Patent Publication Number: US-11658794-B2

Title: Radio frequency module and communication device

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application is based on and claims priority to Japanese Patent Application No. 2020-083277 filed on May 11, 2020. The entire disclosure of the above-identified application, including the specification, drawings and claims is incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     The present disclosure relates to radio frequency modules and communication devices. 
     BACKGROUND 
     To enable faster and higher-capacity communications, recent communications services have been working towards broadening communication bandwidth and making a simultaneous use of communication bands. 
     Japanese Unexamined Patent Application Publication No. 2006-128881 discloses a multiplexer capable of duplexing and multiplexing radio frequency signals in two different communication bands. Such multiplexer includes an LC filter including an inductor and a capacitor, and is capable of duplexing and multiplexing radio frequency signals in broad communication bands. 
     BRIEF SUMMARY 
     The Third Generation Partnership Project (3G PP) specifies the transfer of a single radio frequency signal independently (herein after also referred to as independent transfer) and the transfer of a plurality of radio frequency signals simultaneously (hereinafter also referred to as simultaneous transfer) in broad communication bands of the Fifth Generation-New Radio (5G-NR), such as n77, n78, and n79, used for Time Division Duplex (TDD). 
     However, as recognized by the present inventor, in transferring radio frequency signals in these broad communication bands for TDD, the conventional technology fails to provide isolation between a signal path through which a radio frequency signal in such a broad TDD communication band is transferred and a signal path through which a radio frequency signal in an adjacent communication band is transferred. This results in an increase in transfer loss. 
     The present disclosure has been conceived in view of the foregoing problem, and its aim is to provide a radio frequency module and a communication device that enable low-loss transfer of signals in TDD communication bands. 
     To achieve the above object, the radio frequency module according to an aspect of the present disclosure includes: a first antenna connection terminal; a second antenna connection terminal different from the first antenna connection terminal; a first filter having a passband which is a first frequency range that includes a first communication band allocated as a communication band for Time Division Duplex (TDD); a second filter having a passband which is a second frequency range that includes a second communication band allocated as a communication band for TDD; and a third filter having a passband which is a third frequency range that includes a third communication band allocated as a communication band for TDD. In the radio frequency module, at least part of the third frequency range is located between the first frequency range and the second frequency range, and the first filter and the second filter are both connected to one of the first antenna connection terminal and the second antenna connection terminal, and the third filter is connected to a remaining one of the first antenna connection terminal and the second antenna connection terminal. 
     The present disclosure provides radio frequency modules and communication devices that enable the low-loss transfer of signals in TDD communication bands. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       These and other advantages and features will become apparent from the following descriptions thereof taken in conjunction with the accompanying Drawings, by way of non-limiting examples of embodiments disclosed herein. 
         FIG.  1    is a diagram showing the circuit configurations of a radio frequency module and a communication device according to Embodiment 1. 
         FIG.  2    is a diagram showing a relationship of the frequencies of the passbands of filters included in the radio frequency module according to Embodiment 1. 
         FIG.  3 A  is a diagram showing the circuit configuration of a radio frequency module according to a variation of Embodiment 1 in a first connection status. 
         FIG.  3 B  is a diagram showing the circuit configuration of the radio frequency module according to the variation of Embodiment 1 in a second connection status. 
         FIG.  3 C  is a schematic cross-sectional view of an exemplary configuration of an antenna module according to Embodiment 1. 
         FIG.  4    is a diagram showing the circuit configurations of a radio frequency module and an antenna module according to Embodiment 2. 
         FIG.  5    is a diagram showing the circuit configurations of a radio frequency module and an antenna module according to Embodiment 3. 
         FIG.  6    is a diagram showing a relationship of the frequencies of the passbands of filters included in the radio frequency module according to Embodiment 3. 
         FIG.  7 A  is a diagram showing the circuit configuration of a radio frequency module according to a variation of Embodiment 3 in a first connection status. 
         FIG.  7 B  is a diagram showing the circuit configuration of the radio frequency module according to the variation of Embodiment 3 in a second connection status. 
         FIG.  8    is a diagram showing the circuit configurations of a radio frequency module and an antenna module according to Embodiment 4. 
         FIG.  9    is a diagram showing the circuit configurations of a radio frequency module and an antenna module according to Embodiment 5. 
         FIG.  10    is a diagram showing a relationship of the frequencies of the passbands of filters included in the radio frequency module according to Embodiment 5. 
         FIG.  11 A  is a diagram showing the circuit configuration of the radio frequency module according to Embodiment 5 in a first connection status. 
         FIG.  11 B  is a diagram showing the circuit configuration of the radio frequency module according to Embodiment 5 in a second connection status. 
         FIG.  12    is a diagram showing the circuit configuration of a radio frequency module according to a variation of Embodiment 5. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     The following describes in detail the embodiments according to the present disclosure with reference to the drawings. Note that the following embodiments and variations thereof show a comprehensive or specific example of the present disclosure. The numerical values, shapes, materials, structural elements, the arrangement and connection of the structural elements, etc. shown in the following embodiments and variations are mere examples, and thus are not intended to limit the present disclosure. Of the structural elements described in the following embodiments and variations, structural elements not recited in any one of the independent claims are described as optional structural elements. Also, the size of the structural elements and the size ratio thereof shown in the drawings are not necessarily exact. 
     In the following description, “signal path” means a transmission line including a filter that passes a radio frequency signal, wiring through which such radio frequency signal propagates, an electrode directly connected to the wiring, a terminal directly connected to the wiring or the electrode, and so forth. 
     Embodiment 1 
     1.1 Configurations of Radio Frequency Module  1  and Communication Device  6   
       FIG.  1    is a diagram showing the circuit configurations of radio frequency module  1  and communication device  6  according to Embodiment 1. As shown in  FIG.  1   , communication device  6  includes radio frequency module  1 , antennas  2 A and  2 B, and radio frequency (RF) signal processing circuit (RFIC)  3 . 
     RFIC  3  is an exemplary RF signal processing circuit that processes radio frequency signals that are to be transmitted or have been received by antennas  2 A and  2 B. More specifically, RFIC  3  performs signal processing, such as down-conversion, on a reception signal input via radio frequency module  1 , and outputs the resulting reception signal to a baseband signal processing circuit (BBIC: not illustrated). Also, RFIC  3  outputs, to radio frequency module  1 , a transmission signal that has been processed on the basis of a signal input from the BBIC. 
     Antenna  2 A is connected to radio frequency circuit  10  of radio frequency module  1 . Antenna  2 A transmits a radio frequency signal output from radio frequency circuit  10 . Antenna  2 A also receives a radio frequency signal from outside, and outputs the received radio frequency signal to radio frequency circuit  10 . Antenna  2 B is connected to radio frequency circuit  20  of radio frequency module  1 . Antenna  2 B transmits a radio frequency signal output from radio frequency circuit  20 . Antenna  2 B also receives a radio frequency signal from outside, and outputs the received radio frequency signal to radio frequency circuit  20 . 
     Note that radio frequency circuits  10  and  20  may not be directly connected to antennas  2 A and  2 B, respectively; a switch, an impedance matching circuit, a circulator, and a distributor, for example, may be interposed between antenna  2 A and radio frequency circuit  10 , and between antenna  2 B and radio frequency circuit  20 . 
     Antenna module  5  includes antennas  2 A and  2 B, and radio frequency module  1 . 
     Radio frequency module  1  includes antenna connection terminals  100  and  200 , and radio frequency circuits  10  and  20 . As shown in  FIG.  1   , radio frequency circuit  10  includes filters  11  and  12 , power amplifiers  51 T and  52 T, low-noise amplifiers  51 R and  52 R, and switches  41  and  42 . Radio frequency circuit  20  includes filter  21 , power amplifier  53 T, low-noise amplifier  53 R, and switch  43 . 
     Antenna connection terminal  100 , which is an example of the first antenna connection terminal, is connected to radio frequency circuit  10 . Antenna connection terminal  200 , which is an example of the second antenna connection terminal that is different from the first antenna connection terminal, is connected to radio frequency circuit  20 . 
     Filter  11 , which is an example of the first filter, is connected to antenna connection terminal  100 . Filter  11  is a radio frequency filter having a passband which is a first frequency range that includes a first communication band allocated as a TDD communication band. 
     Filter  12 , which is an example of the second filter, is connected to antenna connection terminal  100 . Filter  12  is a radio frequency filter having a passband which is a second frequency range that includes a second communication band allocated as a TDD communication band. 
     Filter  21 , which is an example of the third filter, is connected to antenna connection terminal  200 . Filter  21  is a radio frequency filter having a passband which is a third frequency range that includes a third communication band allocated as a TDD communication band. 
     Radio frequency module  1  and antenna module  5  with the above configurations enable: (1) an independent transfer of a signal in the first communication band; (2) an independent transfer of a signal in the second communication band; (3) an independent transfer of a signal in the third communication band; (4) a simultaneous transfer of a signal in the first communication band and a signal in the second communication band; (5) a simultaneous transfer of a signal in the first communication band and a signal in the third communication band; (6) a simultaneous transfer of a signal in the second communication band and a signal in the third communication band; and (7) a simultaneous transfer of a signal in the first communication band, a signal in the second communication band, and a signal in the third communication band. 
       FIG.  2    is a diagram showing a relationship of the frequencies of the passbands of the filters included in radio frequency module  1  according to Embodiment 1. The drawing shows the relationship of the frequencies of the first communication band, second communication band, and third communication band allocated as TDD communication bands, and filters  11 ,  12 , and  21 . In the present embodiment, the first communication band, third communication band, and second communication band are located in the stated order from the lower frequency side. Accordingly, the first frequency range that includes the first communication band, the third frequency range that includes the third communication band, and the second frequency range that includes the second communication band are located in the stated order from the lower frequency side. Stated differently, the third frequency range is located between the first frequency range and the second frequency range. Note that the third frequency range may overlap the first frequency range and the second frequency range; at least part of the third frequency range is simply required to be located between the first frequency range and the second frequency range. Accordingly, at least part of the passband of filter  21  is located between the passband of filter  11  and the passband of filter  12 . 
     Note that the first communication band, third communication band, and second communication band may be located in the stated order from the higher frequency side. Accordingly, the first frequency range that includes the first communication band, the third frequency range that includes the third communication band, and the second frequency range that includes the second communication band may be located in the stated order from the higher frequency side. 
     As shown in  FIG.  1   , one end of filter  11  and one end of filter  12  are both connected to antenna connection terminal  100 , and one end of filter  21  is connected to antenna connection terminal  200 . Filters  11  and  12  are included in multiplexer  31 . 
     Here, the frequency spacing between the first frequency range (first communication band) and the third frequency range (third communication band) is smaller than the frequency spacing between the first frequency range (first communication band) and the second frequency range (second communication band). Also, the frequency spacing between the second frequency range (second communication band) and the third frequency range (third communication band) is smaller than the frequency spacing between the first frequency range (first communication band) and the second frequency range (second communication band). As such, due to a small frequency spacing between communication bands, the isolation between two signals to be simultaneously transferred can decrease and consequently transfer loss can increase in, for example, simultaneous transfer of a signal in the first communication band and a signal in the third communication band or simultaneous transfer of a signal in the second communication band and a signal in the third communication band. Also, in the independent transfer of a signal in the first communication band, the signal in the first communication band can leak into a signal path through which a signal in the third communication band is transferred. Also, in the independent transfer of a signal in the second communication band, the signal in the second communication band can leak into the signal path through which a signal in the third communication band is transferred. In the independent transfer of a signal in the third communication band, the signal in the third communication band can leak into a signal path through which a signal in the first communication band is transferred and a signal path through which a signal in the second communication band is transferred. Furthermore, in the simultaneous transfer of a signal in the first communication band and a signal in the second communication band, the signal in the first communication band and the signal in the second communication band can leak into the signal path through which a signal in the third communication band is transferred. 
     In view of the foregoing concerns, in radio frequency module  1  according to the present embodiment, filters  11  and  12  are connected to antenna connection terminal  100 , and filter  21  is connected to antenna connection terminal  200 . Stated differently, this configuration, in which filter  11  and filter  21  are connected to different antennas, achieves high isolation between a signal in the first communication band that passes through filter  11  and a signal in the third communication band that passes through filter  21 . Also, this configuration, in which filter  12  and filter  21  are connected to different antennas, achieves high isolation between a signal in the second communication band that passes through filter  12  and a signal in the third communication band that passes through filter  21 . 
     The foregoing configuration achieves high isolation between two signals to be simultaneously transferred, that is, a signal in the first communication band and a signal in the third communication band or a signal in the second communication band and a signal in the third communication band. This configuration thus enables low-loss signal transfer. The foregoing configuration also achieves high isolation between the signal path through which a signal in the first communication band is transferred and the signal path through which a signal in the third communication band is transferred in the independent transfer of a signal in the first communication band, thus enabling low-loss signal transfer. The foregoing configuration also achieves high isolation between the signal path through which a signal in the second communication band is transferred and the signal path through which a signal in the third communication band is transferred in the independent transfer of a signal in the second communication band, thus enabling low-loss signal transfer. The foregoing configuration also achieves high isolation between the signal path through which a signal in the third communication band is transferred and the signal paths through which signals in the first communication band and the second communication band are transferred in the independent transfer of a signal in the third communication band, thus enabling low-loss signal transfer. The foregoing configuration also achieves high isolation between the signal paths through which signals in the first communication band and the second communication band are transferred and the signal path through which a signal in the third communication band is transferred in the simultaneous transfer of a signal in the first communication band and a signal in the second communication band, thus enabling a low-loss signal transfer. 
