JP4601415B2 - Surface acoustic wave device and communication device - Google Patents

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 same.

  Conventionally, surface acoustic wave devices have been widely used as frequency selective filters used in the RF stage of mobile communication devices such as mobile phones and automobile phones. In general, characteristics required for a frequency selective filter include a wide passband, a low loss, a high attenuation characteristic, and the like. Furthermore, in recent years, in order to reduce the size, weight, and cost of mobile communication devices, the number of components used has been reduced, and it has been required to add new functions to the surface acoustic wave device.

  One such function is a balanced-unbalanced conversion function such that the surface acoustic wave device can be configured as an unbalanced input-balanced output type or a balanced input-unbalanced output type. Here, the balanced input or balanced output means that a signal is input or output with a potential difference between two signal lines, while the unbalanced input or unbalanced output means that the signal is ground potential. An input or output having the potential of one line with respect to. In order to provide the surface acoustic wave device with a balanced-unbalanced conversion function, the signals of the signal lines have the same amplitude in the transmission characteristics within the passband between the balanced signal terminal and the unbalanced signal terminal. It is necessary that the phase is inverted 180 degrees, which are called amplitude balance and phase balance (hereinafter, these are collectively referred to as balance).

  Since conventional surface acoustic wave devices are generally of an unbalanced input-unbalanced output type, if a circuit or electronic component connected to the subsequent stage of the surface acoustic wave device is of a balanced input type, the surface acoustic wave The circuit configuration is such that a balanced-unbalanced converter (hereinafter also referred to as a balun) is inserted between the apparatus and the subsequent stage. Similarly, in the case where the circuit or electronic component in the previous stage of the surface acoustic wave device is a balanced output type, the circuit configuration has a balun inserted between the previous stage and the surface acoustic wave device.

  Therefore, in order to reduce the number of parts used by eliminating such a balun, an unbalanced input-balanced output type surface acoustic wave device or a balanced input-unbalanced surface acoustic wave device having a balanced-unbalance conversion function is provided. The balanced output type surface acoustic wave device is being put to practical use.

  FIG. 16 shows a plan view of a conventional surface acoustic wave filter 2001 having such a balance-unbalance conversion function (see Patent Document 1). As shown in FIG. 16, in the surface acoustic wave filter 2001, three IDT (Inter-Digital Transducer) electrodes 2201 to 2203 are arranged close to each other along the propagation direction of the surface acoustic wave on the piezoelectric substrate. One comb-like electrode of the electrode 2201 is connected to the unbalanced signal terminal 2510, IDT electrodes 2202 and 2203 are disposed on both sides of the central IDT electrode 2201, and the three IDT electrodes 2201 to 2203 are sandwiched between them. The electrode pattern 2101 having reflector electrodes 2301 and 2302 disposed thereon and the three IDT electrodes 2401 to 2403 are arranged close to each other along the propagation direction of the surface acoustic wave, and the central IDT electrode 2401 is divided into two to acoustically Are connected to balanced signal terminals 2520 and 2521 so that they are connected in series and electrically connected in series, and IDT electrodes 2402 and 2403 having opposite polarities are arranged on both sides of the central IDT electrode 2401, respectively. Reflector electrode to sandwich three IDT electrodes 2401-2403 The electrode patterns 2102 on which 2501 and 2502 are arranged are connected in cascade. Note that the comb-like electrode on the side (the other side) of the IDT electrode 2201 to which the unbalanced signal terminal 2510 is not connected and the comb-like electrode positioned outside the electrode patterns 2101 and 2102 in the IDT electrodes 2202, 2203, 2402, and 2403 Is grounded. With such a configuration, the surface acoustic wave filter 2001 can have a balanced-unbalanced conversion function. Further, by connecting the electrode patterns 2101 and 2102 in two stages in cascade, the amount of attenuation outside the pass band can be increased and the attenuation characteristics can be improved by mutual interference of standing waves between the first and second stages. . That is, a surface acoustic wave filter having similar characteristics is configured in a two-stage cascade connection configuration, so that the signal attenuated at the first stage is further attenuated at the second stage, and the attenuation outside the passband is doubled. Can do.

  Patent Document 2 proposes a conventional surface acoustic wave element 3101 having a balanced-unbalanced conversion function as shown in FIG. Here, parts similar to those of the surface acoustic wave filter 2001 shown in FIG.

As shown in FIG. 17, the surface acoustic wave element 3101 has the same basic structure as the surface acoustic wave filter 2001 shown in FIG. 16, and two IDTs adjacent to the IDT electrode 2401 to which the balanced signal terminals 2520 and 2521 are connected. Of the electrodes 2402 and 2403, a balanced signal terminal (in this example, balanced) is located closer to the IDT electrode (in this example, IDT electrode 2402) whose outermost electrode finger adjacent to the IDT electrode 2401 located in the center is grounded. A reactance component (capacitor 3200 in this example) is formed on the signal terminal 2520) on the piezoelectric substrate or inside or outside the package on which the surface acoustic wave element 3101 is mounted. By adopting such a configuration, an attempt is made to improve the balance (particularly the phase balance).
Japanese Patent Laid-Open No. 11-097966 Japanese Patent Laid-Open No. 2004-096244

  18 to 20 show the results of verifying the filter characteristics of the surface acoustic wave filter 2001 shown in FIG. 16 and the surface acoustic wave element 3101 shown in FIG.

  FIG. 18 is a diagram showing the frequency dependence of insertion loss, FIG. 19 is a diagram showing the frequency dependence of VSWR (voltage standing wave ratio), FIG. 20 (a) is the amplitude balance, and FIG. ) Is a diagram showing the frequency dependence of the degree of phase balance. 18 to 20, the solid line shows the characteristics of the surface acoustic wave element 3101 shown in FIG. 17 in which no reactance component is added to the balanced signal terminals 2520 and 2521 (that is, the structure of the surface acoustic wave filter 2001 shown in FIG. 16). The broken lines indicate the characteristics of a configuration in which a capacitor 3200 is connected in parallel as a reactance component to one of the balanced signal terminals 2520 and 2521, respectively. Here, among the broken lines, the long broken line indicates the characteristic of the configuration in which the capacitor 3200 is connected in parallel to the balanced signal terminal 2520, and the short broken line indicates the balanced signal terminal 2521. From these figures, it was found that both the surface acoustic wave filter 2001 shown in FIG. 16 and the surface acoustic wave element 3101 shown in FIG. 17 have a large undulation (ripple) in the passband and a large VSWR. This is presumably because impedance matching between the two balanced signal terminals 2520 and 2521 is not achieved. Further, it was confirmed that the balance of the surface acoustic wave element 3101 shown in FIG. 17 is not improved as compared with the surface acoustic wave filter 2001 shown in FIG.

  As described above, the surface acoustic wave filter 2001 disclosed in Patent Document 1 and the surface acoustic wave element 3101 disclosed in Patent Document 2 have problems that the insertion loss and VSWR characteristics required as a frequency selection filter are not sufficient. There was a point.

  The present invention has been made in view of the above-described problems of the prior art, and has an object of having an excellent filter pass characteristic of low insertion loss and low VSWR, and a balance-unbalance conversion function. A surface acoustic wave device and a communication device including the same are provided.

  The surface acoustic wave device according to the present invention includes 1) a plurality of electrode fingers that are long on the lower surface of the piezoelectric substrate along the direction of propagation of the surface acoustic wave propagating on the piezoelectric substrate. An electrode comprising three or more odd IDT electrodes and reflector electrodes each provided on both sides of the odd IDT electrodes and provided with a plurality of long electrode fingers in a direction orthogonal to the propagation direction A plurality of groups are arranged in cascade, and a connection pad electrode connected to the electrode group, and an annular ground electrode surrounding the electrode group and the connection pad electrode are arranged. Mounting the surface acoustic wave element having an annular ground conductor facing the annular ground electrode, a connection pad conductor facing the connection pad electrode, and a through ground conductor connected to the annular ground conductor formed on the upper surface The annular ground electrode and the connection pad electrode are bonded to the annular ground conductor and the connection pad conductor, respectively, and mounted on the substrate with the lower surface of the piezoelectric substrate facing the upper surface of the mounting substrate. The IDT electrode disposed at the center of the first electrode group is connected to the connection pad electrode as an unbalanced signal terminal, and the IDT electrode disposed at the center of the last electrode group. Is one of the comb-like electrodes facing each other with the electrode fingers divided into two, and the connection pad electrode is connected to each as a balanced signal terminal, and is arranged at the center of the first stage. The IDT electrode positioned on both sides of the IDT electrode is configured such that the comb-like electrode outside the plurality of stages is connected to the annular ground electrode, and the IDT electrode disposed in the center of the final stage The IDT electrodes located on both sides are connected to the annular ground electrode at the comb-shaped electrodes outside the plurality of stages, and the centers of the IDT electrodes arranged at the center of the first stage and the last stage are: The through-grounding conductor is formed asymmetrically with respect to a virtual axis provided in a direction perpendicular to the propagation direction through this center. It is characterized by that.

  In the surface acoustic wave device according to the present invention, 2) in the configuration of 1), the through-grounding conductor is disposed asymmetrically with respect to the virtual axis.

  The surface acoustic wave device according to the present invention is characterized in that, in 3) the configuration of 1), the through-grounding conductor has at least one diameter different from that of the other.

  The surface acoustic wave device according to the present invention is characterized in that, 4) in the configuration of 1), the number of the through grounding conductors is different on both sides of the virtual axis.

  Further, in the surface acoustic wave device according to the present invention, in addition to the group in which the through-grounding conductor is asymmetrically formed with respect to the virtual axis, It has the group formed symmetrically with respect to the virtual axis.

  In the surface acoustic wave device of the present invention, 6) A long electrode finger is provided on the lower surface of the piezoelectric substrate along the direction of propagation of the surface acoustic wave propagating on the piezoelectric substrate in a direction perpendicular to the propagation direction. A plurality of odd-numbered IDT electrodes of three or more, and reflector electrodes each provided on both sides of the odd-numbered IDT electrodes and provided with a plurality of long electrode fingers in a direction orthogonal to the propagation direction. A plurality of electrode groups are connected in cascade, and a connection pad electrode connected to the electrode group and an annular ground electrode surrounding the electrode group and the connection pad electrode are provided. The surface acoustic wave device is formed on a mounting substrate on which an annular ground conductor facing the annular ground electrode and a connection pad conductor facing the connection pad electrode are formed on an upper surface, and the lower surface of the piezoelectric substrate and the Implementation The annular ground electrode and the connection pad electrode are mounted to be bonded to the annular ground conductor and the connection pad conductor, respectively, facing the upper surface of the substrate, and disposed at the center of the electrode group in the first stage. The IDT electrode is connected to the connection pad electrode as an unbalanced signal terminal, and the IDT electrode disposed at the center of the electrode group at the final stage has an electrode finger and a comb that faces each other. One of the tooth-like electrodes is divided into two, and the connection pad electrode is connected to each as a balanced signal terminal, and the IDT electrodes located on both sides of the IDT electrode disposed in the center of the first stage are The comb-like electrodes on the outside of a plurality of stages are connected to the annular ground electrode, and the IDT electrodes positioned on both sides of the IDT electrode disposed in the center of the final stage are The comb-like electrode outside is connected to the annular ground electrode, and the centers of the IDT electrodes arranged at the center of the first stage and the last stage are aligned in a direction orthogonal to the propagation direction. At least one of the annular ground electrode and the annular ground conductor is formed asymmetrically with respect to a virtual axis provided in a direction orthogonal to the propagation direction through the center. It is a feature.

