JPH08298435A - Surface acoustic wave convolver device and communication device using the same - Google Patents

Abstract

(57) [Summary] [Purpose] Sufficient migration resistance, good microfabrication of input comb electrodes, no increase in propagation loss due to increase in electrode finger resistance of input comb electrodes, and yield in wire bonding. -Providing a surface acoustic wave convolver device and a communication device using the same, without reducing reliability. [Structure] The first and second piezoelectric elements are formed on the first main surface of the piezoelectric substrate 11.
In the surface acoustic wave convolver device, at least the input electrodes 12 and 13 for exciting the surface acoustic waves and the output electrode 14 for taking out the convolution signal of the two surface acoustic wave signals by utilizing the nonlinear effect, A surface acoustic wave convolver device, wherein at least the output electrode 14 is made of an aluminum alloy containing an impurity metal.

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 convolver device for taking out a convolution signal of two surface acoustic wave signals by utilizing a physical nonlinear effect, and a communication such as a spread spectrum communication system using the same. Regarding the device.

[0002]

2. Description of the Related Art A surface acoustic wave convolver for extracting a convolution signal of two surface acoustic wave signals has been increasing in importance in recent years as a key device for performing spread spectrum communication, and is being actively studied.

FIG. 7 is a schematic view showing a conventional surface acoustic wave convolver device.

In the figure, 111 is a piezoelectric substrate made of Y-cut (Z-propagation) lithium niobate or the like, and 112 and 113 are comb-shaped input electrodes formed on the surface of the piezoelectric substrate 111.

Reference numeral 114 denotes an output electrode formed on the surface of the piezoelectric substrate 111, which also serves as a waveguide for a surface acoustic wave.

These electrodes are formed by the same manufacturing method as other surface acoustic wave devices such as filters and resonators, and are usually made of pure aluminum, and are usually formed directly on the surface of the piezoelectric substrate 111 by using a photolithography technique. It

Here, the width of the output electrode 114 is equal to the width of the input electrode 11.
It is almost equal to the cross width of 2,113.

The mechanism of such convolution is described in detail, for example, in "Shibayama," Application of surface acoustic waves ", Television, 30, 457 (1976)".

The surface acoustic wave convolver device is mounted on a package base made of metal or ceramic with a space on the propagation path of the surface acoustic wave secured, and after being bonded by wires or face-down bonding using bumps, it is reliable. It is hermetically sealed with a cap made of metal or the like to maintain the sex.

A package containing these surface acoustic wave devices is arranged on a printed wiring board such as glass / epoxy together with a convolver peripheral circuit such as a convolver input / output matching circuit, a spread spectrum communication transmitting / receiving circuit, etc. It is used as a wave convolver device and spread spectrum communication device.

When the conventional surface acoustic wave convolver element is used in a communication device using a normal surface acoustic wave convolver (for example, an input power of 10 mW or less), it has low cost and low surface acoustic wave device like other surface acoustic wave devices. In terms of pattern formability, pure aluminum is usually used for the comb-shaped input and output electrodes.

When the power input to the comb-shaped input electrode is not large (for example, the input power is 10 mW or less), it deteriorates with time due to the vibration of the surface acoustic wave in the comb-shaped input electrode.
So-called stress migration was not considered to be a problem.

Further, the output electrode 114 as shown in the conventional example.
Is approximately equal to the crossing width of the input electrodes 112 and 113, and a higher-order surface acoustic wave is excited. For example, the width of the output electrode is four wavelengths of the surface acoustic wave excited from the input electrode. In the convolver element as described above, when the input power (for example, 10 dBm or less) that is used in a communication device using a normal surface acoustic wave convolver, deterioration with time due to the vibration of the surface acoustic wave at the output electrode, so-called stress migration is usually a problem. It was supposed to not.

Further, in a surface acoustic wave device such as a filter or a resonator, in order to improve the migration resistance of the comb-shaped electrode or the resonator, the comb-shaped electrode or the resonator may be formed of an aluminum alloy doped with copper. Thi
n Solid Films 64, (1979) pp9
-15 ”. Further, it is disclosed in Japanese Patent Publication No. 61-4701011 that the migration resistance can be improved by doping aluminum with copper and silicon.

