JP2018196110A - Multiplexer, high-frequency front-end circuit, and communication device - Google Patents

Abstract

To provide a multiplexer with improved isolation between a transmission path and a reception path connected with a common terminal.SOLUTION: A multiplexer 1A comprises: a common terminal 101, a reception terminal 120 and transmission terminals 110 and 130; a reception filter 20 arranged between the common terminal 101 and the reception terminal 120; a transmission filter 10 arranged between the common terminal 101 and the transmission terminal 110; a transmission filter 30 arranged between the common terminal 101 and the transmission terminal 130; an inductor 21 connected in series between the common terminal 101 and the reception filter 20; an inductor 12 connected between the transmission terminal 110 and the transmission filter 10; and an inductor 32 connected between the transmission terminal 130 and the transmission filter 30. The inductor 21 and the inductor 12 are coupled with each other magnetically, and the inductor 21 and the inductor 32 are coupled with each other magnetically.SELECTED DRAWING: Figure 1A

Description

  The present invention relates to a multiplexer, a high frequency front end circuit, and a communication device.

  Recent mobile phones are required to support a plurality of frequency bands and a plurality of wireless systems, so-called multiband and multimode, in one terminal. In order to cope with this, a multiplexer for demultiplexing a high-frequency signal having a plurality of radio carrier frequencies is arranged immediately below one antenna.

  Patent Document 1 discloses a multiplexer having a configuration in which a plurality of filters having different pass bands are connected to a common terminal. An inductor is connected between one of the plurality of filters and the common terminal.

US Pat. No. 9,391,666

  Isolation is an example of a parameter for evaluating the performance of a multiplexer. As a configuration for ensuring isolation, conventionally, a configuration in which an inductance component is added to the inside of the filter can be cited.

  However, as the frequency band assigned to the multiplexer increases, that is, as the number of common connections of filters having different pass bands increases, the number of combinations of frequency bands that should ensure isolation increases. For this reason, it is difficult to improve the isolation characteristics of the multiplexer only with an inductance component (so-called ladder L or pole L) added inside the filter. In particular, if a high-power transmission signal leaks to the reception path between the transmission path where the transmission filter is arranged and the reception path where the reception filter is arranged, the reception sensitivity of the multiplexer is lowered.

  Accordingly, the present invention has been made to solve the above-described problems, and includes a multiplexer, a high-frequency front-end circuit, and a communication device that have improved isolation between a transmission path and a reception path connected to a common terminal. The purpose is to provide.

  In order to achieve the above object, a multiplexer according to one embodiment of the present invention includes a common terminal, a first reception terminal, a first transmission terminal, and a second transmission terminal, and between the common terminal and the first reception terminal. A first reception filter disposed between the common terminal and the first transmission terminal, and a second transmission filter disposed between the common terminal and the second transmission terminal. A transmission filter; a first inductor connected in series between the common terminal and the first reception filter; a second inductor connected between the first transmission terminal and the first transmission filter; A third inductor connected between the second transmission terminal and the second transmission filter, wherein the first inductor and the second inductor are magnetically coupled, and the first inductor and the third inductor An inductor is a magnetic field connection. It is.

  According to the above configuration, the high-frequency component leaking to the first reception filter out of the high-frequency transmission signal that has passed through the first transmission filter from the first transmission terminal, and the second inductor and the first inductor that are magnetically coupled from the first transmission terminal. By reversing the phase of the high-frequency component going to the first reception filter via the two, it becomes possible to cancel these two high-frequency components. The high-frequency component leaking to the first reception filter out of the high-frequency transmission signal that has passed through the second transmission filter from the second transmission terminal, and the third inductor and the first inductor that are magnetically coupled from the second transmission terminal. By inverting the phase of the high frequency component directed to one reception filter, it becomes possible to cancel these two high frequency components. That is, it is possible to improve the isolation between the transmission path where the transmission filter is arranged and the reception path where the reception filter is arranged. Therefore, it is possible to suppress a transmission signal having relatively high power from leaking to the reception path and reducing reception sensitivity.

  The second inductor is connected in series between the first transmission terminal and the first transmission filter, and the third inductor is connected in series between the second transmission terminal and the second transmission filter. The inductance value of the first inductor may be larger than the inductance value of the second inductor and larger than the inductance value of the third inductor.

  When an inductor is connected in series to a signal path, the propagation loss of a high-frequency signal increases as the inductance value of the inductor increases. In particular, in a transmission path where high power needs to be transmitted, it is important to improve the performance of the multiplexer to reduce the propagation loss of high-frequency signals as much as possible.

  According to the above configuration, the second inductor and the third inductor connected in series to the transmission path have a smaller inductance value than the first inductor connected in series to the reception path. Therefore, the magnetic field between the first inductor and the second inductor The propagation loss of the high-frequency transmission signal can be reduced while securing the coupling and the magnetic field coupling between the first inductor and the third inductor. Therefore, the high frequency propagation performance of the multiplexer can be improved.

  The first reception filter uses the first reception band of the first transmission band and the first reception band assigned to the first frequency band as a pass band, and the first transmission filter includes the first transmission band. The second transmission filter may use the second transmission band of the second transmission band and the second reception band assigned to a second frequency band different from the first frequency band as a pass band. Good.

  According to the above configuration, the high-frequency component leaking to the first reception filter out of the high-frequency transmission signal that has passed through the first transmission filter and the first inductor via the second inductor and the first inductor magnetically coupled from the first transmission terminal. By reversing the phase of the high frequency component directed to the reception filter, these two high frequency components can be canceled out. Therefore, it is possible to improve the isolation between the transmission signal and the reception signal in the first frequency band.

  Further, the high-frequency component leaking to the first reception filter out of the high-frequency transmission signal that has passed through the second transmission filter and the third inductor and the first inductor magnetically coupled from the second transmission terminal to the first reception filter. By inverting the phase of the high frequency component, it is possible to cancel these two high frequency components. Therefore, it is possible to improve cross isolation between the reception signal in the first frequency band and the transmission signal in the second frequency band.

