference numeral 5 is an output electrode also serving as a waveguide formed on the surface of the piezoelectric substrate 1, and reference numeral 6 is for transmitting an output signal from the output electrode 5. Output bonding wires, 7a and 7b are input lead pins for relaying and transmitting signals to the input bonding wires 4a and 4b, and 8 is an output bonding wire 6
Output lead pins for relaying and transmitting the output signal of No. 1, a package stem 9 to which the piezoelectric substrate 1 is fixed, 10a and 10b to input side external circuits, 11 to output side external circuits, and 14 to a mounting substrate on which the package stem 9 is mounted. .

Although the package stem 9 is actually used in a hermetically sealed state using a sealing cap,
It is omitted in the figure.

The input / output electrodes 2, 3 and 5 are made of a conductive material such as aluminum and are usually formed directly on the surface of the piezoelectric substrate 1 by using a photolithography technique.

In the surface acoustic wave device having such a structure, when an electric signal having the carrier angular frequency ω is input to the comb-shaped input electrode 2, the surface acoustic wave is excited by the piezoelectric effect of the piezoelectric substrate 1. Similarly, the carrier angular frequency ω is applied to the comb-shaped input electrode 3.
When the electric signal of is input, the surface acoustic wave is excited. These two surface acoustic waves propagate in opposite directions on the piezoelectric substrate 1 while being confined in the output electrode, with the output electrode 5 acting as a waveguide. When these two surface acoustic waves overlap each other on the output electrode 5, a convolution signal (angular frequency 2ω) of these two surface acoustic waves is generated due to the physical nonlinear effect of the piezoelectric substrate 1. The convolution signal thus generated is taken out from the output electrode 5 as an electric signal.

Usually, in such a surface acoustic wave convolver element, the impedance of the input electrodes 2, 3 and the output electrode 5 is different from the impedance of the external peripheral circuit. A matching circuit for impedance matching is connected to.
In addition to the matching circuit, a filter for removing unnecessary waves other than signals in the signal input section and signal output section,
An amplifier for amplifying the input signal and the output signal is connected.

In the present invention, the input side external circuits 10a, 10
b is at least an impedance matching circuit, a filter,
The external circuit configured by a part or all of the means of the amplifier, and the output side external circuit 11 is an external circuit configured by at least a part of or the impedance matching circuit, the filter, and the amplifier. The input side external circuits 10a and 10b and the output side external circuit 11 are arranged on the mounting substrate 14, respectively.

[0009]

However, the signal level of the convolution signal that can be taken out as an electric signal is extremely low, which is about 10 ^-5 to 10 ^-6 of the input signal level. Therefore, in the above conventional technique, a part of the signal propagating through the input side external circuit is radiated into the air and directly reaches the output side external circuit, and the input signal component is mixed into the output signal, resulting in noise of the convolution waveform. There is a problem that the floor increases and it becomes difficult to detect the convolution output signal.

Further, since the input signal component reaching the output side external circuit also includes a component having the same carrier angular frequency (2ω) as the convolution signal component, the convolution signal fluctuates and the convolution signal is changed. There is a problem that it becomes difficult to detect.

Further, if the noise floor of the convolution waveform increases or the convolution signal fluctuates, there is a problem that the reliability of the communication decreases in the communication system using the convolution signal as the synchronization signal.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to provide a surface acoustic wave device which suppresses mixing of an input signal component with an output signal and which can easily detect a convolution signal. Another object of the present invention is to provide a highly reliable communication system using this surface acoustic wave device.

The above object is to provide the first and second piezoelectric substrates on the piezoelectric substrate.
At least two input electrodes for exciting the surface acoustic wave of
It also serves as a waveguide for propagating the first and second surface acoustic waves excited from the input electrode in opposite directions and extracting convolution signals of the two surface acoustic waves generated by the nonlinear effect of the piezoelectric substrate. A package for accommodating a surface acoustic wave element having an output electrode, an input side external circuit including at least an impedance matching unit, a signal amplifying unit, and a part or all of the frequency band limiting unit, and at least an impedance matching unit. And a signal amplifying means, and an output side external circuit constituted by a part or all of the frequency band limiting means, in a surface acoustic wave device, wherein the input side external circuit or the output side external circuit is provided inside the package. This is achieved by placing at least a portion.

