JP2019165435A - Composite multiplexer - Google Patents

Abstract

To provide a composite multiplexer having excellent isolation characteristics even when it is configured to cope with a high frequency.SOLUTION: A composite multiplexer 1 includes a first multiplexer 11, a second multiplexer 21, and a second LC circuit 16. The first multiplexer 11 includes a plurality of band pass filter circuits 12 and 13 and a plurality of first LC circuits 14 and 15 respectively connected to end portions opposite to a first terminal 3 of the band pass filter circuits 12 and 13. The second multiplexer 21 includes a plurality of band pass filter circuits 22 and 23. The second LC circuit 16 is connected between the first terminal 3 and the second multiplexer 21.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a composite multiplexer used for mobile communication equipment and the like.

  In 5G, which is the next generation communication standard, a frequency band of 3 GHz to 6 GHz is used. Therefore, a band-pass filter that can be used in this frequency band is also required. Patent Document 1 discloses an LC filter used in such a frequency band.

  However, steepness is not sufficient in the LC filter. Therefore, the LC filter is unsuitable for a carrier aggregation multiplexer in the 5G communication standard.

  On the other hand, the elastic wave filter is excellent in the steepness of the filter characteristics. In particular, in the case of an elastic wave filter using a plate wave S0 mode, it is easy to increase the frequency. For example, in the acoustic wave filter described in Patent Document 2, an acoustic multilayer film and a piezoelectric film are laminated on a support substrate. The S0 mode of the plate wave propagating through the piezoelectric film has a high sound speed of about 6000 m / sec. Therefore, even when used in the 3 GHz to 6 GHz band, the line width of the electrode fingers and the gap between the electrode fingers need not be so narrow. Accordingly, problems such as variations in production and a decrease in power durability do not occur even in a high frequency band.

JP 2017-092546 A WO2017 / 068888

  However, it has been found that when a multiplexer is configured using a filter having a pass band of 3 GHz to 6 GHz, a new problem arises that the isolation characteristics between the filters are not sufficient. This is presumably because the effect of residual inductors and parasitic capacitance becomes greater when the frequency is higher than when the frequency is low.

  An object of the present invention is to provide a composite multiplexer having good isolation characteristics even when the frequency is increased.

  A composite multiplexer according to the present invention is a composite multiplexer having a first terminal connected to an antenna terminal and a plurality of second terminals which are input / output terminals, one end of which is connected to the first terminal. A plurality of band-pass filter circuits and a plurality of first LC circuits connected to the plurality of band-pass filter circuits, respectively, and the first terminal of each of the band-pass filter circuits A first multiplexer connected to the plurality of second terminals via the first LC circuits, and one end connected to the first terminal, A second multiplexer having a plurality of band-pass filter circuits, each end of the band-pass filter circuit opposite to the first terminal being connected to the plurality of second terminals; The first Comprising terminal and, a second LC circuit coupled between said second multiplexer.

  In the composite multiplexer according to the present invention, preferably, the plurality of first LC circuits form attenuation poles for constituting a pass band of the band pass filter circuit. In this case, the steepness of the filter characteristic in the first multiplexer can be effectively enhanced.

  In the composite multiplexer according to the present invention, the second LC circuit is a 90-degree delay circuit that delays the phase of the propagated signal by 90 degrees. In this case, the phase can be varied by 90 degrees between the signals propagated through the first multiplexer and the second multiplexer.

  In the composite multiplexer according to the present invention, more preferably, the first LC circuit is a 90-degree delay circuit that delays the phase of the propagated signal by 90 degrees. In this case, the isolation characteristics can be further improved.

  In a specific aspect of the composite multiplexer according to the present invention, the band-pass filter circuit is configured by an elastic wave filter. In this case, high frequency can be easily realized.

  In still another specific aspect of the composite multiplexer according to the present invention, the first multiplexer and the second multiplexer are first and second duplexers, respectively.

  In still another specific aspect of the composite multiplexer according to the present invention, one of the band-pass filter circuits of the first multiplexer and one of the band-pass filter circuits of the second multiplexer have the same Band A band-pass filter circuit, wherein one other band-pass filter circuit of the first multiplexer and one other band-pass filter circuit of the second multiplexer are in the same band band. It is a pass filter circuit.

  According to the present invention, it is possible to provide a composite multiplexer having good isolation characteristics even when the frequency is increased.

It is a circuit diagram of the composite multiplexer of the 1st Embodiment of this invention. FIG. 2 is a circuit diagram showing a configuration of a band-pass filter circuit of a first duplexer in the composite multiplexer shown in FIG. 1. It is front sectional drawing for demonstrating the elastic wave resonator which comprises the elastic wave filter used with the composite multiplexer of 1st Embodiment. (A) is a circuit diagram showing an example of the first and second LC circuits, and (b) is a circuit diagram showing another example of the first and second LC circuits. (A) is a circuit diagram which shows the further another example of the 1st, 2nd LC circuit, (b) is a circuit diagram which shows another example of the 1st, 2nd LC circuit. It is a figure which shows the passage characteristic of Band77 of a comparative example and an Example. It is a figure which shows the passage characteristic of Band79 of a comparative example and an Example. It is a figure which shows the isolation characteristic from Band77 to Band79 in the composite multiplexer of a comparative example and an Example. It is a figure which shows the VSWR characteristic in the antenna terminal in a comparative example and an Example. It is a figure which shows the VSWR characteristic in the terminal by the side of Band77 in a comparative example and an Example. It is a figure which shows the VSWR characteristic in the terminal by the side of Band79 in a comparative example and an Example. It is a circuit diagram for demonstrating the transmission state of the transmission signal of Band77 in the composite multiplexer of 1st Embodiment. It is a circuit diagram for demonstrating the transmission state of the received signal of Band79 in the composite multiplexer of 1st Embodiment. It is a circuit diagram for demonstrating the transmission state of the isolation signal in the composite multiplexer of 1st Embodiment. FIG. 5 is a circuit diagram of a composite multiplexer according to a second embodiment.

  Hereinafter, the present invention will be clarified by describing specific embodiments of the present invention with reference to the drawings.

  It should be pointed out that each embodiment described in this specification is an exemplification, and a partial replacement or combination of configurations is possible between different embodiments.

  FIG. 1 is a circuit diagram of a composite multiplexer according to the first embodiment of the present invention. The composite multiplexer 1 has a first terminal 3 connected to the antenna terminal 2. The composite multiplexer 1 has a plurality of second terminals 4 and 5. The second terminals 4 and 5 are used as input / output terminals. A first duplexer 11 as a first multiplexer is connected to the first terminal 3. A second duplexer 21 as a second multiplexer is connected to the first terminal 3 via a second LC circuit 16.

  The composite multiplexer 1 is used in Band 77 and Band 79 used in 5G. The communication band of Band 77 is 3300 MHz to 4200 MHz, and the communication band of Band 79 is 4400 MHz to 5000 MHz. Since the composite multiplexer 1 is used in carrier aggregation, each end of the first and second duplexers 11 and 21 is commonly connected to the first terminal 3. Further, the second terminal 4 is used as an input / output terminal of the Band 77. The second terminal 5 is used as an input / output terminal of Band 79.

  The composite multiplexer of the present invention is not limited to the combination of Band 77 and Band 79, and can be applied to various combinations of Bands.

  The first duplexer 11 has a plurality of band-pass filter circuits 12 and 13. The band-pass filter circuit 12 is a band-pass filter circuit for Band 77, and the band-pass filter circuit 13 is a band-pass filter circuit for Band 79. One ends of the plurality of band-pass filter circuits 12 and 13 are commonly connected to the first terminal 3. In the first duplexer 11, the first LC circuit 14 is connected between the band-pass filter circuit 12 and the second terminal 4. The first LC circuit 14 forms a band 77 band together with the band-pass filter circuit 12. In particular, the first LC circuit 14 forms an attenuation pole and enhances the steepness of the band 77 pass band.

  Similarly, a first LC circuit 15 is connected between the band-pass filter circuit 13 and the second terminal 5. The first LC circuit 15 forms an attenuation pole. Therefore, the steepness of the pass band in Band 79 is enhanced by the band pass filter circuit 13 and the first LC circuit 15.

  As described above, in the first duplexer 11, the ends of the plurality of bandpass filter circuits 12, 13 opposite to the side connected to the first terminal 3 are respectively the first LC circuit 14. , 15 to the plurality of second terminals 4, 5, respectively.

  In the present embodiment, the first LC circuit 14 also has a function of delaying the phase by 90 degrees. Similarly, the first LC circuit 15 delays the phase of the propagated signal by 90 degrees.

  The second duplexer 21 has a plurality of bandpass filter circuits 22 and 23. The band-pass filter circuit 22 is a band-pass filter circuit for Band 77. The band-pass filter circuit 23 is a band-pass filter circuit for Band 79. One ends of the band-pass filter circuit 22 and the band-pass filter circuit 23 are commonly connected to the first terminal 3 via the second LC circuit 16. The end of the band-pass filter circuit 22 opposite to the side connected to the first terminal 3 is connected to the second terminal 4 for Band 77. The end of the band-pass filter circuit 23 opposite to the side connected to the first terminal 3 is connected to the second terminal 5 which is a transmission / reception terminal for Band 79.

  The second LC circuit 16 is configured to delay the phase of the propagated signal by 90 degrees. That is, the second LC circuit 16 is a 90-degree delay circuit, like the first LC circuits 14 and 15.

  Since the composite multiplexer 1 is configured as described above, the isolation characteristic between the Band 77 and the Band 79 can be effectively enhanced. This effect will be described in more detail later with examples.

  FIG. 2 is a circuit diagram for explaining the circuit configuration of the band-pass filter circuits 12 and 13 of the first duplexer 11 in the composite multiplexer 1. The band-pass filter circuits 22 and 23 in the second duplexer also have a similar circuit configuration.

  In FIG. 2, portions of the first duplexer 11 closer to the first terminal 3 than the first LC circuits 14 and 15 are shown, and the first LC circuits 14 and 15 are not shown.

  As shown in FIG. 2, one end of the band pass filter circuit 12 and the band pass filter circuit 13 is commonly connected to the first terminal 3. An impedance matching inductor L1 is connected between the first terminal 3 and the ground potential.

  The band pass filter circuit 12 and the band pass filter circuit 13 are ladder type filters. In the band-pass filter circuit 12, a plurality of series arm resonators S1 to S3 and a plurality of parallel arm resonators P1 to P3 are connected to form a ladder type circuit.

  An inductor L4 is connected between the parallel arm resonator P1 and the ground potential. An inductor L2 is connected between the connection point between the parallel arm resonator P1 and the inductor L4 and the series arm.

  An inductor L3 is connected between the connection point between the series arm resonators S2 and S3 and the ground potential. One end of each of the parallel arm resonators P2 and P3 is commonly connected, and is connected to the ground potential via the inductor L5.

  In the band-pass filter circuit 13, a plurality of series arm resonators S11 to S14 and a plurality of parallel arm resonators P11 to P14 are connected so as to constitute a ladder type circuit. One ends of the parallel arm resonators P11 and P12 are connected in common and connected to the ground potential. One ends of the parallel arm resonators P13 and P14 are also connected in common and connected to the ground potential. Further, an inductor L6 is connected to the side opposite to the first terminal 3 of the series arm resonator S11. An inductor L7 is connected between the commonly connected portion of the parallel arm resonators P11 and P12 and the ground potential.

  In the bandpass filter circuit 12, the inductor L2 and the inductor L3 are connected to form an attenuation pole outside the passband. The inductor L4 and the inductor L5 are connected to widen the frequency interval between the resonance frequency and the antiresonance frequency of the parallel arm resonator.

  In the band-pass filter circuit 13, the inductor L6 is connected to achieve impedance matching with the second terminal 5 shown in FIG. The inductor L7 is connected to form an attenuation pole outside the passband.

  The band-pass filter circuit 22 and the band-pass filter circuit 23 of the second duplexer 21 are configured in the same manner as the band-pass filter circuit 12 and the band-pass filter circuit 13.

  Returning to FIG. 1, in the composite multiplexer, a first LC circuit 14 is connected to the band-pass filter circuit 12 in order to further form an attenuation pole outside the band, and the first LC circuit 14 is connected to the band-pass filter circuit 13. An LC circuit 15 is connected. Thereby, the steepness of the filter characteristic is further enhanced.

  All of the series arm resonators S1 to S3, the parallel arm resonators P1 to P3, the series arm resonators S11 to S14, and the parallel arm resonators P11 to P14 shown in FIG. Accordingly, the band-pass filter circuit 12 and the band-pass filter circuit 13, and the band-pass filter circuit 22 and the band-pass filter circuit 23 are all ladder-type elastic wave filter circuits.

  FIG. 3 is a front sectional view showing an example of the acoustic wave resonator. The acoustic wave resonator 31 has a support substrate 32. An acoustic multilayer film 33 is laminated on the support substrate 32. A piezoelectric plate 34 is laminated on the acoustic multilayer film 33. An IDT electrode 35 is provided on the piezoelectric plate 34. Reflectors are arranged on both sides of the IDT electrode 35 in the elastic wave propagation direction. In addition, illustration of this reflector is abbreviate | omitted.

  The support substrate 32 is made of an appropriate material such as a semiconductor material such as silicon, or a piezoelectric material such as silicon oxynitride, silicon nitride, or alumina.

  The acoustic multilayer film 33 includes low acoustic impedance layers 33a, 33c, and 33e and high acoustic impedance layers 33b, 33d, and 33f. Low acoustic impedance layers 33a, 33c, and 33e and high acoustic impedance layers 33b, 33d, and 33f are alternately stacked. The acoustic impedance of the low acoustic impedance layers 33a, 33c, and 33e is lower than the acoustic impedance of the high acoustic impedance layers 33b, 33d, and 33f. Any suitable material can be used as the material of the low acoustic impedance layers 33a, 33c, and 33e and the high acoustic impedance layers 33b, 33d, and 33f as long as the relationship of the acoustic impedance is satisfied. Examples of such materials include insulating materials such as silicon oxide, silicon oxynitride, silicon nitride, and alumina, semiconductor materials such as silicon, and metals such as Al, Pt, and AlCu alloys.

The piezoelectric plate 34 is made of an appropriate piezoelectric material such as LiTaO ₃ or LiNbO ₃ . The IDT electrode 35 is also made of an appropriate metal or alloy. Further, the IDT electrode 35 may be formed of a laminated metal film.

In the composite multiplexer 1, bandpass filter circuits 12 and 13 and bandpass filter circuits 22 and 23 are configured using a plurality of acoustic wave resonators 31. Therefore, the plate wave S
By using the 0 mode or the like, high frequency can be easily achieved.

  Returning to FIG. 1, the first LC circuits 14 and 15 and the second LC circuit 16 have a circuit configuration in which an inductor L and a capacitor C are connected. FIG. 4A is a circuit diagram illustrating an example of such an LC circuit, and FIG. 5A is a circuit diagram illustrating another example.

  In the LC circuit 41 shown in FIG. 4A, the inductors L11 and L11 are connected to the transmission path to which the output ends are connected. That is, the inductors L11 and L11 are connected in series to the series arm of the ladder filter. A capacitor C11 is connected between the transmission path and the ground potential.

  Note that an LC circuit 41A shown in FIG. 4B may be used instead of the LC circuit 41 shown in FIG.

  Conversely, in the LC circuit 42 shown in FIG. 5A, capacitors C12 and C12 are connected to a path through which a signal is transmitted. An inductor L12 is connected between the path through which this signal is transmitted and the ground potential.

  Instead of the LC circuit 42 shown in FIG. 5A, an LC circuit 42A shown in FIG. 5B may be used.

  The LC circuit 41 or the LC circuit 42 constitutes the first and second LC circuits 14, 15 and 16 described above.

  The composite multiplexer 1 transmits a Band 77 transmission signal and a Band 79 reception signal. In this case, since the first and second LC circuits 14 to 16 are provided, the isolation characteristics can be effectively improved. This will be clarified by describing the following examples and comparative examples.

  The band-pass filter circuit 12 of the first duplexer 11 in the example of the first embodiment was created according to the following design parameters.

  Further, the band-pass filter circuit 13 was configured according to the design parameters shown in Table 2 below.

  The inductance values of the inductors L1 to L7 were as shown in Table 3 below.

  As a circuit configuration in the first and second LC circuits, the LC circuit 41 shown in FIG. The inductance value of the inductor L11 was 1.9 nH, and the capacitance of the capacitor C11 was 0.8 pF.

  The design parameters of the band-pass filter circuits 22 and 23 in the second duplexer 21 are the same.

  For comparison, the first and second LC circuits 14 to 16 are not used, and one end of the first duplexer and the second duplexer are not commonly connected to each other. Similarly, a multiplexer circuit was configured.

  In the comparative example, since the first and second duplexers are not connected in parallel, the capacitances of the resonators are all doubled and the inductance values are all halved compared to the example.

  FIG. 6 shows transmission characteristics of transmission signals in Band 77. FIG. 7 shows the pass characteristic of the received signal of Band 79. FIG. 8 is a diagram showing isolation characteristics from Band 77 to Band 79 side. 9 shows the VSWR characteristics at the antenna terminal, FIG. 10 shows the VSWR characteristics at the Band 77 side terminal, and FIG. 11 shows the VSWR characteristics at the Band 79 side terminal.

  6 to 11, the solid line indicates the result of the example, and the broken line indicates the result of the comparative example.

  As shown in FIG. 8, it can be seen that the isolation characteristic is effectively improved according to the example compared to the comparative example. That is, the isolation in the Band 77 band is improved to 42.2 dB in the comparative example and 52.2 dB in the example. In the Band 79 band, the comparative example is improved to 54.2 dB compared to 52.4 dB.

  Further, as is apparent from FIGS. 6 and 7, it can be seen that the pass characteristics are improved according to the embodiment with respect to the comparative example in any band of Band 77 and Band 79. Furthermore, as shown in FIGS. 9 to 11, it can be seen that the VSWR characteristics are also improved according to the example with respect to the comparative example.

  As described above, the reason why the isolation characteristics are improved with respect to the comparative example in the example is considered as follows.

  FIG. 12 is a diagram illustrating a state in which a Band 77 transmission signal is transmitted from the second terminal 4 which is the Band 77 side terminal to the first terminal 3 side. As indicated by an arrow A 1, on the first duplexer 11 side, a transmission signal is transmitted to the first terminal 3 via the first LC circuit 14 and the band-pass filter circuit 12. In this case, the first LC circuit 14 delays the phase of the transmission signal by 90 degrees.

  On the other hand, the transmission signal of Band 77 is transmitted to the first terminal 3 via the band-pass filter circuit 22 and the second LC circuit 16 of the second duplexer 21 as indicated by the arrow A2. In this case, the phase of the transmitted signal is delayed by 90 degrees in the second LC circuit 16. Therefore, at the first terminal 3, the phases of both transmission signals indicated by the arrows A1 and A2 are aligned. Therefore, the signals propagated through both transmission paths are combined without canceling each other and output to the first terminal 3 and the antenna terminal 2.

  As shown in FIG. 13, the received signal of Band 79 is transmitted from the first terminal 3 to the second terminal 5 which is a terminal of Band 79. In this case, the received signal passes through the band-pass filter circuit 13 and the first LC circuit 15 of the first duplexer 11 in the transmission path indicated by the arrow B1. Therefore, the phase of the received signal is delayed by 90 degrees. On the other hand, in the transmission path indicated by the arrow B 2, the signal is transmitted to the second terminal 5 via the second LC circuit 16 and the band pass filter circuit 23. Even in this case, the phase of the signal is delayed by 90 degrees by the second LC circuit 16. Therefore, at the second terminal 5, the phases of the signals transmitted through the transmission path indicated by the arrow B1 and the transmission path indicated by the arrow B2 are aligned. Therefore, the received signals are synthesized without canceling each other.

  On the other hand, as shown in FIG. 14, the isolation between the second terminal 4 that is the Band 77 side terminal and the second terminal 5 on the Band 79 side is the second indicated by the path indicated by the arrows C1 and C2. The signal leaked from the terminal 4 to the second terminal 5 side passes through the first LC circuit 14 and the first LC circuit 15. Therefore, the phase is delayed by 180 degrees. On the other hand, the phase of the signal leaked through the transmission path indicated by the arrows D1 and D2 is not delayed. Therefore, at the second terminal 5, the phase of the signal transmitted through the paths indicated by the arrows C1 and C2 is different from the phase of the signal transmitted through the transmission paths indicated by the arrows D1 and D2 by 180 degrees. . Therefore, both signals cancel each other, and the isolation characteristics are improved.

  For the above reasons, in the above embodiment, the transmission characteristics between the second terminal 4 and the first terminal 3 and the transmission characteristics between the second terminal 5 and the first terminal 3 are not deteriorated. The isolation characteristic between the second terminal 4 for Band 77 and the second terminal 5 for Band 79 can be effectively improved.

  In the composite multiplexer 1 of the first embodiment, the first and second duplexers 11 and 21 are commonly connected to the first terminal 3, but the composite multiplexer 51 of the second embodiment shown in FIG. As described above, each of the first multiplexer 61 and the second multiplexer 62 may be a quadplexer having four band-pass filter circuits 61a to 61d and 62a to 62d. In this case, in the first multiplexer 61, the first LC circuits 63a to 63d are connected to the ends of the band-pass filter circuits 61a to 61d on the opposite side to the first terminal 3, respectively. The second LC circuit 16 is connected between the second multiplexer 62 and the first terminal 3. The second multiplexer 62 is also a quadplexer as described above.

  Thus, in the present invention, the first and second multiplexers are not limited to duplexers, but may be triplexers, quadplexers, or multiplexers having five or more band-pass filter circuits. When the number of band-pass filter circuits in the multiplexer is N, the first LC circuit is connected to each of the N filters in the first multiplexer, and the second LC circuit 16 is further connected to the first LC circuit 16. It is connected between the terminal 3 and the second multiplexer. Accordingly, when the number of band-pass filter circuits in the first and second multiplexers is N, N + 1 LC circuits are used as a whole.

DESCRIPTION OF SYMBOLS 1 ... Composite multiplexer 2 ... Antenna terminal 3 ... 1st terminal 4, 5 ... 2nd terminal 11 ... 1st duplexer 12, 13, 22, 23 ... Band pass type filter circuit 14, 15 ... 1st LC circuit 16 ... 2nd LC circuit 21 ... 2nd duplexer 31 ... Elastic wave resonator 32 ... Support substrate 33 ... Acoustic multilayer film 33a, 33c, 33e ... Low acoustic impedance layer 33b, 33d, 33f ... High acoustic impedance layer 34 ... Piezoelectric plate 35 ... IDT electrodes 41, 41A, 42, 42A ... LC circuit 51 ... Composite multiplexer 61 ... First multiplexers 61a-61d ... Band pass filter circuit 62 ... Second multiplexers 62a-62d ... Band pass filter circuit 63a to 63d... First LC circuits C11 and C12... Capacitors L1 to L7, L11 and L12. 3, P11~P14 ... the parallel arm resonators S1~S3, S11~S14 ... series arm resonator

Claims (7)

A composite multiplexer having a first terminal connected to an antenna terminal and a plurality of second terminals being input / output terminals,
A plurality of band-pass filter circuits having one end connected to the first terminal, and a plurality of first LC circuits respectively connected to the plurality of band-pass filter circuits, A first multiplexer in which an end of the pass-type filter circuit opposite to the first terminal is connected to the plurality of second terminals via the first LC circuits;
One end is connected to the first terminal, and a plurality of band-pass filter circuits are provided, and the end of each band-pass filter circuit opposite to the first terminal is the second plurality of band-pass filter circuits. A second multiplexer respectively connected to the terminals of
A composite multiplexer comprising: the first terminal; and a second LC circuit connected between the second multiplexer.   2. The composite multiplexer according to claim 1, wherein the plurality of first LC circuits form attenuation poles for forming a pass band of the band pass filter circuit.   3. The composite multiplexer according to claim 1, wherein the second LC circuit is a 90-degree delay circuit that delays a phase of a propagated signal by 90 degrees.   The composite multiplexer according to any one of claims 1 to 3, wherein the first LC circuit is a 90-degree delay circuit that delays a phase of a propagated signal by 90 degrees.   The composite multiplexer according to claim 1, wherein the band-pass filter circuit is configured by an elastic wave filter.   6. The composite multiplexer according to claim 1, wherein the first multiplexer and the second multiplexer are first and second duplexers, respectively.   The band-pass filter circuit of one of the first multiplexers and the band-pass filter circuit of one of the second multiplexers are band-pass filter circuits of the same Band, and other than the first multiplexer 7. The composite multiplexer according to claim 6, wherein the one band-pass filter circuit and the other one of the second multiplexers are other band-pass filter circuits of the same Band. .

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