  The first reception filter, the first transmission filter, and the second transmission filter are any of a surface acoustic wave filter, an acoustic wave filter using a BAW (Bulk Acoustic Wave), an LC resonance filter, and a dielectric filter. It may be.

  As a result, the first reception filter, the first transmission filter, and the second transmission filter can be reduced in size, so that the multiplexer can be reduced in size and price.

  The multiplexer according to one aspect of the present invention includes a common terminal, a first transmission terminal, a first reception terminal, and a second reception terminal, and a first disposed between the common terminal and the first transmission terminal. A transmission filter, a first reception filter disposed between the common terminal and the first reception terminal, a second reception filter disposed between the common terminal and the second reception terminal, and the common A first inductor connected in series between a terminal and the first transmission filter; a second inductor connected between the first reception terminal and the first reception filter; the second reception terminal; A third inductor connected between the second reception filter, the first inductor and the second inductor are magnetically coupled, and the first inductor and the third inductor are magnetically coupled. ing.

  According to the above configuration, the high frequency component leaking to the first reception filter out of the high frequency transmission signal that has passed through the first transmission filter from the first transmission terminal, and the first inductor and the second inductor that are magnetically coupled from the first transmission terminal. By reversing the phase of the high-frequency component going to the first receiving terminal via the two, it becomes possible to cancel these two high-frequency components. The high-frequency component leaking to the second reception filter out of the high-frequency transmission signal passing through the first transmission filter from the first transmission terminal and the first and third inductors magnetically coupled from the first transmission terminal By inverting the phase of the two high frequency components directed to the receiving terminal, it becomes possible to cancel these two high frequency components. That is, it is possible to improve the isolation between the transmission path where the transmission filter is arranged and the reception path where the reception filter is arranged. Therefore, it is possible to suppress a transmission signal having relatively high power from leaking to the reception path and reducing reception sensitivity.

  The second inductor is connected in series between the first reception terminal and the first reception filter, and the third inductor is connected in series between the second reception terminal and the second reception filter. The inductance value of the first inductor may be smaller than the inductance value of the second inductor and smaller than the inductance value of the third inductor.

  As a result, the first inductor connected in series to the transmission path has a smaller inductance value than the second inductor and the third inductor connected in series to the reception path, so that the magnetic field coupling between the first inductor and the second inductor, and The propagation loss of the high-frequency transmission signal can be reduced while ensuring the magnetic field coupling between the first inductor and the third inductor. Therefore, the high frequency propagation performance of the multiplexer can be improved.

  The first transmission filter uses the first transmission band of the first transmission band and the first reception band assigned to the first frequency band as a pass band, and the first reception filter includes the first reception band. The second reception filter may use the second reception band of the second transmission band and the second reception band allocated to a second frequency band different from the first frequency band as the pass band. Good.

  According to the above configuration, the first high-frequency component leaked to the first reception filter out of the high-frequency transmission signal that has passed through the first transmission filter, and the first inductor and the second inductor that are magnetically coupled from the first transmission terminal. By inverting the phase of the high frequency component directed to the receiving terminal, it is possible to cancel these two high frequency components. Therefore, it is possible to improve the isolation between the transmission signal and the reception signal in the first frequency band.

  Further, the high frequency component leaking to the second reception filter out of the high frequency transmission signal that has passed through the first transmission filter and the first and third inductors magnetically coupled from the first transmission terminal to the second reception terminal. By inverting the phase of the high frequency component, it is possible to cancel these two high frequency components. Therefore, it is possible to improve cross isolation between the reception signal in the second frequency band and the transmission signal in the first frequency band.

  The first transmission filter, the first reception filter, and the second reception filter may be any of a surface acoustic wave filter, an acoustic wave filter using a BAW, an LC resonance filter, and a dielectric filter. Good.

  As a result, the first transmission filter, the first reception filter, and the second reception filter can be reduced in size, so that the multiplexer can be reduced in size and price.

  Further, an antenna terminal connected to the antenna element and an impedance matching circuit connected between the antenna terminal and the common terminal may be provided.

  As a result, even if the inductance values of the first inductor, the second inductor, and the third inductor are adjusted with priority given to the coupling degree of the magnetic field coupling, impedance matching between each transmission path and each reception path is performed by the impedance matching circuit. Can be optimized. Therefore, the degree of freedom in setting the inductance values of the first inductor, the second inductor, and the third inductor is improved.

  A high-frequency front-end circuit according to one embodiment of the present invention includes any of the multiplexers described above and an amplifier circuit connected to the multiplexer.

  As a result, it is possible to provide a high-frequency front-end circuit with improved isolation between the transmission path where the transmission filter is arranged and the reception path where the reception filter is arranged.

  In addition, a communication device according to one embodiment of the present invention includes an RF signal processing circuit that processes a high-frequency signal transmitted and received by an antenna element, and the high-frequency signal that is transmitted between the antenna element and the RF signal processing circuit. A high-frequency front-end circuit as described.

  As a result, it is possible to provide a communication device with improved isolation between the transmission path where the transmission filter is arranged and the reception path where the reception filter is arranged.

  According to the multiplexer, the high-frequency front-end circuit, and the communication device according to the present invention, it is possible to improve the isolation between the transmission path and the reception path connected to the common terminal.