Further, in the surface acoustic wave device, it is achieved by providing a substrate inside the package and disposing at least a part of the input side external circuit or the output side external circuit on the substrate. Further, it is achieved by covering the periphery of the surface acoustic wave element and at least a part of the input side external circuit or the output side external circuit on the same surface of the substrate with a conductive material. At least one of a metal, a conductive resin mold, a conductive film, a non-metal coated with a conductive film, or a conductive rubber is used as the conductive substance.

In addition, the impedance matching means is
The above object is achieved by using a part or all of an inductance element, a capacitor element, and a resistance element. Further, the signal amplifying means is a high frequency amplifier. Further, the frequency band limiting means,
It is characterized by being one of a low-pass filter, a high-pass filter, and a band-pass filter. In addition, by using the surface acoustic wave device in a communication system, the above object is achieved.

According to the above configuration of the present invention, since the input signal component directly reaching the output side external circuit from the input side external circuit arranged outside the surface acoustic wave device can be suppressed, the noise floor of the convolution waveform is reduced. And the convolution output signal can be easily detected.

Further, according to the present invention, by using these surface acoustic wave devices, it is possible to facilitate synchronization establishment and construct a highly reliable communication system.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will now be described in detail with reference to the drawings along with examples.

[First Embodiment] FIG. 1 is a schematic plan view showing a first embodiment of a surface acoustic wave device according to the present invention. In the figure, 1 is a piezoelectric substrate made of Y-cut Z-propagating lithium niobate or the like, 2 and 3 are comb-shaped input electrodes formed on the surface of the piezoelectric substrate 1, and 4a and 4b are provided with respective signals to the comb-shaped input electrodes 2 and 3. Input bonding wire, 5 is an output electrode also serving as a waveguide on the surface of the piezoelectric substrate 1, 6 is an output bonding wire for outputting an output signal of the output electrode 5, and 7a and 7b are input bonding wires 4a and 4b. Input lead pins for relaying input signals, 8 is output bonding wire 6
Lead pins for relaying the output signal of the device, 9 is a package stem for mounting and fixing the piezoelectric substrate 1, 10a, 10b
Is an external circuit on the input side, 11 is an external circuit on the output side, 14 is a mounting substrate on which the package stem 9 is mounted and fixed, 15, 16
Is an input terminal for inputting an input signal, 17 is an output terminal for outputting an output signal to an external peripheral circuit, and 20 is a substrate arranged on the package stem 9.

Here, the package stem 9 is usually a hermetically sealed type package using Kovar or the like, or a ceramic package.

Although the package stem 9 actually has a sealing cap and is used in a hermetically sealed state,
In the figure, illustration of the sealing cap is omitted.

The input side external circuits 10a and 10b and the output side external circuit 11 include an impedance matching circuit, a signal amplifying circuit, and a part or all of the frequency band limiting circuit. For example, the impedance matching circuit is configured by a part or all of an inductance element, a capacitor element, and a resistance element, the signal amplification circuit is configured by a wideband high frequency amplifier, and the frequency band limitation circuit is a lowpass filter or a highpass filter. , Bandpass filter.

FIG. 7 shows an example of the impedance matching circuit. Although the impedance matching circuit for the comb-shaped input electrode 2 is shown as an example in the same drawing, the same impedance matching circuit as that shown in FIG. 7 can be used for the impedance matching circuit for the comb-shaped input electrode 3 and the output electrode 5.

Although the impedance matching circuit using the inductance element and the capacitance element is shown in the figure, it goes without saying that an impedance matching circuit having a configuration other than this may be used.

In this embodiment, as shown in FIG.
The input-side external circuit units 10a and 10b are arranged on the mounting substrate 14, while the output-side external circuit unit 11 is arranged on the substrate 20 on the package stem 9 together with the piezoelectric substrate 1 and included in the surface acoustic wave device. Has been.

In the surface acoustic wave convolver having such a structure, when an electric signal having the carrier angular frequency ω is input to the comb-shaped input electrode 2, the surface acoustic wave is excited by the piezoelectric effect of the piezoelectric substrate 1. Similarly, when an electric signal having a carrier angular frequency ω is input to the comb-shaped input electrode 3, a surface acoustic wave is excited.

