JPH09199975A - Surface acoustic wave device, receiver using the same, and communication system - Google Patents

Abstract

(57) Abstract: It is an object to provide a surface acoustic wave device capable of improving isolation (separation) between input and output inside a package. A surface acoustic wave device comprising a surface acoustic wave element having at least one input electrode and at least one output electrode formed on a piezoelectric substrate, and a package for housing the surface acoustic wave element. At least an input signal of a wire for connecting the input electrode of the surface acoustic wave element and the lead terminal for input signal of the package and a wire for connecting the output electrode and the lead terminal for output signal of the package Either one of the power supply wire and the output signal wire is surrounded by a shield member, and the shield member is connected to a reference potential.

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, a receiving device using the same, and a communication system.

[0002]

2. Description of the Related Art A surface acoustic wave device uses surface acoustic waves propagating on the surface of a piezoelectric substrate and is used in many fields as a filter, convolver, etc., and its operating frequency range is from video band to high frequency band. It has spread. However, in the high frequency band, there is a problem in that an input signal sneak into the output terminal due to electromagnetic coupling between the input and output, causing a decrease in the isolation (separation) between the input and the output.

As a solution to this problem, Japanese Patent Laid-Open No. 5-218792 has been proposed.

FIG. 10 shows a conventional example of this type.
It is a back view of the substrate in which the surface acoustic wave device is mounted. In the figure, 31 is a shield frame, 32 is a mounting substrate, 3
3 is a surface acoustic wave device input lead terminal, 34 is a surface acoustic wave device input conductive pattern, 35 is a surface acoustic wave device output lead terminal, 36 is a surface acoustic wave device output conductive pattern, and 37.
a and 37b are lead terminals for grounding the surface acoustic wave device, and 38
Is a shield plate, and 39 is a conductive pattern for grounding.

Of the lead terminals of the surface acoustic wave device mounted on the mounting board 32, ground lead terminals 37a, 37.
Conductive pattern 3 for grounding of the mounting substrate 32 connected to b
9 is arranged so as to cross the input / output lead terminals 33 and 35 of the surface acoustic wave device. Further, the shield plate 38 is arranged directly above the grounding conductive pattern 39 arranged between the input / output lead terminals, and is connected to the grounding conductive pattern 39 by using a solder, so that the input signal is spilled to the output terminal. By pressing down, the isolation between input and output (separation and insulation) is improved.

As described above, in the surface acoustic wave device, attention is paid to the isolation between the input and the output because the output level is extremely low compared to the input signal level.
This is to prevent the input signal from being spatially directly guided and transmitted to the output signal.

[0007]

However, the surface acoustic wave device having the above-described structure has a problem in that it is not possible to suppress the sneak to the output terminal side due to the input signal generated inside the package used as the holding member.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a surface acoustic wave device capable of improving isolation (separation) between input and output inside a package.

According to the present invention, the above object is to provide a surface acoustic wave element and a package for housing the surface acoustic wave element,
An input signal wire for connecting the input electrode of the surface acoustic wave element and an input signal lead terminal of the package, and an output signal for connecting the output electrode and the output signal lead terminal of the package. In a surface acoustic wave device including a wire for use, at least one of the input signal wire and the output signal wire is surrounded by a shield member, and the shield member is connected to a reference potential. It

[0010]

According to the above-mentioned structure of the present invention, it is possible to suppress the mixing of the input signal component into the output signal by using the shielding member, so that the unwanted wave wraps around due to the electromagnetic coupling generated between the input / output signal wires. Can be suppressed and the isolation between input and output can be improved.

[0011]

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

[First Embodiment] FIG. 1 is a schematic view showing a first embodiment of a surface acoustic wave device according to the present invention. In this embodiment, a case where a surface acoustic wave convolver element is used as the surface acoustic wave element is given as an example. In the figure, 1 is a piezoelectric substrate made of Y-cut Z-propagation 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.
Is an input signal wire, 5 is an output electrode as a waveguide formed on the surface of the piezoelectric substrate 1, 6 is an output signal wire, and 7 is an output signal wire.
a and 7b are input lead pins as input connection electrodes,
Reference numeral 8 is an output lead pin as an output connection electrode, 9 is a stem, and 10 is a shield member.