[0015]

However, no study has been made on migration at the output electrode of a surface acoustic wave convolver, and in particular, in order to improve the convolution efficiency, an elastic wave that excites a surface acoustic wave of the 0th mode is generated. No consideration has been given to surface wave convolvers.
As a result of studying migration of a surface acoustic wave convolver, the present inventors have found the following problems. Even with an input power (for example, 10 dBm or less) that is used in a communication device using a normal surface acoustic wave convolver,
Depending on conditions such as the configuration of the convolver element and the bandwidth of the input signal, a standing wave is generated on the output electrode, so that migration occurs at the output electrode and the characteristics of the convolver deteriorate. In a convolver device, migration is more likely to occur at the output electrode than at the input comb electrode. Further, in order to improve the convolution efficiency, by providing a means for converging the surface acoustic wave to the comb-shaped electrode itself or the peripheral portion by an arc-shaped comb-shaped electrode or a multi-strip coupler, the surface acoustic waves are concentrated on the output electrode. In the surface acoustic wave convolver element having a structure, the migration deterioration of the output electrode is remarkable. In particular, when an arc-shaped comb-shaped electrode is used as the input comb-shaped electrode and the width of the output electrode is set to a value in which only the 0th-order mode surface acoustic wave propagates, migration deterioration of the output electrode becomes significant.

When the comb-shaped electrode or the resonator is made of an aluminum alloy containing copper or silicon, 1) In particular, when the comb-shaped electrode fingers or the resonator are several microns or less,
Residues are likely to be generated during etching, which makes microfabrication difficult. 2) The resistivity is large, resulting in a large insertion loss at the comb-shaped electrode. 3) The hardness of the electrode film is large, so that the input electrode and the like are The bondability of wire bonding for inputting an electric signal is deteriorated, and problems such as manufacturing yield and reliability are reduced.

It is an object of the present invention to apply a surface acoustic wave convolver element for applying an input power (for example, 10 dBm or less) to the extent that it is used in a communication device using a normal surface acoustic wave convolver, in particular, an elastic surface on or around the input electrode itself. In a convolver element having a means for converging waves and having an output electrode width such that only the 0th-order surface acoustic wave propagates to the output electrode, the convolver element has sufficient migration resistance, Good workability, no increase in propagation loss due to increase in electrode finger resistance of input comb electrodes,
It is another object of the present invention to provide a surface acoustic wave convolver element, a device, and a spread spectrum communication system using the same, which does not reduce yield and reliability in wire bonding.

[0018]

The above object is to provide a convolver element, in particular, a means for converging a surface acoustic wave on or around the input electrode itself, and to propagate only a zero-order mode surface acoustic wave to the output electrode. In a convolver element having such an output electrode width, it is achieved by forming the output electrode with an aluminum alloy.

According to the above-mentioned means of the present invention, it is possible to provide a highly reliable surface acoustic wave convolver device in which the output electrode has the migration resistance secured.

The above object can also be achieved by forming the output electrode from an aluminum alloy and the input comb-shaped electrode from pure aluminum.

According to the above means of the present invention, since the output electrode is formed of an aluminum alloy, migration resistance is ensured and reliability is high, and the input comb-shaped electrode is formed of pure aluminum. It is possible to provide a surface acoustic wave convolver element that can be easily microfabricated, does not have an increase in propagation loss due to an increase in electrode finger resistance of an input comb-shaped electrode, etc., and has no reduction in yield and reliability in wire bonding.

In order to improve the convolution efficiency of the convolver, the present inventors have studied a surface acoustic wave convolver having an output electrode width that excites a surface acoustic wave of the 0th mode. It was discovered that the output electrode portion is more likely to occur than the input electrode portion.

That is, in a surface acoustic wave convolver used in a normal communication device (for example, an input power of 10 mW or less), pure aluminum is used for an input electrode, especially a comb-shaped electrode having a wide crossing width such as an arc-shaped comb-shaped electrode. However, so-called stress migration in the comb-shaped input electrode does not cause much problem.