     Further, since the frequency spacing between broad communication bands for TDD has been conventionally small, variations in the signal phase at an end of the passband increase as a result of an attempt to achieve isolation between the adjacent TDD communication bands, when the antennation slope is required to be steep in the proximity of the passband. This results in an increase in amplification variations caused by a ripple in the passband, leading to the degradation in error vector magnitude (EVM). In particular, TDD communication bands that support NR are involved in a stringent EVM specification, and thus EVM degradation needs to be prevented. Radio frequency module  1  according to the present embodiment is effective also in terms of being capable of preventing EVM degradation. 
     The following describes circuit components other than the filters included in radio frequency circuits  10  and  20 . 
     Power amplifier  51 T is a transmission amplifier that amplifies a transmission signal in the first frequency range that includes the first communication band. The input terminal of power amplifier  51 T is connected to transmission input terminal  110 . Low-noise amplifier  51 R is a reception amplifier that amplifies a reception signal in the first frequency range that includes the first communication band. The output terminal of low-noise amplifier  51 R is connected to reception output terminal  120 . 
     Power amplifier  52 T is a transmission amplifier that amplifies a transmission signal in the second frequency range that includes the second communication band. The input terminal of power amplifier  52 T is connected to transmission input terminal  130 . Low-noise amplifier  52 R is a reception amplifier that amplifies a reception signal in the second frequency range that includes the second communication band. The output terminal of low-noise amplifier  52 R is connected to reception output terminal  140 . 
     Power amplifier  53 T is a transmission amplifier that amplifies a transmission signal in the third frequency range that includes the third communication band. The input terminal of power amplifier  53 T is connected to transmission input terminal  210 . Low-noise amplifier  53 R is a reception amplifier that amplifies a reception signal in the third frequency range that includes the third communication band. The output terminal of low-noise amplifier  53 R is connected to reception output terminal  220 . 
     Switch  41  includes common terminal  41   a , and selection terminals  41   b  and  41   c . Switch  41  exclusively switches between connecting common terminal  41   a  and selection terminal  41   b  and connecting common terminal  41   a  and selection terminal  41   c . Common terminal  41   a  is connected to the other end of filter  11 , selection terminal  41   b  to the output terminal of power amplifier  51 T, and selection terminal  41   c  to the input terminal of low-noise amplifier  51 R. Switch  41  performs the switching operation to enable radio frequency circuit  10  to transfer a transmission signal in the first communication band and a reception signal in the first communication band in different time slots. 
     Switch  42  includes common terminal  42   a , and selection terminals  42   b  and  42   c . Switch  42  exclusively switches between connecting common terminal  42   a  and selection terminal  42   b  and connecting common terminal  42   a  and selection terminal  42   c . Common terminal  42   a  is connected to the other end of filter  12 , selection terminal  42   b  to the output terminal of power amplifier  52 T, and selection terminal  42   c  to the input terminal of low-noise amplifier  52 R. Switch  42  performs the switching operation to enable radio frequency circuit  10  to transfer a transmission signal in the second communication band and a reception signal in the second communication band in different time slots. 
     Switch  43  includes common terminal  43   a , and selection terminals  43   b  and  43   c . Switch  43  exclusively switches between connecting common terminal  43   a  and selection terminal  43   b  and connecting common terminal  43   a  and selection terminal  43   c . Common terminal  43   a  is connected to the other end of filter  21 , selection terminal  43   b  to the output terminal of power amplifier  53 T, and selection terminal  43   c  to the input terminal of low-noise amplifier  53 R. Switch  43  performs the switching operation to enable radio frequency circuit  20  to transfer a transmission signal in the third communication band and a reception signal in the third communication band in different time slots. 
     1.2 Configuration of Radio Frequency Module According to Variation 
     The radio frequency module according to the present embodiment may include, between radio frequency circuits  10  and  20  and antennas  2 A and  2 B, switch  45  that performs a switching operation described below. 
       FIG.  3 A  is a diagram showing the circuit configuration of a radio frequency module according to a variation of Embodiment 1 in a first connection status.  FIG.  3 B  is a diagram showing the circuit configuration of the radio frequency module according to the variation of Embodiment 1 in a second connection status. 
     As shown in  FIG.  3 A  and  FIG.  3 B , the radio frequency module according to the present variation further includes switch  45 , in addition to the structural elements included in radio frequency module  1  according to Embodiment 1. 
     Switch  45 , which is an exemplary first switch, includes common terminal  45   a  (first common terminal), common terminal  45   b  (second common terminal), selection terminal  45   c  (first selection terminal), and selection terminal  45   d  (second selection terminal). Switch  45  connects common terminal  45   a  exclusively to selection terminal  45   c  or  45   d , and connects common terminal  45   b  exclusively to selection terminal  45   c  or  45   d . Common terminal  45   a  is connected to antenna connection terminal  100 , common terminal  45   b  to antenna connection terminal  200 , selection terminal  45   c  to one end of filter  11  and one end of filter  12 , and selection terminal  45   d  to one end of filter  21 . 
     With the above configuration, the radio frequency module according to the present variation is in either the first connection status shown in  FIG.  3 A  or the second connection status shown in  FIG.  3 B . In the first connection status, radio frequency circuit  10  and antenna  2 A are connected, and radio frequency circuit  20  and antenna  2 B are connected. In the second connection status, radio frequency circuit  10  and antenna  2 B are connected, and radio frequency circuit  20  and antenna  2 A are connected. 
     Stated differently, in the radio frequency module according to the present variation, filters  11  and  12  are both connected to one of antenna connection terminals  100  and  200  via selection terminal  45   c , and filter  21  is connected to the remaining one of antenna connection terminals  100  and  200  via selection terminal  45   d.    
     In the radio frequency module according to the present variation, filters  11  and  12  are connected to one of antenna connection terminals  100  and  200 , and filter  21  is connected to the remaining one of antenna connection terminals  100  and  200 . This configuration, in which filter  11  and filter  21  are connected to different antennas, achieves high isolation between a signal in the first communication band that passes through filter  11  and a signal in the third communication band that passes through filter  21 . Also, this configuration, in which filter  12  and filter  21  are connected to different antennas, achieves high isolation between a signal in the second communication band that passes through filter  12  and a signal in the third communication band that passes through filter  21 . 
     In radio frequency module  1  according to Embodiment 1, antenna module  5  may be an antenna module that transfers radio frequency signals in a millimeter-wave frequency range. For example, the first frequency range may include 24.25 GHz to 27.50 GHz, the second frequency range may include one of 37.00 GHz to 40.00 GHz and 39.50 GHz to 43.50 GHz, and the third frequency range may include one of 26.50 GHz to 29.50 GHz and 27.50 GHz to 28.35 GHz. In this case, for example, n258 (24.25 GHz to 27.50 GHz) of 5G-NR is applied to the first communication band, n260 (37.00 GHz to 40.00 GHz) or n259 (39.50 GHz to 43.50 GHz) of 5G-NR is applied to the second communication band, and n257 (26.50 GHz to 29.50 GHz) or n261 (27.50 GHz to 28.35 GHz) of 5G-NR is applied to the third communication band. 