These two surface acoustic waves propagate in opposite directions on the piezoelectric substrate 1 while being confined in the output electrode, with the output electrode 5 acting as a waveguide. When the two surface acoustic waves overlap on the output electrode 5, a convolution signal (angular frequency 2ω) of these two surface acoustic waves is generated due to the physical nonlinear effect of the piezoelectric substrate 1. The convolution generated in this way includes the output electrode 5, the output bonding wire 6 and the output side external circuit section 11,
It is taken out as an electric signal from the output terminal 17 via the output lead pin 8.

In the surface acoustic wave device described in this embodiment,
Although a part of the signal propagating through the input side external circuits 10a and 10b is radiated into the air, the output side external circuit 11 is arranged in the package stem 9 sealed with a sealing cap (not shown). Therefore, the mixing of the input signal component into the output signal can be suppressed, and the noise floor of the convolution waveform is reduced. Therefore, it becomes easy to detect the convolution output signal.

In this embodiment, the package stem 9
The example in which the output-side external circuit 11 is arranged is given, but at least one of the elements forming the output-side external circuit 11 is
One may be arranged inside the package stem 9.

Further, although the output side external circuit 11 is housed in the package stem 9, conversely, the input side external circuit may be housed in the package stem 9 and the output side external circuit may be arranged outside the package stem 9. .

[Second Embodiment] FIG. 2 is a schematic plan view showing a second embodiment of the surface acoustic wave device according to the present invention. In this figure, the same members as those of the first embodiment shown in FIG. 1 are designated by the same reference numerals, and the overlapping description will be partially omitted.

This embodiment is different from the first embodiment in that the piezoelectric substrate 1 and the output side external circuit 11 are arranged on the substrate 20 in the package stem 9.

Also in this embodiment, a part of the signal propagating through the input side external circuits 10a and 10b is radiated into the air, but the output side external circuit 11 is sealed with a sealing cap (not shown). Since it is disposed in the package stem 9 that has been formed, it is possible to suppress mixing of the input signal with the output signal, and it becomes easy to detect the convolution output signal.

Further, the piezoelectric substrate 1 and the output side external circuit 11
Since the relative positions of the piezoelectric substrate 1 and the output-side external circuit 11 on the substrate 20 are determined by disposing them on the same substrate 20, it is easy to determine the position of the output bonding wire 6. Therefore, the manufacturing yield is improved.

In this embodiment, the package stem 9
The example in which the output-side external circuit 11 is arranged is given, but at least one of the elements forming the output-side external circuit 11 is
One may be arranged inside the package stem 9.

A part or all of the input side external circuits 10a and 10b may be housed in the package stem 9.

[Third Embodiment] FIG. 3 is a schematic plan view showing a third embodiment of the surface acoustic wave device according to the present invention. The same members as those shown in FIG. 1 are designated by the same reference numerals, and overlapping description will be partially omitted. Here, 23 is a conductive substance that covers the output side external circuit.

This embodiment is different from the first embodiment in that the conductive material 23 is arranged around the output side external circuit 11 formed on the substrate 20 in the package stem 9. Examples of the conductive substance include a metal, a conductive resin mold, a conductive film, and a nonmetal coated with a conductive film.

Here, as the metal, iron, copper, nickel, kovar (an alloy of iron and nickel) or the like can be used.

As the conductive resin mold, a material having conductivity in an insulating resin such as a silicon resin, an epoxy resin, a phenol resin, or a polyester resin, for example, silver, carbon, graphite, copper or the like is used. What was formed by diffusing can be used.

Examples of the resin film include copper foil, silver foil, aluminum foil, polyester film and the like coated with an insulating resin such as a silicone resin, an epoxy resin, a phenol resin and a polyester resin. .

As the non-metal coated with a conductive film, for example, an insulating material such as plastic, silicon resin, epoxy resin, phenol resin, polyester resin, etc., copper foil, silver foil, aluminum foil, etc. It is possible to use a sheet obtained by pasting the above conductive foil or a sheet coated with the above conductive resin.

Further, as the conductive rubber, for example, conductive filler such as silver filler, silver-plated copper filler, silver-plated aluminum filler, silver-plated glass filler, etc. is added to silicon rubber. What was filled with can be used.

A conductive material 2 is provided around the output side external circuit 11.
By arranging 3, the effect of suppressing the mixing of the input signal component into the output signal is improved, and the detection of the convolution output signal is further facilitated.

In this embodiment, the package stem 9
The example in which the output-side external circuit 11 is arranged is given, but at least one of the elements forming the output-side external circuit 11 is
One may be arranged inside the package stem 9.

In addition, in this embodiment, in the surface acoustic wave device described in the first embodiment, the conductive material 23 is arranged around the output side external circuit 11 formed on the substrate 20 in the package stem 9. Although the structure is adopted, the conductive material 23 may be arranged around the output side external circuit 11 of the surface acoustic wave device as described in the second embodiment.

Further, a part or all of the input side external circuits 10a and 10b may be housed in the package stem 9 and the conductive material 23 may be arranged around the package stem 9.

In the second to third embodiments, the input side external circuits 10a and 10b and the output side external circuit 11 include an impedance matching circuit, a signal amplifying circuit, and a part or all of the frequency band limiting circuit. . For example, the impedance matching circuit is configured by a part or all of an inductance element, a capacitor element, and a resistance element, the signal amplification circuit is configured by a wideband high frequency amplifier, and the frequency band limitation circuit is a lowpass filter or a highpass filter. , Bandpass filter.

Further, in the above-mentioned Examples 1 to 3, as the piezoelectric substrate 1, in addition to the Y-cut Z-propagation lithium niobate mentioned in this Example, a piezoelectric substrate such as crystal or lithium tantalate, a semiconductor, or the like. A glass substrate having a structure in which a piezoelectric substance is added can be used.

Further, although the elastic convolver is used in the first to third embodiments, another convolver such as an AE convolver may be used.

Further, in the above-mentioned first to third embodiments, the structure in which the convolution output is taken out from one position of the output electrode 5 is shown, but the structure in which the convolution output is taken out from a plurality of positions of the output electrode 5 and combined. It may be one.

Further, in the above-mentioned Examples 1 to 3, the shape of the input electrode finger is shown as a linear shape, but in order to focus the surface acoustic wave excited by the input electrode on the output electrode side, it may be formed in a substantially arc shape. Good. Further, the electrode finger of the input electrode may be a split electrode (double electrode). By using the split electrode, it is possible to suppress the reflection of the surface acoustic wave inside the electrode and further improve the characteristics of the element.

[Fourth Embodiment] FIG. 4 is a block diagram showing an example of a communication system using the surface acoustic wave device as described above. In the figure, reference numeral 40 denotes a transmitting device. The transmitter 40 spread-spectrum modulates a signal to be transmitted using a spread code and transmits the signal from an antenna 401. The transmitted signal is received by the receiving device 41 and demodulated. The receiving device 41 includes an antenna 411, a high frequency signal processing unit 412, a synchronizing circuit 413, a code generator 414,
It comprises a spread demodulation circuit 415 and a demodulation circuit 416.
The reception signal received by the antenna 411 is filtered and amplified by the high-frequency signal processing unit 412, and is output as it is as the transmission frequency band signal or as an appropriate intermediate frequency band signal. The signal is input to the synchronizing circuit 413.

The synchronizing circuit 413 is a surface acoustic wave device 4131 shown in the embodiment of the present invention, and a modulating circuit 4132 for modulating the reference spread code input from the code generator 414.
And a signal processing circuit 4 that processes the signal output from the surface acoustic wave device 4131 and outputs a spread code synchronization signal and a clock synchronization signal for the transmission signal to the code generator 414.
It consists of 133. An output signal from the high frequency signal processing unit 412 and an output signal from the modulation circuit 4132 are input to the surface acoustic wave device 4131 to the surface acoustic wave device via input side external circuits such as a filter, an amplifier and a matching circuit, A convolution operation of two input signals is performed. Here, assuming that the reference spreading code input from the code generator 414 to the modulation circuit 4132 is a code obtained by time-reversing the spreading code transmitted from the transmitting side, in the surface acoustic wave device 4131 using the surface acoustic wave convolver element. A correlation peak is output when the synchronization-specific spreading code component and the reference spreading code included in the received signal match on the output electrode of the surface acoustic wave device 4131. Next, the signal processing circuit 4
In 133, the correlation peak is detected from the signal input from the surface acoustic wave device 4131, the deviation amount of the code synchronization is calculated from the time from the code start of the reference spreading code to the correlation peak output, and the code synchronization signal and the clock are generated. The signal is output to the code generator 414.