[0024]

【Example】

 Example 1 An example of the present invention will be described below.

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

In the figure, 10 is a surface acoustic wave convolver element,
Reference numeral 11 is a piezoelectric substrate made of Y-cut (Z-propagation) lithium niobate or the like, 12 and 13 are comb-shaped input electrodes formed on the surface of the piezoelectric substrate 11, and 14 is an output electrode formed on the surface of the piezoelectric substrate 11. Is.

Reference numeral 15 denotes an output electrode 14 provided on the output electrode 14 and an electrode bonding portion (bonding pad) for electrically extracting an output signal from the output electrode.

In the surface acoustic wave convolver having such a structure, the comb-shaped input electrodes 12 and 13 are
The surface acoustic wave excited from 13 is formed into a substantially arc shape so as to converge on the inlet end of the output electrode 14.

Further, the comb-shaped input electrodes 12 and 13 are formed by an ordinary photolithography method using an aluminum alloy containing 1% by weight of copper formed by a sputtering method.

The output electrode 14 is the input electrode 12,
The surface acoustic wave has a width of approximately two wavelengths of the surface acoustic wave excited by the element 13, and is configured to excite the surface acoustic wave of only the zero-order mode.

The output electrode 14 is formed by an ordinary photolithography method using an aluminum alloy formed by a sputtering method, and is usually formed in the same process as the input electrodes 12 and 13.

The wire bonding pad 15 is usually formed simultaneously with the input electrodes 12 and 13 and the output electrode 14 in the same step.

In the surface acoustic wave convolver device having such a structure, when an input signal is applied to the input comb electrodes 12 and 13, the surface acoustic waves are excited. Here, the input comb-shaped electrodes 12 and 13 are arc-shaped, and the cross width is 10 times the wavelength of the surface acoustic wave excited from the input electrodes 12 and 13.
To 20 wavelengths. Input comb electrode 12,
The surface acoustic wave excited by 13 is converged, and the output electrode 1
It is input from the inlet end portions on both sides of 4. The output electrode 14 has a width of two wavelengths of the surface acoustic wave excited from the input electrodes 12 and 13, and is configured so that the surface acoustic wave of only the 0th-order mode propagates. The surface acoustic waves input from both sides efficiently propagate on the output electrode 14.

Therefore, the surface acoustic wave energy power density from the input comb-shaped electrode portions 12 and 13 is concentrated on the output electrode 14 portion.

Therefore, for pure aluminum, 10d
In a surface acoustic wave convolver element having an output electrode width of four wavelengths or more of the surface acoustic wave wavelength, which is excited by a higher-order surface acoustic wave of Bm or less as shown in the related art, migration does not occur. Even if the input power does not exist, the convolution characteristics deteriorate due to migration, but migration resistance can be improved by using an aluminum alloy.

Although the width of the output electrode 14 has a width of two wavelengths of the surface acoustic wave excited from the input electrodes 12 and 13 in the present embodiment, the zero-order width on the output electrode is shown. The electrode width is such that the surface acoustic wave of the mode is excited, that is, the width of the output electrode 14 is equal to that of the input electrode 12,
2 or less of the wavelength of the surface acoustic wave excited from No. 13, and the propagation direction of the surface acoustic wave is parallel to the crystal axis as in the Y-cut (Z propagation) lithium niobate substrate shown in this embodiment. In a substrate in which the surface acoustic wave intensity distribution at the output electrode entrance is symmetrical, the width of the output electrode 14 may be 4 wavelengths or less of the wavelength of the surface acoustic wave excited from the input electrodes 12 and 13. .

In the above embodiment, the input electrodes 12,
Although an example using an arc type is shown as 13, a focusing means such as a parabolic horn waveguide or a multi-strip coupler may be provided between the input electrode and the output electrode as a focusing means for the surface acoustic wave.

Further, the input electrodes 12 and 13 may have a so-called chirp shape in which at least one of the electrode width and the period of the input electrode finger gradually changes.

The width of the output electrode 14 and the input electrode 12,
Also in a convolver element in which the cross width of 13 is almost equal and a surface acoustic wave of a higher order mode is excited, for example, the width of the output electrode is 4 wavelengths or more of the wavelength of the surface acoustic wave excited from the input electrode. Depending on conditions such as the configuration and the bandwidth of the input signal, a standing wave is generated on the output electrode, and migration easily occurs. Therefore, it is effective to use the aluminum alloy for the output electrode 14.

Further, it is obvious that the application of the surface acoustic wave convolver of this embodiment is not limited to the spread spectrum communication device.

Furthermore, it is also obvious that a large input power (10 mW or more) is effective.

[Common Example] In this example, an aluminum alloy in which aluminum is doped with copper has been shown as an aluminum alloy. However, other than copper, silicon, titanium, palladium, nickel, niobium and scandium are also used. One kind of metal such as zinc, zinc, etc. can be used. Further, a multi-component aluminum alloy in which a plurality of the above-mentioned metals are doped into aluminum may be used.

The content of impurities is 0.01 to 5% by weight.
If so, the effect can be obtained.

In the above embodiment, Y-cut (Z propagation) lithium niobate was used for the convolver substrate 11, but 9 ° cut (Z propagation), 128 ° Y cut (X propagation), etc. The lithium niobate may be cut or propagated.

In addition to lithium niobate, a piezoelectric single crystal substrate such as lithium tantalate or lithium borate may be used.

Further, a thin film of zinc oxide, silicon oxide or the like may be formed on a part or all of the piezoelectric single crystal substrate of lithium niobate or the like.

Further, the substrate 11 is not limited to a piezoelectric single crystal such as lithium niobate, but may be a material and structure having a parametric mixing effect, such as a structure in which a piezoelectric film is added on a semiconductor substrate or a glass substrate. I wish I had it.

Further, in the above-mentioned embodiment, by forming the comb-shaped input electrodes 12 and 13 into double electrodes (split electrodes), it is possible to suppress the reflection of the surface acoustic waves at the input electrodes and to improve the characteristics of the device. Can be

Furthermore, although the sputtering method is used as the film forming method in the above-mentioned embodiment, the film forming method is not limited to this, and other film forming methods such as ion beam sputtering, electron beam evaporation, and resistance heating evaporation may be used.

Furthermore, in the above embodiment, after the aluminum alloy film is formed, an annealing treatment may be performed.

Further, in the above embodiment, the input electrode,
By incorporating an undercoating layer such as chromium or titanium in the output electrode, the migration resistance is further improved.

In the above embodiment, the output electrode 14
Although the example in which the number of the output take-out pads 15 is one is shown, the number may be plural.

In the above embodiment, the output electrode 14
And a width of a portion of the electrode joint portion (bonding pad) 15 that electrically takes out an output signal from the output electrode and is in contact with the output electrode 14 is 0.2 to 5 times the wavelength of the surface acoustic wave excited from the input signal. By setting the range, it is possible to prevent the surface acoustic wave from leaking from the output electrode 14 to the electrode bonding portion (bonding pad) 15 and further prevent deterioration of the electrode bonding portion (bonding pad) 15 due to migration.

[Embodiment 2] Another embodiment of the present invention will be described below. FIG. 2 is a schematic view showing another embodiment of the surface acoustic wave device according to the present invention.

In the figure, 10 is a surface acoustic wave convolver element,
Reference numeral 11 is a piezoelectric substrate made of Y-cut (Z-propagation) lithium niobate or the like, 12 and 13 are comb-shaped input electrodes formed on the surface of the piezoelectric substrate 11, and 14 is an output electrode formed on the surface of the piezoelectric substrate 11. Is.

Reference numeral 15 denotes an output electrode 14 provided on the output electrode 14 and an electrode bonding portion (bonding pad) for electrically extracting an output signal from the output electrode.

In the surface acoustic wave convolver having this structure, the comb-shaped input electrodes 12 and 13 are arc-shaped so that the surface acoustic waves excited from the input electrodes 12 and 13 are converged at the inlet end of the output electrode. .

Further, the comb-shaped input electrodes 12 and 13 are formed by a normal photolithography method using pure aluminum formed by a sputtering method.

The output electrode 14 is the input electrode 12,
It has a width corresponding to two wavelengths of the surface acoustic wave excited from 13, and is configured to excite the surface acoustic wave of only the 0th mode.

The output electrode 14 is formed by an ordinary photolithography method using an aluminum alloy containing copper in a weight ratio of 2% formed by a sputtering method.

The wire bonding pad 15 is usually formed in the same process as the output electrode 14.

In the surface acoustic wave convolver element having such a configuration, when an input signal is applied to the input comb electrodes 12 and 13, the surface acoustic waves are excited respectively. Here, the input comb-shaped electrodes 12 and 13 are arc-shaped, and the cross width is 10 times the wavelength of the surface acoustic wave excited from the input electrodes 12 and 13.
To 20 wavelengths. Input comb electrode 12,
The surface acoustic wave excited by 13 is converged, and the output electrode 1
It is input from the inlet end portions on both sides of 4. The output electrode 14 has a width of two wavelengths of the surface acoustic wave excited from the input electrodes 12 and 13, and is configured so that the surface acoustic wave of only the 0th-order mode propagates. The surface acoustic waves input from both sides efficiently propagate on the output electrode.

Therefore, the surface acoustic wave energy power density from the input comb-shaped electrode portions 12 and 13 is concentrated on the output electrode 14 portion.

Therefore, for pure aluminum, 10d
In a surface acoustic wave convolver device having an output electrode width of four wavelengths or more of the wavelength of the surface acoustic wave, which is excited by a higher-order mode surface acoustic wave of Bm or less,
Although the convolution characteristics deteriorate due to migration even with an input power that does not cause migration, migration resistance can be improved by using an aluminum alloy.

The input comb-shaped electrodes 12 and 13 are arc-shaped, and the crossing width has a width corresponding to 10 to 20 wavelengths of the surface acoustic wave excited from the input electrodes 12 and 13. Since it is sufficiently wider than the output electrode, deterioration of convolution characteristics due to migration does not pose a problem even with pure aluminum.

Further, in the embodiment of the present invention, since the input comb-shaped electrodes 12 and 13 are made of pure aluminum, 1) residues are more likely to occur during the etching process compared to aluminum alloys, and especially the comb-shaped electrode fingers and resonances. If the size of the element is less than a few microns, it becomes difficult to perform microfabrication. 2) The resistivity is large, so that the insertion loss in the comb-shaped electrode is large. 3) The hardness of the electrode film is large, and the electrical signal is input to the input electrode. It is possible to avoid problems such as a decrease in the bondability of the wire bonding for inputting, and a decrease in manufacturing yield and reliability.

In this embodiment, the output electrode 14
Although the width of the surface acoustic wave is two wavelengths of the surface acoustic wave excited from the input electrodes 12 and 13, the electrode width is such that the 0th-order surface acoustic wave is excited on the output electrode. That is, the width of the output electrode 14 is equal to that of the input electrode 1
2 or less of the wavelength of the surface acoustic wave excited from Nos. 2 and 13, and the propagation direction of the surface acoustic wave is parallel to the crystal axis as in the Y-cut (Z propagation) lithium niobate substrate shown in this embodiment. In a substrate in which the intensity distribution of the surface acoustic wave at the output electrode entrance is bilaterally symmetric, the width of the output electrode 14 is less than or equal to four wavelengths of the surface acoustic wave excited by the input electrodes 12 and 13. Good.

In the above embodiment, the input electrodes 12, 13 are
As an example, a circular arc type is used as the above, but as a focusing means for the surface acoustic wave, a focusing means such as a parabolic horn waveguide or a multistrip coupler may be provided between the input electrode and the output electrode 14. .

The width of the output electrode 14 and the input electrode 12,
In a convolver element in which the cross width of 13 is almost equal and the surface acoustic wave of a higher order mode is excited, for example, the width of the output electrode 14 is 4 wavelengths or more of the wavelength of the surface acoustic wave excited from the input electrode. Also, depending on the conditions such as the configuration and the bandwidth of the input signal, a standing wave is generated on the output electrode,
Since the migration easily occurs, the output electrode 1
It is effective to make 4 an aluminum alloy.

[Embodiment 3] An embodiment of the present invention will be described below. FIG. 3 is a schematic view showing another embodiment of the surface acoustic wave device according to the present invention.

In this figure, the same members as those in FIG. 2 are designated by the same reference numerals.

Further, an electrode joint portion for electrically extracting an output signal from the output electrode (bonding pad 15 and connecting portion 1 for connecting the bonding pad and the output electrode).
5 ') is made of pure aluminum.

As a result, the hardness of the electrode bonding portion (bonding pad) 15 can be reduced as compared with the case of forming the aluminum alloy, so that the bonding strength with the aluminum or gold bonding wire and the yield can be improved.

Further, in the present embodiment, the output electrode 14
And the width of the portion of the electrode connecting portion 15 'that electrically takes out the output signal from the output electrode and is in contact with the output electrode 14 is 0.2 of the wavelength of the surface acoustic wave excited from the input signals 12 and 13.
By setting the range to 5 times, the surface acoustic wave does not leak from the output electrode 14 to the bonding pad 15, and the electrode bonding portion (bonding pad 15 15) It is possible to prevent deterioration due to migration.

Further, it is obvious that the application of the surface acoustic wave convolver of this embodiment is not limited to the spread spectrum communication device.

Furthermore, even if the input power is large (10 mW or more), it is effective.

[Embodiment 4] FIG. 4 is a block diagram showing an example of a communication system using the surface acoustic wave device described above. In the figure, 40 indicates a transmitter. This transmitter 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 receiver 41 and demodulated. The receiver 41 includes an antenna 411 and a high frequency signal processing unit 41.
2, a synchronization circuit 413, a code generator 414, a spread demodulation circuit 415, and a demodulation circuit 416. Antenna 41
The received signal received at 1 is appropriately 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 synchronization circuit 413 is a surface acoustic wave device 4131 according to the embodiment of the present invention, a modulation circuit 4132 that modulates a reference spread code input from a code generator 414, and a surface acoustic wave device 41.
The signal output from 31 is processed, and the spread code synchronization signal and the clock synchronization signal for the transmission signal are generated by the code generator 4
It is composed of a signal processing circuit 4133 which outputs the signal to the fourteen.

The output signal from the high frequency signal processing unit 412 and the output signal from the modulation circuit 4132 are input to the surface acoustic wave element 4131, and the convolution operation of the two input signals is performed. Here, when 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, the surface acoustic wave device 4131 uses only the synchronization signal included in the reception signal. The spread code component and the reference spread code are the surface acoustic wave device 4
When they match on the waveguide 131, the correlation peak is output. In the signal processing circuit 4133, the surface acoustic wave device 41
The correlation peak is detected from the signal input from the reference numeral 31, the shift amount of the code synchronization is calculated from the time from the code start of the reference spread code to the output of the correlation peak, and the code synchronization signal and the clock signal are sent to the code generator 414. Is output. 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 transmission side.
This spread code is input to the spread demodulation circuit 415, and the signal before spread modulation is restored. Spread modulation / demodulation circuit 415
The signal output from is a signal that is modulated by a commonly used modulation method such as so-called frequency modulation or phase modulation, and thus data demodulation is performed by the demodulation circuit 416 known to those skilled in the art.

[Embodiment 5] 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, reference numeral 501 denotes a serial-parallel converter for converting data input in series into n pieces of parallel data, and 5
02-1 to n are multiplier groups for multiplying each parallelized data and n spread codes output from the spread code generator,
Reference numeral 503 is a spreading code generator that generates n different spreading codes and spreading codes dedicated to synchronization, and 504 is a spreading code dedicated to synchronization output from the spreading code generator 503 and n pieces of multiplier groups 502-1 to 502-1. 505 that adds the outputs of the
Is a high frequency stage for converting the output of the adder 504 into a transmission frequency signal, and 506 is a transmission antenna.

Further, in FIG. 6, 601 is a receiving antenna, 602 is a high frequency signal processing unit, 603 is a synchronizing circuit for capturing and maintaining synchronization with the spread code and clock on the transmitting side, and 604 is a code input from the synchronizing circuit 603. A spreading code generator that generates n + 1 spreading codes and a reference spreading code that are the same as the spreading code group on the transmission side according to the synchronization signal and the clock signal, and 605 is a carrier reproduction spreading code output from the spreading code generator 604. And high-frequency signal processing unit 60
A carrier reproduction circuit for reproducing a carrier signal from the output of 2.
Reference numeral 606 is a baseband demodulation circuit that performs demodulation in the baseband using the output of the carrier reproduction circuit 605, the output of the high frequency signal processing unit 602 and the output of the spread code generator 604, and 607 is baseband demodulation. Circuit 60
6 is a parallel-to-serial converter that performs parallel-to-serial conversion of n pieces of parallel demodulated data, which are the outputs of 6.

In the above configuration, on the transmission side, the input data is first converted by the serial-parallel converter 501 into n pieces of parallel data equal to the number of code division multiplexes. On the other hand, the spreading code generator 503 generates n + 1 pieces of spreading codes PN0 to PNn having the same code period but different from each other. Of these, PN0 is dedicated to synchronization and carrier reproduction, and is directly input to the adder 504 without being modulated by the parallel data. The remaining n spread codes are modulated by n parallel data in the multiplier groups 502-1 to 502-1 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. The baseband signal is subsequently fed to the high frequency stage 5
At 05, it is converted into a high frequency signal having an appropriate center frequency and transmitted from the transmitting antenna 506.

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 the transmission frequency band signal or as an appropriate intermediate frequency band signal. The signal is input to the synchronizing 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.

An output signal from the high frequency signal processing unit 602 and an output signal from the modulation circuit 6032 are input to the surface acoustic wave element 6031, and a convolution operation of the two input signals is performed. Here, if the reference spreading code input from the code generator 604 to the modulation circuit 6032 is a time-reversed code of the synchronization-only spreading code transmitted from the transmitting side, the surface acoustic wave device 6031 includes the received signal. A correlation peak is output when the synchronization-only spreading code component and the reference spreading code match on the waveguide of the surface acoustic wave device 6031.

In the signal processing circuit 6033, the correlation peak is detected from the signal input from the surface acoustic wave device 6031, and the deviation amount of the code synchronization is calculated from the time from the code start of the reference spread code to the correlation peak output. , The code synchronization signal and the clock signal are 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 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 has a structure using a phase locked loop, for example. The received signal and the spread code for synchronization 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 synchronization-specific spreading code match, and the synchronization-specific spreading code on the transmitting side is not modulated with data. It is despread and carrier components appear in its 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 composed of a phase detector, a loop filter and a voltage oscillator, and a signal whose phase is locked to a carrier component output from the band pass filter from the voltage controlled oscillator. Is output as a reproduced carrier wave. The reproduced carrier wave is input to the baseband demodulation circuit 606.

In the base band demodulation circuit, a base band signal is generated from the reproduced carrier wave and the output of the high frequency signal processing section 602. The baseband signal is divided into n pieces and spread code groups PN1 to PN output from the spread code generator 604.
By n, despreading is performed for each code division channel, and then data demodulation is performed. The parallel demodulated n demodulated data are converted into serial data by the parallel-serial converter 607 and output.

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

[0089]

As described above, according to the present invention, a surface acoustic wave convolver element for applying an input power (for example, 10 dBm or less) to the extent of being used in a communication device using a normal surface acoustic wave convolver, particularly, In a convolver device having a means for converging surface acoustic waves on or around the input electrode itself and having an output electrode width such that only the zero-order mode surface acoustic wave propagates to the output electrode, the output electrode is formed of an aluminum alloy. By doing so, a surface acoustic wave convolver element, device, having sufficient migration resistance,
And a spread spectrum communication system using the same can be provided.

Since the output electrode is formed of an aluminum alloy and the input comb-shaped electrode is formed of pure aluminum, the output electrode is formed of an aluminum alloy, so that the migration resistance is secured and the reliability is high.
Moreover, since the input comb electrodes are made of pure aluminum, fine processing is easy, there is no increase in propagation loss due to the increase in electrode finger resistance of the input comb electrodes, and the yield and reliability in wire bonding do not decrease, and the elastic surface A wave convolver device can be provided.

[Brief description of drawings]

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

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

FIG. 3 is a schematic 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 and a receiver 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 transmitter and a receiver of a communication system using the surface acoustic wave device of the present invention.

FIG. 7 is a schematic view showing a conventional example of the present invention.

[Explanation of symbols]

10 Surface Acoustic Wave Convolver Element 11 Piezoelectric Substrate 12, 13 Comb Input Electrode 14 Output Electrode 15 Bonding Output Electrode Pad 110 Surface Acoustic Wave Convolver Element 111 Y-Cut (Z Propagation) Piezoelectric Substrate 112, 113 Piezoelectric Material Comb type input electrode 114 formed on the surface of the substrate 1 Output electrode formed on the surface of the piezoelectric substrate 1 40 Transmitter 401 Transmitting antenna 41 Receiver 411 Receiving antenna 412 High frequency signal processing unit 413 Synchronous circuit 414 Code generator 415 Spread demodulation circuit 416 Demodulation circuit 501 Serial-parallel converters 502-1 to n for converting data input in series into n parallel data 503 Spreading code generator 504 Adder 505 High frequency stage 506 Transmission antenna 601 Receiving antenna 602 High frequency signal processing unit 603 Synchronization circuit 604 Spread code generator 605 Carrier recovery circuit 606 Baseband demodulation circuit 607 Parallel-serial converter

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Akane Yokota, 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Akihiro Koyama 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Incorporated (72) Inventor Tadashi Eguchi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (12)

[Claims] 1. A first and a second surface on a first main surface of a piezoelectric substrate.
Surface acoustic wave convolver device having at least an input electrode for exciting a surface acoustic wave of the above, and an output electrode for taking out a convolution signal of the two surface acoustic wave signals by utilizing a non-linear effect, at least the output electrode The surface acoustic wave convolver device is characterized in that it is made of an aluminum alloy containing an impurity metal. 2. The surface acoustic wave convolver device according to claim 1, wherein the input electrode is made of pure aluminum. 3. The surface acoustic wave convolver device according to claim 1, wherein the impurity metal is at least one of copper, silicon, titanium, palladium, nickel, niobium, scandium, and zinc. . 4. The elasticity according to any one of claims 1 to 3, wherein the width of the output electrode is configured so that surface acoustic waves of substantially only the 0th mode are excited. Surface wave convolver device. 5. The surface acoustic wave convolver device according to claim 1, wherein the input electrode has a shape for focusing a surface acoustic wave on the output electrode. 6. The surface acoustic wave convolver device according to claim 5, wherein the input electrode has a substantially arc shape. 7. The input electrode has a chirp shape in which at least one of electrode width and period of the input electrode finger gradually changes.
The surface acoustic wave convolver device according to the paragraph. 8. A multi-strip coupler or a horn waveguide as a means for converging a surface acoustic wave on the output electrode.
The surface acoustic wave convolver device according to claim 1. 9. The width of the contact portion between the output electrode and the joint for electrically extracting the output signal from the output electrode is 0.2 to 5 of the wavelength of the surface acoustic wave excited from the input signal.
9. The surface acoustic wave convolver device according to claim 1, wherein the surface acoustic wave convolver device has a double range. 10. The surface acoustic wave convolver device according to claim 1, wherein the power applied to the input electrode is approximately 10 mW or less. 11. The surface acoustic wave convolver device according to any one of claims 1 to 10, wherein a joint portion for electrically extracting an output signal from the output electrode is made of pure aluminum. 12. A communication device using the surface acoustic wave device according to claim 1. Description: