JP4844652B2 - Antenna duplexer - Google Patents

Description

  The present invention relates to an antenna duplexer used in a wireless communication device such as a mobile phone.

  A conventional antenna duplexer will be described below.

  As shown in FIG. 24, the antenna duplexer is connected between the output terminals 301 and 305 in the order of the transmission side filter 302, the phase shift circuit 303 (the portion surrounded by the dotted line in the figure), and the reception side filter 304 in this order. An antenna terminal 306 is connected between the filter 302 and the phase shift circuit 303. A surface acoustic wave filter is applied as the transmission side filter 302.

  When the antenna duplexer having such a configuration is used for a portable terminal device, only improvement in power resistance when a signal is input from the input terminal 301 to the transmission filter 302 has been performed.

  However, when the hop antenna of the mobile terminal device is fully extended or fully retracted, it becomes the best state and the antenna terminal of the antenna duplexer and the antenna are phase-matched. Under other conditions, that is, when the antenna is not fully extended or the antenna is damaged, the antenna duplexer is in a phase-shift mismatch between the antenna terminal and the antenna. The tip of the antenna terminal may be open.

  Normally, in order to suppress loss and noise due to the transmission signal wrapping around the receiving circuit inside the antenna duplexer, the receiving circuit is open in the transmission frequency band from the output end of the transmitting filter and the output terminal on the antenna side. As shown, a phase shift circuit is provided.

  Therefore, in the state of phase shift mismatch between the antenna terminal of the antenna duplexer and the antenna, a part of the signal output from the output end of the transmission filter is reflected by the transmission filter. In addition, when the tip of the antenna duplexer is open, the output signal is input to the transmission filter from the output end side in a form close to total reflection. In this case, it is conceivable that a high frequency voltage and a high frequency current of about twice as much as a maximum are applied by superimposing the input signal and the reflected wave. Therefore, in the case of an antenna duplexer using a surface acoustic wave filter as a transmission-side filter, the largest power is applied to the SAW resonator on the output side, so that the SAW resonator close to the output terminal side deteriorates. Had.

  Therefore, an object of the present invention is to provide an antenna duplexer that has power durability and has stable characteristics even when a signal is input from the antenna terminal side.

  To achieve this object, the antenna duplexer of the present invention includes an input terminal, a transmission-side filter having an input side connected to the input terminal, and a reception-side filter having an input side connected to the output side of the transmission-side filter. And an output terminal connected to the output side of the reception side filter, and an antenna terminal connected between the transmission side filter and the reception side filter, wherein the transmission side filter is configured by a ladder-type elastic wave filter. And the parallel arm resonator closest to the antenna terminal is composed of a plurality of resonators, and prevents the deterioration of the electrode due to reflection of the transmission signal at the antenna terminal. Can be achieved.

  As described above, according to the present invention, it is possible to provide an antenna duplexer that has power durability with respect to input of signals from the antenna terminal side and has stable characteristics.

Block circuit diagram of antenna duplexer in Embodiment 1 of the present invention Circuit diagram of reception-side filter in Embodiment 1 of the present invention Configuration diagram of SAW resonator in first to eighth embodiments of the present invention Top view of transmission-side filter in Embodiment 1 of the present invention Circuit diagram of transmitting filter shown in FIG. 1 is a circuit diagram showing a basic structure of a surface acoustic wave filter according to Embodiment 1 of the present invention. Basic configuration circuit diagram of the surface acoustic wave filter shown in FIG. FIG. 7 is a circuit diagram for explaining a connection method when the basic structure shown in FIG. 6 is formed using the basic configuration circuit shown in FIG. Circuit diagram of surface acoustic wave filter in Comparative Example 2 of the present invention Circuit diagram of surface acoustic wave filter in Comparative Example 3 of the present invention Top view of transmission-side filter in Embodiment 2 of the present invention Circuit diagram of transmission filter shown in FIG. Circuit diagram of transmission-side filter in Embodiment 3 of the present invention Circuit diagram of transmission-side filter in Embodiment 4 of the present invention Circuit diagram of transmitting filter in embodiment 5 of the present invention The top view of the transmission side filter in the comparative example 4 of this invention Circuit diagram of transmission-side filter in Comparative Example 5 of the present invention Basic configuration circuit diagram for configuring the transmission-side filter shown in FIG. FIG. 18 is a circuit diagram for explaining a connection method of the basic configuration circuit shown in FIG. 18 constituting the transmission side filter shown in FIG. Circuit diagram of reception-side filter in Embodiment 6 of the present invention Circuit diagram of reception-side filter in Embodiment 7 of the present invention Circuit diagram of reception-side filter in embodiment 8 of the present invention Circuit diagram of reception-side filter in Comparative Example 6 of the present invention Block diagram of conventional antenna duplexer

  The invention according to claim 1 of the present invention includes an input terminal, a transmission side filter having an input side connected to the input terminal, a reception side filter having an input side connected to the output side of the transmission side filter, and the reception side. An output terminal connected to the output side of the side filter, and an antenna terminal connected between the transmission side filter and the reception side filter, wherein the transmission side filter is a ladder-type elastic wave filter and The parallel arm resonator closest to the antenna terminal is an antenna duplexer composed of multiple resonators. Even if the transmitted signal is reflected by the antenna terminal, the surface acoustic wave filter is prevented from degrading and is stable. The operation can be obtained.

  Embodiments of the present invention will be described below.

(Embodiment 1)
In Embodiment 1 of the present invention, an antenna duplexer in the 800 MHz band (transmission band: 824 MHz to 849 MHz, reception band 869 MHz to 894 MHz) will be described.

  FIG. 1 is a block circuit diagram of an antenna duplexer according to the first embodiment. A transmission side filter 2, a phase shift circuit 3 (portion surrounded by a dotted line in the figure), a reception side filter between input and output terminals 1 and 5. The antenna terminal 6 is connected between the transmitting filter 2 and the phase shift circuit 3 in the order of 4.

  As shown in FIG. 2, the reception filter 4 of this antenna duplexer has SAW resonators 10a, 10b, 10c, 11a, 11b, and 11c arranged in a series arm and a parallel arm, and has three series arms and three parallel arms. A ladder type surface acoustic wave filter composed of a total of six stages of SAW resonators was used. These SAW resonators are provided with reflector electrodes 101 on both sides of a pair of interdigital transducer electrodes 100 on a piezoelectric substrate as shown in FIG.

  4 is a top view of the surface acoustic wave filter used as the transmission-side filter 2 of the antenna duplexer according to Embodiment 1 of the present invention. FIG. 5 is a circuit diagram of the surface acoustic wave filter shown in FIG. The SAW resonator is composed of two stages of parallel arms and a total of seven stages. 40 is a piezoelectric substrate, 41 is an input electrode, 42 is an output electrode, 43, 44a, 44b, 45a and 45b are series arm SAW resonators, 46 and 47 are parallel arm SAW resonators, and 48 is a ground electrode.

  As shown in FIG. 3, the SAW resonator constituting this surface acoustic wave filter is basically one in which reflector electrodes are provided on both sides of a pair of interdigital transducer electrodes. The series arm SAW resonators 44a and 44b and 45a and 45b are SAW resonators having the same structure.

  That is, this surface acoustic wave filter has a basic arm SAW resonator and a parallel arm SAW resonator circuit shown in FIG. 7 as basic configurations, and is connected as shown in FIG. 6 and the series arm SAW resonators are combined into one SAW resonator, and the surface acoustic wave filter shown in FIG. 6 is used as a basic structure. In FIG. 6, the series arm SAW resonators 64 and 65 are shown in FIG. This corresponds to the series arm SAW resonators 44a and 44b and 45a and 45b shown in FIG.

  For comparison, a surface acoustic wave filter shown in FIGS. 9 and 10 equivalent to the surface acoustic wave filter shown in FIG. 6 is prepared. The surface acoustic wave filter configured as shown in FIG. 9 is obtained by dividing the series arm SAW resonator 64 into 94a and 94b in the surface acoustic wave filter shown in FIG. 6, and the surface acoustic wave filter shown in FIG. The series arm SAW resonators 63 and 64 of the surface acoustic wave filter shown are divided into 103a, 103b, 104a, and 104b, respectively.

  Assuming that the capacities of the series arm SAW resonators 63, 64, 65 and the parallel arm SAW resonators 66, 67 shown in FIG. 6 are C63, C64, C65, C66, C67, respectively, the attenuation amount of the reception band of the transmission side filter is secured. Therefore, since the capacity is reduced, the relationship is (C63, C64)> C65, C66 = C67.

  Table 1 shows the capacities of the corresponding series arm and parallel arm SAW resonators in FIGS. 5, 9, and 10 when these capacities are set to 1, respectively.

  The aperture length of the SAW resonator obtained by dividing the SAW resonator shown in FIG. 6 is the same before and after the division, and the logarithm of the SAW resonator divided into N stages is N times the logarithm before the division. Accordingly, the capacity of each SAW resonator after division into N stages is N times the capacity of the SAW resonator before division. Accordingly, in FIGS. 5, 9, and 10, the divided SAW resonators are divided into two parts, so that they have twice the capacity before the division.

  Therefore, in the surface acoustic wave filter shown in FIG. 5, C43 = C44a (or C44b) * 2, (C45a, C45b)> C43> (C44a, C44b), and C46 = C47.

  These surface acoustic wave filters were evaluated for power durability. As a test method, the environmental temperature is 85 ° C., the applied frequency is 849 MHz, and when the power application time exceeds 100 hours, the applied power is resistant to power, and the applied power is increased from 30 dBm to 1 dBm. The power was 1 dBm lower than the applied power at which the lifetime was less than 100 hours in the test, and was defined as the power durability limit level of the surface acoustic wave filter.

  This power durability evaluation test is performed when the antenna terminal 6 and the output terminal 5 are each terminated with 50Ω in the antenna duplexer shown in FIG. The terminal 5 was used in two cases where power was applied to the input terminal 1 with 50Ω terminated. The results are shown in (Table 2).

  Table 2 also shows SAW resonators whose deterioration was confirmed by observing the surface of the surface acoustic wave filter after the test. In any surface acoustic wave filter, the surface acoustic wave filter of the reception-side filter 4 did not deteriorate.

  As can be seen from (Table 2), when the antenna terminal is opened, the surface acoustic wave filter deteriorates with lower power than when the antenna terminal is terminated with 50Ω. Further, like the surface acoustic wave filter of the first embodiment, the intermediate stage SAW resonators 44a and 44b having a small capacity are divided into multiple stages so as to have the same capacity as that of the first series arm SAW resonator 43 on the input terminal side. At the same time, it can be seen from the comparison with Comparative Examples 2 and 3 that it is effective to divide the final stage series arm SAW resonators 45a and 45b so that their capacities are larger than those of the first stage series arm SAW resonator 43, respectively.

  In particular, as can be seen from Comparative Examples 2 and 3, a design in which the power durability is determined by the final series arm SAW resonators 95 and 105 even when the antenna terminal is terminated by 50Ω has been conventionally performed. Such a multi-stage division of the series arm SAW resonator on the input terminal 1 side of the power does not improve the power resistance, but when the antenna terminal 6 is in an open state, the power of the final stage is still lower with a lower power. It can be seen that the serial arm SAW resonator deteriorates.

(Embodiments 2 to 5)
In the second to fifth embodiments, description will be made using a 1.9 GHz band antenna duplexer (transmission band: 1.85 GHz to 1.91 GHz, reception band 1.93 GHz to 1.99 GHz). The configuration of this antenna duplexer is the same as that shown in FIG.

  In the second to fifth embodiments, the ladder type surface acoustic wave filter shown in FIG.

  As the transmission-side filter 2, a ladder-type surface acoustic wave having the configuration shown in FIG. 12 in the second embodiment, FIG. 13 in the third embodiment, FIG. 14 in the fourth embodiment, and FIG. 15 in the fifth embodiment. A filter was used. FIG. 11 shows a layout on the piezoelectric substrate of the transmission side filter shown in the second embodiment. 110 is a piezoelectric substrate, 111 is an input electrode, 112 is an output electrode, 113a, 113b, 114a, 114b, 114c, 114d, 115a, 115b are series arm SAW resonators, and 116, 117 are parallel arm SAW resonators.

  As can be seen from this figure, the surface acoustic wave filter has a completely different structure when the output electrode 112 side is viewed from the input electrode 111 side and when the input electrode 111 side is viewed from the output electrode 112 side. They are formed so as to be the same, that is, symmetrical in terms of circuit and arrangement on the piezoelectric substrate 110. As Comparative Example 4, a surface acoustic wave filter having the same circuit configuration as that of the second embodiment and having a different arrangement on the piezoelectric substrate 110 is shown in FIG. As can be seen from this figure, in Comparative Example 4, the area of the interdigital transducer electrodes 115c and 115d of the serial arm SAW resonators 115a and 115b on the output electrode 112 side and the area of the pad electrode 115e is different from that of the other serial arm SAW resonator 113a. , 113b and 114a to 114d are smaller.

  Moreover, the ladder type surface acoustic wave filter which became the basic structure of Embodiments 2-5 and the comparative example 4 was set as the comparative example 5, and this structure is shown in FIG. This surface acoustic wave filter has a series-arm SAW resonator and a parallel-arm SAW resonator circuit shown in FIG. 18 as a basic configuration and is connected as shown in FIG. 19 by the image impedance method, and the adjacent parallel-arm SAW resonator and series-arm SAW are connected. Each resonator is combined into one SAW resonator.

  Accordingly, if the SAW resonator capacities in the surface acoustic wave filter shown in FIG. 17 are C173, C174, C175, C176, and C177 (each number corresponds to the SAW resonator number in FIG. 17), C173 = 2 × C174 and C173 = C175. When the capacitance of each SAW resonator of FIG. 17 is 1, the capacitance of each SAW resonator of the surface acoustic wave filters of FIGS. 11 and 13 to 16 corresponding to this is shown in Table 3.

  Also in the second to fifth embodiments, the SAW resonator divided in the basic structure surface acoustic wave filter (FIG. 17) has the same opening length before and after the division, and the logarithm is divided into N stages. The SAW resonator is set to N times the logarithm before division. Therefore, the capacity of each divided SAW resonator divided into N stages is N times the capacity of the SAW resonator before division.

  Each surface acoustic wave filter was subjected to a power durability evaluation test similar to that of the first embodiment. However, the ambient temperature is 50 ° C., the applied frequency is 1.91 GHz, the applied power is increased from 27 dBm to 1 dBm, and the test is performed with a power 1 dBm lower than the applied power at which the lifetime is less than 100 hours. The sex limit level. The results are shown in (Table 4).

  Table 4 also shows SAW resonators whose deterioration was confirmed by observing the surface of the surface acoustic wave filter after the test. In any of the surface acoustic wave filters, the reception-side surface acoustic wave filter did not deteriorate in the tested range.

  As can be seen from (Table 4), it can be seen that when the antenna terminal is opened, the surface acoustic wave filter deteriorates with lower power than when the antenna terminal is terminated. Further, as can be seen from a comparison between the second embodiment and the comparative example 4, even if the circuit configuration of the surface acoustic wave filter is the same, it can be seen that the power durability is different if the layout on the piezoelectric substrate is different.

  In Comparative Example 4, since the areas of the bus bars and pad electrodes of the final series arm SAW resonators 115a and 115b are smaller than those of other series arm SAW resonators, the heat generated during energization is radiated. It is considered that the power resistance is lowered. In other words, taking into consideration the heat dissipation of the heat generated during energization, the layout on the piezoelectric substrate as well as the circuit is symmetric, so that the bias of heat dissipation can be minimized and the power durability is improved. be able to. Also, when considering the layout on the piezoelectric substrate, the SAW resonator closest to the output terminal 5 to which power larger than the input power may be applied in the situation where the antenna terminal is opened or the first deterioration occurs. It can be easily considered that the area of the bus bar and the pad of the SAW resonator to be widened is increased to improve the heat radiation efficiency.

  Further, as can be seen from the third embodiment, a mode in which the parallel arm SAW resonator deteriorates when the power resistance of the series arm SAW resonator is improved is observed. From the observation after the test, it was found that the cause of deterioration was that electric discharge was generated between the interdigital transducer electrodes of the parallel arm SAW resonator close to the output terminal 5. That is, also in this case, due to the superposition of the reflected wave at the antenna terminal and the input signal, a higher high-frequency voltage is applied to the parallel arm SAW resonator than when the antenna terminal is terminated by 50Ω and power is input from the input terminal. For this reason, it is considered that a discharge occurred between the interdigital transducer electrodes. Therefore, when the parallel arm SAW resonator close to the output terminal 5 is divided and the high frequency voltage applied to each SAW resonator is divided as in the fourth and fifth embodiments, deterioration of the parallel arm SAW resonator can be suppressed. The power resistance when the antenna terminal is opened can be further improved. The power durability limit level is also determined by the normally observed series arm SAW resonator.

(Embodiments 6 to 8)
In the sixth to eighth embodiments, a 1.9 GHz band antenna duplexer (transmission band: 1.85 GHz to 1.91 GHz, reception band 1.93 GHz to 1.99 GHz) will be described. The configuration of the antenna duplexer is the same as that shown in FIG.

  However, a ladder-type surface acoustic wave filter having the same configuration as that of the fourth embodiment is used as the transmission-side filter 2, and the reception-side filter 4 is shown in FIG. 20 for the sixth embodiment, FIG. 21 for the seventh embodiment, and FIG. 21 for the eighth embodiment. 22 and Comparative Example 6 used ladder type surface acoustic wave filters shown in FIG.

  20 to 22, the first stage on the input terminal 1 side is the series arm SAW resonators 203, 213, and 223a. In FIG. 21, only the parallel arm SAW resonator closest to the input terminal 1 side is divided into two stages, and in FIG. 22, the surface acoustic wave filter shown in FIG. Both the near series arm SAW resonators 223a and 223b and the parallel arm SAW resonators 226a and 226b are divided into two stages.

  In the ladder-type surface acoustic wave filter of FIG. 23 (Comparative Example 6), the first stage on the input terminal 1 side is a parallel arm SAW resonator 236. In the seventh and eighth embodiments, the divided series arm SAW resonators 216a, 216b, 223a, 223b, 226a, and 226b have the same opening length as the series arm SAW resonators 203 and 206 before the division, and logarithmically. The SAW resonator divided into N stages is N times the logarithm before division. Therefore, the capacity of each divided SAW resonator divided into N stages is N times the capacity of the SAW resonator before division. In the seventh and eighth embodiments, each of the SAW resonators is divided into two stages, so that each SAW resonator has a capacity twice as large as that before the division.

  Each of the above surface acoustic wave filters was subjected to the same power durability evaluation test as in the second to fifth embodiments. The results are shown in (Table 5).

  Table 5 also shows SAW resonators whose deterioration was confirmed by observing the surface of the surface acoustic wave filter after the test. Further, in any surface acoustic wave filter, in the test with the antenna terminal opened, the transmission-side surface acoustic wave filter did not deteriorate in the range in which the test was performed.

  As can be seen from (Table 5), the receiving side filter 4 has high power durability by using a ladder type surface acoustic wave filter of the serial arm SAW resonators 203, 213, and 223a in the first stage of the input terminal 1 side. I understand. This is probably because most of the transmission power is reflected by the antenna terminal of the phase shift circuit 3 in the antenna duplexer having the phase shift circuit 3. Even in consideration of the case where the antenna terminal is in an open state, the power durability can be further improved by multi-stage the SAW resonator on the input terminal 1 side of the reception filter 4.

  The points of the present invention are described below.