In practice, the conductor stem 9 has a sealing cap on the upper part and is used in a state of being hermetically sealed with the stem 9, but the sealing cap is omitted in the drawing.

The input / output electrodes 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.

Further, the comb-shaped input electrodes 2 and 3 and the input lead pins 7a and 7b are electrically connected by the input signal wires 4a and 4b. Similarly, the output electrode 5 and the output lead pin 8 are electrically connected by the output signal wire 6.

The shield member 10 is connected to the reference potential on the stem 9 using solder or the like. Examples of the material of the shielding member 10 include a metal, a conductive resin mold, a conductive film, a non-metal body coated with a conductive film, and a conductive rubber.

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 silicone resin, an epoxy resin, a phenol resin, 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 a copper foil, a silver foil, an aluminum foil, a 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, 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.

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.

In a surface acoustic wave device using a surface acoustic wave convolver element having a structure as shown in FIG. 1, when an electric signal of carrier angular frequency ω is input to the comb-shaped input electrode 2, the surface acoustic wave is generated by the piezoelectric effect of the substrate. Be excited. Similarly,
When an electric signal having a carrier angular frequency ω is input to the comb-shaped input electrode 3, surface acoustic waves are excited.

These two surface acoustic waves propagate in the opposite directions on the piezoelectric substrate 1 while being confined in the output electrode by the output electrode 5 acting as a waveguide. When these two surface acoustic waves overlap on the output electrode 5, a convolution (angular frequency 2ω) of these two surface acoustic waves occurs 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. The convolution signal generated at the output electrode 5 is taken out of the stem 9 via the wire 6 and the output lead pin 8.

Here, the input signal wires 4a, 4b
Although a part of the signal propagating through is radiated in the air, a shield member 10 is arranged around the output signal wire 6. Since the shield member 10 is connected to the reference potential of the stem 9, electromagnetic coupling between the input / output signal wires is prevented. Therefore, due to the shielding effect, it is possible to suppress unwanted waves from wrapping between the input / output signal wires and improve the isolation between the input and output.

Although the shield member is used for the output signal wire in the above embodiment, it may be used for the input signal wire. Even when used as an input signal wire, the shielding member is connected to the reference potential of the package stem,
Radiation from the input signal wire itself can be suppressed. Further, by applying a shielding member for both the input / output signal wires, it is possible to further suppress the mixing of the input signal with the output signal. Further, by sealing with the sealing cap, it is possible to prevent interfering signals from being mixed from outside the surface acoustic wave device.

[Second Embodiment] FIG. 2 is a schematic view showing a second embodiment of the present invention, in which a bonding wire is used as a shield member. In the figure, the same parts as those in FIG. 1 are designated by the same reference numerals, and the overlapping description will be partially omitted.

In the figure, 11 is a reference potential electrode formed on the piezoelectric substrate 1, and 12 is a reference potential connecting wire. In the figure, the shield member 10 is simplified by reducing the number of bonding wires.

The basic operation of the present invention is the same as that of the previous embodiment described with reference to FIG. 1, and a part of the signal propagating through the input signal wires 4a and 4b is radiated into the air, but the output signal wire. A shield member 10 is arranged around the circumference 6.
Since the shield member 10 is connected to the reference potential of the conductor stem 9 by using the reference potential electrode 11 and the reference potential connection wire 12 formed on the piezoelectric substrate 1, there is no difference between the input / output signal wires. To prevent electromagnetic coupling. Therefore,
Due to the shielding effect, it is possible to suppress unwanted waves from wrapping between the input / output signal wires and improve the isolation between the input and output.

Further, by using the bonding wire as the shield member 10, the shield can be formed at the same time when the input / output wires are bonded, and the working process can be simplified.

