JP2010011187A - Surface acoustic wave device and communication apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface acoustic wave device that improves both out-band attenuation adjacent to a pass band and that on more high-frequency side outside the pass band, and to provide a communication apparatus. <P>SOLUTION: A first reference potential through conductor 17 is formed right under the first region of a ring electrode 12, and a second reference potential through conductor 18 is formed right under the second region of the ring electrode 12. The reference potential bus bar electrode of a second IDT electrode 2 is connected to a region which is a predetermined distance away from the first region 25 of the ring electrode 12, and the reference potential bus bar electrode of a fourth IDT electrode 4 is connected to a region which is a predetermined distance away from the second region 26 of the ring electrode 12. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a surface acoustic wave device such as a surface acoustic wave filter or 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. The present invention relates to a surface acoustic wave device and a communication device as a surface acoustic wave filter that can be applied to the above.

  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 (radio frequency) 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) not only receive the signal wave (fundamental wave) of the reception frequency but also the second harmonic and third harmonic signals, so the second harmonic and the third harmonic. It is required to secure out-of-band attenuation at the wave frequency. 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 passband and the out-of-band attenuation is improved by a configuration in which an inductor is added in series to a parallel surface acoustic wave element (parallel surface acoustic wave resonator) (Patent Document 1). See).

  Further, in Cited Document 2, an impedance element is connected in series to a parallel arm resonator (parallel surface acoustic wave resonator), and an attenuation pole is formed outside the pass band, thereby increasing the out-of-band attenuation. Is disclosed.

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.

  A surface acoustic wave device according to the present invention includes a piezoelectric substrate and a direction orthogonal to the propagation direction along the propagation direction of the surface acoustic wave propagating on the principal surface of the piezoelectric substrate, which is formed on the principal surface of the piezoelectric substrate. A surface acoustic wave element having three or more odd-numbered IDT electrodes having a plurality of long electrode fingers, an annular electrode formed on the main surface so as to surround the surface acoustic wave element, and a main surface of the piezoelectric substrate A surface acoustic wave including a mounting substrate having a first reference potential through conductor connected to the annular electrode and a second reference potential through conductor connected to the annular electrode. In the apparatus, the first reference potential through conductor is formed immediately below the first portion of the annular electrode on the extension of the propagation direction, and the second reference potential through conductor is an extension of the propagation direction. The first in the annular electrode on top The reference potential bus bar electrode of the central IDT electrode is connected to the third part of the annular electrode on the extension in the direction orthogonal to the propagation direction. The reference potential bus bar electrode of the IDT electrode disposed on one side with respect to the central IDT electrode is opposite to the third portion of the annular electrode and from the first portion. The reference potential bus bar electrode of the IDT electrode, which is connected to a part separated by a predetermined distance and is disposed on the other side with respect to the central IDT electrode, is on the opposite side of the third part of the annular electrode. Thus, the second part is connected to a part away from the second part by a predetermined distance.

  In the surface acoustic wave device, the predetermined distance is preferably 100 μm or more.

  In the surface acoustic wave device, the length of the first connection wiring that connects the reference potential bus bar electrode of the IDT electrode disposed on one side with respect to the central IDT electrode and the annular electrode, and The length of the second connection wiring connecting the reference potential bus bar electrode of the IDT electrode and the annular electrode arranged on the other side with respect to the central IDT electrode is equal to the reference potential bus bar of the central IDT electrode. It is preferable that the length of the third connection wiring that connects the electrode and the third portion of the annular electrode is longer.

  In the surface acoustic wave device described above, an electrode finger that is long in a direction orthogonal to the propagation direction between the surface acoustic wave element and the input signal terminal or between the surface acoustic wave element and the output signal terminal. And a surface acoustic wave resonator having a plurality of IDT electrodes and reflector electrodes each provided on both sides of the IDT electrode and provided with a plurality of long electrode fingers in a direction orthogonal to the propagation direction. Is preferred.

  A communication apparatus according to 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, a high-frequency attenuation pole appears due to resonance between the capacitors of the odd number of IDT electrodes and the inductor of the wiring, and the reference potential bus bar electrode of the central IDT electrode is orthogonal to the propagation direction. By connecting to the third part of the annular electrode that is on the extension in the direction to be increased, the number of inductors in the wiring 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, since the frequency of the attenuation pole can be adjusted by increasing the number of wiring inductors, the out-of-band attenuation on the high frequency side outside the pass band can be increased without greatly affecting the characteristics in the vicinity of the pass band. Thereby, the attenuation amount outside the pass band of the surface acoustic wave filter can be improved even at a high frequency of 6 GHz.

  Since the communication device of the present invention includes at least one of the reception circuit and the transmission circuit having the surface acoustic wave device, the cut-off characteristic of the surface acoustic wave device as the surface acoustic wave filter is improved, and thus the sensitivity is improved. A remarkably good communication device can be realized.

  Hereinafter, 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.

[Surface acoustic wave device]
FIG. 1 is a perspective view of a surface acoustic wave device 102 according to this embodiment. As shown in the figure, the surface acoustic wave device 102 of this embodiment is mainly composed of a piezoelectric substrate 22 and a mounting substrate 23 on which the piezoelectric substrate 22 is mounted. The entire piezoelectric substrate 22 is covered with a 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 piezoelectric substrate 22 shown in FIG. As shown in FIG. 2, the first IDT electrode 1, the second IDT electrode 2, and the third IDT electrode are arranged on the main surface of the piezoelectric substrate 22 along the propagation direction of the surface acoustic wave propagating through the main surface. 3, the 4th IDT electrode 4, and the 5th IDT electrode 5 are arranged in order. Each IDT electrode has a configuration provided with a plurality of electrode fingers extending long in a direction orthogonal to the propagation direction and a bus bar electrode 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. The first to fifth IDT electrodes and the reflector electrodes 6 and 7 constitute a surface acoustic wave element.

  An input signal electrode 8, an output signal electrode 9, and a ground electrode 10 are formed on the main surface of the piezoelectric substrate 22. A surface acoustic wave resonator 11 is disposed between the surface acoustic wave element and the input signal terminal 8. The surface acoustic wave resonator 11 includes an IDT electrode having a plurality of long electrode fingers in a direction orthogonal to the propagation direction of the surface acoustic wave, and arranged on both sides of the IDT electrode. The surface acoustic wave element and the surface acoustic wave resonator 11 are connected in series.

  An annular electrode 12 is formed so as to surround the surface acoustic wave element, the surface acoustic wave resonator 11, each terminal, and the like.

  FIG. 3 is a plan view showing the main surface 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. That is, an annular conductor pattern 13 having a slightly wider width 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 14 is formed at a position corresponding to the input signal electrode 8 of the piezoelectric substrate 22. 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 are input signal terminals 20, output signal terminals 21, and reference signals formed on the lower surface of the mounting board 23 through through conductors that penetrate the mounting board 23 in the thickness direction, respectively. It is connected to the potential terminal 19. In the present embodiment, the reference potential is a ground potential, but is not necessarily zero volts.

  A first reference potential through conductor 17 and a second reference potential through conductor 18 indicated by dotted lines are formed at predetermined positions directly 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 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 formed, for example, by filling a through hole penetrating between the upper and lower main surfaces of the mounting substrate 23 with a conductor made of Ag. 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 with the annular conductor 11 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.

  The first reference potential through conductor 17 is formed immediately below the first portion 25 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 second portion 26 opposite to the first portion 25 on the extension line in the propagation direction of the surface acoustic wave. The reference potential bus bar electrode 3a of the central IDT electrode (third IDT electrode 3) is connected to the first wiring pattern on the third portion 27 of the annular electrode 12 on the extension in the direction orthogonal to the propagation direction of the surface acoustic wave. 30 is connected.

  Further, the reference potential bus bar electrode 2a of the second IDT electrode 2 arranged on one side with respect to the central IDT electrode 3 is a first connection portion that is separated from the first portion 25 of the annular electrode 12 by a predetermined distance. 34 is connected via a second wiring pattern 31. The reference potential bus bar electrode 3a of the third IDT electrode 3 disposed on the other side with respect to the central IDT electrode 3 is a second connection portion separated from the second portion 26 of the annular electrode 12 by a predetermined distance. 35 is connected via a third wiring pattern 32. In other words, the first reference potential through conductor 17 is located between the third portion 27 and the first connection portion 34 in the annular electrode 12, and the third portion 27 and the second portion in the annular electrode 12 are located. The second reference potential through conductor 18 is located between the connection portion 34 and the second reference potential through conductor 18.

  Each of the first, second, and third wiring patterns 30, 31, and 32 has a three-dimensional wiring structure. For example, the first wiring pattern 30 intersects the 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.

  In the surface acoustic wave device according to the present embodiment, the first inductor L1 is routed through the first wiring pattern 30, the third portion 27 to the first portion 25 of the annular electrode 12, and the first reference potential through conductor 17. Is formed. Similarly, a second inductor L <b> 2 is formed by a path of the first wiring pattern 30, the third portion 27 to the second portion 26 of the annular electrode 12, and the second reference potential through conductor 18. In addition, the third inductor L3 is formed by the path of the second wiring pattern 31, the connection portion between the second wiring pattern 31 and the annular electrode 12, the first portion 25 of the annular electrode 12, and the first reference potential through conductor 17. Yes. Further, a fourth inductor L4 is formed by a path of the third wiring pattern 32, the connection portion between the third wiring pattern 32 and the annular electrode 12, the second portion 26 of the annular electrode 12, and the second reference potential through conductor 18. Yes. By providing the first to fourth inductors L1 to L4 in this way, an attenuation pole appears on the high frequency side, and the attenuation on the high frequency side outside the passband can be increased. In this case, the frequency of the attenuation pole can be adjusted only by the wiring pattern without performing complicated work such as adjusting the pitch of the IDT electrode, and the influence on the out-of-band attenuation near the pass band is suppressed to a higher frequency. The out-of-band attenuation on the side can be increased.

  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.

  Further, 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 each IDT electrode is sealed.

  Next, a method for manufacturing the surface acoustic wave device according to this embodiment will be described. First, a surface acoustic wave element including first to fifth IDT electrodes 1 to 5 and reflector electrodes 6 and 7, an annular electrode 12, input / output electrodes 8 and 9, a ground electrode 10, first to third wiring patterns 30, 31, 32 is 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 is formed to cover and protect the surface acoustic wave element. 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 of the surface acoustic wave device, 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 coefficient Is preferable as the piezoelectric substrate 22. Of these pyroelectric piezoelectric single crystals, the piezoelectric substrate 1 with significantly reduced pyroelectricity due to solid solution of oxygen defects, Fe, or the like is excellent in the reliability of the surface acoustic wave device. 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.

〔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. 5, 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 device was obtained.

  The reference potential bus bar electrode of the second IDT electrode 2 arranged on one side with respect to the third third IDT electrode 3 is opposite to the third portion 27 of the annular electrode 12 and the first portion. The reference potential bus bar electrode of the fourth IDT electrode 4 that is connected to a portion that is a predetermined distance away from the central electrode 25 and that is disposed on the other side of the third third IDT electrode 3 is It was made to be connected to a part opposite to the third part 27 and 150 μm away from the second part 26.

  In addition, a first reference potential through conductor 17 and a second reference potential through conductor 18 were formed at portions facing directly below the annular electrode 12 of a mounting substrate (not shown) made of a ceramic multilayer substrate. The first and second reference potential through conductors 17 and 18 were formed using silver.

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.

Then, 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 of FIG. 5, the reference potential bus bar electrodes of the first, third, and fifth IDT electrodes 1, 3, and 5 are connected to the ground electrode 10 and the reference potential of the second IDT electrode 2. The bus bar electrode was connected to the first portion 25 of the annular electrode 22, and the reference potential bus bar electrode of the fourth IDT electrode 4 was connected to the second portion 26 of the annular electrode 22. 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.

Explanation of symbols

1 to 5: First to fifth IDT electrodes 1a to 5a: reference potential bus bar electrodes 6, 7: reflector electrodes 8: input signal electrodes 9: output signal electrodes 10: ground electrodes 11: surface acoustic wave resonators 25 to 25 27: First to third parts 34 of the annular electrode, 35: First and second connection parts

Claims (5)

A piezoelectric substrate;
An odd number of 3 or more provided with a plurality of long electrode fingers in the direction orthogonal to the propagation direction along the propagation direction of the surface acoustic wave propagating on the principal surface of the piezoelectric substrate formed on the principal surface of the piezoelectric substrate A surface acoustic wave device having the IDT electrode of
An annular electrode formed on the main surface so as to surround the surface acoustic wave element;
The piezoelectric substrate is mounted so as to face the main surface of the piezoelectric substrate, and includes a first reference potential through conductor connected to the annular electrode, and a mounting substrate having a second reference potential through conductor. A surface acoustic wave device,
The first reference potential through conductor is formed immediately below the first portion of the annular electrode on the extension of the propagation direction, and the second reference potential through conductor is on the extension of the propagation direction. Formed immediately below the second part of the electrode facing the first part,
A reference potential bus bar electrode of the IDT electrode in the center is connected to a third portion of the annular electrode on an extension in a direction orthogonal to the propagation direction;
A reference potential bus bar electrode of the IDT electrode disposed on one side with respect to the central IDT electrode is opposite to the third part of the annular electrode and the first part, and the first The reference potential bus bar electrode of the IDT electrode, which is connected to a first connection site that is a predetermined distance away from one site and is disposed on the other side with respect to the central IDT electrode, is connected to the annular electrode. A surface acoustic wave device that is connected to a second connection site that is opposite to the third site and the second site and that is a predetermined distance away from the second site.   The surface acoustic wave device according to claim 1, wherein the predetermined distance is 100 μm or more.   The length of the first connection wiring connecting the reference potential bus bar electrode of the IDT electrode and the annular electrode arranged on one side with respect to the central IDT electrode, and the other with respect to the central IDT electrode The length of the second connection wiring that connects the reference potential bus bar electrode of the IDT electrode and the annular electrode arranged on the side of the IDT electrode is such that the reference potential bus bar electrode of the IDT electrode in the center and the third of the annular electrode The surface acoustic wave device according to claim 1, wherein the surface acoustic wave device is longer than a length of the third connection wiring for connecting the part.   An IDT electrode comprising a plurality of electrode fingers long in a direction orthogonal to the propagation direction between the surface acoustic wave element and the input signal terminal or between the surface acoustic wave element and the output signal terminal; 4. The surface acoustic wave resonator according to claim 1, wherein the surface acoustic wave resonator includes a reflector electrode that is disposed on both sides of the IDT electrode and includes a plurality of long electrode fingers in a direction orthogonal to the propagation direction. Surface acoustic wave device.   A communication apparatus comprising at least one of a reception circuit and a transmission circuit, comprising the surface acoustic wave device according to claim 1.