JP2010087576A - Surface acoustic wave element, surface acoustic wave apparatus, and communication apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface acoustic wave apparatus for compatibly improving out-band attenuation near a pass band and out-band attenuation more on the high frequency side out of the pass band, and a communication apparatus. <P>SOLUTION: The reference potential bus bar electrode 1a of a first IDT electrode 1 is connected through first connection wiring 30 to the first part 25 of an annular electrode 12 positioned on the extension in a direction along a propagation direction and on the side of the first IDT electrode 1, the reference potential bus bar electrode 3a of a third IDT electrode 3 is connected through second connection wiring 31 to the second part 26 of the annular electrode 12 on the extension in a direction orthogonal to the propagation direction, and the reference potential bus bar electrode 2a of a second IDT electrode 2 is connected through fourth connection wiring 33 to the fourth part 28 separated from the first part 25 by a prescribed interval in a direction from the second part 26 to the first part 25 along the annular ring 12. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a surface acoustic wave element, a surface acoustic wave device such as a surface acoustic wave filter and a surface acoustic wave resonator used in a mobile communication device such as a mobile phone, and a communication device including the surface acoustic wave device.

  Conventionally, a surface acoustic wave filter has been widely used as a frequency selection filter (hereinafter also referred to as a filter) used in an RF stage of a mobile communication device such as a mobile phone or a car phone. In general, characteristics required for a frequency selective filter include various characteristics such as a wide passband, low loss, and high attenuation.

  In addition, Rx filters such as GSM (Global System for Mobile Communications) leak not only the signal wave of the reception frequency but also the second harmonic wave and the third harmonic wave. It is required to secure out-of-band attenuation. However, when the frequency of the third harmonic wave such as PCS (Personal Communication Services) is around 6 GHz, it is difficult to increase the amount of attenuation because electrical interference is likely to occur between the IDT electrodes. Therefore, there is a great demand for increasing the attenuation in a high frequency band such as 6 GHz.

  In response to these required characteristics, a surface acoustic wave filter having a ladder type circuit in which a surface acoustic wave element having an IDT (Inter Digital Transducer) electrode and a reflector electrode for converting an electric signal into a surface acoustic wave is configured in a ladder type is provided. Proposed.

  For example, Patent Document 1 discloses a surface acoustic wave filter in which a ladder type circuit is configured by a plurality of surface acoustic wave elements on a piezoelectric substrate. A technique is disclosed in which an attenuation pole is formed outside the pass band and the amount of attenuation outside the band is improved by adopting a configuration in which an inductor is added in series to the parallel surface acoustic wave element (see Patent Document 1).

  Further, cited document 2 discloses that an impedance element is connected in series to a parallel arm resonator and an attenuation pole is formed outside the pass band, thereby increasing the amount of attenuation outside the band.

Patent Document 3 discloses that an out-of-band attenuation is improved by adding an inductor in series to each of the parallel arm resonators.
JP-A-5-183380 JP-A-10-163808 JP 2004-7250 A

  However, in the conventional technique, it is difficult to adjust the position where the attenuation pole is set, and both the out-of-band attenuation near the passband and the out-of-band attenuation on the higher frequency side outside the passband are improved at the same time. There was a problem that it was difficult.

  Therefore, the present invention has been completed in view of the above-described conventional problems, and the object thereof is to achieve both the out-of-band attenuation near the passband and the out-of-band attenuation on the higher frequency side outside the passband. And obtaining a surface acoustic wave device and a communication device that can be improved.

  The surface acoustic wave element of the present invention is formed on a piezoelectric substrate and a main surface of the piezoelectric substrate, and is arranged in order along the propagation direction of the surface acoustic wave propagating on the main surface of the piezoelectric substrate. A surface acoustic wave device comprising: an IDT electrode; and an annular electrode formed on a main surface of the piezoelectric substrate so as to surround the first to fifth IDT electrodes. Each of the IDT electrodes has a reference potential bus bar electrode, and the reference potential bus bar electrode of the first IDT electrode extends on the direction along the propagation direction and is located on the first IDT electrode side. The reference potential bus bar electrode of the third IDT electrode is connected to the first portion of the electrode via the first connection wiring, and the second potential of the annular electrode on the extension in the direction orthogonal to the propagation direction Connected to the part via the second connection wiring The reference potential bus bar electrode of the fifth IDT electrode has a third connection wiring on a third portion of the annular electrode located on the fifth IDT electrode side on the extension in the direction along the propagation direction. The reference potential bus bar electrode of the second IDT electrode is connected to the second part with the first part sandwiched between the first part and the annular part on the annular electrode. The fourth potential wiring bar bar electrode of the fourth IDT electrode is sandwiched between the third region and the third region, and the third region is sandwiched between the third region and the fourth region. Is connected via a fifth connection wiring to a fifth part on the annular electrode which is separated from the part by a predetermined distance.

  The surface acoustic wave device of the present invention includes the surface acoustic wave element and a mounting substrate on which the surface acoustic wave element is mounted.

  A communication device of the present invention includes at least one of a reception circuit and a transmission circuit having the surface acoustic wave device.

  According to the surface acoustic wave device of the present invention, resonance occurs between the capacitor component of the first to fifth IDT electrodes and the inductor component formed by the connection structure of the first to fifth IDT electrodes and the annular electrode. When the high-frequency attenuation pole appears, the inductor component increases, and the frequency of the high-frequency attenuation pole due to resonance can be adjusted low. As a result, the out-of-band attenuation on the higher frequency side outside the pass band can be increased.

  Further, the surface acoustic wave device of the present invention includes the surface acoustic wave element and a mounting substrate on which the surface acoustic wave element is mounted, thereby increasing the out-of-band attenuation on the higher frequency side outside the pass band. be able to.

  In addition, since the communication device of the present invention includes at least one of the reception circuit and the transmission circuit having the above-described surface acoustic wave device, the cut-off characteristic as the surface acoustic wave filter is improved. An apparatus can be realized.

  Hereinafter, a surface acoustic wave element, a surface acoustic wave device, and a communication device according to an embodiment of the present invention will be described in detail with reference to the drawings. In this embodiment, a resonator type surface acoustic wave filter will be described as an example of a surface acoustic wave device. In the drawings described below, parts having the same configuration are denoted by the same reference numerals. Further, the number of electrodes, the distance between electrodes, and the like, such as the size of each electrode and the distance between the electrodes, are schematically illustrated and do not necessarily match the actual ones.

  FIG. 1 is a perspective view of a surface acoustic wave device according to this embodiment. As shown in the figure, the surface acoustic wave device of this embodiment is mainly composed of a surface acoustic wave element 40 and a mounting substrate 23 on which the surface acoustic wave element 40 is mounted. The entire surface acoustic wave element 40 is covered with the sealing resin 24. In the drawing, the sealing resin 24 is indicated by a dotted line for convenience.

  FIG. 2 is a plan view of the main surface on the mounting surface side of the surface acoustic wave element 40 shown in FIG. The surface acoustic wave element 40 is mainly composed of the piezoelectric substrate 22 and various electrodes formed on the main surface of the piezoelectric substrate 22. More specifically, the first to fifth IDT electrodes 1 to 5, the surface acoustic wave resonator 11, the input signal electrode 8, the output signal electrode 9, the ground electrode 10, the annular electrode 12, and these electrodes and resonators. It is provided with wiring for connecting each other.

  As shown in the enlarged plan view of FIG. 7, the first IDT electrode 1, the second IDT electrode 2, the third IDT electrode 3, the fourth IDT electrode 4, and the fifth IDT electrode 5 Are arranged in order along the propagation direction of the surface acoustic wave propagating on the principal surface of the surface. Each IDT electrode has a configuration including a plurality of electrode fingers extending in a direction orthogonal to the propagation direction and bus bar electrodes 1a to 5a connecting the electrode fingers.

  Reflector electrodes 6 and 7 are disposed on both sides of the first to fifth IDT electrodes. The reflector electrodes 6 and 7 include a plurality of electrode fingers extending long in a direction orthogonal to the propagation direction.

  A surface acoustic wave resonator 11 is disposed between these IDT electrodes and the input signal terminal 8. The surface acoustic wave resonator 11 includes an IDT electrode provided with a plurality of electrode fingers that are long in a direction orthogonal to the propagation direction of the surface acoustic wave, and a reflector electrode disposed on both sides of the IDT electrode. Of the first to fifth IDT electrodes, the first, third, and fifth IDTs and the surface acoustic wave resonator 11 are connected via a wiring pattern.

  An annular electrode 12 is formed so as to surround the first to fifth IDT electrodes 1 to 5, the surface acoustic wave resonator 11, each terminal, and the like.

  FIG. 3 is a plan view showing the main surface (first main surface 23A) of the mounting substrate 23 on the side where the piezoelectric substrate 22 is mounted. The mounting substrate 23 is made of an insulator such as ceramics. On the main surface of the mounting substrate 23, conductor patterns are formed at positions corresponding to various electrodes formed on the mounting surface of the piezoelectric substrate 22. Specifically, an annular conductor pattern 13 that is slightly wider than the annular electrode 22 is formed at a position corresponding to the annular electrode 12 of the piezoelectric substrate 22, and an input signal pad is disposed at a position corresponding to the input signal electrode 8 of the piezoelectric substrate 22. 14 is formed, an output signal pad 15 is formed at a position corresponding to the output signal electrode 9 of the piezoelectric substrate 22, and a ground pad 16 is formed at a position corresponding to the ground electrode 10 of the piezoelectric substrate 22. The input signal pad 14, the output signal pad 15, and the ground pad 16, as shown in the transparent perspective view of FIG. 8, are each provided on the lower surface (second state) of the mounting substrate 23 through through conductors that penetrate the mounting substrate 23 in the thickness direction. The input signal terminal 20, the output signal terminal 21, and the reference potential terminal 19 formed on the main surface 23B) are connected. In the present embodiment, the reference potential is a ground potential, but is not necessarily zero volts.

  Further, a first reference potential penetrating conductor 17 and a second reference potential penetrating conductor 18 indicated by dotted lines in FIG. 3 are formed at predetermined positions immediately below the annular conductor pattern 13. The first reference potential through conductor 17 and the second reference potential through conductor 18 are through conductors that penetrate the mounting substrate 23 in the thickness direction. The first reference potential through conductor 17 and the second reference potential through conductor 18 are respectively connected to a reference potential terminal 19 formed on the lower surface of the mounting substrate 23. The first reference potential through conductor 17 and the second reference potential through conductor 18 are made of, for example, a conductor such as Ag in a through hole that penetrates the first main surface 23A and the second main surface 23B of the mounting substrate 23. It is formed by filling. The diameters of the first reference potential through conductor 17 and the second reference potential through conductor 18 are about 50 to 100 μm. By setting the thickness to about 50 to 100 μm, the electrical and mechanical connection between the annular conductor pattern 13 and the reference potential terminal 19 can be improved.

  In FIG. 2, a dotted line 17 ′ is shown at a position corresponding to the first reference through conductor 17, and a dotted line 18 ′ is shown at a position corresponding to the second reference potential through conductor 18. As shown in FIG. 2, the first reference potential through conductor 17 is formed immediately below the fourth portion 28 of the annular electrode 12 on the extension line in the propagation direction of the surface acoustic wave. On the other hand, the second reference potential penetrating conductor 18 is formed immediately below the fifth portion 29 at a position facing the fourth portion 28 on the extension line in the propagation direction of the surface acoustic wave.

  Next, a connection structure between the reference potential bus bar electrodes 1a to 5a of the first to fifth IDT electrodes 1 to 5 and the annular electrode 12 will be described.

  First, the reference potential bus bar electrode 1a of the first IDT electrode 1 is formed on the first portion 25 of the annular electrode 12 on the extension of the direction along the propagation direction of the surface acoustic wave and on the first IDT electrode 1 side. They are connected via the first connection wiring 30. The reference potential bus bar electrode 3a of the third IDT electrode 3 is connected to the second portion 26 of the annular electrode 12 on the extension in the direction perpendicular to the propagation direction of the surface acoustic wave via the second connection wiring 31. ing. The reference potential bus bar electrode 5a of the fifth IDT electrode 5 is connected to the third portion 27 of the annular electrode 12 on the extension of the direction along the propagation direction of the surface acoustic wave and on the fifth IDT electrode 5 side. 3 connection wirings 32. The reference potential bus bar electrode 2a of the second IDT electrode 2 has a fourth portion on the annular electrode 12 that is spaced apart from the first portion 25 by a predetermined distance with the first portion 25 sandwiched between the second portion 26 and the second potential portion 26. The part 28 is connected via a fourth connection wiring 33. The reference potential bus bar electrode 4a of the fourth IDT electrode 4 has a fifth portion 29 on the annular electrode 12 that is spaced apart from the third portion by a predetermined distance with the third portion interposed between the second portion 26 and the third portion 29. Are connected to each other via a fifth connection wiring 34.

  Since the annular electrode 12 and the reference potential bus bar electrodes 1a to 5a have such a connection structure, an attenuation pole is formed on the high frequency side outside the frequency band, and the band attenuation amount on the high frequency side outside the currency band. Can be increased. This is because the reference potential bus bar electrodes 1 a to 5 a and the annular electrode 12 are connected by the first to fifth connection wirings 30 to 34, thereby comparing the first to fifth connection wirings 30 to 34. This is because a large inductor component appears. In this case, the frequency of the attenuation pole can be adjusted only by the wiring pattern without performing complicated work such as the design change of the IDT electrode intersection width and logarithm, and the influence on the out-of-band attenuation near the passband is reduced. In addition, the out-of-band attenuation on the high frequency side can be increased.

  Here, paying attention to the connection structure of the first and second IDT electrodes 1 and 2 to the annular electrode 12, the first connection wiring for connecting the reference potential bus bar electrode 1 a of the first IDT electrode 1 and the annular electrode 12. 30, the inductor L1 is formed, and the annular electrode 12 between the first part 25 and the fourth part 28, and the fourth part 28 and the reference potential bus bar electrode 2a of the second IDT electrode 2 are connected. The inductor L2 by the loop circuit is formed by capacitive coupling between the fourth connection wiring 33 and the second IDT electrode 2 and the first IDT electrode 1. A high frequency attenuation pole is formed by the resonance of the composite C and the inductor L2 on the loop circuit. The inductor L1 by the connection wiring 30 connecting the first IDT electrode, the reference potential bus bar electrode 1a, and the annular electrode 12, the combined capacitance of the first IDT and second IDT electrodes on the loop circuit, and the inductor L2 cause a plurality of attenuations. When a pole is generated and the combined capacity of the first IDT electrode 1 and the second IDT electrode 2 is sufficiently smaller than the capacity C1 of the first IDT electrode 1, the attenuation characteristic in the vicinity of the pass frequency band is maintained, The high frequency attenuation pole can be moved. As a result, the out-of-band attenuation on the higher frequency side outside the pass band can be increased. In the present embodiment, a similar loop circuit is also formed in the connection structure between the fourth and fifth IDT electrodes 4 and 5 and the annular electrode 12. An equivalent circuit of the above circuit is shown in FIG. The first IDT electrode capacitance corresponds to C1 in FIG. 9, and the combined capacitance of the loop circuit corresponds to C2. The first connection wiring inductor L1 corresponds to L1 in FIG. 9, and the wiring inductor L2 on the loop circuit corresponds to L2 in FIG.

  In the present embodiment, the second, fourth, and fifth connection wirings 31, 33, and 34 each have a three-dimensional wiring structure. For example, the second connection wiring 31 intersects with a wiring pattern that connects the second IDT electrode 2 and the output electrode 9, and an insulating layer 33 is interposed between the two at the intersection. Similarly, the fourth and fifth connection wirings 33 and 34 also realize three-dimensional wiring by sandwiching the insulating layer 33 therebetween. By adopting such a three-dimensional wiring structure, the wiring can be arranged with high density, and the surface acoustic wave element can be miniaturized.

  The first, third, and fifth IDT electrodes 1, 3, and 5 are connected to the input electrode 8, and the fourth and sixth IDT electrodes 4 and 6 are connected to the output electrode 9.

  In addition, the annular electrode 12 of the piezoelectric substrate 22 and the annular conductor pattern 13 of the mounting substrate 23 are connected via a conductive bonding material such as solder, and various electrodes formed on the main surface of the piezoelectric substrate 22 are sealed. is doing.

  Next, a method for manufacturing the surface acoustic wave element 40 and the surface acoustic wave device according to the present embodiment will be described.