       FIG.  3 C  is a schematic cross-sectional view of an exemplary configuration of antenna module  5  according to Embodiment 1. In the case where antenna module  5  is an antenna module that transfers radio frequency signals in a millimeter-wave frequency range, antennas  2 A and  2 B, filter  21  and multiplexer  31 , and RFIC  3  are disposed on module board  60  as shown in  FIG.  3 C . 
     Antennas  2 A and  2 B are, for example, planar antennas or linear antennas disposed on principal surface  60   a  of module board  60 . In a plan view of module board  60 , antennas  2 A and  2 B do not overlap. 
     Filter  21  and multiplexer  31  may each be implemented as, for example, a distributed-constant filter. Here, a distributed-constant filter is a filter that includes at least one of a half-wave line or a quarter-wave line. 
     Note that antennas  2 A and  2 B may not be disposed on the same module board  60  on which filter  21  and multiplexer  31  are disposed, and thus may be disposed on different boards. 
     Also note that antenna module  5  may include RFIC  3 . 
     Embodiment 2 
     While the radio frequency module according to Embodiment 1 includes radio frequency circuits  10  and  20  that are connected to different antennas, the radio frequency module according to the present embodiment includes radio frequency circuits  10  and  20  that are connected to the same antenna  2 . 
     2.1 Configuration of Radio Frequency Module  1 A 
       FIG.  4    is a diagram showing the circuit configurations of radio frequency module  1 A and antenna module  5 A according to Embodiment 2. 
     Antenna module  5 A includes antenna  2  and radio frequency module  1 A. Antenna module  5 A according to the present embodiment is different from antenna module  5  according to Embodiment 1 in that a single antenna  2  is disposed and that radio frequency module  1 A includes switch  40 . The following omits the descriptions of the same points as those of antenna module  5  and radio frequency module  1  according to Embodiment 1 and focuses on the differences to describe antenna module  5 A and radio frequency module  1 A according to the present embodiment. 
     Antenna  2  is connected to switch  40  of radio frequency module  1 A. Antenna  2  transmits a radio frequency signal output from radio frequency circuit  10  or  20 . Antenna  2  also receives a radio frequency signal from outside, and outputs the received radio frequency signal to radio frequency circuit  10  or  20 . 
     Switch  40  may not be directly connected to antenna  2 ; an impedance matching circuit, a circulator, and a distributor, for example, may be interposed between antenna  2  and switch  40 . 
     As shown in  FIG.  4   , radio frequency module  1 A includes antenna connection terminal  100 , radio frequency circuits  10  and  20 , and switch  40 . 
     Switch  40  includes common terminal  40   a , and selection terminal  40   b  (first selection terminal) and selection terminal  40   c  (second selection terminal). Switch  40  exclusively switches between connecting common terminal  40   a  and selection terminal  40   b  and connecting common terminal  40   a  and selection terminal  40   c.    
     As shown in  FIG.  4   , one end of filter  11  and one end of filter  12  are both connected to selection terminal  40   b , and one end of filter  21  is connected to selection terminal  40   c . Filters  11  and  12  are included in multiplexer  31 . 
     Radio frequency module  1 A and antenna module  5 A with the above configurations enable: (1) an independent transfer of a signal in the first communication band; (2) an independent transfer of a signal in the second communication band; (3) an independent transfer of a signal in the third communication band; and (4) a simultaneous transfer of a signal in the first communication band and a signal in the second communication band. 
     Here, as shown in  FIG.  2   , the frequency spacing between the first frequency range (first communication band) and the third frequency range (third communication band) is smaller than the frequency spacing between the first frequency range (first communication band) and the second frequency range (second communication band). Also, the frequency spacing between the second frequency range (second communication band) and the third frequency range (third communication band) is smaller than the frequency spacing between the first frequency range (first communication band) and the second frequency range (second communication band). As such, for example, in the independent transfer of a signal in the first communication band, the signal in the first communication band can leak into the signal path through which a signal in the third communication band is transferred. Also, in the independent transfer of a signal in the second communication band, the signal in the second communication band can leak into the signal path through which a signal in the third communication band is transferred. In the independent transfer of a signal in the third communication band, the signal in the third communication band can leak into the signal paths through which signals in the first communication band and the second communication band are transferred. Furthermore, in the simultaneous transfer of a signal in the first communication band and a signal in the second communication band, the signal in the first communication band and the signal in the second communication band can leak into the signal path through which a signal in the third communication band is transferred. 
     In view of the foregoing concerns, in radio frequency module  1 A according to the present embodiment, filters  11  and  12  are connected to selection terminal  40   b  of switch  40 , and filter  21  is connected to selection terminal  40   c  of switch  40 . Stated differently, in this configuration, filter  11  and filter  21  are not simultaneously connected because of the exclusive connection by switch  40 . This configuration thus achieves high isolation between filter  11  and filter  21 . Also, in this configuration, filter  12  and filter  21  are not simultaneously connected because of the exclusive connection by switch  40 . This configuration thus achieves high isolation between filter  12  and filter  21 . 
     The foregoing configuration thus achieves high isolation between the signal path through which a signal in the first communication band is transferred and the signal path through which a signal in the third communication band is transferred in the independent transfer of a signal in the first communication band, thus enabling a low-loss signal transfer. The foregoing configuration also achieves high isolation between the signal path through which a signal in the second communication band is transferred and the signal path through which a signal in the third communication band is transferred in the independent transfer of a signal in the second communication band, thus enabling low-loss signal transfer. The foregoing configuration also achieves high isolation between the signal path through which a signal in the third communication band is transferred and the signal paths through which signals in the first communication band and the second communication band are transferred in the independent transfer of a signal in the third communication band, thus enabling a low-loss signal transfer. The foregoing configuration also achieves high isolation between the signal paths through which signals in the first communication band and the second communication band are transferred and the signal path through which a signal in the third communication band is transferred in the simultaneous transfer of a signal in the first communication band and a signal in the second communication band, thus enabling a low-loss signal transfer. 
     In radio frequency module  1  according to Embodiment 1 and radio frequency module  1 A according to Embodiment 2, filters  11 ,  12 , and  21  may be disposed on the same board or inside of the same package. Also, radio frequency circuits  10  and  20  may be disposed on the same board or inside of the same package. 
     This configuration achieves the downsizing of radio frequency modules  1  and  1 A. 
     Alternatively, in radio frequency module  1  according to Embodiment 1 and radio frequency module  1 A according to Embodiment 2, filters  11  and  12  may be disposed on a different board or inside of a different package from a board or a package on which or inside of which filter  21  is disposed. Also, radio frequency circuits  10  and  20  may be disposed on different boards or inside of different packages. 
     This configuration further enhances the isolation between the signal paths of the first communication band and the second communication band and the signal path of the third communication band. 
     In radio frequency module  1  according to Embodiment 1 and radio frequency module  1 A according to Embodiment 2, for example, the first frequency range may include one of 3300 MHz to 4200 MHz and 3300 MHz to 3800 MHz, the second frequency range may include one of 5150 MHz to 5850 MHz and 5150 MHz to 7125 MHz, and the third frequency range may include 4400 MHz to 5000 MHz. In this case, for example, n77 (3300 MHz to 4200 MHz) or n78 (3300 MHz to 3800 MHz) of 5G-NR is applied to the first communication band, Wireless Local Area Network (WLAN: 5.15 GHz to 7.125 GHz band) or New Radio Unlicensed (NR-U) is applied to the second communication band, and n79 (4400 MHz to 5000 MHz) or n78 of 5G-NR is applied to the third communication band. 
     Note that NR-U, which is a 5G-NR communication band of 5 GHz or greater defined by 3GPP, corresponds to an Unlicensed National Information Infrastructure (U-NII) communication band that is an unlicensed communication band defined by the Federal Communications Commission (FCC). Also, WLAN (5.15 GHz to 7.125 GHz band) is compliant with IEEE 802.11, which is a wireless LAN standard specified by Institute of Electrical and Electronics Engineers. 
     In radio frequency module  1  according to Embodiment 1 and radio frequency module  1 A according to Embodiment 2, for example, the first frequency range may include 1700 MHz to 2700 MHz, the second frequency range may include 4400 MHz to 5000 MHz, and the third frequency range may include 3300 MHz to 4200 MHz. In this case, for example, n40 (2300 MHz to 2400 MHz) or n41 (2496 MHz to 2690 MHz) of 5G-NR is applied to the first communication band, n79 (4400 MHz to 5000 MHz) of 5G-NR is applied to the second communication band, and n77 (3300 MHz to 4200 MHz) or n78 (3300 MHz to 3800 MHz) of 5G-NR is applied to the third communication band. 
     Also, in radio frequency module  1  according to Embodiment 1 and radio frequency module  1 A according to Embodiment 2, for example, the first frequency range may include 1700 MHz to 2700 MHz, the second frequency range may include one of 5150 MHz to 5850 MHz and 5150 MHz to 7125 MHz, and the third frequency range may include 4400 MHz to 5000 MHz. In this case, for example, n40 (2300 MHz to 2400 MHz) or n41 (2496 MHz to 2690 MHz) of 5G-NR is applied to the first communication band, WLAN (5.15 GHz to 7.125 GHz band) or NR-U is applied to the second communication band, and n79 (4400 MHz to 5000 MHz) of 5G-NR is applied to the third communication band. 
     Embodiment 3 
     While the radio frequency modules according to Embodiments 1 and 2 have the circuit configuration for transferring signals in the first through third communication bands, the radio frequency module according to the present embodiment has a configuration that further includes a circuit for transferring signals in a fourth communication band. 
       FIG.  5    is a diagram showing the circuit configurations of radio frequency module  1 B and antenna module  5 B according to Embodiment 3. 
     Antenna module  5 B includes antennas  2 A and  2 B, and radio frequency module  1 B. Antenna module  5 B according to the present embodiment is different from antenna module  5  according to Embodiment 1 in the circuit configuration of radio frequency circuit  20 B included in radio frequency module  1 B. The following omits the descriptions of the same points as those of antenna module  5  and radio frequency module  1  according to Embodiment 1 and focuses on the difference to describe antenna module  5 B and radio frequency module  1 B according to the present embodiment. 
     Note that radio frequency circuits  10  and  20 B may not be directly connected to antennas  2 A and  2 B, respectively; a switch, an impedance matching circuit, a circulator, and a distributor, for example, may be interposed between antenna  2 A and radio frequency circuit  10 , and between antenna  2 B and radio frequency circuit  20 B. 
     Radio frequency module  1 B includes antenna connection terminals  100  and  200 , and radio frequency circuits  10  and  20 B. As shown in  FIG.  5   , radio frequency circuit  10  includes filters  11  and  12 , power amplifiers  51 T and  52 T, low-noise amplifiers  51 R and  52 R, and switches  41  and  42 . Radio frequency circuit  20 B includes filters  21  and  22 , power amplifiers  53 T and  54 T, low-noise amplifiers  53 R and  54 R, and switches  43  and  44 . 
     Filter  21 , which is an exemplary third filter, is connected to antenna connection terminal  200 . Filter  21  is a radio frequency filter having a passband which is the third frequency range that includes the third communication band allocated as a TDD communication band. 
     Filter  22 , which is an exemplary fourth filter, is connected to antenna connection terminal  200 . Filter  22  is a radio frequency filter having a passband which is a fourth frequency range that includes a fourth communication band allocated as a TDD communication band. Note that the fourth communication band may not be a communication band for TDD, and thus may be, for example, a communication band for Frequency Division Duplex (FDD). 
     Radio frequency module  1 B and antenna module  5 B with the above configurations enable: (1) an independent transfer of a signal in the first communication band; (2) an independent transfer of a signal in the second communication band; (3) an independent transfer of a signal in the third communication band; (4) an independent transfer of a signal in the fourth communication band; (5) a simultaneous transfer of a signal in the first communication band and a signal in the second communication band; (6) a simultaneous transfer of a signal in the third communication band and a signal in the fourth communication band; (7) a simultaneous transfer of a signal in the first communication band and a signal in the third communication band; (8) a simultaneous transfer of a signal in the second communication band and a signal in the third communication band; (9) a simultaneous transfer of a signal in the fourth communication band and a signal in the first communication band; (10) a simultaneous transfer of a signal in the fourth communication band and a signal in the second communication band; and (11) a simultaneous transfer of at least three of a signal in the first communication band, a signal in the second communication band, a signal in the third communication band, and a signal in the fourth communication band. 
       FIG.  6    is a diagram showing a relationship of the frequencies of the passbands of the filters included in radio frequency module  1 B according to Embodiment 3. The drawing shows the relationship of the frequencies of the first communication band, second communication band, third communication band, and fourth communication band, and filters  11 ,  12 ,  21 , and  22 . In the present embodiment, the fourth communication band, first communication band, third communication band, and second communication band are located in the stated order from the lower frequency side. Accordingly, the fourth frequency range that includes the fourth communication band, the first frequency range that includes the first communication band, the third frequency range that includes the third communication band, and the second frequency range that includes the second communication band are located in the stated order from the lower frequency side. Stated differently, the third frequency range is located between the first frequency range and the second frequency range. Note that the third frequency range may overlap the first frequency range and the second frequency range; at least part of the third frequency range is simply required to be located between the first frequency range and the second frequency range. Also, the fourth frequency range is lower than the first frequency range. Note that the fourth frequency range may overlap the first frequency range. Accordingly, at least part of the passband of filter  21  is located between the passband of filter  11  and the passband of filter  12 . Also, the passband of filter  22  is lower than the passband of filter  11 . 
     The fourth communication band, first communication band, third communication band, and second communication band may be located in the stated order from the higher frequency side. Accordingly, the fourth frequency range that includes the fourth communication band, the first frequency range that includes the first communication band, the third frequency range that includes the third communication band, and the second frequency range that includes the second communication band may be located in the stated order from the higher frequency side. 
     As shown in  FIG.  5   , one end of filter  11  and one end of filter  12  are both connected to antenna connection terminal  100 , and one end of filter  21  and one end of filter  22  are both connected to antenna connection terminal  200 . Filters  11  and  12  are included in multiplexer  31 , and filters  21  and  22  are included in multiplexer  32 . 
     Here, the frequency spacing between the first frequency range (first communication band) and the third frequency range (third communication band) is smaller than the frequency spacing between the first frequency range (first communication band) and the second frequency range (second communication band). Also, the frequency spacing between the second frequency range (second communication band) and the third frequency range (third communication band) is smaller than the frequency spacing between the first frequency range (first communication band) and the second frequency range (second communication band). As such, due to a small frequency spacing between communication bands, the isolation between two signals to be simultaneously transferred can decrease and consequently transfer loss can increase in, for example, simultaneous transfer of a signal in the first communication band and a signal in the third communication band or simultaneous transfer of a signal in the second communication band and a signal in the third communication band. 
     Also, the frequency spacing between the fourth frequency range (fourth communication band) and the first frequency range (first communication band) is smaller than the frequency spacing between the fourth frequency range (fourth communication band) and the third frequency range (third communication band). Also, the frequency spacing between the third frequency range (third communication band) and the first frequency range (first communication band) is smaller than the frequency spacing between the fourth frequency range (fourth communication band) and the third frequency range (third communication band). As such, due to a small frequency spacing between communication bands, the isolation between two signals to be simultaneously transferred can decrease and consequently transfer loss can increase in, for example, simultaneous transfer of a signal in the fourth communication band and a signal in the first communication band. 
     Also, in the independent transfer of a signal in the first communication band, the signal in the first communication band can leak into the signal paths through which signals in the third communication band and the fourth communication band are transferred. Also, in the independent transfer of a signal in the second communication band, the signal in the second communication band can leak into the signal path through which a signal in the third communication band is transferred. In the independent transfer of a signal in the third communication band, the signal in the third communication band can leak into the signal paths through which signals in the first communication band and the second communication band are transferred. In the independent transfer of a signal in the fourth communication band, the signal in the fourth communication band can leak into the signal path through which a signal in the first communication band is transferred. Furthermore, in the simultaneous transfer of a signal in the first communication band and a signal in the second communication band, the signal in the first communication band and the signal in the second communication band can leak into the signal path through which a signal in the third communication band is transferred. Also, in the simultaneous transfer of a signal in the third communication band and a signal in the fourth communication band, the signal in the third communication band and the signal in the fourth communication band can leak into the signal path through which a signal in the first communication band is transferred. 
     In view of the foregoing concerns, in radio frequency module  1 B according to the present embodiment, filters  11  and  12  are connected to antenna connection terminal  100 , and filters  21  and  22  are connected to antenna connection terminal  200 . Stated differently, this configuration, in which filter  21  and filter  11  are connected to different antennas, achieves high isolation between a signal in the third communication band that passes through filter  21  and a signal in the first communication band that passes through filter  11 . Also, this configuration, in which filter  21  and filter  12  are connected to different antennas, achieves high isolation between a signal in the third communication band that passes through filter  21  and a signal in the second communication band that passes through filter  12 . Also, this configuration, in which filter  22  and filter  11  are connected to different antennas, achieves high isolation between a signal in the fourth communication band that passes through filter  22  and a signal in the first communication band that passes through filter  11 . Also, this configuration, in which filter  22  and filter  12  are connected to different antennas, achieves high isolation between a signal in the fourth communication band that passes through filter  22  and a signal in the second communication band that passes through filter  12 . 
     The foregoing configuration thus achieves high isolation between two signals to be simultaneously transferred, that is: a signal in the first communication band and a signal in the third communication band; a signal in the first communication band and a signal in the fourth communication band; a signal in the second communication band and a signal in the third communication band; or a signal in the second communication band and a signal in the fourth communication band. This configuration thus enables a low-loss signal transfer. The foregoing configuration also achieves high isolation between the signal path through which a signal in the first communication band is transferred and the signal paths through which signals in the third communication band and the fourth communication band are transferred in the independent transfer of a signal in the first communication band, thus enabling a low-loss signal transfer. The foregoing configuration also achieves high isolation between the signal path through which a signal in the second communication band is transferred and the signal path through which a signal in the third communication band is transferred in the independent transfer of a signal in the second communication band, thus enabling a low-loss signal transfer. The foregoing configuration also achieves high isolation between the signal path through which a signal in the third communication band is transferred and the signal paths through which signals in the first communication band and the second communication band are transferred in the independent transfer of a signal in the third communication band, thus enabling a low-loss signal transfer. The foregoing configuration also achieves high isolation between the signal path through which a signal in the first communication band is transferred and the signal path through which a signal in the fourth communication band is transferred in the independent transfer of a signal in the fourth communication band, thus enabling a low-loss signal transfer. The foregoing configuration also achieves high isolation between the signal paths through which signals in the first communication band and the second communication band are transferred and the signal paths through which signals in the third communication band and the fourth communication band are transferred in the simultaneous transfer of a signal in the first communication band and a signal in the second communication band or simultaneous transfer of a signal in the third communication band and a signal in the fourth communication band, thus enabling a low-loss signal transfer. 
     Power amplifier  54 T is a transmission amplifier that amplifies a transmission signal in the fourth frequency range that includes the fourth communication band. The input terminal of power amplifier  54 T is connected to transmission input terminal  230 . Low-noise amplifier  54 R is a reception amplifier that amplifies a reception signal in the fourth frequency range that includes the fourth communication band. The output terminal of low-noise amplifier  54 R is connected to reception output terminal  240 . 
     Switch  44  includes common terminal  44   a , and selection terminals  44   b  and  44   c . Switch  44  exclusively switches between connecting common terminal  44   a  and selection terminal  44   b  and connecting common terminal  44   a  and selection terminal  44   c . Common terminal  44   a  is connected to the other end of filter  22 , selection terminal  44   b  to the output terminal of power amplifier  54 T, and selection terminal  44   c  to the input terminal of low-noise amplifier  54 R. Switch  44  performs the switching operation to enable radio frequency circuit  20 B to transfer a transmission signal in the fourth communication band and a reception signal in the fourth communication band in different time slots. 
     3.1 Configuration of Radio Frequency Module According to Variation 
     The radio frequency module according to the present embodiment may include, between radio frequency circuits  10  and  20 B and antennas  2 A and  2 B, switch  46  that performs a switching operation described below. 
       FIG.  7 A  is a diagram showing the circuit configuration of a radio frequency module according to a variation of Embodiment 3 in a first connection status.  FIG.  7 B  is a diagram showing the circuit configuration of the radio frequency module according to the variation of Embodiment 3 in a second connection status. 