In the above-described first and second embodiments, the surface acoustic wave convolver having a structure in which the convolution output signal is taken out from one place of the output electrode as the surface acoustic wave element is shown, but the output signals are outputted from a plurality of places. It may have a structure for taking out.

Although an elastic convolver is used as the surface acoustic wave element, another convolver such as an AE convolver may be used.

[Third Embodiment] FIG. 3 is a schematic view showing a third embodiment of the surface acoustic wave device according to the present invention. In the figure, the same parts as those in FIG. 1 are designated by the same reference numerals, and the overlapping description will be partially omitted.

In this embodiment, a surface acoustic wave matched filter element is used as the surface acoustic wave element.
And different.

Also in this embodiment, the input electrode 2 and the input lead pin 7 are electrically connected by the input signal wire 4. Similarly, the output electrode 5 and the output lead pin 8
Are electrically connected by the output signal wire 6. Although a part of the signal propagating through the input signal wire 4 is radiated into the air, a shield member 10 is arranged around the output signal wire 6. The shield member 10 is a stem 9
Since it is connected to the reference potential of, the electromagnetic coupling between the input / output signal wires is prevented. Therefore, due to the shielding effect, it is possible to suppress unwanted waves from wrapping between the input / output signal wires and improve the isolation between the input and output.

Examples of the material of the shield member 10 include metals, conductive resin molds, conductive films, non-metals coated with a conductive film, and conductive rubbers.

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 silicone 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 a copper foil, a silver foil, an aluminum foil, a 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, insulating materials such as plastic, silicon resin, epoxy resin, phenol resin, polyester resin, 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.

As the conductive rubber, for example, a conductive filler such as a silicon rubber, a silver filler, a silver-plated copper filler, a silver-plated aluminum filler, or a silver-plated glass filler is used. What was filled with can be used.

Although the shield member 10 is arranged around the output signal wire 6 in this embodiment, the shield member 10 may be arranged around the input signal wire. Alternatively, they may be arranged around both the input and output wires.

In the above-described first to third embodiments, the shield member 10 is arranged around the output signal wire 6, but the shield member 10 includes the input signal wire 4a,
You may arrange | position around 4b, 4. Alternatively, they may be arranged around both the input and output wires.

That is, no matter what surface acoustic wave element is used, at least one of the input signal wire and the output signal wire is surrounded by a shield member, and the shield member is surrounded by a reference potential. The structure connected to is not limited to the embodiment but belongs to the technical scope of the present invention.

Further, in each of the above embodiments, the case where the surface acoustic wave convolver element or the surface acoustic wave matched filter element is used is shown, but when the surface acoustic wave element is used in a band pass filter, a delay line, etc. ,
To prevent the input signal from mixing with the output signal,
Of course, the present invention may be applied.

[Fourth Embodiment] FIG. 4 is a block diagram showing an example of a communication system using the surface acoustic wave device as shown in the first or second embodiment.

In the figure, reference numeral 100 indicates a transmitter. The transmitting apparatus 100 performs spread spectrum modulation on a signal to be transmitted using a spread code and transmits the signal from an antenna 1001. The transmitted signal is received by the receiving device 101 and demodulated. The receiving device 101 includes an antenna 1011, a high frequency signal processing unit 1012, a synchronization circuit 1013, a code generator 1014, a spread demodulation circuit 1015, and a demodulation circuit 1016.

The reception signal received by the antenna 1011 is filtered and amplified within a predetermined band by the high frequency signal processing unit 1012, and is output as it is as a transmission frequency band signal or as an appropriate intermediate frequency band signal. . The signal is input to the synchronization circuit 1013.