After the synchronization is established, the code generator 414 generates a spread code having the same clock and spread code phase as the spread code on the transmitting side. This spreading code is a spreading demodulation circuit 41.
The signal before being input to the signal 5 and subjected to spread modulation is restored.
Since the signal output from the spread modulation / demodulation circuit 415 is a signal that has been modulated by a modulation method such as so-called amplitude modulation, frequency modulation, phase modulation, etc., data demodulation is performed by the applicable demodulation circuit 416.

Surface acoustic wave device 4131 used in this configuration
Uses the configuration described in any one of the first to third embodiments, can suppress mixing of the input signal component into the output signal, and can reduce the noise floor of the convolution waveform. Therefore, the convolution output signal can be easily detected, and a highly reliable communication system capable of accurately performing synchronization promotion can be obtained.

[Fifth Embodiment] FIGS. 5 and 6 are block diagrams showing an example of a transmitter and a receiver of a communication system using the surface acoustic wave device as described above. In FIG. 5, which shows a block diagram of a transmission device, 501 is a serial-parallel converter that converts serially input data into n pieces of parallel data, and 502-1 to n are parallelized data and spread code generators. A group of multipliers for multiplying the n spreading codes output from 503 by n different spreading codes PN
1 to PNn and a spreading code generator for generating a spreading code PN0 dedicated to synchronization, and 504 adds the spreading code PN0 dedicated to synchronization output from the spreading code generator 503 and n outputs of the multiplier groups 502-1 to 502-1. 505 is a high frequency stage for converting the output of the adder 504 into a transmission frequency signal,
6 is a transmitting antenna.

Further, in FIG. 6 showing a block diagram of the receiving apparatus, 601 is a receiving antenna, 602 is a high frequency signal processing section, 603 is a synchronizing circuit for capturing synchronization with the spread code and clock on the transmitting side and maintaining synchronization tracking, Reference numeral 604 is a spread code generator for generating n + 1 spread codes and reference spread codes, which are the same as the spread code group on the transmission side, in response to the code synchronization signal and clock signal input from the synchronization circuit 603,
Reference numeral 05 is a carrier reproduction circuit for reproducing a carrier signal from the carrier reproduction spread code PN0 output from the spread code generator 604 and the output of the high frequency signal processing unit 602, and 606 is the output of the carrier reproduction circuit 605 and the high frequency signal processing unit 602.
Of the baseband demodulation circuit 6 and the output of the spreading code generator 604 using the n spreading codes PN1 to PNn.
It is a parallel-to-serial converter that performs parallel-to-serial conversion of n pieces of parallel demodulated data output from 06.

In the above configuration, on the transmitting side, the input data is first converted into n parallel data equal to the number of code division multiplexes by the serial-parallel converter 501. On the other hand, the spreading code generator 503 has the same code period and generates n + 1 different spreading codes PN0 to PNn.
Of these, PN0 is dedicated to synchronization and carrier reproduction, is not modulated by the parallel data, and is directly input to the adder 504. The remaining n spread codes PN1 to PNn are modulated by n parallel data in the multiplier groups 502-1 to 50n and input to the adder 504. The adder 504 linearly adds the n + 1 input signals and outputs the added baseband signal to the high frequency stage 505. Subsequently, the baseband signal is converted into a high-frequency signal having an appropriate center frequency in the high-frequency stage 505 and transmitted from the transmission antenna 506.

Next, on the receiving side, the signal received by the receiving antenna 601 is appropriately filtered and amplified by the high frequency signal processing unit 602, and is output as it is as a transmission frequency band signal or as an appropriate intermediate frequency band signal. It The signal is input to the synchronization circuit 603. The synchronization circuit 603 processes the signals output from the surface acoustic wave device 6031 and the modulation circuit 6032 for modulating the reference spread code input from the code generator 604 and the surface acoustic wave device 6031 described in the embodiment of the present invention. , A signal processing circuit 6033 for outputting a spread code synchronization signal and a clock synchronization signal for the transmission signal to a spread code generator 604.