     As shown in  FIG.  7 A  and  FIG.  7 B , the radio frequency module according to the present variation further includes switch  46 , in addition to the structural elements included in radio frequency module  1 B according to Embodiment 3. 
     Switch  46 , which is an example of the first switch, includes common terminal  46   a  (first common terminal), common terminal  46   b  (second common terminal), selection terminal  46   c  (first selection terminal), and selection terminal  46   d  (second selection terminal). Switch  46  connects common terminal  46   a  exclusively to selection terminal  46   c  or  46   d , and connects common terminal  46   b  exclusively to selection terminal  46   c  or  46   d . Common terminal  46   a  is connected to antenna connection terminal  100 , common terminal  46   b  to antenna connection terminal  200 , selection terminal  46   c  to one end of filter  11  and one end of filter  12 , and selection terminal  46   d  to one end of filter  21  and one end of filter  22 . 
     With the above configuration, the radio frequency module according to the present variation is either in the first connection status shown in  FIG.  7 A  or the second connection status shown in  FIG.  7 B . In the first connection status, radio frequency circuit  10  and antenna  2 A are connected, and radio frequency circuit  20 B and antenna  2 B are connected. In the second connection status, radio frequency circuit  10  and antenna  2 B are connected, and radio frequency circuit  20 B and antenna  2 A are connected. 
     Stated differently, in the radio frequency module according to the present variation, filters  11  and  12  are both connected to one of antenna connection terminals  100  and  200  via selection terminal  46   c , and filters  21  and  22  are connected to the remaining one of antenna connection terminals  100  and  200  via selection terminal  46   d.    
     In the radio frequency module according to the present variation, filters  11  and  12  are connected to one of antenna connection terminals  100  and  200 , and filters  21  and  22  are connected to the remaining one of antenna connection terminals  100  and  200 . This configuration, in which filter  21  and filter  11  are connected to different antennas, achieves high isolation between a signal in the third communication band that passes through filter  21  and a signal in the first communication band that passes through filter  11 . Also, this configuration, in which filter  21  and filter  12  are connected to different antennas, achieves high isolation between a signal in the third communication band that passes through filter  21  and a signal in the second communication band that passes through filter  12 . Also, this configuration, in which filter  22  and filter  11  are connected to different antennas, achieves high isolation between a signal in the fourth communication band that passes through filter  22  and a signal in the first communication band that passes through filter  11 . Also, this configuration, in which filter  22  and filter  12  are connected to different antennas, achieves high isolation between a signal in the fourth communication band that passes through filter  22  and a signal in the second communication band that passes through filter  12 . 
     In radio frequency module  1 B according to Embodiment 3, for example, the first frequency range may include one of 26.50 GHz to 29.50 GHz or 27.50 GHz to 28.35 GHz, the second frequency range may include 39.50 GHz to 43.50 GHz, the third frequency range may include 37.00 GHz to 40.00 GHz, and the fourth frequency range may include 24.25 GHz to 27.50 GHz. In this case, for example, n257 (26.50 GHz to 29.50 GHz) or n261 (27.50 GHz to 28.35 GHz) of 5G-NR is applied to the first communication band, n259 (39.50 GHz to 43.50 GHz) of 5G-NR is applied to the second communication band, n260 (37.00 GHz to 40.00 GHz) of 5G-NR is applied to the third communication band, and n258 (24.25 GHz to 27.50 GHz) of 5G-NR is applied to the fourth communication band. 
     Embodiment 4 
     While the radio frequency module according to Embodiment 3 includes radio frequency circuits  10  and  20 B that are connected to different antennas, the radio frequency module according to the present embodiment includes radio frequency circuits  10  and  20 B that are connected to the same antenna. 
     4.1 Configuration of Radio Frequency Module  1 C 
       FIG.  8    is a diagram showing the circuit configurations of radio frequency module  1 C and antenna module  5 C according to Embodiment 4. 
     Antenna module  5 C includes antenna  2  and radio frequency module  1 C. Antenna module  5 C according to the present embodiment is different from antenna module  5 B according to Embodiment 3 in that a single antenna  2  is disposed and that radio frequency module  1 C includes switch  47 . The following omits the descriptions of the same points as those of antenna module  5 B and radio frequency module  1 B according to Embodiment 3 and focuses on the differences to describe antenna module  5 C and radio frequency module  1 C according to the present embodiment. 
     Antenna  2  is connected to switch  47  of radio frequency module  1 C. Antenna  2  transmits a radio frequency signal output from radio frequency circuit  10  or  20 B. Antenna  2  also receives a radio frequency signal from outside, and outputs the received radio frequency signal to radio frequency circuit  10  or  20 B. 
     Note that switch  47  may not be directly connected to antenna  2 ; an impedance matching circuit, a circulator, and a distributor, for example, may be interposed between antenna  2  and switch  47 . 
     As shown in  FIG.  8   , radio frequency module  1 C includes antenna connection terminal  100 , radio frequency circuits  10  and  20 B, and switch  47 . 
     Switch  47 , which is an example of the first switch, includes common terminal  47   a , and selection terminal  47   b  (first selection terminal) and selection terminal  47   c  (second selection terminal). Switch  47  exclusively switches between connecting common terminal  47   a  and selection terminal  47   b  and connecting common terminal  47   a  and selection terminal  47   c.    
     As shown in  FIG.  8   , one end of filter  11  and one end of filter  12  are both connected to selection terminal  47   b , and one end of filter  21  and one end of filter  22  are both connected to selection terminal  47   c . Filters  11  and  12  are included in multiplexer  31 , and filters  21  and  22  are included in multiplexer  32 . 
     Radio frequency module  1 C and antenna module  5 C with the above configurations enable: (1) an independent transfer of a signal in the first communication band; (2) an independent transfer of a signal in the second communication band; (3) an independent transfer of a signal in the third communication band; (4) an independent transfer of a signal in the fourth communication band; (5) a simultaneous transfer of a signal in the first communication band and a signal in the second communication band; and (6) a simultaneous transfer of a signal in the third communication band and a signal in the fourth communication band. 
     Here, as shown in  FIG.  6   , the frequency spacing between the first frequency range (first communication band) and the third frequency range (third communication band) is smaller than the frequency spacing between the first frequency range (first communication band) and the second frequency range (second communication band). Also, the frequency spacing between the second frequency range (second communication band) and the third frequency range (third communication band) is smaller than the frequency spacing between the first frequency range (first communication band) and the second frequency range (second communication band). Also, the frequency spacing between the fourth frequency range (fourth communication band) and the first frequency range (first communication band) is smaller than the frequency spacing between the fourth frequency range (fourth communication band) and the third frequency range (third communication band). Also, the frequency spacing between the third frequency range (third communication band) and the first frequency range (first communication band) is smaller than the frequency spacing between the fourth frequency range (fourth communication band) and the third frequency range (third communication band). 