  In the surface acoustic wave device according to the present invention, in 7) the configuration of 6) above, at least one of the annular ground electrode and the annular ground conductor has portions having different widths so as to be asymmetric with respect to the virtual axis. It is characterized by having.

  In the surface acoustic wave device according to the present invention, in the configuration of 8) or 6) or 7), at least one of the annular ground electrode and the annular ground conductor is formed asymmetrically with respect to the virtual axis. And a portion formed symmetrically with respect to the virtual axis.

  In the surface acoustic wave device of the present invention, 9) An electrode finger that is long in the direction orthogonal to the propagation direction along the propagation direction of the surface acoustic wave propagating on the piezoelectric substrate is provided on the lower surface of the piezoelectric substrate. A plurality of odd-numbered IDT electrodes of three or more, and reflector electrodes each provided on both sides of the odd-numbered IDT electrodes and provided with a plurality of long electrode fingers in a direction orthogonal to the propagation direction. A plurality of electrode groups are connected in cascade, and a connection pad electrode connected to the electrode group and an annular ground electrode surrounding the electrode group and the connection pad electrode are provided. The surface acoustic wave element formed on the upper surface is formed with an annular ground conductor facing the annular ground electrode, a connection pad conductor facing the connection pad electrode, and a through ground conductor connected to the annular ground conductor. The annular ground electrode and the connection pad electrode are bonded to the annular ground conductor and the connection pad conductor, respectively, with the lower surface of the piezoelectric substrate and the upper surface of the mounting substrate facing the mounting substrate. The IDT electrode that is mounted and disposed in the center of the electrode group in the first stage is connected to the connection pad electrode as an unbalanced signal terminal, and is disposed in the center of the electrode group in the last stage. The IDT electrode has the electrode fingers and one of the opposing comb electrodes is divided into two, and the connection pad electrode is connected to each as a balanced signal terminal, and is arranged in the center of the first stage. Further, the IDT electrodes located on both sides of the IDT electrode have the comb-like electrodes on the outer side of the plurality of stages connected to the annular ground electrode, and the IDT arranged at the center of the final stage. The IDT electrodes positioned on both sides of the electrode are such that the comb-like electrodes outside the plurality of stages are connected to the annular ground electrode, and the center of the IDT electrode disposed at the center of the first and last stages Are arranged in a direction perpendicular to the propagation direction, and the through-grounding conductor is asymmetric with respect to a virtual axis provided in a direction perpendicular to the propagation direction through this center. It is formed, and at least one of the annular ground electrode and the annular ground conductor is formed asymmetrically with respect to the virtual axis.

  The surface acoustic wave device according to the present invention is characterized in that 10) In the configuration of 9), the through-grounding conductor is disposed asymmetrically with respect to the virtual axis.

  The surface acoustic wave device according to the present invention is characterized in that, 11) in the configuration of 9), the through-grounding conductor has at least one diameter different from the diameter of the other.

  The surface acoustic wave device according to the present invention is characterized in that in 12) the configuration of 9), the number of the through grounding conductors is different on both sides of the virtual axis.

  In the surface acoustic wave device according to the present invention, in 13) the configuration of 9) described above, at least one of the annular ground electrode and the annular ground conductor has portions with different widths so as to be asymmetric with respect to the virtual axis. It is characterized by having.

  In addition, in the surface acoustic wave device according to the present invention, 14) in any one of the above-described 9) to 13), in addition to the group in which the through-grounding conductor is formed asymmetrically with respect to the virtual axis, It has the group formed symmetrically with respect to the virtual axis.

  In the surface acoustic wave device according to the present invention, in any one of 15) to 9) to 13), at least one of the annular ground electrode and the annular ground conductor is formed asymmetrically with respect to the virtual axis. And a portion formed symmetrically with respect to the virtual axis.

  Further, the surface acoustic wave device of the present invention is 16) In any one of the constitutions 1) to 15) described above, the unbalanced signal terminal is arranged along the propagation direction in a direction perpendicular to the propagation direction. Surface acoustic wave having one IDT electrode having a plurality of long electrode fingers, and a reflector electrode having a plurality of long electrode fingers arranged on both sides of the IDT electrode and orthogonal to the propagation direction A resonator is connected.

  Further, the surface acoustic wave device of the present invention is 17) In any one of the above 1) to 15), the balanced signal terminal is long in the direction perpendicular to the propagation direction along the propagation direction. Surface acoustic wave resonance having one IDT electrode having a plurality of electrode fingers and a reflector electrode having a plurality of electrode fingers arranged on both sides of the IDT electrode and extending in a direction perpendicular to the propagation direction The child is connected.

  In the surface acoustic wave device according to the present invention, 18) In any one of 1) to 17) above, an electrode finger long in the direction orthogonal to the propagation direction is provided between the odd number of IDT electrodes. A plurality of inserted reflector electrodes are provided, and the distance between the centers of adjacent electrode fingers of the inserted reflector electrode is from the electrode fingers located at both ends to the electrode fingers located at the center. It is characterized by gradually becoming shorter.

  A communication apparatus according to the present invention includes 19) at least one of a reception circuit and a transmission circuit using the surface acoustic wave device according to any one of 1) to 18) as a filter unit. Is.

  According to the surface acoustic wave device of the present invention, 1) An electrode finger that is long in the direction orthogonal to the propagation direction along the propagation direction of the surface acoustic wave propagating on the piezoelectric substrate is provided on the lower surface of the piezoelectric substrate. 3 or more odd number IDT electrodes provided in plurality, and reflector electrodes each provided on both sides of these odd number IDT electrodes and provided with a plurality of long electrode fingers in a direction orthogonal to the propagation direction. The electrode group is arranged in a plurality of stages and connected in cascade, and is provided with a connection pad electrode connected to the electrode group and an annular ground electrode surrounding the electrode group and the connection pad electrode. A piezoelectric substrate is mounted on the mounting substrate in which the surface wave element is formed with an annular ground conductor on the upper surface facing the annular ground electrode, a connection pad conductor facing the connection pad electrode, and a through ground conductor connected to the annular ground conductor. The annular ground electrode and the connection pad electrode are mounted to be joined to the annular ground conductor and the connection pad conductor, respectively, with the lower surface facing the upper surface of the mounting substrate, and arranged at the center of the first stage electrode group. The IDT electrode is connected to the pad electrode for connection as an unbalanced signal terminal, and the IDT electrode disposed in the center of the last-stage electrode group is one of comb-like electrodes each having an electrode finger. Are divided into two parts, and connection pad electrodes are connected to each as a balanced signal terminal, and the IDT electrodes located on both sides of the IDT electrode disposed in the center of the first stage are formed by annular grounding of the plurality of stages of comb-like electrodes. The IDT electrodes that are connected to the electrodes and located on both sides of the IDT electrode disposed in the center of the final stage have a plurality of outer comb-like electrodes connected to the annular ground electrode, and the first stage and the final stage In the center of The center of the provided IDT electrode is arranged so as to be aligned in a direction orthogonal to the propagation direction, and the through-grounding conductor passes through this center on a virtual axis provided in a direction orthogonal to the propagation direction. Since it is formed asymmetrically with respect to the IDT electrode, an inductance component can be obtained by passing an annular grounding electrode, an annular grounding conductor, and a through-grounding conductor formed asymmetrically with respect to the virtual axis in the path until the IDT electrode is grounded. Since they are connected, these inductance components function as a matching circuit, and as a result, the low insertion loss and the low VSWR filter pass characteristics are excellent. In addition, since the size of such an inductance component can be adjusted by the design of the through-grounding conductor, it can have a function as a desired matching circuit, resulting in low insertion loss and low VSWR, and excellent filter passing characteristics. Can be obtained with high productivity. Further, the through-ground conductor forming the inductance component is formed asymmetrically with respect to the virtual axis provided in the direction orthogonal to the propagation direction at the center of the IDT electrode disposed in the center. Since the parasitic capacitance formed by the electrode, the IDT electrode and the through grounding conductor can be made different on both sides of the virtual axis, fine adjustment is made so that the impedance between the two connection pad electrodes as balanced signal terminals is matched. Can be more balanced. Further, since a plurality of stages are connected in cascade, the amount of attenuation outside the pass band increases due to interference of standing waves at each stage, and a surface acoustic wave device having excellent out-of-band attenuation characteristics is obtained.

  According to the surface acoustic wave device of the present invention, 2) in the configuration of 1) above, when the through grounding conductor is disposed asymmetrically with respect to the virtual axis, the arrangement of the through grounding conductor is appropriately set. Since the size of the inductance component can be controlled by this, the function as a desired matching circuit can be obtained, and a low insertion loss and a low VSWR can be obtained with excellent filter passing characteristics with good productivity. It becomes.

  According to the surface acoustic wave device of the present invention, 3) In the configuration of 1) above, when the through-ground conductor has at least one diameter different from the diameter of the other, the diameter of the through-ground conductor is set appropriately. Since the size of the inductance component can be controlled by this, the function as a desired matching circuit can be obtained, and a low insertion loss and a low VSWR can be obtained with excellent filter passing characteristics with good productivity. It becomes.

  According to the surface acoustic wave device of the present invention, 4) in the configuration of 1) above, when the number of through-ground conductors is different on both sides of the virtual axis, the number of through-ground conductors is set appropriately so that the inductance component Therefore, a function as a desired matching circuit can be obtained, and a low insertion loss and a low VSWR can be obtained with excellent filter pass characteristics with good productivity.

  According to the surface acoustic wave device of the present invention, 5) In any one of the above-described 1) to 4), in addition to the group formed asymmetrically with respect to the virtual axis, the through-grounding conductor is a virtual When having a group formed symmetrically with respect to the axis, a capacitance formed by two connection pad electrodes as balanced signal terminals and a through-ground conductor by the group formed symmetrically with respect to the virtual axis Can be made equal on both sides of the virtual axis, and the occurrence of different parasitic capacitances in the two connection pad electrodes as balanced signal terminals can be suppressed, so that the balance is excellent.

  Further, according to the surface acoustic wave device of the present invention, 6) an electrode that is long on the lower surface of the piezoelectric substrate in a direction perpendicular to the propagation direction along the propagation direction of the surface acoustic wave propagating on the piezoelectric substrate. Three or more odd-numbered IDT electrodes each having a plurality of fingers, and reflector electrodes each having a plurality of electrode fingers which are arranged on both sides of the odd-numbered IDT electrodes and which are long in a direction orthogonal to the propagation direction; The electrode group is composed of a plurality of stages and connected in cascade, and a connection pad electrode connected to the electrode group and an annular ground electrode surrounding the electrode group and the connection pad electrode are provided. The surface acoustic wave device comprises a mounting substrate having an annular ground conductor facing the annular ground electrode and a connection pad conductor facing the connection pad electrode formed on the upper surface, and a lower surface of the piezoelectric substrate and an upper surface of the mounting substrate. Face to face A grounding electrode and a connection pad electrode are joined to and mounted on an annular grounding conductor and a connection pad conductor, respectively, and the IDT electrode disposed in the center of the first stage electrode group has an unbalanced signal at the connection pad electrode. The IDT electrode connected as a terminal and arranged in the center of the last-stage electrode group is divided into two of the opposing comb-like electrodes each having an electrode finger, and each has a connection pad electrode The IDT electrodes that are connected as balanced signal terminals and are located on both sides of the IDT electrode disposed in the center of the first stage have a plurality of outer comb-like electrodes connected to the annular ground electrode, and the center of the final stage The IDT electrodes located on both sides of the arranged IDT electrodes have a plurality of outer comb-like electrodes connected to the annular ground electrode, and the centers of the IDT electrodes arranged at the center of the first and last stages are , Propagation direction The annular ground electrode and the annular ground conductor are arranged asymmetrically with respect to a virtual axis provided in a direction perpendicular to the propagation direction through this center. Therefore, an inductance component is connected to the path from which the IDT electrode is grounded via an annular ground electrode and an annular ground conductor, at least one of which is formed asymmetrically with respect to the virtual axis. Therefore, these inductance components function as a matching circuit, and as a result, low insertion loss and low VSWR result in excellent filter pass characteristics. In addition, since the magnitude of such an inductance component can be adjusted by the design of at least one of the annular ground electrode and the annular ground conductor, it can have a function as a desired matching circuit, and can have a low insertion loss and a low level. A VSWR is obtained, and a filter having excellent filter passing characteristics can be obtained with high productivity. In addition, at least one of the annular ground electrode and the annular ground conductor forming the inductance component is formed asymmetrically with respect to a virtual axis provided in the direction orthogonal to the propagation direction at the center of the IDT electrode disposed in the center. Therefore, since the parasitic capacitance formed by the reflector electrode, the IDT electrode, the annular ground electrode and the annular ground conductor can be made different on both sides of the virtual axis, two connection pad electrodes as balanced signal terminals can be obtained. Fine adjustment can be made so that the impedance between the two matches, and the degree of balance becomes higher. Further, since a plurality of stages are connected in cascade, the amount of attenuation outside the pass band increases due to interference of standing waves at each stage, and a surface acoustic wave device having excellent out-of-band attenuation characteristics is obtained.

  According to the surface acoustic wave device of the present invention, 7) In the configuration of 6) above, at least one of the annular ground electrode and the annular ground conductor has a portion having a different width so as to be asymmetric with respect to the virtual axis. In some cases, the size of the inductance component can be controlled by appropriately setting the width of at least one of the annular ground electrode and the annular ground conductor, so that a function as a desired matching circuit can be obtained, and low insertion loss and A low VSWR can be obtained with good filter pass characteristics and good productivity.

  According to the surface acoustic wave device of the invention, 8) in the configuration of 6) or 7), at least one of the annular ground electrode and the annular ground conductor is formed asymmetrically with respect to the virtual axis; , Two connection pad electrodes as a balanced signal terminal, an annular ground electrode, and an annular ground conductor by the portion formed symmetrically with respect to the virtual axis. Can be made equal on both sides of the virtual axis, so that it is possible to suppress the generation of different parasitic capacitances in the two connection pad electrodes serving as balanced signal terminals, so that the degree of balance is excellent. It will be.

  Further, according to the surface acoustic wave device of the present invention, 9) an electrode that is long on the lower surface of the piezoelectric substrate in a direction perpendicular to the propagation direction along the propagation direction of the surface acoustic wave propagating on the piezoelectric substrate Three or more odd-numbered IDT electrodes each having a plurality of fingers, and reflector electrodes each having a plurality of electrode fingers which are arranged on both sides of the odd-numbered IDT electrodes and which are long in a direction orthogonal to the propagation direction; The electrode group is composed of a plurality of stages and connected in cascade, and a connection pad electrode connected to the electrode group and an annular ground electrode surrounding the electrode group and the connection pad electrode are provided. The surface acoustic wave device is formed on a mounting substrate in which an annular ground conductor facing the annular ground electrode, a connection pad conductor facing the connection pad electrode, and a through ground conductor connected to the annular ground conductor are formed on the upper surface. Pressure The bottom surface of the board faces the top surface of the mounting board, and the annular ground electrode and connection pad electrode are mounted on the annular ground conductor and connection pad conductor, respectively. The IDT electrode is connected to the pad electrode for connection as an unbalanced signal terminal, and the IDT electrode disposed in the center of the last-stage electrode group has an electrode finger, and each of the opposed comb-like electrodes The IDT electrodes located on both sides of the IDT electrode disposed in the center of the first stage are divided into two comb-like electrodes on the outer side of the IDT electrode disposed in the center of the first stage. The IDT electrodes that are connected to the annular ground electrode and located on both sides of the IDT electrode disposed in the center of the final stage have a plurality of outer comb-like electrodes connected to the annular ground electrode, Last stage The center of the IDT electrode arranged in the center is arranged in the direction orthogonal to the propagation direction, and the through-ground conductor is provided in the direction orthogonal to the propagation direction through this center. Since it is formed asymmetrically with respect to the virtual axis, and at least one of the annular grounding electrode and the annular grounding conductor is formed asymmetrically with respect to the virtual axis, at least one of the paths until the IDT electrode is grounded Is connected via an annular ground electrode and an annular ground conductor formed asymmetrically with respect to the virtual axis, and a through-ground conductor formed asymmetrically with respect to the virtual axis. Therefore, these inductance components function as a matching circuit, and as a result, low insertion loss and low VSWR result in excellent filter pass characteristics. In addition, since the magnitude of such an inductance component can be adjusted over a wide range by designing both the through-grounding conductor and the annular grounding electrode and / or the annular grounding conductor, it has a function as a desired matching circuit. As a result, a low insertion loss and a low VSWR can be obtained with good filter pass characteristics and good productivity. Further, the through-ground conductor forming the inductance component and at least one of the annular ground electrode and the annular ground conductor are arranged on a virtual axis provided in the direction perpendicular to the propagation direction at the center of the IDT electrode disposed at the center. Since the parasitic capacitance formed by the reflector electrode, the IDT electrode, the through-grounding conductor, the annular grounding electrode, and the annular grounding conductor can be made different on both sides of the virtual axis. Fine adjustment can be made so that the impedance between the two pad electrodes for connection as signal terminals is matched, and the balance becomes higher. Further, since a plurality of stages are connected in cascade, the amount of attenuation outside the pass band increases due to interference of standing waves at each stage, and a surface acoustic wave device having excellent out-of-band attenuation characteristics is obtained.

  According to the surface acoustic wave device of the present invention, 10) In the configuration of 9) above, when the through-grounding conductor is disposed asymmetrically with respect to the virtual axis, the arrangement of the through-grounding conductor is appropriately set. Since the size of the inductance component can be controlled by this, the function as a desired matching circuit can be obtained, and a low insertion loss and a low VSWR can be obtained with excellent filter passing characteristics with good productivity. It becomes.

  Further, according to the surface acoustic wave device of the present invention, 11) in the configuration of 9), when the through-grounding conductor has at least one diameter different from the diameter of the other, the diameter of the through-grounding conductor is appropriately set. Since the size of the inductance component can be controlled by this, the function as a desired matching circuit can be obtained, and a low insertion loss and a low VSWR can be obtained with excellent filter passing characteristics with good productivity. It becomes.

  According to the surface acoustic wave device of the present invention, 12) In the configuration of 9) described above, when the number of through-grounding conductors is different on both sides of the virtual axis, the number of through-grounding conductors is set appropriately so that the inductance component Therefore, a function as a desired matching circuit can be obtained, and a low insertion loss and a low VSWR can be obtained with excellent filter pass characteristics with good productivity.

  According to the surface acoustic wave device of the invention, 13) in the configuration of 9), at least one of the annular ground electrode and the annular ground conductor has a portion having a different width so as to be asymmetric with respect to the virtual axis. In some cases, the size of the inductance component can be controlled by appropriately setting the width of at least one of the annular ground electrode and the annular ground conductor, so that a function as a desired matching circuit can be obtained, and low insertion loss and A low VSWR can be obtained with good filter pass characteristics and good productivity.

  According to the surface acoustic wave device of the present invention, 14) in any one of the above-mentioned 9) to 13), the through-grounding conductor is a virtual in addition to the group formed asymmetrically with respect to the virtual axis. When having a group formed symmetrically with respect to the axis, a capacitance formed by two connection pad electrodes as balanced signal terminals and a through-ground conductor by the group formed symmetrically with respect to the virtual axis Can be made equal on both sides of the virtual axis, and the occurrence of different parasitic capacitances in the two connection pad electrodes as balanced signal terminals can be suppressed, so that the balance is excellent.

  According to the surface acoustic wave device of the invention, 15) in any one of 9) to 13), at least one of the annular ground electrode and the annular ground conductor is formed asymmetrically with respect to the virtual axis. Two connection pad electrodes and an annular ground electrode as balanced signal terminals by the portion formed symmetrically with respect to the virtual axis. And the capacitance formed by at least one of the annular ground conductors can be made equal on both sides of the virtual axis, so that it is possible to suppress the occurrence of different parasitic capacitances in the two connection pad electrodes as balanced signal terminals. Since it is possible, the balance is excellent.

  Further, according to the surface acoustic wave device of the present invention, 16) in any one of the above-mentioned 1) to 15), the unbalanced signal terminal is arranged along the propagation direction in a direction perpendicular to the propagation direction. Surface acoustic wave resonance having one IDT electrode having a plurality of long electrode fingers and a reflector electrode having a plurality of long electrode fingers arranged on both sides of the IDT electrode and orthogonal to the propagation direction When the resonator is connected, the surface acoustic wave resonator is manufactured so that the resonance frequency of the surface acoustic wave resonator becomes a desired value, thereby controlling the position of the attenuation pole caused by the surface acoustic wave resonator. Therefore, the attenuation pole can be formed at a desired position, and the attenuation characteristic outside the pass band is excellent.

  Further, according to the surface acoustic wave device of the present invention, 17) in any of the above-mentioned configurations 1) to 15), the balanced signal terminal has an electrode that is long in the direction perpendicular to the propagation direction along the propagation direction. A surface acoustic wave resonator having one IDT electrode provided with a plurality of fingers and a reflector electrode provided on both sides of the IDT electrode and provided with a plurality of electrode fingers long in a direction perpendicular to the propagation direction. When connected, it is possible to control the position of the attenuation pole caused by the surface acoustic wave resonator by fabricating the surface acoustic wave resonator so that the resonance frequency of the surface acoustic wave resonator becomes a desired value. Therefore, the attenuation pole can be formed at a desired position, and the attenuation characteristic outside the pass band is excellent.

  Further, according to the surface acoustic wave device of the present invention, 18) in any one of the above-mentioned 1) to 17), the electrode fingers that are long in the direction perpendicular to the propagation direction are placed between the odd number of IDT electrodes. A plurality of inserted reflector electrodes are arranged, and the distance between the centers of the adjacent electrode fingers of the inserted reflector electrode is gradually increased from the electrode fingers located at both ends toward the electrode fingers located at the center. When it is shorter, the amplitude mode can be increased by the insertion reflector electrode, and the distance between the centers of the adjacent electrode fingers of the insertion reflector electrode is changed from the electrode fingers located at both ends to the electrode fingers located at the center. Since the surface wave is gradually shortened toward the surface, it is possible to prevent the surface acoustic wave from being converted into a bulk wave, so that the amplitude mode can be increased without disturbing the propagation of the surface acoustic wave. Is broadband It becomes.

  Further, according to the communication device of the present invention, since 19) the surface acoustic wave device according to any one of 1) to 18) described above is used as a filter means, at least one of a reception circuit and a transmission circuit is provided. Since a balun is not required, downsizing is possible, and a surface acoustic wave device having a low insertion loss, a low VSWR, and excellent filter passing characteristics is used, so that sensitivity is remarkably improved.

  Hereinafter, the surface acoustic wave device of the present invention will be described in detail with reference to the drawings. In the drawings described below, the same portions are denoted by the same reference numerals, and redundant description is omitted. Further, the size of each electrode, the distance between the electrodes, the number of electrode fingers constituting the IDT electrode, the interval thereof, and the like are schematically illustrated for explanation.

  1 and 2 (a) to 2 (f) show a first embodiment of a surface acoustic wave device according to the present invention.

  FIG. 1 is a plan view showing an example of a surface acoustic wave device according to the first embodiment of the surface acoustic wave device of the present invention. FIG. 2 is a plan view of the surface acoustic wave device of the present invention on which the surface acoustic wave device is mounted. It is a top view which shows an example of the mounting board | substrate in 1 embodiment, (a)-(f) is a top view of each layer which comprises a mounting board | substrate, respectively. FIGS. 3A to 3F and FIGS. 4A to 4F are plan views of respective layers showing other examples of the mounting substrate in the first embodiment of the surface acoustic wave device of the invention. It is.

  As shown in FIG. 1, the surface acoustic wave element 101 in the first embodiment of the surface acoustic wave device of the present invention is in the propagation direction X of the surface acoustic wave propagating on the piezoelectric substrate 100 on the lower surface of the piezoelectric substrate 100. Along with this, three or more odd-numbered IDT electrodes having a plurality of long electrode fingers in a direction orthogonal to the propagation direction X, in this example, three IDT electrodes 301 to 303 and three IDT electrodes 301 to An electrode group 201 including reflector electrodes 401 and 402 each having a plurality of long electrode fingers arranged on both sides of 303 and orthogonal to the propagation direction X, and a surface acoustic wave propagating on the piezoelectric substrate 100 Three or more odd number of IDT electrodes having a plurality of long electrode fingers in the direction orthogonal to the propagation direction X along the propagation direction X, in this example, three IDT electrodes 501 to 503 and three Arranged on both sides of the IDT electrodes 501 to 503 and orthogonal to the propagation direction X A plurality of electrode groups 202 including reflector electrodes 601 and 602 each having a plurality of long electrode fingers are arranged in cascade in two stages, in this example, and connected to the electrode groups 201 and 202. The connection pad electrodes 701 to 703 and the annular ground electrode 801 surrounding the electrode groups 201 and 202 and the connection pad electrodes 701 to 703 are arranged. In this example, the electrode groups 201 and 202 are connected in two stages, but the number of stages can be freely set as long as the number of stages is two or more. However, although the amount of attenuation outside the passband increases when the number of stages increases, the propagation loss of the surface acoustic wave becomes longer and the propagation loss increases. Therefore, the number of stages may be determined in consideration of the effects of both.

  In this surface acoustic wave element 101, the IDT electrode 301 disposed in the center of the first-stage electrode group 201 is connected to the connection pad electrode 701 as an unbalanced signal terminal and disposed in the center of the last-stage electrode group 202. In the IDT electrode 501, each of the opposing comb-like electrodes each having an electrode finger is divided into two, and connection pad electrodes 702 and 703 are connected as balanced signal terminals to the center of the first stage, respectively. The IDT electrodes 302 and 303 located on both sides of the arranged IDT electrode 301 have a plurality of outer comb-like electrodes connected to the annular ground electrode 801, and the IDT electrodes arranged in the center of the final stage. The IDT electrodes 502 and 503 located on both sides of the 501 have a plurality of outer comb-like electrodes connected to the annular ground electrode 801, and the IDT electrodes 301 and 501 disposed at the center of the first and last stages. The center is arranged in a direction perpendicular to the propagation direction X. That. Here, in order to give the surface acoustic wave element 101 a balance-unbalance conversion function, the electrode fingers are designed so that the IDT electrodes 302 and 303 are in opposite phases to each other (invert the polarity). Further, the comb on the side not connected to each annular ground electrode 801 is connected so that the first IDT electrode 302 and the last IDT electrode 502 are connected, and the first IDT electrode 303 and the last IDT electrode 503 are connected. Tooth-like electrodes are connected, and the first electrode group 201 and the last electrode group 202 are connected in cascade. When three or more electrode groups are connected in cascade, the centers of the IDT electrodes arranged at the center of the first stage and the final stage are aligned, and the centers of the IDT electrodes disposed at the centers of the other stages are also aligned. Further, since it is possible to prevent different parasitic capacitances from occurring in the two connection pad electrodes 702 and 703 as balanced signal terminals, the balance can be further improved.

  In this example, IDT electrodes 302, 303, 502, and 503 have a plurality of outer comb-like electrodes that are connected to an annular ground electrode 801 via reflector electrodes 401, 402, 601, and 602, respectively. . Further, the connection pad electrodes 701 to 703 may be formed inside a plurality of stages, that is, in a region between the electrode group 201 and the electrode group 202. However, as shown in FIG. For example, signal interference between the connection pad electrodes 701 to 703 can be reduced, and a surface acoustic wave device with good signal isolation can be obtained.

  The mounting substrate 900 according to the first embodiment of the surface acoustic wave device of the present invention has an annular ground conductor 1001 and a connection pad electrode facing the annular ground electrode 801 on the upper surface as shown in FIG. Connection pad conductors 1101 to 1103 facing 701 to 703 and through-grounding conductors 1201 and 1202 connected to the annular grounding conductor 1001 are formed. Here, the through grounding conductors 1201 and 1202 are formed asymmetrically with respect to the virtual axis Y provided in the direction orthogonal to the propagation direction X at the center of the IDT electrodes 301 and 501 disposed in the center.

  The mounting substrate 900 has a structure in which a plurality of layers are stacked. In this example, the layers shown in FIGS. 2A to 2F are laminated in order from the upper surface, and the annular ground conductor 1001 is connected to the internal ground conductor patterns 1210a and 1210b through the through ground conductors 1201 and 1202, The internal ground conductor patterns 1210a and 1210b are connected to the bottom ground conductor patterns 1220a and 1220b through the through ground conductors 1201 and 1202. The connection pad conductors 1101 to 1103 are connected to the internal signal conductor patterns 1221 to 1223 via the through-ground conductor 1203, and the signal conductors formed on the lower surface via the through-ground conductor 1203 are connected to the internal signal conductor patterns 1221 to 1223. These are connected to patterns 1231 to 1233, respectively. 2A shows the upper surface of the mounting substrate 900, FIG. 2B shows the first layer on the upper surface side, and FIG. 2C shows the first layer shown in FIG. 2D shows the inner ground conductor pattern forming surface formed between the second layer shown in FIG. 2D, FIG. 2D shows the second layer, FIG. 2E shows the lower surface conductor pattern forming surface 2 ( f) is a plan view showing the lower surface. In FIG. 2 (f), the solid line portion is a portion where the bottom ground conductor patterns 1220a and 1220b and the signal conductor patterns 1231 to 1233 are exposed.

  The annular ground electrode 801 and the connection pad electrodes 701 to 703 are joined to the annular ground conductor 1001 and the connection pad conductors 1101 to 1103 with the lower surface of the piezoelectric substrate 100 and the upper surface of the mounting substrate 900 facing each other as described above. Thus, the surface acoustic wave device of the present invention can be obtained.

  In the surface acoustic wave element 101, a conductor film is formed on the lower surface of a piezoelectric substrate 100 such as lithium tantalate using a vacuum film forming apparatus or the like, and the IDT electrodes 301 to 303, 501 are formed using a photolithography technique. ˜503, reflector electrodes 401, 402, 601, 602, connection pad electrodes 701 to 703, and annular ground electrode 801 can be processed by a normal manufacturing method. The IDT electrodes 301 to 303 and 501 to 503 are preferably formed of a conductor having a small mass such as aluminum.

  The mounting substrate 900 is made of an insulating material and used by stacking a plurality of insulating layers. For these insulating layers, for example, ceramics or glass ceramics are used, and a green sheet is produced by molding a slurry in which a metal oxide such as ceramics and an organic binder are homogeneously kneaded with an organic solvent or the like into a sheet shape. 1001, 1101 to 1103, 1210, 1220, 1221 to 1223, 1231 to 1233, and through conductors 1201 to 1233 are formed by metal conductors, and then these green sheets are laminated and pressed together to form and fire integrally. It is produced by.

  In order to mount the surface acoustic wave element 101 on the mounting substrate 900, solder paste, Au—Sn is formed on the annular ground electrode 801 and the connection pad electrodes 701 to 703 or the annular ground conductor 1001 and the connection pad conductors 1101 to 1103. A bonding layer made of a paste or the like may be formed by screen printing or the like, arranged so as to face each other, and then bonded by reflow melting.

  In this manner, the IDT electrodes 301 to 303 and 501 to 503 and the connection pad electrodes 701 to 703 are hermetically sealed by the piezoelectric substrate 100, the mounting substrate 900, the annular ground electrode 801, and the annular ground conductor 1001, thereby improving the airtightness. Since it can maintain favorable, it can be set as the reliable surface acoustic wave apparatus which can be operated stably over a long period of time.

  According to such a surface acoustic wave device of the present invention, the IDT electrodes 302, 303, 502, and 503 are formed asymmetrically with respect to the annular ground electrode 801, the annular ground conductor 1001, and the symmetry axis Y in the path to the ground. Since the inductance components are connected through the through-ground conductors 1201 and 1202, the inductance components function as a matching circuit, resulting in a low insertion loss and a low VSWR. Excellent characteristics. In addition, since the magnitude of such an inductance component can be adjusted by the design of the through-grounding conductors 1201 and 1202, a function as a desired matching circuit can be provided, and a low insertion loss and a low VSWR can be obtained. A product having excellent characteristics can be obtained with good productivity. Since the through-ground conductors 1201 and 1202 forming the inductance component are formed asymmetrically with respect to the virtual axis Y, the reflector electrodes 401, 402, 601 and 602 and the IDT electrodes 301 to 303 and 501 to 503 Since the parasitic capacitance formed between the through-ground conductors 1201 and 1202 can be made different on both sides of the virtual axis Y, the impedance between the two connection pad electrodes 702 and 703 as balanced signal terminals is finely matched. Since it can be adjusted, the surface acoustic wave device has a higher degree of balance. In addition, since the two stages of the electrode group 201 and the electrode group 202 are cascaded in this example, the amount of attenuation outside the passband increases due to standing wave interference at each stage, and the out-of-band attenuation characteristics The surface acoustic wave device is excellent. Further, since the reflector electrodes 401, 402, 601, and 602 are grounded via the annular ground electrode 801, the surface acoustic wave has a high reflection efficiency and the surface acoustic wave has a good attenuation characteristic outside the passband. It becomes a device.

  The through-ground conductors 1201 and 1202 are preferably arranged closer to the connection pad conductor 1101 connected to the unbalanced signal terminal than the connection pad conductors 1102 and 1103 to which the balanced signal terminal is joined. With such a configuration, it is possible to prevent different parasitic capacitances from occurring in the two connection pad electrodes 702 and 703 as balanced signal terminals, so that the balance can be further improved. .

  Here, as shown in FIG. 2A, the through-grounding conductors 1201 and 1202 are formed asymmetrically with respect to the virtual axis Y. In this example, the through-grounding conductor is on one side of the virtual axis Y. When 1201 and the through ground conductor 1202 on the other side are arranged asymmetrically with respect to the virtual axis Y, the size of the inductance component can be controlled by appropriately setting the positions of the through ground conductors 1201 and 1202 Therefore, it is preferable because a function as a desired matching circuit can be obtained and an excellent low insertion loss and low VSWR can be obtained. In addition, as shown in FIG. 2D, by arranging the through grounding conductors 1201 and 1202 symmetrically with respect to the virtual axis Y in the second layer, different parasitic capacitances are generated in the balanced signal terminals 702 and 703. Since it can prevent more reliably, it can be excellent in the degree of balance.

  Further, as shown in FIGS. 3A to 3F, in this example, the through-grounding conductor 1201 has a diameter of the through-grounding conductor 1202 so that at least one of the through-grounding conductors 1201 and 1202 is different from the other diameter. If configured so as to be larger than the diameter of 1201, the size of the inductance component can be controlled by appropriately setting the diameters of the through-ground conductors 1201 and 1202, so that a function as a desired matching circuit is obtained. It is preferable because it can be excellent in low insertion loss and low VSWR.

  Further, as shown in FIGS. 4A to 4F, the through-grounding conductors 1201 and 1202 may be configured so that the numbers are different on both sides of the virtual axis Y. That is, the number of through grounding conductors 1201 formed on one side of the virtual axis Y may be different from the number of through grounding conductors 1202 formed on the other side. By adopting such a configuration, the size of the inductance component can be controlled by appropriately setting the number of through-grounding conductors 1201 and 1202, so that a function as a desired matching circuit can be obtained and inserted. It can be made excellent in loss and VSWR. In addition, the IDT electrodes 302, 303, 502, and 503 can be reliably grounded by providing a large number of through-ground conductors 1201 and 1202, thus preventing an increase in floor level outside the passband and an elastic surface with excellent filter characteristics. It can be a wave device. When a plurality of through-ground conductors 1201 and 1202 are provided, the internal ground conductor patterns 1210a and 1210b may be provided so as to correspond to the respective through-ground conductors 1201 and 1202, or a plurality of through-ground conductors. 1201 and 1202 may be connected together so as to be connected to one internal ground conductor pattern, but as shown in FIG. 4 (c), the interior to which the through ground conductors 1201 and 1202 are connected respectively. When the ground conductor patterns 1210a and 1210b are separated and a plurality of through-ground conductors 1202 are connected to one internal ground conductor pattern 1210b, inductance components are independently provided on both sides of the virtual axis Y. The size of the inductance component can be controlled more precisely by appropriately setting the shape and area of the internal ground conductor pattern 1210b. Thus, the function as a desired matching circuit can be obtained, and the balance, insertion loss, and VSWR can be made excellent.

  Further, the through grounding conductors 1201 and 1202 may have a group formed symmetrically with respect to the virtual axis Y in addition to a group formed asymmetric with respect to the virtual axis Y. With such a configuration, two connection pad electrodes 702 and 703 as balanced signal terminals and through-grounding conductors 1201 and 1202 are formed by a group formed symmetrically with respect to the virtual axis Y. Since the capacitance can be made equal on both sides of the virtual axis Y, it is possible to suppress the generation of different parasitic capacitances in the two connection pad electrodes 702 and 703 as balanced signal terminals. Can be.

  Next, a second embodiment of the surface acoustic wave device of the present invention will be described with reference to FIGS.

  FIG. 5 is a plan view showing an example of a surface acoustic wave element according to the second embodiment of the surface acoustic wave device of the present invention, and FIG. 6 is a mounting substrate according to the second embodiment of the surface acoustic wave device of the present invention. FIG. 5A is a plan view showing each layer constituting a mounting substrate. FIG. 7 shows another example of the surface acoustic wave device according to the second embodiment of the surface acoustic wave device of the present invention. FIGS. 8 and 9 show the mounting of the surface acoustic wave device according to the second embodiment of the present invention. FIG. 8 and 9, the laminated structure other than the upper surface of the mounting substrate is the same as that shown in FIGS.

  As shown in FIG. 5, the surface acoustic wave element 101 in the second embodiment of the surface acoustic wave device of the present invention is the same as that shown in FIG. 1 except that the annular ground electrode 801 is formed asymmetrically with respect to the virtual axis Y. The basic structure of the surface acoustic wave device 101 according to the first embodiment of the surface acoustic wave device of the present invention is the same as that shown in FIG.

  The mounting substrate 900 in the second embodiment of the surface acoustic wave device of the present invention has a structure in which a plurality of layers are laminated as shown in FIG. Except for the point formed asymmetrically and the through-grounding conductors 1201 and 1202 being arranged symmetrically with respect to the virtual axis Y, the laminated structure is the same as in FIGS. Omitted.

  The annular ground electrode 801 and the connection pad electrodes 701 to 703 are joined to the annular ground conductor 1001 and the connection pad conductors 1101 to 1103 such that the lower surface of the piezoelectric substrate 100 and the upper surface of the mounting substrate 900 face each other. The surface acoustic wave device according to the second embodiment can be obtained.

  By adopting such a configuration, at least one of the annular ground electrode 801 and the annular ground conductor 1001, which is formed asymmetrically with respect to the symmetry axis Y, in the path until the IDT electrodes 302, 303, 502, and 503 are grounded, passes through. Since the inductance components are connected through the ground conductors 1201 and 1202, these inductance components function as a matching circuit, and as a result, excellent filter pass characteristics with low insertion loss and low VSWR. It will have. In addition, since the magnitude of such an inductance component can be adjusted by the design of at least one of the annular ground electrode 801 and the annular ground conductor 1001, a function as a desired matching circuit can be provided, and low insertion loss can be achieved. In addition, a low VSWR can be obtained with good productivity with excellent filter passing characteristics. Further, at least one of the annular ground electrode 801 and the annular ground conductor 1001 forming the inductance component is an imaginary axis Y provided in the direction orthogonal to the propagation direction X at the center of the IDT electrodes 301 and 501 disposed in the center. The parasitic capacitance formed by the reflector electrodes 401, 402, 601 and 602, the IDT electrodes 302, 303, 502 and 503, the annular ground electrode 801 and the annular ground conductor 1001. Since it can be made different on both sides of the virtual axis Y, it can be finely adjusted so that the impedance between the two connection pad electrodes 702 and 703 as balanced signal terminals is matched. It becomes a surface acoustic wave device.

  As shown in FIGS. 5 and 6, at least one of the annular ground electrode 801 and the annular ground conductor 1001 is formed to have a portion having a different width so as to be asymmetric with respect to the virtual axis Y. With such a configuration, the magnitude of the inductance component can be controlled by appropriately setting the width of at least one of the annular ground electrode 801 and the annular ground conductor 1001, so that the function as a desired matching circuit can be achieved. Therefore, a low insertion loss and a low VSWR can be obtained with excellent filter pass characteristics and good productivity. Further, at least one of the annular ground electrode 801 and the annular ground conductor 1001 has a portion formed asymmetrically with respect to the virtual axis Y and a portion formed symmetrically with respect to the virtual axis Y. As a result, two connection pad electrodes 702 and 703 as balanced signal terminals, connection pad conductors 1102 and 1103 to which these are connected, and an annular ground electrode 801 are formed symmetrically with respect to the virtual axis Y. And the capacitance formed by the annular ground conductor 1001 can be made equal on both sides of the virtual axis Y, and the occurrence of different parasitic capacitances in the two connection pad electrodes 702 and 703 as balanced signal terminals can be suppressed. Therefore, the balance is excellent.

  Further, as shown in FIGS. 7 and 8, portions of the annular ground electrode 801 and the annular ground conductor 1001 formed to have different widths so as to be asymmetric with respect to the virtual axis Y, in this example, the annular ground electrode 801 , A portion formed so as to project in an L shape on the inner peripheral surface of the corner portion of the annular grounding conductor 1101 is connected pad electrodes 702 and 703 as balanced signal terminals and a connection pad to which these are joined By providing only the connection pad electrode 701 as an unbalanced signal terminal and the connection pad conductor 1101 to which the conductors 1102 and 1103 are joined, the two connection pad electrodes 702 and 703 as balanced signal terminals are provided. Since it is possible to more reliably prevent different parasitic capacitances from being generated, the balance is further improved.

  Furthermore, each electrode pattern of the surface acoustic wave element 101 and the internal structure of the mounting substrate 900 are the same except that at least one of the annular ground electrode 801 and the annular ground conductor 1001 is formed asymmetrically with respect to the virtual axis Y. When each conductor pattern is also formed symmetrically with respect to the virtual axis Y, it is possible to more reliably suppress the occurrence of different parasitic capacitances in the two connection pad electrodes 702 and 703 as balanced signal terminals. This is desirable because the balance does not deteriorate.

  Here, in the second embodiment of the surface acoustic wave device according to the present invention, the surface acoustic wave element 101 shown in FIGS. 5 and 7 is virtually connected to both the through-grounding conductors 1201 and 1202 and the annular grounding conductor 1001 as shown in FIG. It may be mounted on a mounting substrate 900 formed so as to be symmetric with respect to the axis Y, or an annular ground electrode 801 as shown in FIG. 1 is formed so as to be symmetric with respect to the virtual axis Y. The surface acoustic wave element 101 may be mounted on the mounting substrate 900 shown in FIGS.

  In the example shown in FIG. 5 to FIG. 8, only one portion of the annular ground electrode 801 and the annular ground conductor 1001 is formed asymmetrically with respect to the virtual axis Y. You may provide in several places. For example, the inner peripheral surface and the outer peripheral surface of the annular ground electrode 801 and the annular ground conductor 1001 are partly removed with a laser to provide a large number of fine planar concavo-convex shapes, and the number of concave or convex portions is set on the virtual axis Y. It may be different on both sides. By forming the ring-shaped ground electrode 801 and the ring-shaped ground conductor 1001 asymmetrically on both sides of the virtual axis Y with such a fine planar concavo-convex shape, the magnitude of the inductance component can be precisely adjusted. Further, the planar concavo-convex shape may be formed on the entire inner peripheral surface / outer peripheral surface of the annular ground electrode 801 and the annular ground conductor 1001, or may be formed on only a part thereof. For example, a fine planar concavo-convex shape is provided in a portion where the annular ground electrode 801 and the annular ground conductor 1001 of FIGS. 7 and 8 are formed asymmetrically with respect to the virtual axis Y, that is, a portion protruding in an L shape on the inner peripheral surface. Alternatively, the number of concave or convex portions on the annular ground electrode 801 and the annular ground conductor 1001 on the side of the connection pad electrodes 702 and 703 and the connection pad conductors 1102 and 1103 as balanced signal terminals on both sides of the virtual axis Y It is also possible to form them with different values. In the latter case, the capacitance formed by the connection pad electrodes 702 and 703 as the two balanced signal terminals, the connection pad conductors 1102 and 1103 to which they are joined, the annular ground electrode 801 and the annular ground conductor 1001 By making them different on both sides of the virtual axis Y, it is possible to finely adjust the impedance between the two balanced signal terminals so that the surface acoustic wave device has a good balance. In FIG. 6, the through-ground conductors 1201 and 1202 are used to connect the annular ground electrode 801 and the annular ground conductor 1001 to the lower surface ground conductor patterns 1210a and 1210b. A caster to be formed may be used.

  In the first embodiment of the surface acoustic wave device of the present invention, only the through-ground conductors 1201 and 1202 are provided on the virtual axis Y, and in the second embodiment, at least one of the annular ground electrode 801 and the annular ground conductor 1001 is provided on the virtual axis Y. Although an example of being asymmetric with respect to the above has been described, by combining these, the through-ground conductors 1201 and 1202 are formed asymmetrically with respect to the virtual axis Y, and the annular ground electrode 801 and the annular ground conductor 1001 are formed. Is configured to be asymmetric with respect to the virtual axis Y (hereinafter referred to as a third embodiment of the surface acoustic wave device of the present invention), the IDT electrodes 302, 303, and 502. , 503 can be controlled over a wider range of the inductance component added to the path until it is grounded, so that it can have a function as a desired matching circuit and low insertion loss. It can be excellent as beauty low VSWR next filter pass characteristics.

  In such a surface acoustic wave device, in order to form the through-grounding conductors 1201 and 1202 asymmetrically with respect to the virtual axis Y, the through-grounding conductors 1201 and 1202 may be disposed asymmetrically with respect to the virtual axis Y. However, it may be formed such that at least one diameter is different from the diameter of the other, the number may be different on both sides of the virtual axis Y, or asymmetric with respect to the virtual axis Y. In addition to the group, it may be formed so as to have a group formed symmetrically with respect to the virtual axis Y. In particular, when a large number of through-grounding conductors 1201 and 1202 are provided and disposed so as to be asymmetric with respect to the virtual axis Y, the IDT electrodes 302, 303, 502, and 503 can be reliably grounded. It is preferable because an increase in the outside floor level can be reliably suppressed and a surface acoustic wave device having excellent filter characteristics can be obtained.

  In order to form at least one of the annular ground electrode 801 and the annular ground conductor 1001 asymmetrically with respect to the virtual axis Y, at least one of the annular ground electrode 801 and the annular ground conductor 1001 is asymmetrical with respect to the virtual axis Y. It may be formed so as to have a portion with a different width, or it may have a portion formed symmetrically with respect to the virtual axis Y and a portion formed symmetrically with respect to the virtual axis Y. It may be formed.

  Further, portions of the through-grounding conductors 1201 and 1202 and at least one of the annular grounding electrode 801 and the annular grounding conductor 1001 that are formed asymmetrically with respect to the virtual axis Y are connection pad electrodes 702 and 703 as balanced signal terminals. Is formed on the side closer to the connection pad electrode 701 as an unbalanced signal terminal, that is, when it is formed on the side of the connection pad electrode 701 outside the plurality of stages, the connection pad as a balanced signal terminal Since it is possible to prevent the generation of different parasitic capacitances in the electrodes 702 and 703, it is preferable because the balance is excellent.

  Thus, according to the third embodiment of the surface acoustic wave device of the present invention, at least one of the annular ground electrode 801 and the annular ground conductor 1001 and the through-ground conductors 1201 and 1202 are asymmetric with respect to the virtual axis Y. By forming, an inductance component can be added to the path until the IDT electrodes 302, 303, 502, 503 are grounded without affecting the connection pad electrodes 702, 703 as balanced signal terminals, and Since the magnitude of the inductance component can be controlled, a surface acoustic wave device having low insertion loss and low VSWR and excellent filter passing characteristics can be provided.

  Next, modified examples of the first to third embodiments of the surface acoustic wave device of the present invention as described above will be described with reference to FIGS. 10 to 12 are plan views showing modifications of the surface acoustic wave element 101 in the surface acoustic wave device of the invention. Hereinafter, based on the structure of the surface acoustic wave element 101 shown in FIG. 1, only the parts changed from the above-described surface acoustic wave device of the present invention will be described, and redundant descriptions regarding similar parts will be omitted.

  In the surface acoustic wave device of the present invention, as shown in FIG. 10, the connection pad electrode 701 as an unbalanced signal terminal of the surface acoustic wave element 101 is connected between the IDT electrode 301 and the connection pad electrode 701 in this example. Are arranged in series in the propagation direction X, one IDT electrode 1401 having a plurality of long electrode fingers in the direction orthogonal to the propagation direction X, and disposed on both sides of the IDT electrode 1401, respectively. A surface acoustic wave resonator 1301 having reflector electrodes 1501 and 1502 provided with a plurality of long electrode fingers in a direction perpendicular to the surface may be connected. With this configuration, the surface acoustic wave resonator 1301 is manufactured so that the resonance frequency of the surface acoustic wave resonator 1301 has a desired value, so that the attenuation pole caused by the surface acoustic wave resonator 1301 can be reduced. Since the position can be controlled, the attenuation pole can be formed at a desired position, and the attenuation characteristic outside the pass band can be excellent. The resonance frequency of the surface acoustic wave resonator 1301 can be controlled by adjusting the size of the capacitance of the IDT electrode 1401 and the inductance of the path until the IDT electrode 1401 is grounded.

  Furthermore, in the surface acoustic wave device of the present invention, as shown in FIG. 11, the connection pad electrodes 702 and 703 as balanced signal terminals of the surface acoustic wave element 101 are connected to the IDT electrode 501 and the connection pad electrode 702 in this example. , 703 in series, along the propagation direction X, one IDT electrode 1401 having a plurality of long electrode fingers in a direction perpendicular to the propagation direction X, and on both sides of the IDT electrode 1401 Surface acoustic wave resonators 1302 and 1303 having reflector electrodes 1501 and 1502 that are respectively disposed and have a plurality of long electrode fingers in a direction orthogonal to the propagation direction X may be connected. With such a configuration, the surface acoustic wave resonators 1302 and 1303 are manufactured so that the resonance frequency of the surface acoustic wave resonators 1302 and 1303 has a desired value. Therefore, the attenuation pole can be formed at a desired position, and the attenuation characteristic outside the passband can be excellent.

  Here, if the surface acoustic wave resonators 1301 to 1303 are connected in series to the connection pad electrodes 701 to 703, they are attenuated sharply on the low frequency side in the vicinity of the resonance frequency compared to the high frequency side. By forming an attenuation pole on the high-frequency side, the attenuation characteristics on the high-frequency side of the passband can be improved, and if connected in parallel, it is steeper on the high-frequency side near the resonance frequency than on the low-frequency side. Therefore, the attenuation characteristic on the low band side of the pass band can be improved by forming the attenuation pole on the low band side of the pass band. For this reason, a connection method may be appropriately selected according to a desired attenuation characteristic. Further, by connecting a surface acoustic wave resonator having the same structure made of the same material to the connection pad electrodes 702 and 703 as balanced signal terminals, two parasitic pads 702 and 703 as balanced signal terminals have different parasitics. Generation of a capacity can be suppressed, and a surface acoustic wave device with excellent balance can be obtained.

  Further, in the surface acoustic wave device of the present invention, as shown in FIG. 12, an odd number of surface acoustic wave elements 101, in this example, three IDT electrodes 301 to 303 and 501 to 503 are arranged in the propagation direction X. Insertion reflector electrodes 1601 to 1604 having a plurality of long electrode fingers in a direction perpendicular to the same are disposed, and the distance between the centers of adjacent electrode fingers of the insertion reflector electrodes 1601 to 1604 is at both ends. It is good also as a structure gradually shortened toward the said electrode finger located in the center part from the electrode finger located. With such a configuration, the amplitude mode can be increased by the insertion reflectors 1601 to 1604, and the distance between the centers of the adjacent electrode fingers of the insertion reflector electrodes 1601 to 1604 is the electrode finger located at both ends. Since it is possible to prevent the surface acoustic wave from being converted into a bulk wave by gradually shortening from the electrode finger to the electrode finger located in the center, increase the amplitude mode without disturbing the propagation of the surface acoustic wave Therefore, a surface acoustic wave device with a wide pass band can be realized. In FIG. 12, the insertion reflector electrodes 1601 to 1604 are disposed on both of the electrode groups 201 and 202. However, the insertion reflector electrode is disposed on only one of the electrode group 201 and the electrode group 202. Also good.

  Such a surface acoustic wave element 101 shown in FIGS. 10 to 12 may be mounted on a mounting substrate 900 as shown in FIGS. As shown in FIG. 7, the annular ground electrode 801 may be formed asymmetrically with respect to the virtual axis Y.

  In addition, the surface acoustic wave device of the present invention can be applied to a communication device. That is, at least one of a receiving circuit and a transmitting circuit using the surface acoustic wave device of the present invention as a filter means is provided. 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, receiving received signals with an antenna, amplifying the received signals that passed through the duplexer with a low-noise amplifier, and then attenuating unnecessary signals with a bandpass filter, The surface acoustic wave device of the present invention can be applied to various filters in a communication device including a receiving circuit that separates a signal and extracts the signal. If the surface acoustic wave device of the present invention is employed, communication with excellent sensitivity is possible. An apparatus can be provided.

  As described above, according to the communication device of the present invention, it is possible to provide a communication device such as an excellent communication device that has a reception circuit and a transmission circuit each having an excellent surface acoustic wave device and whose sensitivity is remarkably good.

  The surface acoustic wave device and the communication device of the present invention are not limited to the above-described embodiments, and can be changed and improved without departing from the gist of the present invention. For example, two or more types of IDT electrodes having different pass bands may be provided in a region in the annular ground electrode 801, and further, the annular ground electrode may be provided so as to individually surround the two or more types of IDT electrodes.

  Specific examples of the present invention will be described.

  Specifically, the surface acoustic wave element 101 shown in FIG. 1 is manufactured so as to function as a surface acoustic wave filter having a center frequency in the 900 MHz band, and the surface acoustic wave element 101 is mounted on the mounting substrate 900 shown in FIG. The surface acoustic wave device of the present invention was fabricated.

First, an IDT electrode 301 to 303, 501 to 503, a reflector electrode 401, 402, 601, 602, and a connection pad are formed on a LiTaO ₃ single crystal piezoelectric substrate 100 having a 38.7 ° Y-cut propagation in the X direction. A fine electrode pattern made of Al (99 mass%)-Cu (1 mass%) of the electrodes 701 to 703 and the annular ground electrode 801 was formed.

  The pattern was produced by photolithography using a sputtering apparatus, a reduction projection exposure machine (stepper), and an RIE (Reactive Ion Etching) apparatus.

  First, the piezoelectric substrate 100 was ultrasonically cleaned with acetone / IPA (isopropyl alcohol) or the like to remove organic components. Next, after the piezoelectric substrate 100 was sufficiently dried by a clean oven, the electrodes 301 to 303, 401, 402, 501 to 503, 601, 602, 701 to 703, and 801 were formed. Each electrode 301 to 303, 401, 402, 501 to 503, 601, 602, 701 to 703, 801 is formed using a sputtering apparatus and made of an Al (99 mass%)-Cu (1 mass%) alloy. The material was used to form a thickness of about 0.20 μm.

  Next, a photoresist is formed by spin coating 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 the photoresist is dissolved in an alkaline developer by a developing apparatus. After the desired pattern is exposed, the electrode film is etched by the RIE apparatus, and each electrode 301 to 303, 401, 402, 501 to 503, 601 of the surface acoustic wave element 101 constituting the surface acoustic wave filter is formed. Patterns 602, 701 to 703, 801 were obtained.

Thereafter, a protective film was formed on a predetermined region of each of the electrodes 301 to 303, 401, 402, 501 to 503, 601, 602, 701 to 703, and 801. That is, a CVD (Chemical Vapor Deposition) apparatus is used to form a pattern of each electrode 301 to 303, 401, 402, 501 to 503, 601, 602, 701 to 703, 801 and a thickness of about 0.02 μm of SiO ₂ on the piezoelectric substrate 100. Formed. Thereafter, the photoresist was patterned by photolithography, and the flip-chip window opening portion was etched at the positions where the electrodes 701 to 703 and 801 were formed by an RIE apparatus or the like. Thereafter, using a sputtering apparatus, a layer made of Al is formed with a thickness of about 1.0 μm, and Al and photoresist except for the formation positions of the electrodes 701 to 703 and 801 are simultaneously removed by a lift-off method, Pads for forming flip chip bumps on 701 to 703, 801 were completed.

  Next, flip-chip bumps made of solder were formed on the pads using a screen printing apparatus. The bump diameter on the connection pad electrodes 701 to 703 was about 80 μm, the height was about 30 μm, and the bump height on the annular ground electrode 801 was about 30 μm.

  Next, the piezoelectric substrate 100 was diced along dicing lines and divided into individual surface acoustic wave elements 101.

  Next, a mounting substrate 900 shown in FIG. 2 was produced. That is, in order to produce LTCC (Low Temperature Co-fired Ceramics), a green sheet is produced by molding a slurry in which a metal oxide and an organic binder are homogeneously kneaded with an organic solvent or the like into a sheet shape, Ring ground conductor 1001, connecting pad conductors 1101 to 1103, through-ground conductors 1201 to 1203, internal ground conductor patterns 1210a and 1210b, internal signal conductor patterns 1221 to 1223, bottom ground conductor patterns 1220a and 1220b, signal conductors at desired positions After forming patterns of patterns 1231 to 1233, these green sheets are laminated and pressure-bonded so as to be integrally formed and fired. The size of the mounting substrate 900 was 2.5 × 2.0 mm square.

  Here, the annular ground conductor 1001 and the connection pad conductors 1101 to 1103 were formed so as to correspond to the annular ground electrode 801 and the connection pad electrodes 701 to 703 of the surface acoustic wave element 101. Further, the annular ground conductor 1001, the connecting pad conductors 1101 to 1103, the internal ground conductor patterns 1210a and 1210b, the internal signal conductor patterns 1221 to 1223, the bottom ground conductor patterns 1220a and 1220b, and the signal conductor patterns 1231 to 1233 use Ag. To a thickness of about 1 μm by screen printing. The through-ground conductors 1201 to 1203 were formed by forming through holes by die-cutting and filling with an Ag-based conductor paste.

  The surface acoustic wave element 101 formed in this way is arranged with the lower surface (electrode formation surface) of the piezoelectric substrate 100 and the upper surface of the mounting substrate 900 facing each other by a flip chip mounting apparatus, and at 240 ° C. in a reflow furnace. The annular ground electrode 801 and each of the connection pad electrodes 701 to 703, the annular ground conductor 1001 and the connection pad conductors 1101 to 1103 are electrically connected to each other by reflow melting for 5 minutes and joining them with bumps made of solder. The IDT electrodes 301 to 303 and 501 to 503 and the connection pad electrodes 701 to 703 are hermetically sealed by connecting the annular ground electrode 801 and the annular ground conductor 1001 together, and the surface acoustic wave device is completed. .

  As a reference example, a surface acoustic wave element 101 in which an annular ground electrode 801 is formed symmetrically with respect to the symmetry axis Y as shown in FIG. 1 is used as a through-ground conductor 1201, 1202 and an annular ground as shown in FIG. A surface acoustic wave device mounted on a mounting substrate 900 in which the conductor 1001 is formed symmetrically with respect to the symmetry axis Y was manufactured in the same process using the same material as in the above example.

  Next, the characteristics of the surface acoustic wave device in Examples and Reference Examples were measured. A signal of 0 dBm was input, and measurement was performed under conditions of a frequency of 920 MHz to 980 MHz and a measurement point of 240 points. The number of samples was 30, and a multi-port network analyzer E5071A manufactured by Agilent Technologies was used as a measuring instrument.

  In the embodiment, as shown in FIG. 2, through-ground conductors 1201 and 1202 are arranged asymmetrically with respect to the virtual axis Y, and inductance components connected to a path until the IDT electrodes 301 to 303 and 501 to 503 are grounded. Was 0.3 nH. FIGS. 13 to 15 are diagrams showing the frequency dependence of the transmission characteristics of the input signal in the surface acoustic wave device of the example manufactured in this way and the surface acoustic wave device of the reference example. 13 to 15, the solid line shows the characteristics of the surface acoustic wave device of the example, and the broken line shows the characteristics of the surface acoustic wave device of the reference example.

  FIG. 13 is a diagram showing the frequency dependence of insertion loss representing transmission characteristics, where the horizontal axis represents frequency (MHz) and the vertical axis represents insertion loss (dB). As is clear from FIG. 13, it was found that the surface acoustic wave device of the example had a lower (smaller) insertion loss and improved filter pass characteristics than the surface acoustic wave device of the reference example.

  FIG. 14 is a diagram showing the frequency dependence of VSWR, where the horizontal axis represents frequency (MHz) and the vertical axis represents VSWR. As is clear from FIG. 14, it was found that the surface acoustic wave device of the example had a lower VSWR and improved the filter passing characteristics than the surface acoustic wave device of the reference example.

  In this configuration, an inductance component is connected to the path until the IDT electrodes 302, 303, 502, and 503 are grounded (that is, the lower surface ground conductor pattern of the surface acoustic wave device). This is because an inductance component is connected to the ground terminal connected to 1220), and this inductance component performs the same function as the matching circuit.

  Further, FIG. 15 (a) is a diagram showing the frequency dependence of the amplitude balance, (b) is a diagram showing the frequency dependence of the phase balance, the horizontal axis is the frequency (MHz), and the vertical axis is the figure. 15 (a) shows the amplitude balance (dB), and FIG. 15 (b) shows the phase balance (deg). As is clear from FIGS. 15A and 15B, the surface acoustic wave device of the embodiment of the present invention has a balance in the vicinity of the pass band (930 MHz to 970 MHz) as compared with the surface acoustic wave device of the reference example. It was confirmed that it was good without any deterioration. This is presumably because it was possible to suppress the addition of different parasitic capacitances to the connection pad electrodes 702 and 703 as balanced signal terminals of the surface acoustic wave device shown in the example of the present invention.

  Thus, according to the surface acoustic wave device of the present invention, it was found that the balance was good, the insertion loss was low, the VSWR was low, that is, the filter passing characteristics were excellent.

  In addition, as a result of measuring the transmission characteristics by changing the magnitude of the inductance component connected to the path until the IDT electrodes 302, 303, 502, and 503 of the surface acoustic wave device of the embodiment are grounded, the magnitude of the inductance component is measured. It has been found that the balance tends to deteriorate when 0.5 nH or more, and is preferably in the range of 0.1 to 0.3 nH.

It is a top view which shows an example of the surface acoustic wave element in 1st Embodiment of the surface acoustic device of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a top view which shows an example of the mounting board | substrate in 1st Embodiment of the surface acoustic wave apparatus of this invention, (a)-(f) is a top view of each layer which each comprises a mounting board | substrate. (A)-(f) is a top view of each layer which shows the other example of the board | substrate for mounting in 1st Embodiment of the surface acoustic wave apparatus of this invention, respectively. (A)-(f) is a top view of each layer which shows the other example of the board | substrate for mounting in 1st Embodiment of the surface acoustic wave apparatus of this invention, respectively. It is a top view which shows an example of the surface acoustic wave element in 2nd Embodiment of the surface acoustic wave apparatus of this invention. It is a top view which shows an example of the mounting board | substrate in 2nd Embodiment of the surface acoustic wave apparatus of this invention, (a)-(f) is a top view of each layer which each comprises a mounting board | substrate. It is a top view which shows the other example of the surface acoustic wave element in 2nd Embodiment of the surface acoustic wave apparatus of this invention. It is a top view which shows the other example of the board | substrate for mounting in 2nd Embodiment of the surface acoustic wave apparatus of this invention. It is a top view which shows the further another example of the mounting board | substrate in 2nd Embodiment of the surface acoustic wave apparatus of this invention. It is a top view which shows an example of the modification of the surface acoustic wave element in the surface acoustic wave apparatus of this invention. It is a top view which shows the other example of the modification of the surface acoustic wave element in the surface acoustic wave apparatus of this invention. It is a top view which shows the further another example of the modification of the surface acoustic wave element in the surface acoustic wave apparatus of this invention. It is a diagram which shows the frequency dependence of the insertion loss showing the transmission characteristic of the surface acoustic wave apparatus of this invention. It is a diagram which shows the frequency dependence of VSWR of the surface acoustic wave apparatus of this invention. (A) is a diagram showing the frequency dependence of the amplitude balance of the surface acoustic wave device of the present invention, and (b) is a diagram showing the frequency dependence of the phase balance of the surface acoustic wave device of the present invention. It is a top view which shows the conventional surface acoustic wave filter with an unbalance-balance conversion function. It is a top view which shows the other example of the conventional surface acoustic wave element with an unbalance-balance conversion function. FIG. 18 is a diagram showing the frequency dependence of insertion loss of the surface acoustic wave filter and the surface acoustic wave element shown in FIGS. 16 and 17. FIG. 18 is a diagram showing the frequency dependence of VSWR of the surface acoustic wave filter and the surface acoustic wave element shown in FIGS. 16 and 17. (A) of the surface acoustic wave filter and surface acoustic wave element shown in FIGS. 16 and 17 are diagrams showing the frequency dependence of the amplitude balance, and (b) are diagrams showing the frequency dependence of the phase balance.