  (1) Series arm SAW having the smallest capacity among the outermost arm (closest to antenna terminal 6) divided into a plurality of series arm SAW resonators in order to prevent deterioration of the transmission side filter due to a reflected wave from the antenna terminal The capacity of the resonator is made larger than the capacity of the series arm SAW resonator other than the outermost arm. Therefore, if the logarithm before the division of the interdigital transducer electrodes of the series arm SAW resonators other than the outermost arm is Ni and the logarithm after the division is Na, Ni ≦ Na may be satisfied. Further, when the crossing width before the division of the interdigital transducer electrode of the serial arm SAW resonator of the outermost arm is Li and the crossing width after the division is La, the resistance per electrode finger is increased by setting La ≦ Li. Is suppressed and the influence of heat generation can be reduced.

  In addition, as the series arm SAW resonator of the transmission filter 2, it is preferable to use a serial arm SAW resonator having a larger capacity as it is closer to the input terminal 1 and the output terminal 5 in consideration of power durability.

  (2) When a ladder-type surface acoustic wave filter is used as the transmission-side filter 2, as shown in FIGS. 14 and 15, the parallel arm SAW resonator closest to the antenna terminal is divided into a plurality of transmission frequencies. In the band, it is possible to improve the voltage resistance of the parallel arm SAW resonator to which a large voltage is applied and to suppress the deterioration. Further, when the parallel arm SAW resonator closest to the antenna terminal is divided into a plurality of parts, the combined capacity after the division is made equal to the capacity before the division, so that a high frequency approximately twice as high as a normally applied high frequency voltage is obtained. Degradation of the parallel arm SAW resonator can be suppressed even with respect to voltage. Further, the parallel arm SAW resonator having the smallest capacity among the divided parallel arm SAW resonators has a larger capacity than the parallel arm SAW resonators other than the divided parallel arms, so that the largest high-frequency voltage can be generated. The withstand voltage of the parallel arm SAW resonator closest to the applied output side terminal (antenna terminal) can be improved.

  (3) When a ladder-type surface acoustic wave filter is used as the reception-side filter 4, the first stage closest to the antenna terminal side is a series arm SAW resonator, and is divided into a plurality of parts and has the largest capacity among the divided series arm SAW resonators. The small series arm SAW resonator can further improve the power durability by making it larger than the capacity of the series arm SAW resonator other than the first stage. That is, assuming that the logarithm of the interdigital transducer electrode before division is Ni and the logarithm after division is Na, Ni ≦ Na may be satisfied.

  Further, assuming that the intersection width before division is Li and the intersection width after division is La, by setting La ≦ Li, an increase in resistance per electrode finger is suppressed, and the influence of heat generation can be reduced.

  (4) When a ladder-type surface acoustic wave filter is used as the reception-side filter 4, the parallel arm SAW resonator closest to the antenna terminal is divided into a plurality of voltages as shown in FIGS. Can be improved and deterioration can be suppressed. By making the combined capacitance after the time division equal to the capacitance before the division, it is possible to suppress the deterioration of the parallel arm SAW resonator even for a high frequency voltage approximately twice as high as a normally applied high frequency voltage. Furthermore, the parallel arm SAW resonator having the smallest capacity among the divided parallel arm SAW resonators can have higher voltage resistance by having a larger capacity than other parallel arm SAW resonators. .

  (5) When a ladder-type surface acoustic wave filter is used for both the transmission-side filter and the reception-side filter, the configuration when viewed from the input side and when viewed from the output side is more circuit-wise, more preferably on the piezoelectric substrate. By designing the layout so as to be symmetric, heat generated during energization can be efficiently dissipated, and power durability can be improved.

DESCRIPTION OF SYMBOLS 1 Input terminal 2 Transmission side filter 3 Phase shift circuit 4 Reception side filter 5 Output terminal 6 Antenna terminal 10a SAW resonator 10b SAW resonator 10c SAW resonator 11a SAW resonator 11b SAW resonator 11c SAW resonator 40 Piezoelectric substrate 41 Input Electrode 42 Output electrode 43 Series arm SAW resonator 44a Series arm SAW resonator 44b Series arm SAW resonator 45a Series arm SAW resonator 45b Series arm SAW resonator 46 Parallel arm SAW resonator 47 Parallel arm SAW resonator 48 Ground Electrode 63 Series arm SAW resonator 64 Series arm SAW resonator 65 Series arm SAW resonator 66 Parallel arm SAW resonator 67 Parallel arm SAW resonator 93 Series arm SAW resonator 95 Series arm SAW resonator 100 IDT electrode 101 Reflector electrode 103a Series arm SAW resonator 103b Row arm SAW resonator 104a Series arm SAW resonator 104b Series arm SAW resonator 105 Series arm SAW resonator 110 Piezoelectric substrate 111 Input electrode 112 Output electrode 113a Series arm SAW resonator 113b Series arm SAW resonator 114a Series arm SAW Resonator 114b Series arm SAW resonator 114c Series arm SAW resonator 114d Series arm SAW resonator 115a Series arm SAW resonator 115b Series arm SAW resonator 116 Parallel arm SAW resonator 117 Parallel arm SAW resonator 203 Series arm SAW resonator 206 Series arm SAW resonator 213 Series arm SAW resonator 216a Series arm SAW resonator 216b Series arm SAW resonator 223a Series arm SAW resonator 223b Series arm SAW resonator 226a Parallel arm SAW resonator 226b Parallel arm SAW resonator 236 Parallel Arm SAW resonator

Claims (12)

An input terminal, a transmission side filter having an input side connected to the input terminal, a reception side filter having an input side connected to the output side of the transmission side filter, an output terminal connected to an output side of the reception side filter, An antenna terminal connected between the transmission-side filter and the reception-side filter, wherein the transmission-side filter is configured by a ladder-type elastic wave filter and a parallel arm resonator closest to the antenna terminal includes a plurality of parallel-arm resonators. An antenna duplexer composed of resonators. 2. The antenna duplexer according to claim 1, wherein, in the transmission-side filter, capacities of the plurality of resonators in a parallel arm closest to the antenna terminal are equal. In the transmission filter, the capacity of the resonator having the smallest capacity among the plurality of resonators in the parallel arm closest to the antenna terminal is larger than the capacity of the resonator in the parallel arm other than the parallel arm closest to the antenna terminal. The antenna duplexer according to claim 1, which is large. 2. The antenna duplexer according to claim 1, wherein in the transmission-side filter, the outermost arm on the antenna terminal side is a series arm resonator, and the series arm resonator has a configuration in which a plurality of resonators are connected in series . 5. The antenna duplexer according to claim 4, wherein, in the transmission-side filter, the plurality of resonators in the series arm that is the outermost arm on the antenna terminal side have substantially the same capacity. 2. The antenna duplexer according to claim 1, wherein a series arm resonator is connected to the first stage on the antenna terminal side in the reception side filter. 7. The antenna duplexer according to claim 6, wherein in the reception-side filter, the series arm resonator connected to the first stage on the antenna terminal side has a configuration in which a plurality of resonators are connected in series. 7. The series arm resonator connected to the antenna terminal side first stage in the reception filter has a configuration in which a plurality of resonators are connected in series, and the plurality of resonators have substantially the same capacity. Antenna duplexer described in 1. In the receiving filter, the series arm resonator connected to the antenna terminal side first stage has a configuration in which a plurality of resonators are connected in series, and the capacitance of each of the plurality of resonators is the same as that in the receiving filter. The antenna duplexer according to claim 6, wherein the antenna duplexer has a capacity larger than that of a resonator connected to a series arm other than the series arm on the antenna terminal side. 2. The antenna duplexer according to claim 1, wherein the parallel arm resonator closest to the antenna terminal in the reception-side filter includes a plurality of resonators. 11. The antenna duplexer according to claim 10, wherein, in the reception-side filter, capacities of the plurality of resonators in a parallel arm closest to the antenna terminal are equal. In the receiving filter, the capacity of the resonator having the smallest capacity among the plurality of resonators in the parallel arm closest to the antenna terminal is larger than the capacity of the resonator in the parallel arm other than the parallel arm closest to the antenna terminal. The antenna duplexer according to claim 10, wherein the antenna duplexer is large.

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