FIG. 3 is a circuit configuration diagram of a multiplexer according to the first embodiment. 5 is a circuit configuration diagram of a multiplexer according to a modification of the first embodiment. FIG. It is a circuit block diagram of the multiplexer which concerns on an Example. It is the graph which compared the isolation characteristic in Band25 of the multiplexer concerning an Example and a comparative example. It is the graph which compared the pass characteristic of the Band25 filter which concerns on an Example and a comparative example. It is a graph showing the voltage standing wave ratio of the Band25 filter which concerns on an Example and a comparative example. It is the graph which compared the isolation characteristic of the Band66 transmission filter-Band25 reception filter of the multiplexer concerning an Example and a comparative example. It is the graph which compared the pass characteristic of the Band66 filter which concerns on an Example and a comparative example. It is a graph showing the voltage standing wave ratio of the Band66 filter which concerns on an Example and a comparative example. It is the graph which compared the isolation characteristic in Band66 of the multiplexer concerning an Example and a comparative example. It is the graph which compared the isolation characteristic of the Band25 transmission filter-Band66 reception filter of the multiplexer concerning an Example and a comparative example. 6 is a circuit configuration diagram of a high-frequency front-end circuit and a communication device according to Embodiment 2. FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that each of the embodiments described below shows a comprehensive or specific example. Numerical values, shapes, materials, constituent elements, arrangement of constituent elements, connection forms, and the like shown in the following embodiments are merely examples, and are not intended to limit the present invention. Among the constituent elements in the following embodiments, constituent elements not described in the independent claims are described as optional constituent elements. Further, the size of components shown in the drawings or the ratio of sizes is not necessarily strict. Moreover, in each figure, the same code | symbol is attached | subjected to the substantially same structure, and the overlapping description may be abbreviate | omitted or simplified. In the following embodiments, “connected” includes not only the case of direct connection but also the case of electrical connection via other elements.

  Further, in the following embodiments, “inductor A and inductor B are magnetically coupled” means “inductor A and inductor B are arranged without a shield member that cuts off the magnetic field, It is defined as “magnetically coupled”.

(Embodiment 1)
[1. Basic configuration of multiplexer 1A]
FIG. 1A is a circuit configuration diagram of a multiplexer 1A according to the first embodiment. As shown in the figure, the multiplexer 1A includes transmission filters 10 and 30, reception filters 20 and 40, inductors 12, 21, and 32, an antenna terminal 100, a common terminal 101, transmission terminals 110 and 130, Reception terminals 120 and 140 and a matching circuit 50 are provided.

  The antenna terminal 100 is a connection terminal connected to the antenna element.

  The common terminal 101 is connected to the transmission filters 10 and 30, the inductor 21, and the reception filter 40, and is connected to the antenna terminal 100 via the matching circuit 50.

  The transmission terminal 110 is a first transmission terminal connected to a power amplifier circuit that amplifies a high-frequency transmission signal. The transmission terminal 130 is a second transmission terminal connected to a power amplifier circuit that amplifies the high-frequency transmission signal.

  The reception terminal 120 is a first reception terminal connected to a low noise amplifier circuit that amplifies a high frequency reception signal.

  The reception terminal 140 is a reception terminal connected to a low noise amplifier circuit that amplifies a high frequency reception signal.

  The transmission filter 10 is disposed between the common terminal 101 and the transmission terminal 110, inputs a high-frequency transmission signal generated by a transmission circuit (RFIC or the like) via the transmission terminal 110, and inputs the high-frequency transmission signal to BandA1. 1 is a first transmission filter that performs filtering in the transmission passband and outputs to the common terminal 101.

  The reception filter 20 is disposed between the common terminal 101 and the reception terminal 120, receives a high frequency reception signal input from the common terminal 101, filters the high frequency reception signal in the reception pass band of Band A2, and receives the reception terminal 120. This is a first reception filter that outputs to.

  The transmission filter 30 is disposed between the common terminal 101 and the transmission terminal 130, inputs a high-frequency transmission signal generated by a transmission circuit (RFIC or the like) via the transmission terminal 130, and inputs the high-frequency transmission signal to BandA3. 2 is a second transmission filter that performs filtering in the transmission passband and outputs to the common terminal 101.

  The reception filter 40 is disposed between the common terminal 101 and the reception terminal 140, receives a high-frequency reception signal input from the common terminal 101, filters the high-frequency reception signal in the reception passband of Band A4, and receives the reception terminal 140. Output to.

  The inductor 12 is a second inductor connected between the transmission terminal 110 and the transmission filter 10.

  The inductor 32 is a third inductor connected between the transmission terminal 130 and the transmission filter 30.

  The inductor 21 is a first inductor connected in series between the common terminal 101 and the reception filter 20.

  The matching circuit 50 is connected between the antenna terminal 100 and the common terminal 101, and is an impedance matching circuit that matches the impedance between the antenna element and the multiplexer 1A. The matching circuit 50 may be configured by, for example, one inductor connected in series to the antenna terminal 100 and the common terminal 101, or between the connection node between the antenna terminal 100 and the common terminal 101 and the ground. It may be a single inductor connected. Further, in addition to these inductors, capacitors may be connected in series or in parallel. That is, the matching circuit 50 only needs to have a circuit configuration in which one or more inductors and one or more capacitors are connected in series or in parallel.

  In the multiplexer 1A having the above circuit configuration, the inductor 21 and the inductor 12 are magnetically coupled, and the inductor 21 and the inductor 32 are magnetically coupled.

  According to this, the high frequency component leaking to the reception filter 20 out of the high frequency transmission signal that has passed through the transmission filter 10 from the transmission terminal 110 and the inductor 12 and 21 magnetically coupled from the transmission terminal 110 to the reception filter 20. It becomes possible to cancel out high frequency components.

  Note that the electromagnetic coupling degree of the inductors 12 and 21 is optimized so that the two high-frequency components have a phase-inverted relationship, and the high-frequency transmission signal passing through the transmission filter 10 from the transmission terminal 110 leaks to the reception filter 20. It is preferable to minimize the high frequency components.

  Further, among the high-frequency transmission signal that has passed through the transmission filter 30 from the transmission terminal 130, a high-frequency component that leaks to the reception filter 20, and a high-frequency component that is directed from the transmission terminal 130 to the reception filter 20 via the magnetically coupled inductors 32 and 21. It becomes possible to cancel each other.