As the surface acoustic wave device 6031, any one of the surface acoustic wave devices shown in the first to third embodiments is used, and the signal from the high frequency signal processing section 602 and the modulation circuit 60 are used.
The signal from 32 is input, and the convolution operation of two input signals is performed. Here, assuming that the code sequence of the reference spreading code input from the code generator 604 to the modulation circuit 6032 is a time-reversed code sequence of the synchronization-only spreading code transmitted from the transmitting side, the surface acoustic wave device 6031
A correlation peak is output when the code string of the synchronization-specific spreading code component and the code string of the reference spreading code included in the received signal match on the output electrode of the surface acoustic wave device 6031.

Next, the signal processing circuit 6033 detects the correlation peak from the signal output from the surface acoustic wave device 6031, and shifts the code synchronization from the time from the code start of the reference spreading code to the correlation peak output. The amount is calculated, a code synchronization signal and a clock signal are generated, and output to the spread code generator 604.

After the synchronization is established, the spreading code generator 604 generates a spreading code group in which the clock and the spreading code phase match with the spreading code group on the transmitting side. Of these code groups, the spread code PN0 dedicated to synchronization is input to the carrier reproduction circuit 605. The carrier reproduction circuit 605 despreads the reception signal converted to the transmission frequency band or the intermediate frequency band which is the output of the high frequency signal processing unit 602 by the synchronization-dedicated spreading code PN0, and reproduces the carrier wave in the transmission frequency band or the intermediate frequency band. .

The carrier reproducing circuit 605 is constructed by using, for example, a circuit utilizing a phase locked loop. The received signal and the synchronization-dedicated spreading code PN0 are multiplied by the multiplier. After the synchronization is established, the clock and code phase of the synchronization-specific spreading code in the received signal and the reference-specific synchronization-specific spreading code PN0 match, and the transmission-side synchronization-specific spreading code is not modulated with data. Is despread at, and a carrier component appears at the output. The output is then input to a bandpass filter, and only the carrier component is extracted and output. The output is then input to a well-known phase-locked loop consisting of a phase detector, a loop filter and a voltage controlled oscillator, and a phase is applied to a carrier component output from the voltage controlled oscillator through a bandpass filter. The locked signal is output as a reproduced carrier wave.

The reproduced carrier wave is input to the baseband demodulation circuit 606. The baseband demodulation circuit 606 generates a baseband signal from the reproduced carrier wave and the output of the high frequency signal processing unit 602. The baseband signal is divided into n pieces and despreaded for each code division channel by the spreading code groups PN1 to PNn output from the spreading code generator 604, and subsequently data demodulation is performed. The parallel demodulated n demodulated data is converted into serial data by the parallel-serial converter 607, and the signal input to the transmission device is output.

As the surface acoustic wave device used in this embodiment,
By using the surface acoustic wave device according to any one of the first to third embodiments, it is possible to easily obtain a convolution output signal and obtain a highly reliable receiving device.

Although the present embodiment is a case of binary modulation, other modulation methods such as quadrature modulation may be used.

[0068]

As described above, according to the present invention, the input side external circuit 10 including at least a part or all of the impedance matching circuit, the filter, and the amplifier.
In the output side external circuit 11 composed of a and 10b and at least part or all of the impedance matching circuit, the filter and the amplifier, at least a part of the input side external circuit or the output side external circuit is arranged in the package. As a result, the input signal component can be prevented from being mixed into the output signal, so that the noise floor of the convolution waveform is reduced, and a surface acoustic wave device in which the convolution output can be easily detected can be obtained.

Further, on the substrate arranged in the package,
By disposing at least a part of the input-side external circuit or the output-side external circuit and the piezoelectric substrate, it becomes easy to determine the position where the bonding wire is connected, and the yield is improved.

Further, by covering at least a part of the input side external circuit or the output side external circuit housed in the package with a conductive material, it is possible to suppress the mixing of the input signal component into the output signal. Better and easier to detect the convolution output signal.