Explanation of symbols

100: Piezoelectric substrate
101: Surface acoustic wave device
201, 202: Electrode group
301, 302, 303, 501, 502, 503, 1401: IDT electrodes
401, 402, 601, 602, 1501, 1502, 1601, 1602, 1603, 1604: Reflector
701: Pad electrode for connection (unbalanced signal terminal)
702, 703: Connection pad electrode (balanced signal terminal)
801: Annular ground electrode
900: PCB for mounting
1001: Annular grounding conductor
1101: Pad conductor for connection (unbalanced signal terminal)
1102, 1103: Pad conductor for connection (balanced signal terminal)
1201, 1202, 1203: Through-ground conductor

Claims (12)

Three or more odd-numbered IDT electrodes having 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 piezoelectric substrate on the lower surface of the piezoelectric substrate; A plurality of electrode groups, each of which is arranged on both sides of the odd number of IDT electrodes and includes reflector electrodes each having a plurality of long electrode fingers in a direction orthogonal to the propagation direction, are arranged in cascade. And a surface acoustic wave element comprising a connection pad electrode connected to the electrode group and an annular ground electrode surrounding the electrode group and the connection pad electrode. the opposing annular grounding conductor and the connecting pad electrode facing the connection pad conductor and said annular ground mounting board on which a plurality of through ground conductor, one end of which is connected to is formed with, the lower of the piezoelectric substrate And the said the top is opposed annular ground electrode and the connecting pad electrode are mounted is bonded to each of the annular grounding conductor and the connecting pad conductor of the mounting substrate,
The IDT electrode disposed in the center of the first stage electrode group has the connection pad electrode connected as an unbalanced signal terminal, and the IDT electrode disposed in the center of the last stage electrode group includes the One of the opposing comb-like electrodes each having an electrode finger is divided into two, and each of the connection pad electrodes is connected as a balanced signal terminal to each of the IDT electrodes disposed in the center of the first stage. The IDT electrodes located on both sides are connected to the annular ground electrode on the outer side of the plurality of stages, and the IDT electrodes located on both sides of the IDT electrode disposed in the center of the final stage. In the IDT electrode, the comb-like electrode outside the plurality of stages is connected to the annular ground electrode,
The centers of the IDT electrodes arranged at the center of the first stage and the last stage are arranged in a direction orthogonal to the propagation direction, and the plurality of through grounding conductors pass through this center. A plurality of through-ground conductors formed asymmetrically with respect to a virtual axis provided in a direction orthogonal to the propagation direction have a diameter of the one disposed on one side of the virtual axis. The elastic surface is different from the diameter of the one disposed on the other side of the shaft, and the other end of the through-grounding conductor is connected to the lower surface ground conductor pattern provided on the lower surface of the mounting substrate. Wave equipment. Three or more odd-numbered IDT electrodes having 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 piezoelectric substrate on the lower surface of the piezoelectric substrate; A plurality of electrode groups, each of which is arranged on both sides of the odd number of IDT electrodes and includes reflector electrodes each having a plurality of long electrode fingers in a direction orthogonal to the propagation direction, are arranged in cascade. In addition, a surface acoustic wave element comprising a connection pad electrode connected to the electrode group and an annular ground electrode surrounding the electrode group and the connection pad electrode is provided on the upper surface of the annular contact.
A mounting substrate on which an annular ground conductor facing the ground electrode, a connection pad conductor facing the connection pad electrode, and a plurality of through ground conductors having one end connected to the annular ground conductor are formed on the mounting substrate. The annular ground electrode and the connection pad electrode are bonded and mounted to the annular ground conductor and the connection pad conductor, respectively, with the lower surface facing the upper surface of the mounting substrate,
The IDT electrode disposed in the center of the first stage electrode group has the connection pad electrode connected as an unbalanced signal terminal, and the IDT electrode disposed in the center of the last stage electrode group includes the One of the opposing comb-like electrodes each having an electrode finger is divided into two, and each of the connection pad electrodes is connected as a balanced signal terminal to each of the IDT electrodes disposed in the center of the first stage. The IDT electrodes located on both sides are connected to the annular ground electrode on the outer side of the plurality of stages, and the IDT electrodes located on both sides of the IDT electrode disposed in the center of the final stage. In the IDT electrode, the comb-like electrode outside the plurality of stages is connected to the annular ground electrode,
The centers of the IDT electrodes arranged at the center of the first stage and the last stage are arranged in a direction orthogonal to the propagation direction, and the plurality of through grounding conductors pass through this center. In addition to the group formed asymmetrically with respect to the virtual axis, the plurality of through grounding conductors are formed asymmetrically with respect to the virtual axis. has a group are formed symmetrically with respect to, these and the other end of the through grounding conductor, elastic you, characterized in that it is connected to the lower surface ground conductor pattern provided on the lower surface of the mounting substrate Surface wave device. 3. The surface acoustic wave device according to claim 1, wherein the plurality of through-grounding conductors have different numbers on both sides of the virtual axis . Three or more odd-numbered IDT electrodes having 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 piezoelectric substrate on the lower surface of the piezoelectric substrate; A plurality of electrode groups, each of which is arranged on both sides of the odd number of IDT electrodes and includes reflector electrodes each having a plurality of long electrode fingers in a direction orthogonal to the propagation direction, are arranged in cascade. And a surface acoustic wave element comprising a connection pad electrode connected to the electrode group and an annular ground electrode surrounding the electrode group and the connection pad electrode. A mounting substrate on which a plurality of through-ground conductors having one end connected to the annular ground conductor are formed on the mounting substrate, the annular ground conductor facing the connection pad electrode, and the connection pad conductor facing the connection pad electrode. And the said the top is opposed annular ground electrode and the connecting pad electrode are mounted is bonded to each of the annular grounding conductor and the connecting pad conductor of the mounting substrate,
The IDT electrode disposed in the center of the first stage electrode group has the connection pad electrode connected as an unbalanced signal terminal, and the IDT electrode disposed in the center of the last stage electrode group includes the One of the opposing comb-like electrodes each having an electrode finger is divided into two, and each of the connection pad electrodes is connected as a balanced signal terminal to each of the IDT electrodes disposed in the center of the first stage. The IDT electrodes located on both sides are connected to the annular ground electrode on the outer side of the plurality of stages, and the IDT electrodes located on both sides of the IDT electrode disposed in the center of the final stage. In the IDT electrode, the comb-like electrode outside the plurality of stages is connected to the annular ground electrode,
The centers of the IDT electrodes arranged at the center of the first stage and the last stage are arranged in a direction orthogonal to the propagation direction, and the plurality of through grounding conductors pass through this center. A plurality of through-ground conductors formed asymmetrically with respect to a virtual axis provided in a direction orthogonal to the propagation direction have a diameter of the one disposed on one side of the virtual axis. It is different from the diameter of the one disposed on the other side of the shaft, and the other end of these through-ground conductors is connected to a lower surface ground conductor pattern provided on the lower surface of the mounting substrate,
At least one of the annular ground electrode and the annular ground conductor is unpaired with respect to the virtual axis.
It characterized in that it is formed in the referred surface acoustic wave device. Three or more odd-numbered IDT electrodes having 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 piezoelectric substrate on the lower surface of the piezoelectric substrate; A plurality of electrode groups, each of which is arranged on both sides of the odd number of IDT electrodes and includes reflector electrodes each having a plurality of long electrode fingers in a direction orthogonal to the propagation direction, are arranged in cascade. And a surface acoustic wave element comprising a connection pad electrode connected to the electrode group and an annular ground electrode surrounding the electrode group and the connection pad electrode. A mounting substrate on which a plurality of through-ground conductors having one end connected to the annular ground conductor are formed on the mounting substrate on which the annular ground conductor opposed to the connection pad electrode and the connection pad conductor opposed to the connection pad electrode are formed. And the said the top is opposed annular ground electrode and the connecting pad electrode are mounted is bonded to each of the annular grounding conductor and the connecting pad conductor of the mounting substrate,
The IDT electrode disposed in the center of the first stage electrode group has the connection pad electrode connected as an unbalanced signal terminal, and the IDT electrode disposed in the center of the last stage electrode group includes the One of the opposing comb-like electrodes each having an electrode finger is divided into two, and each of the connection pad electrodes is connected as a balanced signal terminal to each of the IDT electrodes disposed in the center of the first stage. The IDT electrodes located on both sides are connected to the annular ground electrode on the outer side of the plurality of stages, and the IDT electrodes located on both sides of the IDT electrode disposed in the center of the final stage. In the IDT electrode, the comb-like electrode outside the plurality of stages is connected to the annular ground electrode,
The centers of the IDT electrodes arranged at the center of the first stage and the last stage are arranged in a direction orthogonal to the propagation direction, and the plurality of through grounding conductors pass through this center. In addition to the group formed asymmetrically with respect to the virtual axis, the plurality of through grounding conductors are formed asymmetrically with respect to the virtual axis. have a group which is formed symmetrically, the other end of the through ground conductor is connected to the lower surface ground conductor pattern provided on the lower surface of the mounting substrate against,
At least one of the annular ground electrode and the annular ground conductor is formed asymmetrically with respect to the virtual axis . The surface acoustic wave device according to claim 4 or 5, wherein the number of the plurality of through grounding conductors is different on both sides of the virtual axis . 6. The surface acoustic wave device according to claim 4 , wherein at least one of the annular ground electrode and the annular ground conductor has a portion having a different width so as to be asymmetric with respect to the virtual axis. . At least one of the annular ground electrode and the annular ground conductor has a portion formed asymmetrically with respect to the virtual axis and a portion formed symmetrically with respect to the virtual axis. The surface acoustic wave device according to claim 4 or 5 . A single IDT electrode provided with a plurality of long electrode fingers in the direction orthogonal to the propagation direction along the propagation direction and the unbalanced signal terminal are disposed on both sides of the IDT electrode, respectively. 9. The elasticity according to claim 1 , wherein a surface acoustic wave resonator having a reflector electrode having a plurality of long electrode fingers in a direction orthogonal to the direction is connected. Surface wave device. A single IDT electrode having a plurality of long electrode fingers in the direction orthogonal to the propagation direction along the propagation direction and the balanced signal terminal are respectively disposed on both sides of the IDT electrode, and the propagation direction Surface acoustic wave having a reflector electrode having a plurality of electrode fingers long in a direction perpendicular to the surface
The surface acoustic wave device according to any one of claims 1 to 9, characterized in that the resonator is connected. An insertion reflector electrode having a plurality of long electrode fingers in a direction orthogonal to the propagation direction is disposed between the odd number of IDT electrodes, and an electrode finger adjacent to the insertion reflector electrode is disposed. The elastic surface according to any one of claims 1 to 10, wherein a center-to-center distance is gradually shortened from the electrode fingers located at both ends toward the electrode fingers located at the center. Wave equipment. 12. A communication apparatus comprising at least one of a receiving circuit and a transmitting circuit using the surface acoustic wave device according to claim 1 as a filter unit .

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