  Note that the electromagnetic field coupling degree of the inductors 32 and 21 is optimized so that the two high-frequency components are in phase-inverted relations, and the high-frequency transmission signal that has passed through the transmission filter 30 from the transmission terminal 130 leaks to the reception filter 20. It is preferable to minimize the high frequency components.

  That is, it is possible to improve isolation between the transmission path where the transmission filters 10 and 30 are arranged and the reception path where the reception filter 20 is arranged. Therefore, it is possible to suppress a high-frequency transmission signal having relatively high power from leaking to the reception path and reducing the reception sensitivity of the multiplexer 1A.

  Further, by arranging the matching circuit 50, the inductance values of the inductors 12, 21, and 32 are adjusted between the antenna element, each transmission path, and each reception path even if the inductance value of the magnetic coupling is preferentially adjusted. Impedance matching can be optimized. Therefore, the degree of freedom for setting the inductance values of the inductors 12, 21, and 32 is improved.

  Note that the matching circuit 50 is not an indispensable component and may be omitted.

  Further, in the multiplexer 1A according to the present embodiment, BandA1 and BandA2 may be in the same frequency band, or may be in different frequency bands. When Band A1 and Band A2 are in the same frequency band, the transmission filter 10 and the reception filter 20 constitute, for example, a duplexer in which a transmission pass band and a reception pass band are assigned to the frequency band. Further, when Band A1 and Band A2 are different frequency bands, the transmission filter 10 and the reception filter 20 constitute a single filter having different pass bands, respectively. Similarly, BandA3 and BandA4 may be in the same frequency band or may be in different frequency bands. When Band A3 and Band A4 are in the same frequency band, the transmission filter 30 and the reception filter 40 constitute, for example, a duplexer in which a transmission pass band and a reception pass band are assigned to the frequency band. In addition, when Band A3 and Band A4 are different frequency bands, the transmission filter 30 and the reception filter 40 constitute a single filter having different pass bands, respectively.

  The transmission filters 10 and 30 and the reception filters 20 and 40 are any of a surface acoustic wave filter, an acoustic wave filter using a BAW (Bulk Acoustic Wave), an LC resonance filter, and a dielectric filter. Thereby, since each filter can be reduced in size, the multiplexer 1A can be reduced in size and price.

  The transmission filters 10 and 30 and the reception filter 20 are preferably elastic wave filters. In particular, the transmission filters 10 and 30 and the reception filter 20 may be ladder type acoustic wave filters including one or more series arm resonators and one or more parallel arm resonators. In this case, the inductors 21, 12 and 32 can have a function of adjusting the attenuation pole of the filter pass characteristic and an impedance matching function.

[2. Configuration of multiplexer according to modification]
1B is a circuit configuration diagram of a multiplexer 1B according to a modification of the first embodiment. The multiplexer 1B according to the present modification has inductors arranged in one transmission path and two reception paths, compared to the multiplexer 1A according to the first embodiment in which inductors are arranged in two transmission paths and one reception path. The point is different as a configuration. Hereinafter, the description of the multiplexer 1B according to the present modification will be omitted while omitting the same points as the multiplexer 1A according to the first embodiment, and different points will be mainly described.

  As shown in FIG. 1B, multiplexer 1B includes transmission filters 10 and 30, reception filters 20 and 40, inductors 22, 31 and 42, antenna terminal 100, common terminal 101, transmission terminals 110 and 130, Reception terminals 120 and 140 and a matching circuit 50 are provided.

  The common terminal 101 is connected to the transmission filter 10, the reception filters 20 and 40, and the inductor 31, and is connected to the antenna terminal 100 via the matching circuit 50.

  The transmission terminal 110 is a transmission terminal connected to a power amplifier circuit that amplifies a high-frequency transmission signal. The transmission terminal 130 is a first transmission terminal connected to a power amplifier circuit that amplifies the high-frequency transmission signal.

  The reception terminal 120 is a second reception terminal connected to a low noise amplifier circuit that amplifies a high frequency reception signal.

  The reception terminal 140 is a first reception terminal connected to a low noise amplifier circuit that amplifies a high frequency reception signal.

  The inductor 22 is a third inductor connected between the reception terminal 120 and the reception filter 20.

  The inductor 42 is a second inductor connected between the reception terminal 140 and the reception filter 40.

  The inductor 31 is a first inductor connected in series between the common terminal 101 and the transmission filter 30.

  In the multiplexer 1B having the above circuit configuration, the inductor 31 and the inductor 22 are magnetically coupled, and the inductor 31 and the inductor 42 are magnetically coupled.

  According to this, the high frequency component leaking to the reception filter 40 out of the high frequency transmission signal that has passed through the transmission filter 30 from the transmission terminal 130 and the inductor 31 and 42 magnetically coupled from the transmission terminal 130 to the reception terminal 140. It becomes possible to cancel out high frequency components.

  Note that the electromagnetic field coupling degree of the inductors 31 and 42 is optimized so that the two high-frequency components have a phase-inverted relationship, and the high-frequency transmission signal that has passed through the transmission filter 30 from the transmission terminal 130 leaks to the reception filter 40. It is preferable to minimize the high frequency components.

  Further, among the high-frequency transmission signal that has passed through the transmission filter 30 from the transmission terminal 130, a high-frequency component that leaks to the reception filter 20, and a high-frequency component that is directed from the transmission terminal 130 to the reception terminal 120 via the magnetically coupled inductors 31 and 22 It becomes possible to cancel each other.

  Note that the electromagnetic field coupling degree of the inductors 31 and 22 is optimized so that the two high-frequency components have a phase-inverted relationship, and the high-frequency transmission signal that has passed through the transmission filter 30 from the transmission terminal 130 leaks to the reception filter 20. It is preferable to minimize the high frequency components.

  That is, it is possible to improve the isolation between the transmission path where the transmission filter 30 is arranged and the reception path where the reception filters 20 and 40 are arranged. Therefore, it is possible to suppress a transmission signal having relatively high power from leaking to the reception path and reducing reception sensitivity.

  In the multiplexer 1B according to this modification, Band A1 and Band A2 may be in the same frequency band or may be in different frequency bands. When Band A1 and Band A2 are in the same frequency band, the transmission filter 10 and the reception filter 20 constitute, for example, a duplexer in which a transmission pass band and a reception pass band are assigned to the frequency band. Further, when Band A1 and Band A2 are different frequency bands, the transmission filter 10 and the reception filter 20 constitute a single filter having different pass bands, respectively. Similarly, BandA3 and BandA4 may be in the same frequency band or may be in different frequency bands. When Band A3 and Band A4 are in the same frequency band, the transmission filter 30 and the reception filter 40 constitute, for example, a duplexer in which a transmission pass band and a reception pass band are assigned to the frequency band. In addition, when Band A3 and Band A4 are different frequency bands, the transmission filter 30 and the reception filter 40 constitute a single filter having different pass bands, respectively.

[3. Configuration of Multiplexer 1A According to Embodiment]
FIG. 2 is a circuit configuration diagram of the multiplexer 1A according to the embodiment. The multiplexer 1A according to the present example is an example in which the multiplexer 1A according to the first embodiment is applied to LTE (Long Term Evolution) Band 25 and 66 quadplexers.

  The transmission filter 10 is a band-pass filter having a transmission band (1850-1915 MHz: first transmission band) of Band 25 (first frequency band) as a pass band.

  The reception filter 20 is a band-pass filter having a band 25 (first frequency band) reception pass band (1930-1995 MHz: first reception band) as a pass band.

  The transmission filter 30 is a band-pass filter having a transmission band (1710-1780 MHz: second transmission band) of Band 66 (second frequency band) as a pass band.

  The reception filter 40 is a band-pass filter having a band 66 (second frequency band) reception pass band (2110-2200 MHz: second reception band) as a pass band.

  The inductor 12 is connected in series between the transmission terminal 110 and the transmission filter 10.

  The inductor 32 is connected in series between the transmission terminal 130 and the transmission filter 30.

  The inductor 21 is connected in series between the common terminal 101 and the reception filter 20.

  In this embodiment, the high-frequency transmission signal of Band 25 leaks to the reception path of Band 25 where the reception filter 20 is arranged, and the high-frequency transmission signal of Band 66 passes through the common terminal 101 to the reception path of Band 25. May be leaked.

  On the other hand, in the multiplexer 1A according to the embodiment, the inductor 21 and the inductor 12 are magnetically coupled, and the inductor 21 and the inductor 32 are magnetically coupled.

  According to this, the high-frequency component P25 leaking to the reception filter 20 among the high-frequency transmission signal that has passed through the transmission filter 10 and the high-frequency component N25 heading toward the reception filter 20 via the inductors 12 and 21 magnetically coupled from the transmission terminal 110. These two high frequency components can be canceled out by phase inversion. Therefore, the isolation between the transmission signal and the reception signal of Band 25 can be improved.

  The high-frequency component P66 leaking to the reception filter 20 in the high-frequency transmission signal that has passed through the transmission filter 30 and the high-frequency component N66 directed to the reception filter 20 via the inductors 32 and 21 magnetically coupled from the transmission terminal 130 are phase-shifted. By reversing, it is possible to cancel these two high-frequency components. Therefore, it is possible to improve cross isolation between reception signals and transmission signals in different frequency bands.

  In the multiplexer 1A according to the present embodiment, the inductance value of the inductor 21 is 5.2 nH, the inductance value of the inductor 12 is 1.5 nH, and the inductance value of the inductor 32 is 3.9 nH. That is, the inductance value of the inductor 21 is larger than the inductance value of the inductor 12 and larger than the inductance value of the inductor 32.

  When an inductor is connected in series to a signal path, the propagation loss of a high-frequency signal increases as the inductance value of the inductor increases. In particular, in a transmission path where high power needs to be transmitted, it is important to improve the performance of the multiplexer 1A to reduce the propagation loss of high-frequency signals as much as possible.

  According to the above relationship between the inductors 12, 21, and 32, the inductor 12 and 32 connected in series to the transmission path where the transmission filter 10 is arranged and the transmission path where the transmission filter 30 is arranged are arranged with the reception filter 20. The inductance value is smaller than that of the inductor 21 connected in series to the receiving path. Therefore, the propagation loss of the high-frequency transmission signal can be reduced while ensuring the magnetic field coupling between the inductor 21 and the inductor 12 and the magnetic field coupling between the inductor 21 and the inductor 32. Therefore, the high frequency propagation performance of the multiplexer 1A can be improved.

  From the viewpoint of reducing the signal propagation loss in the transmission path as much as possible, in the multiplexer 1B according to the modification, the inductance value of the inductor 31 is smaller than the inductance value of the inductor 22 and smaller than the inductance value of the inductor 42. It is preferable. Thereby, the propagation loss of the high-frequency transmission signal can be reduced while ensuring the magnetic field coupling between the inductor 31 and the inductor 32 and the magnetic field coupling between the inductor 31 and the inductor 42. Therefore, the high-frequency propagation performance of the multiplexer 1B can be improved.

  The inductors 12, 21, and 32 may be, for example, chip-like inductance elements arranged on a mounting substrate on which the transmission filters 10 and 30 and the reception filters 20 and 40 are mounted. In this case, the magnetic field coupling degree between the inductor 12 and the inductor 21 and the magnetic field coupling degree between the inductor 12 and the inductor 32 are the distance between the chip-shaped inductor 12 and the inductor 21, the arrangement direction, and the chip-shaped inductor 32. And the distance between the inductor 21 and the arrangement direction.

  Further, at least one of the inductors 12, 21, and 32 may be an inductance element built in the mounting substrate. In this case, the inductance element built in the mounting board is constituted by, for example, a coil pattern laminated on the mounting board. In this case, the magnetic field coupling degree between the inductor 12 and the inductor 21 and the magnetic field coupling degree between the inductor 12 and the inductor 32 are the distance and arrangement relationship between the inductor 12 and the inductor 21 built in the substrate, and the chip-like inductor. It adjusts by the space | interval of 32 and the inductor 21, and arrangement | positioning relationship. The arrangement relationship between the two inductors built in the substrate includes overlapping or separating the winding axes of the call pattern.

  Note that the multiplexer 1B according to the modification can also be applied to LTE Band25 and 66 quadplexers. An example in which the multiplexer 1B according to the modification is applied to LTE Band 25 and 66 quadplexers will be described below.

  The transmission filter 10 is a band-pass filter having a transmission band (1850-1915 MHz: second transmission band) of Band 25 (second frequency band) as a pass band.

  The reception filter 20 is a band-pass filter having a reception band (1930-1995 MHz: second reception band) of Band 25 (second frequency band) as a pass band.

  The transmission filter 30 is a band-pass filter whose transmission band is a Band 66 (first frequency band) transmission pass band (1710-1780 MHz: first transmission band).

  The reception filter 40 is a band-pass filter having a reception pass band (2110-2200 MHz: first reception band) of Band 66 (first frequency band) as a pass band.

  The inductor 22 is connected in series between the reception terminal 120 and the reception filter 20.

  The inductor 42 is connected in series between the reception terminal 140 and the reception filter 40.

  The inductor 31 is connected in series between the common terminal 101 and the transmission filter 30.

  In this embodiment, the high-frequency transmission signal of Band 66 leaks to the reception path of Band 66 where the reception filter 40 is disposed, and may leak to the reception path of Band 25 via the common terminal 101. There is.

  In contrast, in the multiplexer 1B according to the modification, the inductor 31 and the inductor 42 are magnetically coupled, and the inductor 31 and the inductor 22 are magnetically coupled.

  According to this, a high-frequency component leaking to the reception filter 40 in the high-frequency transmission signal that has passed through the transmission filter 30 and a high-frequency component that is directed from the transmission terminal 130 to the reception terminal 140 via the magnetically coupled inductors 31 and 42 are obtained. By inverting the phase, it is possible to cancel these two high-frequency components. Therefore, the isolation between the transmission signal and the reception signal of Band 66 can be improved.

  Further, the high-frequency component leaking to the reception filter 20 in the high-frequency transmission signal that has passed through the transmission filter 30 and the high-frequency component directed to the reception terminal 120 via the inductors 31 and 22 magnetically coupled from the transmission terminal 130 are phase-inverted. Thus, these two high-frequency components can be canceled out. Therefore, it is possible to improve cross isolation between reception signals and transmission signals in different frequency bands.

[4. Comparison of characteristics of multiplexers according to examples and comparative examples]
Next, the high-frequency propagation characteristics of the multiplexer 1A according to the embodiment and the multiplexer according to the comparative example are compared.

  The multiplexer according to the comparative example has the same circuit elements as the circuit elements constituting the multiplexer 1A according to the embodiment. However, the inductor 21 and the inductor 12 are not magnetically coupled, and the inductor 21 Unlike the multiplexer 1A according to the embodiment, the inductor 32 and the inductor 32 are not magnetically coupled.

  FIG. 3A is a graph comparing the isolation characteristics at Band 25 of the multiplexers according to the example and the comparative example.

  In the multiplexer according to the comparative example, the high-frequency transmission signal of Band 25 leaks to the reception path of Band 25 where the reception filter 20 is arranged.

  On the other hand, in the multiplexer 1A according to the embodiment, since the inductor 21 and the inductor 12 are magnetically coupled, the high-frequency component P25 leaking to the reception filter 20 among the high-frequency transmission signals that have passed through the transmission filter 10 of the Band 25 The phase of the high frequency component N25 heading toward the reception filter 20 via the inductors 12 and 21 magnetically coupled from the transmission terminal 110 is inverted. As a result, these two high-frequency components P25 and N25 are canceled, and it can be seen that the isolation is improved particularly in the reception band of Band 25 (the area within the broken line in FIG. 3A).

  FIG. 3B is a graph comparing the pass characteristics of the Band 25 filter according to the example and the comparative example. The upper part of the figure shows the comparison of the pass characteristics of the Band 25 transmission filter, and the lower part of the figure shows the comparison of the pass characteristics of the Band 25 reception filter. As shown in the upper part of the figure, it can be seen that the attenuation in the reception band of the Band 25 transmission filter 10 is also improved in accordance with the improvement in the isolation in the Band 25 reception band. On the other hand, with respect to the reception filter 20 of Band 25, it can be seen that the pass characteristics do not substantially change depending on the presence or absence of magnetic coupling between the inductors 21 and 12.

  FIG. 4 is a graph showing the voltage standing wave ratio (VSWR) of the Band 25 filter according to the example and the comparative example. The upper part of the figure shows the VSWR when the multiplexer is seen from the antenna terminal 100 side, the middle part of the figure shows the VSWR when the multiplexer is seen from the transmission terminal 110 side, and the lower part of the figure shows the VSWR. VSWR when the multiplexer is viewed from the receiving terminal 120 side is shown.

  As shown in FIG. 4, it can be seen that the input and output impedances of the transmission filter and the reception filter of Band 25 are almost unchanged depending on the presence or absence of magnetic coupling between the inductors 21 and 12.

  FIG. 5A is a graph comparing the isolation characteristics of the Band66 transmission filter-Band25 reception filter of the multiplexers according to the example and the comparative example.

  In the multiplexer according to the comparative example, the high-frequency transmission signal of Band 66 leaks to the reception path of Band 25 where the reception filter 20 is arranged.

  On the other hand, in the multiplexer 1A according to the embodiment, since the inductor 21 and the inductor 32 are magnetically coupled, the high-frequency component P66 that leaks to the reception filter 20 among the high-frequency transmission signals that have passed through the transmission filter 30 of the Band 66 The phase of the high-frequency component N66 from the transmission terminal 130 to the reception filter 20 via the magnetically coupled inductors 32 and 21 is inverted. As a result, these two high-frequency components P66 and N66 are canceled, and it can be seen that cross-isolation is improved particularly in the reception band of Band 25 (the area within the broken line in FIG. 5A).

  FIG. 5B is a graph comparing the pass characteristics of the Band 66 filter according to the example and the comparative example. The upper part of the figure shows the comparison of the pass characteristics of the Band 66 transmission filter, and the lower part of the figure shows the comparison of the pass characteristics of the Band 66 reception filter. As shown in the upper part of the figure, it can be seen that the attenuation in the vicinity of the Band 25 reception band of the Band 66 transmission filter 30 is improved as cross isolation in the Band 25 reception band is improved. On the other hand, with respect to the reception filter 40 of Band 66, it can be seen that the pass characteristics do not substantially change depending on the presence or absence of magnetic coupling between the inductors 32 and 21.

  FIG. 6 is a graph showing the voltage standing wave ratio (VSWR) of the Band 66 filter according to the example and the comparative example. The upper part of the figure shows the VSWR when the multiplexer is viewed from the antenna terminal 100 side, the middle part of the figure shows the VSWR when the multiplexer is viewed from the transmission terminal 130 side, and the lower part of the figure shows the VSWR. VSWR when the multiplexer is viewed from the receiving terminal 140 side is shown.

  As shown in FIG. 6, regarding the transmission filter and reception filter of Band 66, it is understood that the input / output impedance does not substantially change depending on the presence or absence of magnetic coupling between the inductors 32 and 21.

  FIG. 7A is a graph comparing the isolation characteristics in Band 66 of the multiplexers according to the example and the comparative example. In the multiplexers according to the example and the comparative example, no inductor is arranged in the reception path in which the reception filter 40 is arranged. Therefore, it is estimated that the effect of improving the isolation due to the magnetic field coupling with the inductor 32 is not seen. However, because of the magnetic field coupling of the inductors 32 and 21, the high-frequency component P66 that leaks to the reception filter 20 in the high-frequency transmission signal of Band 66 is canceled out, and therefore, the high-frequency component that leaks to the reception filter 40 of the high-frequency transmission signal of Band 66 It is estimated that it is relatively reduced. As a result, it can be seen that isolation is also improved in the Band 66 reception band.

  FIG. 7B is a graph comparing the isolation characteristics of the Band25 transmission filter-Band66 reception filter of the multiplexers according to the example and the comparative example. In the multiplexers according to the example and the comparative example, no inductor is arranged in the reception path in which the reception filter 40 is arranged. Therefore, it is estimated that the improvement effect of the cross isolation due to the magnetic coupling with the inductor 12 is not seen. . However, because of the magnetic field coupling of the inductors 12 and 21, the high frequency component P25 leaking to the reception filter 20 of the Band 25 high frequency transmission signal is canceled out, so that the high frequency component leaking to the reception filter 40 of the Band 25 high frequency transmission signal is also present. It is estimated that it is relatively reduced. As a result, it can be seen that cross-isolation is also improved in the Band 66 reception band.

(Embodiment 2)
In the present embodiment, the high-frequency front-end circuit 3 and the communication device 4 including the multiplexer 1A according to the above-described example will be described.

  FIG. 8 is a circuit configuration diagram of the high-frequency front-end circuit 3 and the communication device 4 according to the second embodiment. The figure shows a high-frequency front-end circuit 3, an antenna element 2, an RF signal processing circuit (RFIC) 80, and a baseband signal processing circuit (BBIC) 90. The high-frequency front-end circuit 3, the RF signal processing circuit 80, and the baseband signal processing circuit 90 constitute the communication device 4.

  The high frequency front end circuit 3 includes a multiplexer 1A according to the embodiment, a transmission side switch 61 and a reception side switch 62, a power amplifier circuit 71, and a low noise amplifier circuit 72.

  The transmission-side switch 61 is a switch circuit having two selection terminals individually connected to the transmission terminals 110 and 130 of the multiplexer 1A and a common terminal connected to the power amplifier circuit 71.

  The reception side switch 62 is a switch circuit having two selection terminals individually connected to the reception terminals 120 and 140 of the multiplexer 1 </ b> A and a common terminal connected to the low noise amplifier circuit 72.

  Each of the transmission side switch 61 and the reception side switch 62 connects a common terminal and a signal path corresponding to a predetermined band according to a control signal from a control unit (not shown), for example, SPDT (Single Pool). It is composed of a Double Throw) type switch. Note that the number of selection terminals connected to the common terminal is not limited to one and may be plural. That is, the high frequency front end circuit 3 may support carrier aggregation.

  The power amplifier circuit 71 is a transmission amplifier circuit that amplifies the high-frequency signal (here, the high-frequency transmission signal) output from the RF signal processing circuit 80 and outputs it to the antenna element 2 via the transmission-side switch 61 and the multiplexer 1A. .

  The low noise amplifier circuit 72 is a reception amplification circuit that amplifies a high-frequency signal (here, a high-frequency reception signal) that has passed through the antenna element 2, the multiplexer 1 </ b> A, and the reception-side switch 62 and outputs the amplified signal to the RF signal processing circuit 80.

  The RF signal processing circuit 80 processes the high-frequency reception signal input from the antenna element 2 via the reception signal path by down-conversion or the like, and the baseband signal processing circuit 90 processes the reception signal generated by the signal processing. Output to. Further, the RF signal processing circuit 80 performs signal processing on the transmission signal input from the baseband signal processing circuit 90 by up-conversion or the like, and outputs a high-frequency transmission signal generated by the signal processing to the power amplifier circuit 71. The RF signal processing circuit 80 is, for example, an RFIC.