The synchronizing circuit 1013 is the first circuit of the present invention.
Alternatively, the surface acoustic wave device 10131 shown in the second embodiment.
A modulation circuit 10132 for modulating the reference spread code input from the code generator 1014, and the surface acoustic wave device 10.
The signal output from 131 is processed, and the spread code signal and the clock synchronization signal for the transmission signal are processed by the code generator 10.
It is composed of a signal processing circuit 10133 which outputs the signal to the circuit 14. An output signal from the high frequency signal processing unit 1012 and an output signal from the modulation circuit 10132 are input to the surface acoustic wave device 10131, and the convolution operation of two input signals is performed. Here, assuming that the reference spreading code input from the code generator 1014 to the modulation circuit 10132 is a code obtained by time-reversing the spreading code transmitted from the transmitting side, in the surface acoustic wave device 10131 using the surface acoustic wave convolver element. A correlation peak is output when the synchronization dedicated spread code component included in the received signal and the reference spread code from the modulation circuit 10132 match on the waveguide of the output electrode of the surface acoustic wave device 10131.

At this time, since the output wire is shielded by the shield member, it is 10 ^{−5 with} respect to the input signal level.
Since it is possible to suppress / prevent the input signal from being mixed into the correlation peak signal having a low level of about -10 ^-6, the removal ratio of the noise component mixed in the correlation peak signal can be improved and a stable correlation peak signal can be obtained. can get. Therefore, the correlation peak signal can be detected to accurately capture the synchronization.

Next, the signal processing circuit 10133 detects the correlation peak from the signal input from the surface acoustic wave device 10131, calculates the deviation amount of the code synchronization according to the signal level of the correlation peak, and calculates the code synchronization signal. And the clock signal is output to the code generator 1014. At this time, the negative feedback loop composed of the surface acoustic wave device 10131, the signal processing circuit 10133, the code generator 1014, and the modulation circuit 10132 convolves the synchronization-dedicated spreading code component from the high-frequency signal processing unit 1012. Since the level of the output signal is high with respect to the noise component, a stable synchronization loop can be established at high speed and synchronization can be ensured.

After the synchronization is established, the code generator 1014 generates a spreading code in which the clock and the spreading code phase match with the spreading code on the transmitting side. This spreading code is a spreading demodulation circuit 1
The signal before input to 015, multiplied by the spread code component dedicated to synchronization from the high frequency signal processing unit 1012, and the signal before spread modulation is restored. Since the signal output from the spread modulation / demodulation circuit 1015 is a signal that has been modulated by a modulation method such as so-called frequency modulation or phase modulation, data demodulation is performed by the corresponding demodulation circuit 1016.

[Fifth Embodiment] FIGS. 5 and 6 show the first and second embodiments.
It is a block diagram which shows an example of a transmitter and a receiver of a communication system using the surface acoustic wave device described in the second embodiment.

In FIG. 5 showing a block diagram of the transmitting apparatus, 1101 is a serial-parallel converter for converting serially input data into n parallel data, and 1102-1 to 110-n are parallelized data and spread data. A multiplier group 1103 for multiplying with n spread codes output from the code generator, a spread code generator 1103 for generating n different spread codes PN1 to PNn and a spread code PN0 dedicated to synchronization, and 1104 for spread. Spreading code PN for synchronization output from code generator 1103
0 is an adder for adding n outputs of the multiplier groups 1102-1 to n, 1105 is a high frequency stage for converting the output of the adder 1104 into a transmission frequency signal, and 1106 is a transmission antenna.

Further, in FIG. 6 showing a block diagram of the receiving apparatus, 1201 is a receiving antenna, 1202 is a high frequency signal processing section, 1203 is a synchronizing circuit which captures synchronization with the spread code and clock on the transmitting side and maintains synchronization tracking, 120
4 is the same as the spreading code group on the transmission side, n +, due to the code synchronization signal and the clock signal input from the synchronization circuit 1203.
A spreading code generator for generating one spreading code and a reference spreading code, 1205 is a carrier for reproducing a carrier signal from the carrier reproduction spreading code PN0 output from the spreading code generator 1204 and the output of the high frequency signal processing unit 1202. A reproducing circuit 1206 is an output of the carrier reproducing circuit 1205, an output of the high frequency signal processing unit 1202, and a spread code generator 120.
A baseband demodulation circuit for demodulating the baseband using the n spread codes PN1 to PNn which are the outputs of 4;
A parallel-serial converter 7 parallel-serial converts the n pieces of parallel demodulated data output from the baseband demodulation circuit 1206.