Furthermore, by using the surface acoustic wave device which suppresses the mixing of the input signal component into the output signal and can easily detect the convolution output in the communication system, a highly reliable communication system can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic plan view showing a first embodiment of a surface acoustic wave device according to the present invention.

FIG. 2 is a schematic plan view showing a second embodiment of the surface acoustic wave device according to the present invention.

FIG. 3 is a schematic plan view showing a third embodiment of the surface acoustic wave device according to the present invention.

FIG. 4 is a block diagram showing an example of a communication system using the surface acoustic wave device of the present invention.

FIG. 5 is a block diagram showing an example of a transmitter of a communication system using the surface acoustic wave device of the present invention.

FIG. 6 is a block diagram showing an example of a receiver of a communication system using the surface acoustic wave device of the present invention.

FIG. 7 is a circuit diagram showing an example of an impedance matching circuit.

FIG. 8 is a schematic plan view showing a conventional surface acoustic wave device.

[Explanation of symbols]

1 Y-cut (Z propagation) piezoelectric substrate such as lithium niobate 2, 3 Comb-shaped input electrodes formed on the surface of the piezoelectric substrate 1 4a, 4b Input bonding wire 5 Output electrode formed on the surface of the piezoelectric substrate 1 Output Bonding wire 7a, 7b Input lead pin 8 Output lead pin 9 Package stem 10a, 10b Input side external circuit 11 Output side external circuit 14 Mounting board 20 Board mounted on the package stem 23 Conductive material covering output side external circuit 40 Transmitting device 401 Transmitting antenna 41 Receiving device 411 Receiving antenna 412 High frequency signal processing unit 413 Synchronizing circuit 414 Code generator 415 Spreading demodulating circuit 416 Demodulating circuit 501 Directly converting data input in series into n parallel data Parallel converter 502-1 to n Multiplier group 503 Spreading Code generator 504 Adder 505 High frequency stage 506 Transmission antenna 601 Reception antenna 602 High frequency signal processing unit 603 Synchronization circuit 604 Spreading code generator 605 Carrier regeneration circuit 606 Baseband demodulation circuit 607 Parallel / serial converter

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takahiro Hachisu 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Akihiro Koyama 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Incorporated (72) Inventor Akira Torizawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (9)

[Claims] 1. A piezoelectric substrate having at least two input electrodes for exciting first and second surface acoustic waves, and the first and second surface acoustic waves excited from the input electrodes are directed in mutually opposite directions. A package for accommodating a surface acoustic wave element having an output electrode also serving as a waveguide for extracting a convolution signal of the two surface acoustic waves generated by the nonlinear effect of the piezoelectric substrate, and at least an impedance matching means and a signal. An input side external circuit composed of a part or all of the amplifying means and the frequency band limiting means, and an output side composed of at least an impedance matching means, a signal amplifying means and a part or all of the frequency band limiting means. In a surface acoustic wave device including an external circuit, a small amount of the input side external circuit or the output side external circuit is provided inside the package. A surface acoustic wave device having a structure in which at least a part thereof is arranged. 2. The structure according to claim 1, wherein a substrate is provided inside the package, and at least a part of the input side external circuit or the output side external circuit is arranged on the substrate. Surface acoustic wave device. 3. The structure according to claim 1, wherein the surface acoustic wave element and at least a part of the input side external circuit or the output side external circuit are arranged on the same surface of the substrate. The surface acoustic wave device described. 4. The surface acoustic wave device according to claim 1, wherein the input side external circuit or the output side external circuit arranged inside the package is covered with a conductive material. . 5. The conductive material is at least one of a metal, a conductive resin mold, a conductive film, a non-metal coated with a conductive film, or a conductive rubber.
5. The surface acoustic wave device according to claim 4, wherein one of them is used. 6. The impedance matching means is configured by a part or all of an inductance element, a capacitor element, and a resistance element, according to claim 1. Surface acoustic wave device. 7. The surface acoustic wave device according to claim 1, wherein the signal amplifying unit is a high frequency amplifier. 8. The surface acoustic wave device according to claim 1, wherein the frequency band limiting unit is one of a low pass filter, a high pass filter, and a band pass filter. 9. A communication system using the surface acoustic wave device according to claim 1. Description: