JP5442428B2 - Duplexer - Google Patents

Description

  The present invention relates to a duplexer that separates transmission signals and reception signals having different frequencies.

  The duplexer is also called a duplexer or an antenna duplexer, and separates a transmission signal and a reception signal having different frequencies, and is mounted on, for example, a mobile phone terminal device. The duplexer includes an antenna terminal, a transmission side terminal, a reception side terminal, a transmission filter, and a reception filter. The transmission signal input from the transmission side terminal passes through the transmission filter, and a signal in a predetermined frequency band (hereinafter, also referred to as “transmission side pass frequency band”) is output from the antenna terminal. Also, the reception signal input from the antenna terminal passes through the reception filter, and a signal in a predetermined frequency band (hereinafter sometimes referred to as “reception side pass frequency band”) is output from the reception side terminal.

  Patent Document 1 includes a ladder-type surface acoustic wave (hereinafter abbreviated as “SAW”) filter as a transmission filter, and a balanced SAW filter for balanced signals as a reception filter. A duplexer provided as is disclosed.

  According to the duplexer disclosed in Patent Document 1, since a balanced SAW filter for balanced signals is provided as a reception filter, the reception-side passage that passes through the reception filter and is output from two reception-side terminals is provided. Signals in the frequency band are signals having opposite phases (phases are shifted by 180 °).

JP 2008-60775 A

  In the duplexer, the transmission signal that passes through the transmission filter is originally directed to the antenna terminal, but part of the transmission signal may leak to the reception side due to leakage power.

  A conventional duplexer including a balanced SAW filter as disclosed in Patent Document 1 is usually designed to output a phase signal close to the same phase in a band other than the reception-side pass frequency band in the reception filter. Therefore, so-called isolation is high isolation. Isolation here refers to the difference in phase between two signals output from two receiving terminals, and is also called differential mode isolation.

  In contrast to differential mode isolation, common mode isolation is the sum of the phases of two signals. In recent years, improvement of the common mode isolation characteristics has been required, but Patent Document 1 does not disclose a technique for improving the common mode isolation characteristics.

  An object of the present invention is to provide a duplexer excellent in common mode isolation characteristics.

A duplexer according to one embodiment of the present invention includes an antenna terminal,
An unbalanced signal terminal;
First and second balanced signal terminals;
A reference ground terminal;
A first filter disposed between the antenna terminal and the unbalanced signal terminal;
A second filter having a longitudinally coupled resonator type first SAW filter unit and disposed between the antenna terminal and the first and second balanced signal terminals;
The first SAW filter unit includes a central IDT electrode, a first adjacent IDT electrode disposed adjacent to the central IDT electrode on one side of the central IDT electrode, and adjacent to the central IDT electrode on the other side of the central IDT electrode. A second adjacent IDT electrode disposed,
The central IDT electrode has a first comb-like electrode having a plurality of first electrode fingers, a plurality of second electrode fingers arranged between the plurality of first electrode fingers, and the first balance A third comb electrode having a second comb-like electrode connected to the signal terminal and a plurality of third electrode fingers arranged between the plurality of first electrode fingers and connected to the second balanced signal terminal; A comb-like electrode, and an insertion reflector having a plurality of ground electrode fingers ,
The insertion reflector is disposed between the second comb-shaped electrode and the third comb-shaped electrode, and is connected to the first comb-shaped electrode;
The first comb-like electrode is grounded by being electrically connected to the reference ground terminal via the insertion reflector .
A duplexer according to another aspect of the present invention includes an antenna terminal,
An unbalanced signal terminal;
First and second balanced signal terminals;
A reference ground terminal;
A first filter disposed between the antenna terminal and the unbalanced signal terminal;
A second filter having a longitudinally coupled resonator type first SAW filter unit and disposed between the antenna terminal and the first and second balanced signal terminals;
The first SAW filter unit includes a central IDT electrode, a first adjacent IDT electrode disposed adjacent to the central IDT electrode on one side of the central IDT electrode, and adjacent to the central IDT electrode on the other side of the central IDT electrode. A second adjacent IDT electrode disposed; a reflector disposed adjacent to the first adjacent IDT electrode on one side of the first adjacent IDT electrode; and the second adjacent IDT electrode on the other side of the second adjacent IDT electrode. And a first SAW filter reflector composed of a reflector disposed adjacently,
The central IDT electrode has a first comb-like electrode having a plurality of first electrode fingers, a plurality of second electrode fingers arranged between the plurality of first electrode fingers, and the first balance A third comb electrode having a second comb-like electrode connected to the signal terminal and a plurality of third electrode fingers arranged between the plurality of first electrode fingers and connected to the second balanced signal terminal; A comb-like electrode, and
The first SAW filter reflector is connected to the first comb electrode by a connection pattern conductor;
The first comb-like electrode is grounded by being electrically connected to the reference ground terminal via the first SAW filter reflector.
A mobile phone terminal device according to another embodiment of the present invention is equipped with the above duplexer.

  According to said structure, the duplexer excellent in the common mode isolation characteristic can be provided.

1 is an equivalent circuit diagram of a duplexer 10 according to a first embodiment of the present invention. It is a figure which expands and shows the 1st SAW filter part. It is a figure which expands and shows the 1st SAW filter part 7A. It is the equivalent circuit schematic of the duplexer 12 which is 2nd Embodiment of this invention. It is a figure which expands and shows the 1st SAW filter part. It is a figure which expands and shows the 1st SAW filter part 11A. It is a figure which expands and shows the 1st SAW filter part 11B. It is a figure which expands and shows the 1st SAW filter part 11C. It is the equivalent circuit schematic of the duplexer 15 which is 3rd Embodiment of this invention. It is a figure which expands and shows the 1st SAW filter part 13 and the 2nd SAW filter part. It is a figure which expands and shows the 1st SAW filter part 13A. It is a graph which shows the relationship between the number of the electrode fingers for grounding of an insertion reflector, and the ripple in a receiving frequency band. It is a graph which shows the relationship between a pitch change rate and a ripple in a receiving frequency band. It is a graph which shows the relationship between a pitch change rate and a ripple in a receiving frequency band. It is a graph which shows the relationship between a pitch change rate and a ripple in a receiving frequency band. It is a graph which shows the common mode isolation characteristic of an Example and a comparative example.

  Hereinafter, a duplexer according to an embodiment of the present invention will be described with reference to the drawings. Note that the drawings used in the following description are schematic, and the dimensional ratios and the like on the drawings do not necessarily match the actual ones.

  FIG. 1 is an equivalent circuit diagram of a duplexer 10 according to the first embodiment of the present invention. The duplexer 10 includes an antenna terminal 1, an unbalanced signal terminal 2, a first balanced signal terminal 3 a, a second balanced signal terminal 3 b, a reference ground terminal 4, a first filter 5, and a second filter 6. Including.

  In the duplexer 10, the first filter 5 is disposed between the antenna terminal 1 and the unbalanced signal terminal 2, and the second filter 6 is disposed between the antenna terminal 1 and the first and second balanced signal terminals 3a and 3b. Is arranged. A transmission signal transmitted from a signal source connected to the duplexer 10 and input from the unbalanced signal terminal 2 passes through the first filter 5, and a signal in the transmission-side pass frequency band is output from the antenna terminal 1. In addition, the reception signal input from the antenna terminal 1 passes through the second filter 6, and signals in the reception-side pass frequency band are output from the first balanced signal terminal 3a and the second balanced signal terminal 3b.

  The first filter 5 is a ladder-type SAW filter having high power durability, and is a first resonator 51, a second resonator 52, a third resonator 53, a fourth resonator, and a plurality of one-port SAW resonators. The resonator 54, the fifth resonator 55, the sixth resonator 56, the seventh resonator 57, and the eighth resonator 58 are connected in a ladder shape.

  The first resonator 51 includes a first resonator electrode 51a, which is an IDT (Inter Digital Transducer) electrode having a plurality of electrode fingers, and first resonance resonators disposed at both ends of the SAW propagation direction with respect to the first resonator electrode 51a. The reflector 51b is connected to the unbalanced signal terminal 2. On the opposite side of the first resonator 51 from the unbalanced signal terminal 2, a second resonator 52 and a third resonator 53 are connected in parallel.

  The second resonator 52 includes a second resonator electrode 52a, which is an IDT electrode having a plurality of electrode fingers, and a second resonance reflector 52b disposed at both ends of the SAW propagation direction with respect to the second resonator electrode 52a. Including. The third resonator 53 includes a third resonator electrode 53a which is an IDT electrode having a plurality of electrode fingers, and third resonance reflectors 53b disposed at both ends of the SAW propagation direction with respect to the third resonator electrode 53a. And is grounded via the first inductor 2a.

  A fourth resonator 54 and a fifth resonator 55 are connected in parallel on the opposite side of the second resonator 52 from the first resonator 51. The fourth resonator 54 includes a fourth resonator electrode 54a which is an IDT electrode having a plurality of electrode fingers, and fourth resonance reflectors 54b disposed at both ends of the SAW propagation direction with respect to the fourth resonator electrode 54a. Including. The fifth resonator 55 includes a fifth resonator electrode 55a which is an IDT electrode having a plurality of electrode fingers, and fifth resonance reflectors 55b disposed at both ends of the SAW propagation direction with respect to the fifth resonator electrode 55a. And is grounded via the second inductor 2b.

  A sixth resonator 56 is connected in series on the opposite side of the fourth resonator 54 from the second resonator 52. The sixth resonator 56 includes an IDT electrode having a plurality of electrode fingers, a sixth resonator electrode 56a, and sixth resonance reflectors 56b disposed at both ends of the SAW propagation direction with respect to the sixth resonator electrode 56a. including. A seventh resonator 57 and an eighth resonator 58 are connected in parallel on the opposite side of the sixth resonator 56 from the fourth resonator 54.

  The seventh resonator 57 includes a seventh resonator electrode 57a, which is an IDT electrode having a plurality of electrode fingers, and seventh resonance reflectors 57b disposed at both ends of the SAW propagation direction with respect to the seventh resonator electrode 57a. Including and connected to the antenna terminal 1. The eighth resonator 58 includes an eighth resonator electrode 58a, which is an IDT electrode having a plurality of electrode fingers, and eighth resonance reflectors 58b disposed at both ends of the SAW propagation direction with respect to the eighth resonator electrode 58a. And is connected to the fifth resonator 55 and grounded via the second inductor 2b.

  In the duplexer 10 of the present embodiment, the transmission signal input from the unbalanced signal terminal 2 passes through the first filter 5, whereby a signal having a transmission-side pass frequency band of frequency 824 to 849 MHz is output from the antenna terminal 1. Designed to be.

  A third inductor 2 c is connected as a matching circuit between the antenna terminal 1 and the branch of the first filter 5 and the second filter 6.

  The second filter 6 includes a first SAW filter unit 7, an antenna terminal side resonator 8, a first balanced signal terminal side resonator 9a, a second balanced signal terminal side resonator 9b, and a fourth inductor 3c. .

  The antenna terminal side resonator 8 is a SAW resonator connected to the antenna terminal 1 in the second filter 6. The antenna terminal side resonator 8 includes an antenna terminal side resonator electrode 81 which is an IDT electrode having a plurality of electrode fingers, and antenna terminal side resonance reflections disposed at both ends of the SAW propagation direction with respect to the antenna terminal side resonator electrode 81. Instrument 82. In the second filter 6, the antenna terminal side resonator 8 is provided in series on the antenna terminal 1 side to which the received signal is input, so that good matching can be achieved.

  Next, the first SAW filter unit 7 will be described with reference to FIG. FIG. 2 is an enlarged view showing the first SAW filter unit 7. The first SAW filter unit 7 is a longitudinally coupled resonator type SAW filter. The first IDT electrode 71 is disposed adjacent to the central IDT electrode 71 on one side of the central IDT electrode 71 in the SAW propagation direction. The electrode 72 includes a second adjacent IDT electrode 73 disposed adjacent to the central IDT electrode 71 on the other side of the central IDT electrode 71 in the SAW propagation direction.

  The central IDT electrode 71 includes a first comb electrode 711 having a plurality of first electrode fingers 711a, a second comb electrode 712 having a plurality of second electrode fingers 712a, and a plurality of third electrode fingers 713a. And a third comb-like electrode 713.

  In the first comb-teeth electrode 711, the second comb-teeth electrode 712, and the third comb-teeth electrode 713, the first electrode fingers 711a, the second electrode fingers 712a, and the third electrode fingers 713a are respectively comb teeth. It is formed so as to protrude in a direction orthogonal to the SAW propagation direction from a strip-like electrode (bus bar) of the electrode.

  The first comb-teeth electrode 711 and the second comb-teeth electrode 712 are arranged such that the strip electrodes are arranged in parallel to each other, and the first electrode finger 711a and the second electrode finger 712a Are arranged opposite to each other so as to be alternately arranged with respect to the SAW propagation direction. The third comb-like electrode 713 is arranged adjacent to the second comb-like electrode 712, and the first comb-like electrode 711 and the third comb-like electrode 713 are arranged in parallel with each other. In addition, the first electrode fingers 711a and the third electrode fingers 713a are arranged to face each other in a meshed state so as to be alternately arranged in the SAW propagation direction in the opposing region of both strip electrodes. The

  The first comb-like electrode 711 is grounded by being electrically connected to the reference ground terminal 4 via a ground bump 75 provided on its own band-like electrode. The second comb-like electrode 712 is connected to the first balanced signal terminal 3a via the first balanced signal terminal side resonator 9a. The third comb electrode 713 is connected to the second balanced signal terminal 3b via the second balanced signal terminal side resonator 9b.

  Thereby, in the duplexer 10, a part of the transmission signal passing through the first filter 5 becomes leakage power and leaks to the second filter 6 side, and is connected to the first balanced signal terminal 3a and the second balanced signal terminal 3b. Even when the signal is propagated to the central IDT electrode 71, the leak signal can be propagated from the first comb electrode 711 to the reference ground terminal 4 via the ground bump 75. Therefore, it is possible to suppress the output of the signal that causes the deterioration of the common mode isolation characteristics to the first balanced signal terminal 3a and the second balanced signal terminal 3b. Therefore, in the duplexer 10, the common mode isolation becomes high isolation, and the common mode isolation characteristics can be improved.

  Further, in the duplexer 10, the configuration in which the first comb-like electrode 711 is connected to the reference ground terminal 4 is not limited to the configuration in which the ground bump 75 is provided, and for example, as shown in FIG. 3. FIG. 3 is an enlarged view of the first SAW filter unit 7A. In the first SAW filter portion 7A shown in FIG. 3, a bridge insulator 76 made of an insulator is provided between the strip electrode of the first comb-like electrode 711 and the two first SAW filter reflectors 74. A connection pattern conductor 77 is provided from above the bridge insulator 76. Thus, the first comb-like electrode 711 and the two first SAW filter reflectors 74 are electrically connected via the connection pattern conductor 77. That is, the first comb-like electrode 711 is connected to the first SAW filter reflector 74 through the ground pattern conductor having a three-dimensional structure formed by the bridge insulator 76 and the connection pattern conductor 77, and the first SAW filter reflector 74. Is grounded by being connected to the reference ground terminal 4. In the duplexer 10 configured as described above, a part of the transmission signal passing through the first filter 5 becomes leakage power and leaks to the second filter 6 side, and the first balanced signal terminal 3a and the second balanced signal terminal 3b. Even when the signal is propagated to the central IDT electrode 71 connected to the first comb-like electrode 711, the leak signal is passed through the ground pattern conductor of the three-dimensional structure by the bridge insulator 76 and the connection pattern conductor 77. To the reference ground terminal 4.

  The first balanced signal terminal side resonator 9a is a SAW resonator, and is a first balanced signal terminal side resonator electrode 91a that is an IDT electrode having a plurality of electrode fingers, and a first balanced signal terminal side resonator electrode. And a first balanced signal terminal-side resonance reflector 92a disposed at both ends of the SAW propagation direction with respect to 91a. The second balanced signal terminal side resonator 9b is a SAW resonator, and corresponds to the second balanced signal terminal side resonator electrode 91b, which is an IDT electrode having a plurality of electrode fingers, and the second balanced signal terminal side resonator electrode 91b. And a second balanced signal terminal-side resonance reflector 92b disposed at both ends of the SAW propagation direction. In the second filter 6, by providing the first balanced signal terminal side resonator 9a and the second balanced signal terminal side resonator 9b on the first balanced signal terminal 3a and second balanced signal terminal 3b sides from which signals are output, , Electrostatic breakdown durability can be improved.

  Further, a signal output wiring for connecting the first balanced signal terminal side resonator 9a and the first balanced signal terminal 3a, and a signal output wiring for connecting the second balanced signal terminal side resonator 9b and the second balanced signal terminal 3b. The fourth inductor 3c is connected as a matching circuit.

  The first adjacent IDT electrode 72 disposed adjacent to the central IDT electrode 71 on one side includes a fourth comb-like electrode 722 having a plurality of fourth electrode fingers 722a and a fifth comb having a plurality of fifth electrode fingers 721a. And a toothed electrode 721.

  In the fourth comb-shaped electrode 722 and the fifth comb-shaped electrode 721, the fourth electrode fingers 722a and the fifth electrode fingers 721a are orthogonal to the SAW propagation direction from the band-shaped electrodes of the respective comb-shaped electrodes. It is formed so as to protrude in the direction. In the fourth comb-like electrode 722 and the fifth comb-like electrode 721, the respective strip-like electrodes are arranged in parallel, and the fourth electrode finger 722a, the fifth electrode finger 721a, Are arranged opposite to each other so as to be alternately arranged with respect to the SAW propagation direction.

  The fourth comb-like electrode 722 is connected to the antenna terminal side resonator 8, and the fifth comb-like electrode 721 is grounded.

  The second adjacent IDT electrode 73 disposed adjacent to the central IDT electrode 71 on the other side includes a sixth comb-like electrode 732 having a plurality of sixth electrode fingers 732a and a seventh comb having a plurality of seventh electrode fingers 731a. And a toothed electrode 731.

  In the sixth comb-like electrode 732 and the seventh comb-like electrode 731, the sixth electrode fingers 732a and the seventh electrode fingers 731a are orthogonal to the SAW propagation direction from the band-like electrodes of the respective comb-like electrodes. It is formed so as to protrude in the direction. The sixth comb-teeth electrode 732 and the seventh comb-teeth electrode 731 are arranged such that the strip electrodes are arranged in parallel with each other, and the sixth electrode finger 732a, the seventh electrode finger 731a, Are arranged opposite to each other so as to be alternately arranged with respect to the SAW propagation direction.

  The sixth comb electrode 732 is connected to the antenna terminal side resonator 8, and the seventh comb electrode 731 is grounded.

  In the first SAW filter unit 7, the first SAW filter reflector is provided on the opposite side of the first adjacent IDT electrode 72 from the central IDT electrode 71 and on the opposite side of the second adjacent IDT electrode 73 from the central IDT electrode 71. 74 is provided. The SAW excited and propagated by the central IDT electrode 71, the first adjacent IDT electrode 72, and the second adjacent IDT electrode 73 is reflected by the first SAW filter reflector 74 to generate a standing wave.

  In the duplexer 10 of the present embodiment, the reception signal input from the antenna terminal 1 passes through the second filter 6, so that a signal having a reception-side pass frequency band of frequency 869 to 894 MHz is converted to the first balanced signal terminal 3 a and It is designed to be output from the second balanced signal terminal 3b.

  FIG. 4 is an equivalent circuit diagram of the duplexer 12 according to the second embodiment of the present invention. The duplexer 12 is similar to the duplexer 10 described above, and corresponding portions are denoted by the same reference numerals and description thereof is omitted. The duplexer 12 differs from the first SAW filter unit 7 of the duplexer 10 in the configuration of the first SAW filter unit 11 and is otherwise the same in configuration. FIG. 5 is an enlarged view of the first SAW filter unit 11.

  The first SAW filter unit 11 is a longitudinally coupled resonator type SAW filter. The first IDT electrode 111 is disposed adjacent to the central IDT electrode 111 on one side of the central IDT electrode 111 in the SAW propagation direction. It includes an electrode 112 and a second adjacent IDT electrode 113 disposed adjacent to the central IDT electrode 111 on the other side of the central IDT electrode 111 in the SAW propagation direction.

  The first adjacent IDT electrode 112 is configured in the same manner as the first adjacent IDT electrode 72 of the first SAW filter unit 7 described above, and includes a fourth comb electrode 1122 having a plurality of fourth electrode fingers 1122a and a plurality of fifth electrodes. And a fifth comb-like electrode 1121 having electrode fingers 1121a. The fourth comb-like electrode 1122 is connected to the antenna terminal side resonator 8, and the fifth comb-like electrode 1121 is grounded.

  The second adjacent IDT electrode 113 is configured in the same manner as the second adjacent IDT electrode 73 of the first SAW filter unit 7 described above, and includes a sixth comb-shaped electrode 1132 having a plurality of sixth electrode fingers 1132a and a plurality of seventh electrodes. And a seventh comb electrode 1131 having electrode fingers 1131a. The sixth comb-shaped electrode 1132 is connected to the antenna terminal-side resonator 8, and the seventh comb-shaped electrode 1131 is grounded.

  A characteristic configuration of the duplexer 12 is the configuration of the central IDT electrode 111 of the first SAW filter unit 11. The central IDT electrode 111 includes a first comb electrode 1111 having a plurality of first electrode fingers 1111a, a second comb electrode 1112 having a plurality of second electrode fingers 1112a, and a plurality of third electrode fingers 1113a. A third comb-like electrode 1113, an insertion reflector 1114 having a plurality of ground electrode fingers 1114 a, and an insertion reflector inductor 1115 connected between the insertion reflector 1114 and the reference ground terminal 4.

  In the first comb-teeth electrode 1111, the second comb-teeth electrode 1112, and the third comb-teeth electrode 1113, the first electrode fingers 1111 a, the second electrode fingers 1112 a, and the third electrode fingers 1113 a are respectively comb teeth. It is formed so as to protrude in a direction orthogonal to the SAW propagation direction from the band-like electrode of the electrode.

  The first comb-teeth electrode 1111 and the second comb-teeth electrode 1112 are arranged such that the strip electrodes are arranged in parallel to each other, and the first electrode finger 1111a and the second electrode finger 1112a Are arranged opposite to each other so as to be alternately arranged with respect to the SAW propagation direction. Further, the third comb-shaped electrode 1113 is disposed adjacent to the second comb-shaped electrode 1112, and the first comb-shaped electrode 1111 and the third comb-shaped electrode 1113 are disposed in parallel with each other. In addition, the first electrode fingers 1111a and the third electrode fingers 1113a are arranged to face each other in a meshed state so as to be alternately arranged in the SAW propagation direction in the opposing region of both strip electrodes. The

  The insertion reflector 1114 includes the second comb-shaped electrode 1112 and the third comb so that the ground electrode finger 1114a is parallel to the electrode fingers of the second comb-shaped electrode 1112 and the third comb-shaped electrode 1113. The grounding electrode finger 1114 a is disposed between the toothed electrode 1113 and the band-like electrode of the first comb-like electrode 1111. The insertion reflector 1114 is connected to the reference ground terminal 4 via the insertion reflector inductor 1115.

  That is, the first comb-shaped electrode 1111 is grounded by being connected to the reference ground terminal 4 via the insertion reflector 1114. The second comb-shaped electrode 1112 is connected to the first balanced signal terminal 3a via the first balanced signal terminal side resonator 9a, and the third comb-shaped electrode 1113 is connected to the second balanced signal terminal side resonator. It is connected to the second balanced signal terminal 3b through 9b.

  In the duplexer 12 configured in this way, part of the transmission signal passing through the first filter 5 becomes leakage power and leaks to the second filter 6 side, and the first balanced signal terminal 3a and the second balanced signal terminal 3b. The leakage signal is transmitted from the first comb-shaped electrode 1111 to the reference ground terminal 4 via the insertion reflector 1114 and the insertion reflector inductor 1115 even if it is propagated to the central IDT electrode 111 connected to Can be propagated. Thereby, it can suppress that the signal used as the factor which degrades a common mode isolation characteristic is output to the 1st balanced signal terminal 3a and the 2nd balanced signal terminal 3b. Therefore, the duplexer 12 has high common mode isolation and can have excellent common mode isolation characteristics.

  Further, by controlling the attenuation pole frequency by the insertion reflector inductor 1115 connected to the insertion reflector 1114, the common mode isolation can be made higher.

  Further, the connection structure between the first comb-shaped electrode 1111 and the reference ground terminal 4 is a connection structure through the insertion reflector 1114, so that the above-described connection structure in which the ground bump 75 is provided, or a bridge insulator The duplexer can be downsized as compared with a connection structure in which a three-dimensional ground pattern conductor is formed by 76 and the connection pattern conductor 77. In the case of a connection structure in which a ground bump 75 or a ground pattern conductor having a three-dimensional structure is provided, it is necessary to provide a predetermined space between the ground bump 75 and the surrounding structure in consideration of manufacturing variations. For example, the ground bump 75 is provided in a region surrounded by a wiring conductor that connects the first adjacent IDT electrode and the second adjacent IDT electrode. However, manufacturing variations occur so that the wiring conductor and the ground bump 75 do not contact each other. In consideration of this, it is necessary to provide an interval of about 60 μm between them. On the other hand, if the connection structure via the insertion reflector 1114 is used, it is possible to draw out to a region where there is little need to provide an interval such as a wiring conductor, and thus the duplexer can be reduced in size. There is also an advantage that the parasitic capacitance that can occur between the wiring conductors can be reduced.

  In the first SAW filter unit 11, the first SAW filter reflector is provided on the opposite side of the first adjacent IDT electrode 112 from the central IDT electrode 111 and on the opposite side of the second adjacent IDT electrode 113 from the central IDT electrode 111. 114 is provided. The SAW excited and propagated by the central IDT electrode 111, the first adjacent IDT electrode 112, and the second adjacent IDT electrode 113 is reflected by the first SAW filter reflector 114 to generate a standing wave.

  In the duplexer 12, the configuration of the first SAW filter unit 11 may be as shown in FIG. 6, for example. FIG. 6 is an enlarged view of the first SAW filter unit 11A. In the first SAW filter unit 11A shown in FIG. 6, the first comb electrode 1111 of the central IDT electrode 111 and the fifth comb electrode 1121 of the first adjacent IDT electrode 112 are connected by the first common electrode finger 115. Has been. The first comb-like electrode 1111 of the central IDT electrode 111 and the seventh comb-like electrode 1131 of the second adjacent IDT electrode 113 are connected by the second common electrode finger 116.

  In the duplexer 12 including the first SAW filter unit 11A configured as described above, the first comb-shaped electrode 1111 is not only connected to the reference ground terminal 4 via the insertion reflector 1114 but also grounded. The fifth comb-shaped electrode 1121 and the first common electrode finger 115 are connected to each other, and the seventh comb-shaped electrode 1131 and the second common electrode finger 116 which are grounded are connected to each other. That is, the first comb-like electrode 1111 is grounded in a state of being connected in parallel by the grounding electrode finger 1114a, the first common electrode finger 115, and the second common electrode finger 116 of the insertion reflector 1114.

  In the duplexer 12, the configuration of the first SAW filter unit 11 may be as shown in FIG. FIG. 7 is an enlarged view showing the first SAW filter unit 11B. In the first SAW filter unit 11B shown in FIG. 7, at least one of the grounding electrode fingers 1114a of the insertion reflector 1114 is between the second electrode fingers 1112a of the second comb-tooth electrode 1112 and the third comb. It is disposed between the third electrode fingers 1113 a of the tooth-like electrode 1113 and is connected to the band-like electrode of the first comb-like electrode 1111.

  In the duplexer 12, the configuration of the first SAW filter unit 11 may be as shown in FIG. FIG. 8 is an enlarged view of the first SAW filter unit 11C. In the first SAW filter section 11C shown in FIG. 8, the first end IDT electrode 117 is disposed on the opposite side of the first adjacent IDT electrode 112 from the central IDT electrode 111, and the second IDT electrode 113 has The second end IDT electrode 118 is disposed on the opposite side.

  The first end IDT electrode 117 includes an eighth comb electrode 1172 having a plurality of eighth electrode fingers 1172a and a ninth comb electrode 1171 having a plurality of ninth electrode fingers 1171a. In the eighth comb-shaped electrode 1172 and the ninth comb-shaped electrode 1171, the eighth electrode finger 1172a and the ninth electrode finger 1171a are orthogonal to the SAW propagation direction from the band-shaped electrode of the respective comb-shaped electrode. It is formed so as to protrude in the direction. The eighth comb-shaped electrode 1172 and the ninth comb-shaped electrode 1171 are configured such that the respective band-shaped electrodes are arranged in parallel to each other, and the eighth electrode finger 1172a and the ninth electrode finger 1171a Are arranged opposite to each other so as to be alternately arranged with respect to the SAW propagation direction. The eighth comb-shaped electrode 1172 is connected in parallel to the second comb-shaped electrode 1112 to the first balanced signal terminal 3a via the first balanced signal terminal-side resonator 9a, and the ninth comb-shaped electrode 1172 The electrode 1171 is grounded.

  The second end IDT electrode 118 includes a tenth comb electrode 1182 having a plurality of tenth electrode fingers 1182a and an eleventh comb electrode 1181 having a plurality of eleventh electrode fingers 1181a. In the tenth comb-shaped electrode 1182 and the eleventh comb-shaped electrode 1181, the tenth electrode finger 1182a and the eleventh electrode finger 1181a are orthogonal to the propagation direction of the SAW from the band-shaped electrode of each comb-shaped electrode. It is formed so as to protrude in the direction. The tenth comb-shaped electrode 1182 and the eleventh comb-shaped electrode 1181 are configured such that the respective strip-shaped electrodes are arranged in parallel and the tenth electrode finger 1182a and the eleventh electrode finger 1181a Are arranged opposite to each other so as to be alternately arranged with respect to the SAW propagation direction. The tenth comb-shaped electrode 1182 is connected in parallel with the third comb-shaped electrode 1113 to the second balanced signal terminal 3b via the second balanced signal terminal side resonator 9b, and the eleventh comb-shaped electrode 1182 is connected. The electrode 1181 is grounded. By providing the end IDT electrode in this manner, the degree of freedom in design can be improved, and characteristics such as the VSWR and the degree of balance in the pass frequency band can be easily optimized.

  FIG. 9 is an equivalent circuit diagram of the duplexer 15 according to the third embodiment of the present invention. The duplexer 15 is similar to the duplexers 10 and 12 described above, and corresponding portions are denoted by the same reference numerals and description thereof is omitted. The duplexer 15 is configured similarly to the duplexers 10 and 12 except that the second filter 6 includes a first SAW filter unit 13 and a second SAW filter unit 14. FIG. 10 is an enlarged view showing the first SAW filter unit 13 and the second SAW filter unit 14.

  In the second filter 6 of the duplexer 15, the first SAW filter unit 13 is disposed on the first balanced signal terminal 3a and the second balanced signal terminal 3b side, and the second SAW filter unit 14 is disposed on the antenna terminal 1 side.

  The first SAW filter unit 13 is a longitudinally coupled resonator type SAW filter, and a first IDT electrode 131 and a first adjacent IDT disposed adjacent to the central IDT electrode 131 on one side of the central IDT electrode 131 in the SAW propagation direction. It includes an electrode 132 and a second adjacent IDT electrode 133 disposed adjacent to the central IDT electrode 131 on the other side of the central IDT electrode 131 in the SAW propagation direction.

  The first adjacent IDT electrode 132 includes a fourth comb electrode 1322 having a plurality of fourth electrode fingers 1322a and a fifth comb electrode 1321 having a plurality of fifth electrode fingers 1321a. The fourth comb-like electrode 1322 is connected to the fourteenth comb-like electrode 1422 of the third adjacent IDT electrode 142 of the second SAW filter unit 14, and the fifth comb-like electrode 1321 is grounded.

  The second adjacent IDT electrode 133 includes a sixth comb electrode 1332 having a plurality of sixth electrode fingers 1332a and a seventh comb electrode 1331 having a plurality of seventh electrode fingers 1331a. The sixth comb-shaped electrode 1332 is connected to the sixteenth comb-shaped electrode 1432 of the fourth adjacent IDT electrode 143 of the second SAW filter unit 14, and the seventh comb-shaped electrode 1331 is grounded.

  The central IDT electrode 131 includes a first comb electrode 1311 having a plurality of first electrode fingers 1311a, a second comb electrode 1312 having a plurality of second electrode fingers 1312a, and a plurality of third electrode fingers 1313a. And an insertion reflector 1314 having a plurality of ground electrode fingers 1314a, and an insertion reflector inductor 1315 connected between the insertion reflector 1314 and the reference ground terminal 4.

  The insertion reflector 1314 includes the second comb-shaped electrode 1312 and the third comb so that the ground electrode finger 1314a is parallel to the electrode fingers of the second comb-shaped electrode 1312 and the third comb-shaped electrode 1313. The grounding electrode finger 1314 a is arranged between the tooth-like electrode 1313 and is connected to the belt-like electrode of the first comb-like electrode 1311. The insertion reflector 1314 is connected to the reference ground terminal 4 via the insertion reflector inductor 1315.

  That is, the first comb-like electrode 1311 is grounded by being connected to the reference ground terminal 4 via the insertion reflector 1314. The second comb-like electrode 1312 is connected to the first balanced signal terminal 3a via the first balanced signal terminal side resonator 9a. The third comb-like electrode 1313 is connected to the second balanced signal terminal 3b via the second balanced signal terminal side resonator 9b.

  In the duplexer 12 configured in this way, part of the transmission signal passing through the first filter 5 becomes leakage power and leaks to the second filter 6 side, and the first balanced signal terminal 3a and the second balanced signal terminal 3b. The leakage signal is transmitted from the first comb-shaped electrode 1311 to the reference ground terminal 4 via the insertion reflector 1314 and the insertion reflector inductor 1315 even if it is propagated to the central IDT electrode 131 connected to Can be propagated. Further, by adjusting the attenuation pole frequency of the common mode isolation with the insertion reflector inductor 1315, a desired frequency band can be further attenuated. Therefore, the duplexer 15 can ensure high attenuation of common mode isolation and have excellent common mode isolation characteristics.

  In the duplexer 15, in the first SAW filter unit 13, at least one of the fourth electrode fingers 1322 a included in the fourth comb-shaped electrode 1322 of the first adjacent IDT electrode 132 is the second comb-shaped electrode of the central IDT electrode 131. It is arranged between the second electrode fingers 1312a of 1312. Furthermore, at least one of the sixth electrode fingers 1332a included in the sixth comb-shaped electrode 1332 of the second adjacent IDT electrode 133 is between the third electrode fingers 1313a included in the third comb-shaped electrode 1313 of the central IDT electrode 131. Is arranged. With such an electrode finger arrangement, a part of the central IDT electrode 131 and a part of the first adjacent IDT electrode 132 or a part of the central IDT electrode 131 and a part of the second adjacent IDT electrode 133 are directly connected. Since it intersects, insertion loss can be reduced.

  In the first SAW filter unit 13, the first SAW filter reflector is provided on the opposite side of the first adjacent IDT electrode 132 from the central IDT electrode 131 and on the opposite side of the second adjacent IDT electrode 133 from the central IDT electrode 131. 134 is provided. The SAW excited and propagated by the central IDT electrode 131, the first adjacent IDT electrode 132, and the second adjacent IDT electrode 133 is reflected by the first SAW filter reflector 134 to generate a standing wave.

  The second SAW filter unit 14 is a longitudinally coupled resonator type SAW filter, and is disposed adjacent to the second central IDT electrode 141 on one side of the second central IDT electrode 141 and the SAW propagation direction of the second central IDT electrode 141. And a fourth adjacent IDT electrode 143 disposed adjacent to the second central IDT electrode 141 on the other side in the SAW propagation direction of the second central IDT electrode 141.