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 1101. on the other hand,
The spreading code generator 1103 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, is not modulated by the parallel data, and has a direct adder 1
It is input to 104. The remaining n spreading codes PN1 to P
Nn is multiplied and modulated by n parallel data in the multiplier groups 1102-1 to 110-n, spreads the occupied frequency band, and is input to the adder 1104. The adder 1104 linearly adds the input n + 1 signals, and
The baseband signal added to 05 is output. The baseband signal is subsequently converted into a high frequency signal having an appropriate center frequency in the high frequency stage 1105, and the transmission antenna 11
It is transmitted from 06.

Next, on the receiving side, the receiving antenna 1201
The signal received at is appropriately filtered and amplified by the high frequency signal processing unit 1202, 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 synchronization circuit 1203. The synchronizing circuit 1203 is the surface acoustic wave device 12 described in the embodiment of the present invention.
031, a modulation circuit 12032 for modulating the reference spreading code input from the code generator 1204, and a signal output from the surface acoustic wave device 12031 are processed to generate a spreading code synchronization signal and a clock synchronization signal for the transmission signal. Signal processing circuit 1203 for outputting to spread code generator 1204
Consists of three.

As the surface acoustic wave device 12031, the surface acoustic wave device provided with any one of the surface acoustic wave convolver elements shown in the first and second embodiments is used. The signal from the high frequency signal processing unit 1202 and the signal from the modulation circuit 12032 are input, and the convolution operation of the two input signals is performed.

Here, the modulation circuit 1 is output from the code generator 1204.
If the code sequence of the reference spreading code input to 2032 is a code sequence obtained by time-reversing the synchronization dedicated spreading code transmitted from the transmitting side, the surface acoustic wave device 12031 has the synchronization dedicated spreading code included in the reception signal. A correlation peak is output when the code string of the component and the code string of the reference spreading code match on the waveguide of the output electrode of the surface acoustic wave device 12031.

Next, the signal processing circuit 12033 detects the correlation peak from the signal output from the surface acoustic wave device 12031, and shifts the code synchronization from the time from the code start of the reference spread 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 1204.

After the synchronization is established, the spreading code generator 1204 generates a spreading code group having the same clock and spreading code phase with respect to the spreading code group on the transmitting side. Of these code groups, the spread code PN0 dedicated to synchronization is the carrier recovery circuit 1205.
Is input to The carrier reproduction circuit 1205 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 1202 by the synchronization-dedicated spreading code PN0, and reproduces the carrier wave in the transmission frequency band or the intermediate frequency band. .

The carrier regenerating circuit 1205 uses, 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 1206. Baseband demodulation circuit 1206
Then, a baseband signal is generated from the reproduced carrier wave and the output of the high frequency signal processing unit 1202. The baseband signal is divided into n pieces and despreaded for each code division channel by the spreading code groups PN1 to PNn which are the outputs of the spreading code generator 1204, and then data demodulation is performed. The demodulated n pieces of parallel demodulated data are converted into serial data by the parallel-serial converter 1207, and the signal input to the transmission device is output.

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

Further, in the above embodiment, an example in which the transmitting device and the receiving device are separately provided as a communication system has been described.
The communication device may be stored in the same package.

[Sixth Embodiment] FIG. 7 is a block diagram showing an example of a communication system using the surface acoustic wave device described in the third embodiment. In the figure, 40 in the upper stage indicates a transmitter. This transmitting apparatus spread-spectrum-modulates a signal to be transmitted using a spread code, and transmits the signal to the antenna 40.
Send from 1. The transmitted signal is received by the receiving device 41, and the transmitted baseband signal is demodulated. The receiving device 41 includes an antenna 411 and a high frequency signal processing unit 41.
2, synchronization circuit 413, code generator 414, spreading demodulation circuit 415, and demodulation circuit 416.