  A method of manufacturing the surface acoustic wave device 40 is as follows. First to fifth IDT electrodes 1 to 5, reflector electrodes 6 and 7, annular electrodes 12, input / output electrodes 8 and 9, ground electrode 10, First to fifth connection wirings 30 to 34, a surface acoustic wave resonator 11 and the like are formed. These electrodes and wiring patterns are made of a conductive material such as Al or an Al alloy (Al-Cu type, Al-Ti type), and are formed by a thin film forming method such as a vapor deposition method, a sputtering method, or a CVD method. It is formed by patterning by a photolithography method or the like. The thickness of these electrodes and wiring patterns is, for example, about 0.1 to 0.3 μm.

Next, an insulating film for covering and protecting various electrodes of the IDT electrode is formed. As the material of the insulating film, Si, SiO ₂ , SiN _x , Al ₂ O ₃ or the like can be used. As the film formation method, a sputtering method, a CVD (Chemical Vapor Deposition) method, an electron beam evaporation method, or the like can be used.

  In the IDT electrode and the reflector electrode, the number of electrode fingers ranges from several to several hundreds. Therefore, for the sake of simplicity, these shapes are simplified in the drawing.

  As the piezoelectric substrate 22 of the surface acoustic wave element, 36 ° ± 3 ° Y-cut X-propagation lithium tantalate single crystal, 42 ° ± 3 ° Y-cut X-propagation lithium tantalate single crystal, 64 ° ± 3 ° Y-cut X-propagating lithium niobate single crystal, 41 ° ± 3 ° Y-cut X-propagating lithium niobate single crystal, 45 ° ± 3 ° X-cut Z-propagating lithium tetraborate single crystal has a large electromechanical coupling coefficient and frequency temperature Since the coefficient is small, it is preferable as the piezoelectric substrate 22. Of these pyroelectric piezoelectric single crystals, if the piezoelectric substrate 1 has a significantly reduced pyroelectric property due to solid solution of oxygen defects, Fe, or the like, the reliability of the surface acoustic wave element is good. The thickness of the piezoelectric substrate 1 is preferably about 0.1 to 0.5 mm, for example. If the thickness is less than 0.1 mm, the piezoelectric substrate 23 becomes brittle, and if it exceeds 0.5 mm, the material cost and component dimensions increase, which is not preferable.

  Such a surface acoustic wave element 40 is mounted on a mounting substrate 23 on which an annular conductor pattern 13 corresponding to the annular electrode 12 is formed. The surface acoustic wave element 40 is mounted on the mounting substrate 23 by joining the annular electrode 12 and the annular conductor pattern 13 via a joint such as solder. Finally, a sealing resin 24 that covers the entire surface acoustic wave element 40 is formed. The sealing resin 24 is manufactured by applying a resin material made of, for example, an epoxy resin so as to cover the surface acoustic wave element 40 and curing it. Thus, the surface acoustic wave device as a product is completed.

〔Communication device〕
Since the communication device according to the present embodiment includes at least one of the reception circuit and the transmission circuit having the above-described surface acoustic wave device, the cutoff characteristic of the surface acoustic wave filter can be improved. An excellent communication device can be realized.

  That is, at least one of a receiving circuit and a transmitting circuit is provided, and the surface acoustic wave device is used as a bandpass filter included in these circuits. For example, the transmission signal output from the transmission circuit is put on the carrier frequency by the mixer, the unnecessary signal is attenuated by the band pass filter, and then the transmission signal is amplified by the power amplifier and transmitted from the antenna through the duplexer. A communication device equipped with a transmission circuit capable of receiving signals or receiving a received signal with an antenna, amplifying the received signal that has passed through the duplexer with a low-noise amplifier, and then attenuating an unnecessary signal with a band-pass filter, and a carrier frequency with a mixer Can be applied to a communication apparatus including a receiving circuit that separates a signal from the signal and transmits the signal to a receiving circuit that extracts the signal.

  FIG. 4 is a block circuit diagram showing the communication apparatus of this embodiment. In FIG. 4, a transmission circuit Tx and a reception circuit Rx are connected to an antenna 140 via a duplexer 150. The high-frequency signal to be transmitted is removed from the unnecessary signal by the filter 210, amplified by the power amplifier 220, and then radiated from the antenna 140 through the isolator 230 and the duplexer 150. The high-frequency signal received by the antenna 140 is amplified by the low-noise amplifier 160 through the duplexer 150, the unnecessary signal is removed by the filter 170, re-amplified by the amplifier 180, and converted to a low-frequency signal by the mixer 190. Is done.

  Therefore, if the surface acoustic wave device according to the present embodiment is employed, an excellent communication device with remarkably good sensitivity can be provided.

  Examples of the surface acoustic wave device of the present invention will be described below. A specific example of the surface acoustic wave device shown in FIG. 1 will be described.

IDT electrodes 1 to 5 and reflector electrodes made of an Al (99 mass%)-Cu (1 mass%) alloy on a piezoelectric substrate 22 made of a LiTaO ₃ single crystal with X-propagation of 38.7 ° Y-cut. A surface acoustic wave element having 6 and 7, an annular electrode 11, input / output electrodes 8 and 9, a ground electrode 10, and first to third wiring patterns 30, 31 and 32 were formed. These electrodes and wiring patterns were produced by photolithography using a sputtering apparatus, a reduction projection exposure machine (stepper), and an RIE (Reactive Ion Etching) apparatus.

  First, the piezoelectric substrate 22 was ultrasonically cleaned with acetone, IPA (isopropyl alcohol) or the like to remove organic components. Next, after sufficiently drying the piezoelectric substrate 22 with a clean oven, a metal layer serving as each electrode and wiring pattern was formed. A sputtering apparatus was used for forming the metal layer, and an Al (99 mass%)-Cu (1 mass%) alloy was used as the material of the metal layer. The thickness of the metal layer at this time was about 0.15 μm.

  Next, a photoresist is spin-coated on the metal layer to a thickness of about 0.5 μm, patterned into a desired shape by a reduction projection exposure apparatus (stepper), and an unnecessary portion of photoresist is developed with an alkaline developer by a developing apparatus. Dissolve to reveal the desired pattern. Thereafter, the metal layer was etched by an RIE apparatus, patterning was completed, and a pattern of each electrode constituting the surface acoustic wave element 40 was obtained. The electrode pattern at this time is as shown in FIG. The dimension S1 between the first part 25 and the fourth part 28 and the dimension S2 between the second part 27, the third part 27 and the fifth part 29 were 30 μm.

Thereafter, a protective film made of a SiO ₂ film was formed on a predetermined region of each electrode and wiring pattern by a CVD method. The thickness of the protective film was set to 0.015 μm.

  Thereafter, patterning was performed by photolithography, and the flip-chip window opening portion was etched by an RIE apparatus or the like. Thereafter, a pad electrode having a structure in which a Cr layer, a Ni layer, and an Au layer were stacked was formed on the flip-chip window opening using a sputtering apparatus. The thickness of the pad electrode at this time was 1.0 μm.

Thereafter, the piezoelectric substrate 22 was mounted on the mounting substrate 23 by connecting the annular electrode 12 of the piezoelectric substrate 22 and the annular conductor pattern 13 of the mounting substrate 23 using solder. The first and second reference potential through conductors 17 and 18 of the mounting substrate 23 are connected to the reference voltage terminal 19 formed on the lower surface of the mounting substrate 23. Thereafter, baking was performed in an N ₂ gas atmosphere to complete a packaged surface acoustic wave device.

(Comparative example)
As a sample for the comparative example, a surface acoustic wave device having the configuration shown in FIG. 5 was produced. The method for manufacturing the surface acoustic wave device is the same as in the above embodiment.

  In the surface acoustic wave device 40 of the embodiment, the reference potential bus bar electrodes 1a, 3a, and 5a of the first, third, and fifth IDT electrodes 1, 3, and 5 are connected to the annular electrode 12, whereas FIG. In the surface acoustic wave element of the comparative example shown, the reference potential bus bar electrodes 1a, 3a and 5a of the first, third and fifth IDT electrodes 1, 3 and 5 are connected to the ground electrode 10 instead of the annular electrode 12. ing. Other configurations are the same as those of the surface acoustic wave device of FIG.

  Next, the characteristics of the surface acoustic wave devices of this example and the comparative example were obtained by computer simulation. The operating frequency of the surface acoustic wave device was set to 0 MHz or more and 8000 MHz or less. A graph of frequency characteristics at this operating frequency is shown in FIG. FIG. 6 is a graph showing the frequency dependence of the transmission characteristic (attenuation amount) representing the transmission characteristic of the filter.

  The filter characteristics of the surface acoustic wave device of this example were very good. That is, as compared with the surface acoustic wave device of the comparative example shown by the broken line in FIG. 6, as shown by the solid line in FIG. 6, the out-of-band attenuation of the surface acoustic wave device of the present embodiment at a high frequency near 6 GHz. Was found to be very large.

1 is a perspective view of a surface acoustic wave device according to an embodiment of the present invention. It is a top view of the main surface of the piezoelectric substrate which comprises the surface acoustic wave apparatus shown in FIG. It is a top view of the main surface of the mounting substrate which comprises the surface acoustic wave apparatus shown in FIG. It is a block diagram of the communication apparatus concerning one Embodiment of this invention. It is a top view of the main surface of the piezoelectric substrate which comprises the surface acoustic wave apparatus of a comparative example. It is the simulation result of the passage characteristic about the surface acoustic wave apparatus of an Example, and the surface acoustic wave apparatus of a comparative example. FIG. 2 is an enlarged plan view of an IDT electrode constituting the surface acoustic wave element shown in FIG. 1. FIG. 2 is a transparent perspective view of a mounting board constituting the surface acoustic wave device shown in FIG. 1. FIG. 2 is an equivalent circuit diagram of a connection portion between an IDT electrode and an annular electrode constituting the surface acoustic wave element shown in FIG. 1.

Explanation of symbols

1 to 5: First to fifth IDT electrodes 6, 7: Reflector electrode 8: Input signal electrode 9: Output signal electrode 10: Ground electrode 11: Surface acoustic wave resonators 25 to 29: First to first annular electrodes 5th site | part 30-34: 1st-5th connection wiring

Claims (6)

A piezoelectric substrate;
First to fifth IDT electrodes formed on the main surface of the piezoelectric substrate and arranged in order along the propagation direction of the surface acoustic wave propagating through the main surface of the piezoelectric substrate;
A surface acoustic wave device comprising: an annular electrode formed on a main surface of the piezoelectric substrate so as to surround the first to fifth IDT electrodes;
Each of the first to fifth IDT electrodes has a reference potential bus bar electrode,
The reference potential bus bar electrode of the first IDT electrode has a first connection wiring on a first portion of the annular electrode on the extension of the direction along the propagation direction and on the first IDT electrode side. Connected through
The reference potential bus bar electrode of the third IDT electrode is connected to a second portion of the annular electrode on an extension in a direction orthogonal to the propagation direction via a second connection wiring,
The reference potential bus bar electrode of the fifth IDT electrode has a third connection wiring on a third portion of the annular electrode located on the fifth IDT electrode side on the extension in the direction along the propagation direction. Connected through
The reference potential bus bar electrode of the second IDT electrode is a fourth part on the annular electrode that is spaced apart from the first part by a predetermined distance with the first part between the second part and the second part. Connected through the fourth connection wiring,
The reference potential bus bar electrode of the fourth IDT electrode is a fifth part on the annular electrode that is spaced apart from the third part by a predetermined distance with the third part interposed between the reference part and the second part. A surface acoustic wave element connected to the first via a fifth connection wiring.   2. The surface acoustic wave device according to claim 1, wherein the second connection wiring extends from a reference potential bus bar electrode of the third IDT electrode in a direction orthogonal to the propagation direction. It further comprises an input / output signal terminal formed on the main surface of the piezoelectric substrate,
The surface acoustic wave element according to claim 1, wherein a surface acoustic wave resonator is connected between the input / output signal terminal and the first to fifth IDT electrodes. A surface acoustic wave device according to any one of claims 1 to 3,
A surface acoustic wave device comprising: a mounting substrate on which the surface acoustic wave element is mounted.   The mounting substrate is formed on a first main surface on which the surface acoustic wave element is mounted and is connected to the annular electrode, and on the side opposite to the first main surface of the mounting substrate. The reference potential terminal formed on the second main surface and electrically connected to the annular conductor pattern, and a through conductor connecting the annular conductor pattern and the reference potential terminal are further provided. The surface acoustic wave device described.   A communication device comprising at least one of a reception circuit and a transmission circuit, comprising the surface acoustic wave device according to claim 4.