  The signal processed by the baseband signal processing circuit 90 is used, for example, for displaying an image as an image signal or for calling as an audio signal.

  The high-frequency front end circuit 3 may include other circuit elements between the above-described components.

  According to the high-frequency front-end circuit 3 and the communication device 4 configured as described above, each transmission filter can be provided even if the number of allocated frequency bands (bands) increases by providing the multiplexer 1A according to the above-described embodiment. It is possible to improve the isolation between the transmission path in which the reception filter is arranged and the reception path in which each reception filter is arranged.

  In addition, the communication device 4 may not include the baseband signal processing circuit 90 according to the high-frequency signal processing method.

(Other embodiments)
As described above, the multiplexer, the high-frequency front-end circuit, and the communication device according to the embodiment of the present invention have been described with reference to the examples and the modified examples. However, the present invention is not limited to the above-described embodiments, examples, and modified examples. Other embodiments realized by combining the constituent elements, modifications obtained by making various modifications conceivable by those skilled in the art within the scope of the present invention without departing from the gist of the present invention, and the present invention Various devices incorporating a high-frequency front-end circuit and a communication device are also included in the present invention.

  In the above description, a Band 25 + Band 66 quadplexer has been described as an example of a multiplexer. However, the present invention is not limited to this, and for example, the present invention is applied to a multiplexer having three or more filters and connected by a common terminal. Can do.

  INDUSTRIAL APPLICABILITY The present invention can be widely used in communication devices such as mobile phones as high isolation and high cross isolation multiplexers, high frequency front end circuits and communication devices that can be applied to multiband and multimode frequency standards.

DESCRIPTION OF SYMBOLS 1A, 1B Multiplexer 2 Antenna element 3 High frequency front end circuit 4 Communication apparatus 10, 30 Transmission filter 12, 21, 22, 31, 32, 42 Inductor 20, 40 Reception filter 50 Matching circuit 61 Transmission side switch 62 Reception side switch 71 Power Amplifier circuit 72 Low noise amplifier circuit 80 RF signal processing circuit (RFIC)
90 Baseband signal processing circuit (BBIC)
100 antenna terminal 101 common terminal 110, 130 transmitting terminal 120, 140 receiving terminal

Claims (11)

A common terminal, a first receiving terminal, a first transmitting terminal, and a second transmitting terminal;
A first reception filter disposed between the common terminal and the first reception terminal;
A first transmission filter disposed between the common terminal and the first transmission terminal;
A second transmission filter disposed between the common terminal and the second transmission terminal;
A first inductor connected in series between the common terminal and the first reception filter;
A second inductor connected between the first transmission terminal and the first transmission filter;
A third inductor connected between the second transmission terminal and the second transmission filter,
The first inductor and the second inductor are magnetically coupled,
The first inductor and the third inductor are magnetically coupled,
Multiplexer. The second inductor is connected in series between the first transmission terminal and the first transmission filter,
The third inductor is connected in series between the second transmission terminal and the second transmission filter,
An inductance value of the first inductor is larger than an inductance value of the second inductor and larger than an inductance value of the third inductor;
The multiplexer according to claim 1. The first reception filter uses the first reception band of the first transmission band and the first reception band assigned to the first frequency band as a pass band,
The first transmission filter uses the first transmission band as a pass band,
The second transmission filter uses the second transmission band of the second transmission band and the second reception band allocated to a second frequency band different from the first frequency band as a pass band.
The multiplexer according to claim 1 or 2. The first reception filter, the first transmission filter, and the second transmission filter are any one of a surface acoustic wave filter, an acoustic wave filter using a BAW (Bulk Acoustic Wave), an LC resonance filter, and a dielectric filter. is there,
The multiplexer according to any one of claims 1 to 3. A common terminal, a first transmission terminal, a first reception terminal, and a second reception terminal;
A first transmission filter disposed between the common terminal and the first transmission terminal;
A first reception filter disposed between the common terminal and the first reception terminal;
A second reception filter disposed between the common terminal and the second reception terminal;
A first inductor connected in series between the common terminal and the first transmission filter;
A second inductor connected between the first reception terminal and the first reception filter;
A third inductor connected between the second reception terminal and the second reception filter,
The first inductor and the second inductor are magnetically coupled,
The first inductor and the third inductor are magnetically coupled,
Multiplexer. The second inductor is connected in series between the first reception terminal and the first reception filter,
The third inductor is connected in series between the second reception terminal and the second reception filter,
An inductance value of the first inductor is smaller than an inductance value of the second inductor and smaller than an inductance value of the third inductor;
The multiplexer according to claim 5. The first transmission filter uses the first transmission band of the first transmission band and the first reception band assigned to the first frequency band as a pass band,
The first reception filter uses the first reception band as a pass band,
The second reception filter uses the second reception band of the second transmission band and the second reception band assigned to a second frequency band different from the first frequency band as a pass band,
The multiplexer according to claim 5 or 6. The first transmission filter, the first reception filter, and the second reception filter are any of a surface acoustic wave filter, an acoustic wave filter using BAW, an LC resonance filter, and a dielectric filter.
The multiplexer according to any one of claims 5 to 7. further,
An antenna terminal connected to the antenna element;
An impedance matching circuit connected between the antenna terminal and the common terminal,
The multiplexer according to any one of claims 1 to 8. A multiplexer according to any one of claims 1 to 9,
An amplification circuit connected to the multiplexer,
High frequency front end circuit. An RF signal processing circuit for processing a high-frequency signal transmitted and received by the antenna element;
The high-frequency front end circuit according to claim 10, wherein the high-frequency signal is transmitted between the antenna element and the RF signal processing circuit.
Communication device.

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