In the receiving device 41, the received signal received by the antenna 411 is appropriately filtered and amplified by the high frequency signal processing section 412 and converted into the transmission frequency band signal or an appropriate intermediate frequency band (IF) signal. And output. The signal is input to the synchronizing circuit 413.

The synchronizing circuit 413 is a surface acoustic wave device 413 using the surface acoustic wave device described in the third embodiment of the present invention.
1 and a signal output from the surface acoustic wave device 4131, and a signal processing circuit 41 that outputs a spread code synchronization signal and a clock synchronization signal for the transmission signal to the code generator 414.
It consists of 33. The surface acoustic wave device 4131 using the SAW matched filter is input as an input signal from the high-frequency signal processing unit 412, and the synchronization-dedicated spread code component included in the received signal and each electrode finger pair of the output electrodes of the surface acoustic wave device 4131. A correlation peak is output when the polarities of the code array match. In this case, the signal level of the correlation peak signal is low with respect to the signal level of this input signal, but since the above-mentioned output wire is shielded by being covered with a shield member,
Since the input signal can be prevented from being mixed in the correlation peak signal, a stable correlation peak signal can be obtained.

The signal processing circuit 4133 detects the synchronizing signal obtained as the correlation peak output from the surface acoustic wave device 4131, reproduces the clock signal, generates the spread code synchronizing signal and the clock signal, and generates the code generator 414. Is output to. After synchronization is established, the code generator 414 generates a spread code whose clock and spread code phase match the spread code on the transmission side. This spread code is output to the spread demodulation circuit 415, and the spread demodulation circuit 415 multiplies the spread code and the output signal of the high frequency signal processing unit 412 to restore the baseband signal before spread modulation. Spread demodulation circuit 4
The signal output from 15 is a signal modulated by a modulation method such as so-called frequency modulation or phase modulation,
Data demodulation is performed by the corresponding demodulation circuit 416.

[Seventh Embodiment] FIGS. 8 and 9 are block diagrams showing an example of a transmitter and a receiver of a communication system using the surface acoustic wave device described in the third embodiment. In FIG. 8, 501 is a serial-parallel converter that converts serially input data into n parallel data, and 502-1 to n are n parallel data and n output from the spread code generator 503. , 503 is a spreading code generator for generating n different spreading codes and a spreading code dedicated to synchronization, and 504 is a spreading code generator 50.
Synchronization-specific spreading code output from No. 3 and multiplier group 502-
An adder for adding n outputs of 1 to n, 505 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. 9, 601 is a receiving antenna, 602 is a high frequency signal processing section, 603 is a synchronizing circuit,
The surface acoustic wave device composed of the SAW matched filter described in the above embodiment is used to capture, track, and maintain the synchronization with the spreading code and the clock on the transmission side. A spreading code generator 604 generates the same n + 1 spreading codes PN and reference spreading code PN0 synchronized with the spreading code group on the transmission side by the code synchronizing signal and the clock signal input from the synchronizing circuit 603. 605 is a spread code generator 60
4, a carrier reproduction circuit for reproducing a carrier signal from the carrier reproduction spread code PN0 and the output of the high-frequency signal processing unit 602; 606, the output of the carrier reproduction circuit 605, the output of the high-frequency signal processing unit 602, and the spread code generator. 6
A baseband demodulation circuit that demodulates a baseband signal using n spread codes PN that are the outputs of 04, and 607 is a parallel series that parallel-serial converts the n pieces of parallel demodulated data that are the outputs of the baseband demodulation circuit 606. It is a converter.

In the above structure, the input data is first converted by the serial-parallel converter 501 into n parallel data equal to the number of code division multiplexes on the transmitting side. On the other hand, the spread code generator 503 generates spread codes PN0 to PNn having n + 1 code periods that are the same but different from each other. Of these, the spreading code PN0 is dedicated to synchronization and carrier reproduction, and is not modulated by the parallel data and is added directly to the adder 50.
4 is input. The remaining n spread codes PN1 to PN are multiplied by n parallel data in the multiplier groups 502-1 to 50n.
It is modulated and input to the adder 504. The adder 504 linearly adds the input n + 1 signals and outputs
The baseband signal added to 05 is output. The baseband signal is subsequently converted into a high frequency signal having an appropriate center frequency in a high frequency stage 505, and a transmission antenna 506 is provided.
Sent by.

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, converted into the transmission frequency band signal or converted into an appropriate intermediate frequency band (IF) signal, and output. To be done. The signal is input to the synchronization circuit 603. Synchronous circuit 6
Reference numeral 03 is a SAW matched filter which is the SAW matched filter described in the above embodiment of the present invention, and a signal output from the surface acoustic wave device 6031 is processed to spread the spread code synchronization signal and the clock synchronization signal with respect to the transmission signal. A signal processing circuit 6033 for outputting to the code generator 604.

The output signal from the high frequency signal processing unit 602 is input to the surface acoustic wave device 6031. Here, in the surface acoustic wave device 6031, a correlation peak is output when the synchronization-specific spreading code component included in the received signal and the polarities of the code arrays of the electrode finger pairs of the output electrodes of the surface acoustic wave device 6031 match. It

In this case, a shield member is provided to prevent signal leakage from the input wire to the input electrode of the surface acoustic wave device 6031 to the output wire. Also, since the package stem is sealed with a sealing cap,
It is possible to prevent noise from being mixed into output signals from inside and outside the surface acoustic wave device 6031, and to make a large difference between the correlation peak level and the noise level. Therefore, accurate synchronization acquisition and synchronization tracking can be stably and reliably performed.

In the signal processing circuit 6033, the correlation peak is detected from the synchronization signal input from the surface acoustic wave device 6031, the transmitted clock signal of the spread code PN0 is regenerated, and the code synchronization signal and the clock signal are generated by the spread code. Bowl 6
It is output to 04.

After the synchronization is established, the spreading code generator 604 generates a spreading code having the same clock and spreading code phase as the spreading code on the transmitting side. The spreading code PN0 dedicated to synchronization of these code groups is input to the carrier reproducing circuit 605. In the carrier reproducing circuit 605, the spread code PN dedicated for synchronization is used.
By 0, the received signal converted to the transmission frequency band or the intermediate frequency band, which is the output of the high frequency signal processing unit 602, is despread and the carrier wave in the transmission frequency band or the intermediate frequency band is reproduced. As the configuration of the carrier reproducing circuit 605, for example, a circuit using a phase locked loop is used. The received signal and the spread code PN0 for synchronization 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 are the same, and the synchronization-specific spreading code PN0 on the transmitting side 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, which locks the phase to the carrier component output from the band-pass filter from the voltage-controlled oscillator. The signal is output as a reproduced carrier.

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 from the carrier reproduction circuit 605 and the output of the high frequency signal processing unit 602. The baseband signal is divided into n pieces and is despread for each code division channel by the spread code groups PN1 to PNn which are the outputs of the spread code generator 604, and then data demodulation is performed as a parallel signal. 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. Further, by using the surface acoustic wave matched filter element in the present communication system, the correlation peak can be directly detected and the structure becomes simple, which is extremely effective for the mobile communication system which is required to be downsized.

[0079]

According to the present invention, a shield member is arranged around at least one of the bonding wires for input or output signals of a surface acoustic wave device, and the shield member is provided with a reference potential of a holding member. By connecting to, it is possible to suppress unwanted waves from wrapping around due to electromagnetic coupling generated between the bonding wires for input / output signals, and improve the isolation between the input and output.

Further, in the receiver and the communication system using the surface acoustic wave device, the noise level of the surface acoustic wave convolver or the surface acoustic wave matched filter is suppressed, and a stable correlation peak is obtained, so that the synchronization signal is captured. And tracking can be secured stably, and a highly reliable communication system can be constructed.

[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 described in the first embodiment or the second embodiment.

FIG. 5 is a block diagram showing an example of a transmitter of a communication system using the surface acoustic wave device described in the first embodiment or the second embodiment.

FIG. 6 is a block diagram showing an example of a receiver of a communication system using the surface acoustic wave device described in the first embodiment or the second embodiment.

FIG. 7 is a block diagram showing an example of a communication system using the surface acoustic wave device described in the third embodiment.

FIG. 8 is a block diagram showing an example of a transmitter of a communication system using the surface acoustic wave device described in the third embodiment.

FIG. 9 is a block diagram showing an example of a receiver of a communication system using the surface acoustic wave device described in the third embodiment.

FIG. 10 is a schematic view showing a conventional surface acoustic wave device.

[Explanation of symbols]

1 piezoelectric substrate 2,3 comb-shaped input electrodes formed on the surface of the piezoelectric substrate 1 4a, 4b input signal wire 5 output electrode formed on the surface of the piezoelectric substrate 1 output signal wire 7a, 7b input lead pin 8 output Lead pin 9 Package stem 10 Shield member 11 Reference potential electrode 12 Reference potential connecting bonding wire 31 Shield frame 32 Mounting board 33 Surface acoustic wave device input lead terminal 34 Surface acoustic wave device input conductive pattern 35 Surface acoustic wave device output lead Terminal 36 Surface acoustic wave device input conductive pattern 37a, 37b Surface acoustic wave device grounding lead terminal 38 Shield plate 39 Grounding conductive pattern 100 Transmitter 1001 Transmitting antenna 101 Receiver 1011 Receiving antenna 1012 High frequency signal processing unit 1013 Synchronous circuit 10 14 code generator 1015 spreading demodulation circuit 1016 demodulation circuit 1101 serial-parallel converter 1102-1 to n for converting data input in series to parallel data 1102-1 to n multiplier group 1103 spreading code generator 1104 adder 1105 high frequency stage 1106 Transmitting antenna 1201 Receiving antenna 1202 High frequency signal processing unit 1203 Synchronizing circuit 1204 Spreading code generator 1205 Carrier reproducing circuit 1206 Baseband demodulating circuit 1207 Parallel / serial converter 40 Transmitter 401 Transmitting antenna 41 Receiver 411 Receiving antenna 412 High frequency signal Processing unit 413 Synchronous circuit 414 Code generator 415 Spreading demodulation circuit 416 Demodulation circuit 501 Serial-parallel converter 502-1 to n for converting data input in series into n parallel data 503 Spreading code generator 50 Adder 505 RF stage 506 transmitting antenna 601 receiving antenna 602 high-frequency signal processing section 603 synchronizing circuit 604 spread code generator 605 carrier reproducing circuit 606 baseband demodulation circuit 607 serializer

(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 Inc. (72) Inventor Akira Torizawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (6)

[Claims] 1. A surface acoustic wave device having at least one input electrode and at least one output electrode formed on a piezoelectric substrate, a package for housing the surface acoustic wave device, and a surface acoustic wave device comprising: Elasticity composed of an input signal wire for connecting the input electrode and the input signal lead terminal of the package, and an output signal wire for connecting the output electrode and the output signal lead terminal of the package In the surface acoustic wave device, at least one of the input signal wire or the output signal wire is surrounded by a shield member,
A surface acoustic wave device, wherein the shielding member is connected to a reference potential. 2. The shield member is made of at least one of a metal, a conductive resin mold, a conductive film, a non-metal coated with a conductive film, and a conductive rubber. The surface acoustic wave device according to claim 1. 3. The surface acoustic wave device according to claim 1, wherein a surface acoustic wave convolver element is used as the surface acoustic wave element. 4. The surface acoustic wave device according to claim 1, wherein a surface acoustic wave matched filter element is used as the surface acoustic wave element. 5. A receiving device comprising the surface acoustic wave device according to claim 3 or 4 as a synchronization detecting element on a receiving side. 6. A communication system using the surface acoustic wave device according to claim 3 or 4 as a synchronization detecting element of a receiving section.