  The third adjacent IDT electrode 142 includes a fourteenth comb-like electrode 1422 having a plurality of fourteenth electrode fingers 1422a and a fifteenth comb-like electrode 1421 having a plurality of fifteenth electrode fingers 1421a. The fourteenth comb-like electrode 1422 is connected to the fourth comb-like electrode 1322 of the first adjacent IDT electrode 132 of the first SAW filter unit 13, and the fifteenth comb-like electrode 1421 is grounded.

  The fourth adjacent IDT electrode 143 includes a sixteenth comb-like electrode 1432 having a plurality of sixteenth electrode fingers 1432a and a seventeenth comb-like electrode 1431 having a plurality of seventeenth electrode fingers 1431a. The sixteenth comb-like electrode 1432 is connected to the sixth comb-like electrode 1332 of the second adjacent IDT electrode 133 of the first SAW filter unit 13, and the seventeenth comb-like electrode 1431 is grounded.

  The second central IDT electrode 141 includes a twelfth comb electrode 1411 having a plurality of twelfth electrode fingers 1411a and a thirteenth comb electrode 1412 having a plurality of thirteenth electrode fingers 1412a. The twelfth comb-shaped electrode 1411 is grounded, and the thirteenth comb-shaped electrode 1412 is connected to the antenna terminal side resonator 8.

  In the second SAW filter unit 14, the second SAW is provided on the opposite side of the third adjacent IDT electrode 142 from the second central IDT electrode 141 and on the opposite side of the fourth adjacent IDT electrode 143 from the second central IDT electrode 141. A filter reflector 144 is provided. The SAW excited and propagated by the second central IDT electrode 141, the third adjacent IDT electrode 142, and the fourth adjacent IDT electrode 143 is reflected by the second SAW filter reflector 144 to generate a standing wave. In this way, the SAW filter unit having a two-stage configuration can provide higher attenuation than the case of a one-stage configuration.

  Further, in the duplexer 15, the configuration of the first SAW filter unit 13 may be as shown in FIG. 11, for example. FIG. 11 is an enlarged view of the first SAW filter unit 13A. In the first SAW filter section 13A shown in FIG. 11, the first comb electrode 1311 of the central IDT electrode 131 and the fifth comb electrode 1321 of the first adjacent IDT electrode 132 are connected by the first common electrode finger 135. Has been. The first comb-like electrode 1311 of the central IDT electrode 131 and the seventh comb-like electrode 1331 of the second adjacent IDT electrode 133 are connected by the second common electrode finger 136.

  In the duplexer 15 including the first SAW filter portion 13A configured as described above, the first comb-like electrode 1311 is not only connected to the reference ground terminal 4 via the insertion reflector 1314 but also grounded, The fifth comb-shaped electrode 1321 and the first common electrode finger 135 are connected to each other, and the seventh comb-shaped electrode 1331 and the second common electrode finger 136 are grounded. That is, the first comb-like electrode 1311 is grounded in a state of being connected in parallel by the grounding electrode finger 1314a, the first common electrode finger 135, and the second common electrode finger 136 of the insertion reflector 1314. As a result, it is possible to improve the effect of suppressing the leakage signal leaking from the first filter 5 to the second filter 6 side from propagating to the first balanced signal terminal 3a and the second balanced signal terminal 3b.

  Next, the number of grounding electrode fingers and the electrode finger pitch of the insertion reflector provided in the duplexers 12 and 15 described above will be described.

  FIG. 12 is a graph showing the relationship between the number of ground electrode fingers of the insertion reflector and the ripple in the reception frequency band. In the graph of FIG. 12, the horizontal axis indicates the number (number) of ground electrode fingers of the insertion reflector, and the vertical axis indicates the reception frequency band ripple (dB). In FIG. 12, the pitch of the electrode fingers for grounding of the insertion reflector is the remaining electrode obtained by removing the pitch average value from the both ends by 10% of the total number of electrode fingers of the central IDT electrode. It is made equal to the average value of the pitches for the fingers (hereinafter referred to as “center IDT electrode finger pitch”). For example, when the central IDT electrode is composed of 100 (50 pairs) electrode fingers, the average value of the remaining 80 central IDT electrode finger pitches excluding 10 from each end and the average pitch of the ground electrode fingers The value is made equal. Here, the average value is equal when the average value of the central IDT electrode finger pitch is P1 and the average value of the pitch of the electrode fingers for grounding is P2, when | P2-P1 | /P1≦0.05. Say. The electrode finger pitch refers to the center-to-center distance between adjacent electrode fingers.

  As is apparent from the graph of FIG. 12, the number of ground electrode fingers is reduced to 18 or less in a state where the average value of the ground electrode finger pitch is equal to the average value of the central IDT electrode finger pitch. The ripple in the frequency band can be suppressed to 1 dB or less.

13A, 13B, and 13C are graphs showing the relationship between the pitch change rate and the ripple in the reception frequency band. In the graphs of FIGS. 13A, 13B, and 13C, the horizontal axis indicates the pitch change rate (%), and the vertical axis indicates the reception frequency band ripple (dB). Here, the pitch change rate Pcr is derived by the following equation (1).
Pcr (%) = ((P2-P1) / P1) × 100 (1)

  FIG. 13A (a) shows the relationship between the pitch change rate Pcr and the reception frequency band ripple when the number of ground electrode fingers of the insertion reflector is set to two. As is clear from FIG. 13A (a), when the number of ground electrode fingers is set to two, by setting the pitch change rate Pcr in the range of −30 to 90%, the ripple in the reception frequency band is set to 1 dB. The following can be suppressed. Further, when the number of ground electrode fingers is set to 2, the pitch change rate Pcr is set in the range of -20 to 80%, whereby the average value of the ground electrode finger pitch is the average of the central IDT electrode finger pitch. With respect to the ripple in the reception frequency band in the reference state (the state where the pitch change rate is 0%) equal to the value, it is possible to suppress the deterioration to 0.3 dB or less.

  FIG. 13A (b) shows the relationship between the pitch change rate Pcr and the reception frequency band ripple when the number of ground electrode fingers of the insertion reflector is set to four. As apparent from FIG. 13A (b), when the number of ground electrode fingers is set to four, by setting the pitch change rate Pcr in the range of −9 to 30%, the ripple in the reception frequency band is set to 1 dB. The following can be suppressed. Further, when the number of grounding electrode fingers is set to 4, the pitch change rate Pcr is set in a range of −8 to 30%, so that the average value of the grounding electrode finger pitch becomes the average of the central IDT electrode finger pitch. It is possible to suppress deterioration of 0.3 dB or less with respect to the ripple in the reception frequency band in the reference state that is equal to the value.

  FIG. 13B (c) shows the relationship between the pitch change rate Pcr and the reception frequency band ripple when the number of ground electrode fingers of the insertion reflector is set to six. As is clear from FIG. 13B (c), when the number of ground electrode fingers is set to 6, by setting the pitch change rate Pcr in the range of −5 to 19%, the ripple in the reception frequency band is 1 dB. The following can be suppressed. Further, when the number of ground electrode fingers is set to 6, the pitch change rate Pcr is set in the range of -4 to 17.5%, so that the average value of the ground electrode finger pitch becomes the central IDT electrode finger pitch. For the ripple in the reception frequency band in the reference state that is equal to the average value, the degradation can be suppressed to 0.3 dB or less.

  FIG. 13B (d) shows the relationship between the pitch change rate Pcr and the reception frequency band ripple when the number of ground electrode fingers of the insertion reflector is set to eight. As is apparent from FIG. 13B (d), when the number of ground electrode fingers is set to 8, the pitch change rate Pcr is set in the range of −3 to 14%, so that the ripple in the reception frequency band is 1 dB. The following can be suppressed. When the number of ground electrode fingers is set to 8, the pitch change rate Pcr is set in the range of -3 to 12.5%, so that the average value of the ground electrode finger pitch is the center IDT electrode finger pitch. For the ripple in the reception frequency band in the reference state that is equal to the average value, the degradation can be suppressed to 0.3 dB or less.

  FIG. 13C (e) shows the relationship between the pitch change rate Pcr and the reception frequency band ripple when the number of ground electrode fingers of the insertion reflector is set to ten. As apparent from FIG. 13C (e), when the number of ground electrode fingers is set to 10, the ripple in the reception frequency band is set to 1 dB by setting the pitch change rate Pcr in the range of −2 to 11%. The following can be suppressed. Further, when the number of ground electrode fingers is set to 10, the pitch change rate Pcr is set to a range of -1 to 10%, so that the average value of the ground electrode finger pitch is the average of the center IDT electrode finger pitch. It is possible to suppress deterioration of 0.3 dB or less with respect to the ripple in the reception frequency band in the reference state that is equal to the value.

(Example)
Examples of the embodiments of the present invention will be described below. These examples are merely examples of embodiments of the present invention, and the present invention is not limited to these. In the following embodiments, the duplexer is designed so that the transmission-side pass frequency band is the frequency 824 to 849 MHz and the reception-side pass frequency band is the frequency 869 to 894 MHz.

<Production of Duplexer of Example 1 and Comparative Example 1>
Example 1
A piezoelectric substrate made of LiTaO ₃ was prepared, a Ti thin film layer having a thickness of 6 nm was formed on the main surface, and an Al—Cu thin film layer having a thickness of 391 nm was formed thereon.

  Next, a photoresist was applied to a thickness of about 0.5 μm on the Ti / Al—Cu laminated film by a resist coating apparatus. Then, a photoresist pattern serving as a resonator, a signal line, a ground line, a pad electrode, an inductor for an insertion reflector, and the like was formed by a reduction projection exposure machine (stepper) so as to have the arrangement position shown in FIG. Thereafter, unnecessary portions of the photoresist were dissolved with an alkali developer by a developing device.

  Next, a RIE (Reactive Ion Etching) apparatus was used to remove the remaining portions by etching while leaving a necessary portion, thereby forming a circuit pattern for realizing the circuit configuration shown in FIG. At this time, the insertion reflector inductor connected to the insertion reflector 1314 shown in FIG. 9 is also formed of the same thin film as the other electrodes, so that the insertion reflector inductor has a relatively large inductance value. it can. Table 1 shows the fabrication conditions for the SAW filter section, and Table 2 shows the fabrication conditions for the resonator. The above-described circuit pattern is formed by repeatedly arranging a desired circuit pattern in a two-dimensional manner on a piezoelectric substrate that is in a state of a large number of mother substrates.

Next, a protective film was formed on a predetermined region of the circuit pattern. That is, CVD (Chemical
An electrode pattern and a SiO ₂ film were formed to a thickness of about 15 nm on the main surface of the piezoelectric substrate by a Vapor Deposition apparatus. Then, the photoresist was patterned by photolithography, and the SiO ₂ film of the flip-chip electrode portion (input / output electrode, pad electrode portion such as ground electrode, and annular electrode portion) was etched by an RIE apparatus or the like.

Next, using a sputtering apparatus, a laminated electrode made of Cr, Ni, Au was formed on the portion where the SiO ₂ film was removed. The electrode film thickness at this time was about 1 μm (Cr: 0.01 μm, Ni: 1 μm, Au: 0.2 μm). Then, the photoresist and the unnecessary portion of the laminated electrode were simultaneously removed by a lift-off method, and the portion where the laminated electrode was formed was used as a flip chip electrode portion for connecting the flip chip bump.

  Thereafter, dicing was performed along dicing lines provided on the piezoelectric substrate, and a large number of chips in a state where electrode patterns were formed on the piezoelectric substrate were obtained.

  Next, a circuit board having a line corresponding to an inductance element provided therein is prepared, and a patterned electrode made of tungsten, an input / output conductor, a ground conductor, and a conductive material (solder) of an annular conductor are printed thereon. A ceramic circuit board was obtained. Then, each chip was temporarily bonded onto the ceramic circuit board by the flip chip mounting apparatus with the electrode formation surface as the bottom surface. The chip was bonded to the ceramic circuit board by baking in a nitrogen atmosphere and melting the solder. The solder melted and adhered to the annular electrode formed on the chip and the annular conductor formed on the ceramic circuit board, whereby the electrode pattern on the chip surface was hermetically sealed.

  Further, a resin was applied to the ceramic circuit board to which the chip was bonded, baked, and the chip was sealed with resin.

  And the duplexer based on Example 1 of the state mounted on the circuit board was obtained by giving a dicing process along the dicing line of a ceramic circuit board, and dividing | segmenting into a piece. The ceramic circuit board in a state of being divided into individual pieces has a planar size of 2.5 × 2.0 mm and has a laminated structure.

  In the duplexer according to the first embodiment, the second filter of the reception filter includes the first SAW filter unit and the second SAW filter unit, and the second comb-shaped electrode and the third comb-shaped electrode at the central IDT electrode of the first SAW filter unit. The duplexer 15 described above, in which the insertion reflector is disposed between the first comb-like electrode and the reference ground terminal via the insertion reflector.

(Comparative Example 1)
A duplexer of Comparative Example 1 was obtained in the same manner as in Example 1 except that the insertion reflector was not provided on the central IDT electrode. In the duplexer of Comparative Example 1, the first comb-like electrode in the central IDT electrode is a floating electrode that is not connected to the reference ground terminal.

<Frequency characteristics of duplexers of Example 1 and Comparative Example 1>
The frequency characteristics of the duplexers of Example 1 and Comparative Example 1 were evaluated. FIG. 14 is a graph showing the common mode isolation characteristics of the example and the comparative example. FIG. 14A shows the common mode isolation characteristics of Example 1 and Comparative Example 1. FIG. In the graph of FIG. 14A, the horizontal axis represents frequency (MHz), and the vertical axis represents common mode isolation (dB). In the graph of FIG. 14A, the characteristic curve of the solid line A1 shows the result of the duplexer of Example 1, and the characteristic curve of the broken line B1 shows the result of the duplexer of Comparative Example 1.

  Table 3 shows the insertion loss and the attenuation amount of isolation on the transmission and reception sides for the duplexers of Example 1 and Comparative Example 1.

  From the results shown in Table 3 and FIG. 14 (a), the duplexer of Example 1 attenuates the common mode isolation in the transmission-side pass frequency band F1 as compared to the duplexer of Comparative Example 1 in which no insertion reflector is provided. It can be seen that the amount is large and has excellent common mode isolation characteristics. Other characteristics are almost the same as the comparative example. In other words, the common mode isolation characteristics could be greatly improved without substantially deteriorating the insertion loss characteristics.

<Production of Duplexer of Example 2 and Comparative Example 2>
(Example 2)
A duplexer of Example 2 was produced in the same manner as Example 1. The duplexer of the second embodiment is obtained by replacing the first SAW filter unit 13 of the duplexer 15 having the circuit configuration shown in FIG. 9 with the first SAW filter unit 7A shown in FIG. Table 4 shows the manufacturing conditions for the SAW filter section, and Table 5 shows the manufacturing conditions for the resonator.

  In the duplexer according to the second embodiment, the second filter of the reception filter includes the first SAW filter unit, and the first comb-like electrode is a three-dimensional structure including a bridge insulator and a connection pattern conductor in the central IDT electrode of the first SAW filter unit. Are connected to a reference ground terminal via a ground pattern conductor.

(Comparative Example 2)
A duplexer of Comparative Example 2 was obtained in the same manner as in Example 2 except that the central IDT electrode was not provided with a three-dimensional ground pattern conductor. The duplexer of Comparative Example 2 is a floating electrode in which the first comb electrode is not connected to the reference ground terminal in the central IDT electrode.

<Frequency characteristics of duplexers of Example 2 and Comparative Example 2>
The frequency characteristics of the duplexers of Example 2 and Comparative Example 2 were evaluated. FIG. 14B shows the common mode isolation characteristics of Example 2 and Comparative Example 2. In the graph of FIG. 14B, the horizontal axis represents frequency (MHz), and the vertical axis represents common mode isolation (dB). In the graph of FIG. 14B, the characteristic curve of the solid line A2 indicates the result of the duplexer of Example 2, and the characteristic curve of the broken line B2 indicates the result of the duplexer of Comparative Example 2.

  Table 6 shows the insertion loss and the attenuation amount of isolation on the transmission and reception sides for the duplexers of Example 2 and Comparative Example 2.

  From the results shown in Table 6 and FIG. 14B, in the central IDT electrode of the first SAW filter portion, the first comb-like electrode is connected to the reference ground via the ground pattern conductor having a three-dimensional structure of the bridge insulator and the connection pattern conductor. The duplexer of Example 2 connected to the terminal has a large attenuation of common mode isolation in the transmission-side pass frequency band F1 as compared with the duplexer of Comparative Example 2 in which the ground pattern conductor having a three-dimensional structure is not provided. It can be seen that they have common mode isolation characteristics.

1 antenna terminal 2 unbalanced signal terminal 3a first balanced signal terminal 3b second balanced signal terminal 4 reference ground terminal 5 first filter 6 second filter 7, 7A, 11, 11A, 11B, 11C, 13, 13A first SAW filter Part 10, 12, 15 Duplexer 14 Second SAW filter part 71, 111, 131 Central IDT electrode 72, 112, 132 First adjacent IDT electrode 73, 113, 133 Second adjacent IDT electrode 1114, 1314 Insert reflector

Claims (8)

An antenna terminal;
An unbalanced signal terminal;
First and second balanced signal terminals;
A reference ground terminal;
A first filter disposed between the antenna terminal and the unbalanced signal terminal;
A second filter having a longitudinally coupled resonator type first SAW filter unit and disposed between the antenna terminal and the first and second balanced signal terminals;
The first SAW filter unit includes a central IDT electrode, a first adjacent IDT electrode disposed adjacent to the central IDT electrode on one side of the central IDT electrode, and adjacent to the central IDT electrode on the other side of the central IDT electrode. A second adjacent IDT electrode disposed,
The central IDT electrode has a first comb-like electrode having a plurality of first electrode fingers, a plurality of second electrode fingers arranged between the plurality of first electrode fingers, and the first balance A third comb electrode having a second comb-like electrode connected to the signal terminal and a plurality of third electrode fingers arranged between the plurality of first electrode fingers and connected to the second balanced signal terminal; A comb-like electrode, and an insertion reflector having a plurality of ground electrode fingers ,
The insertion reflector is disposed between the second comb-shaped electrode and the third comb-shaped electrode, and is connected to the first comb-shaped electrode;
A duplexer in which the first comb-like electrode is grounded by being electrically connected to the reference ground terminal via the insertion reflector . The duplexer according to claim 1 , further comprising an inductor connected between the insertion reflector and the reference ground terminal. The insertion reflector is
The number of the plurality of ground electrode fingers is two;
The average number of pitches of the electrode fingers for grounding is P1, and the average value of the pitch of the electrode fingers for grounding is P1, the number corresponding to 10% of all the electrode fingers of the central IDT electrode is removed from both ends of the central IDT electrode. Where P2 is the following formula (1)
Pcr (%) = ((P2-P1) / P1) × 100 (1)
In represented by a pitch change rate Pcr is, duplexer according to claim 1 or 2 is set in a range of -30～90%. The first adjacent IDT electrode has a fourth comb-shaped electrode having a plurality of fourth electrode fingers and a fifth comb-shaped electrode having a plurality of fifth electrode fingers arranged between the plurality of fourth electrode fingers. An electrode, and
The second adjacent IDT electrode has a sixth comb-like electrode having a plurality of sixth electrode fingers and a seventh comb-teeth having a plurality of seventh electrode fingers arranged between the plurality of sixth electrode fingers. An electrode, and
The duplexer according to any one of claims 1 to 3 , wherein the fifth and seventh comb electrodes are grounded. The second filter has a longitudinally coupled resonator type second SAW filter unit disposed between the first SAW filter unit and the antenna terminal;
The fourth and sixth comb electrodes are connected to the second SAW filter unit;
At least one of the plurality of fourth electrode fingers is disposed between the plurality of second electrode fingers;
The duplexer according to claim 4 , wherein at least one of the plurality of sixth electrode fingers is disposed between the plurality of third electrode fingers. The first comb-like electrode and the fifth comb-like electrode are connected by a first common electrode finger,
The duplexer according to claim 4 , wherein the first comb-like electrode and the seventh comb-like electrode are connected by a second common electrode finger. An antenna terminal;
An unbalanced signal terminal;
First and second balanced signal terminals;
A reference ground terminal;
A first filter disposed between the antenna terminal and the unbalanced signal terminal;
A second filter having a longitudinally coupled resonator type first SAW filter unit and disposed between the antenna terminal and the first and second balanced signal terminals;
The first SAW filter unit includes a central IDT electrode, a first adjacent IDT electrode disposed adjacent to the central IDT electrode on one side of the central IDT electrode, and adjacent to the central IDT electrode on the other side of the central IDT electrode. A second adjacent IDT electrode disposed; a reflector disposed adjacent to the first adjacent IDT electrode on one side of the first adjacent IDT electrode; and the second adjacent IDT electrode on the other side of the second adjacent IDT electrode. And a first SAW filter reflector composed of a reflector disposed adjacently,
The central IDT electrode has a first comb-like electrode having a plurality of first electrode fingers, a plurality of second electrode fingers arranged between the plurality of first electrode fingers, and the first balance A third comb electrode having a second comb-like electrode connected to the signal terminal and a plurality of third electrode fingers arranged between the plurality of first electrode fingers and connected to the second balanced signal terminal; A comb-like electrode, and
The first SAW filter reflector is connected to the first comb electrode by a connection pattern conductor;
A duplexer in which the first comb-like electrode is grounded by being electrically connected to the reference ground terminal via the first SAW filter reflector. A mobile phone terminal device equipped with the duplexer according to claim 1.

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