     As such, for example, in the independent transfer of a signal in the first communication band, the signal in the first communication band can leak into the signal paths through which signals in the third communication band and the fourth communication band are transferred. Also, in the independent transfer of a signal in the second communication band, the signal in the second communication band can leak into the signal path through which a signal in the third communication band is transferred. Also, in the independent transfer of a signal in the third communication band, the signal in the third communication band can leak into the signal paths through which signals in the first communication band and the second communication band are transferred. In the independent transfer of a signal in the fourth communication band, the signal in the fourth communication band can leak into the signal path through which a signal in the first communication band is transferred. Furthermore, in the simultaneous transfer of a signal in the first communication band and a signal in the second communication band, the signal in the first communication band and the signal in the second communication band can leak into the signal path through which a signal in the third communication band is transferred. Also, in the simultaneous transfer of a signal in the third communication band and a signal in the fourth communication band, the signal in the third communication band and the signal in the fourth communication band can leak into the signal path through which a signal in the first communication band is transferred. 
     In view of the foregoing concerns, in radio frequency module  1 C according to the present embodiment, filters  11  and  12  are connected to selection terminal  47   b  of switch  47 , and filters  21  and  22  are connected to selection terminal  47   c  of switch  47 . Stated differently, in this configuration, filter  11  and filter  21  are not simultaneously connected because of the exclusive connection by switch  47 . This configuration thus achieves high isolation between filter  11  and filter  21 . Also, in this configuration, filter  12  and filter are not simultaneously connected because of the exclusive connection by switch  47 . This configuration thus achieves high isolation between filter  12  and filter  21 . Also, in this configuration, filter  11  and filter  22  are not simultaneously connected because of the exclusive connection by switch  47 . This configuration thus achieves high isolation between filter  11  and filter  22 . Also, in this configuration, filter  12  and filter  22  are not simultaneously connected because of the exclusive connection by switch  47 . This configuration thus achieves high isolation between filter  12  and filter  22 . 
     The foregoing configuration thus achieves high isolation between the signal path through which a signal in the first communication band is transferred and the signal path through which a signal in the third communication band is transferred in the independent transfer of a signal in the first communication band, thus enabling low-loss signal transfer. The foregoing configuration also achieves high isolation between the signal path through which a signal in the second communication band is transferred and the signal path through which a signal in the third communication band is transferred in the independent transfer of a signal in the second communication band, thus enabling a low-loss signal transfer. The foregoing configuration also achieves high isolation between the signal path through which a signal in the third communication band is transferred and the signal paths through which signals in the first communication band and the second communication band are transferred in the independent transfer of a signal in the third communication band, thus enabling a low-loss signal transfer. The foregoing configuration also achieves high isolation between the signal path through which a signal in the first communication band is transferred and the signal path through which a signal in the fourth communication band is transferred in the independent transfer of a signal in the fourth communication band, thus enabling a low-loss signal transfer. The foregoing configuration also achieves high isolation between the signal paths through which signals in the first communication band and the second communication band are transferred and the signal path through which a signal in the third communication band is transferred in the simultaneous transfer of a signal in the first communication band and a signal in the second communication band, thus enabling a low-loss signal transfer. The foregoing configuration also achieves high isolation between the signal paths through which signals in the third communication band and the fourth communication band are transferred and the signal path through which a signal in the first communication band is transferred in the simultaneous transfer of a signal in the third communication band and a signal in the fourth communication band, thus enabling a low-loss signal transfer. 
     In radio frequency module  1 B according to Embodiment 3 and radio frequency module  1 C according to Embodiment 4, filters  11 ,  12 ,  21 , and  22  may be disposed on the same board or inside of the same package. Also, radio frequency circuits  10  and  20 B may be disposed on the same board or inside of the same package. 
     This configuration achieves the downsizing of radio frequency modules  1 B and  1 C. 
     Alternatively, in radio frequency module  1 B according to Embodiment 3 and radio frequency module  1 C according to Embodiment 4, filters  11  and  12  may be disposed on a different board or inside of a different package from a board or a package on which or inside of which filters  21  and  22  are disposed. Also, radio frequency circuits  10  and  20 B may be disposed on different boards or inside of different packages. 
     This configuration further enhances the isolation between the signal paths of the first communication band and the second communication band and the signal paths of the third communication band and the fourth communication band. 
     In radio frequency module  1 B according to Embodiment 3 and radio frequency module  1 C according to Embodiment 4, for example, the first frequency range may include one of 3300 MHz to 4200 MHz and 3300 MHz to 3800 MHz, the second frequency range may include one of 5150 MHz to 5850 MHz and 5150 MHz to 7125 MHz, the third frequency range may include 4400 MHz to 5000 MHz, and the fourth frequency range may include 1700 MHz to 2700 MHz. In this case, for example, n77 or n78 of 5G-NR is applied to the first communication band, WLAN or NR-U (5.15 GHz to 7.125 GHz band) is applied to the second communication band, n79 or n78 of 5G-NR is applied to the third communication band, and one of n1 (transmission band: 1920 MHz to 1980 MHz, reception band: 2110 MHz to 2170 MHz), n3 (transmission band: 1710 MHz to 1785 MHz, reception band: 1805 MHz to 1880 MHz), and n41 (2496 MHz to 2690 MHz) of 5G-NR is applied to the fourth communication band. 
     With this configuration, in the simultaneous transfer of signals in the fourth communication band (n41 of 5G-NR) and the second communication band (WLAN), for example, the frequency range of WLAN (5.15 GHz to 7.125 GHz band) includes the frequency (5200 MHz) that is the second harmonic of a transmission signal in n41 of 5G-NR (e.g., the center frequency of 2600 MHz). In view of this, in radio frequency module  1 B according to Embodiment 3, two antennas  2 A and  2 B enable isolation between filter  12  that passes a signal in the second communication band and filter  22  that passes a signal in the fourth communication band. This configuration is thus capable of preventing the harmonic that is the second harmonic of a transmission signal in n41 of 5G-NR from entering a signal path in which filter  22  is disposed. This configuration thus prevents the degradation in the signal quality of a transmission signal in WLAN, and also attenuates the lowering of the receiving sensitivity of WLAN. 
     Also, in the simultaneous transfer of signals in the fourth communication band (n1 of 5G-NR) and the first communication band (n77 of 5G-NR), for example, the frequency range of n77 of 5G-NR (3300 MHz to 4200 MHz) includes the frequency (3900 MHz) that is the second harmonic of a transmission signal in n1 of 5G-NR (e.g., the center frequency of 1950 MHz). In view of this, in radio frequency module  1 B according to Embodiment 3, two antennas  2 A and  2 B enable isolation between filter  11  that passes a signal in the first communication band and filter  22  that passes a signal in the fourth communication band. This configuration is thus capable of preventing the harmonic that is the second harmonic of a transmission signal in n1 of 5G-NR from entering a signal path in which filter  11  is disposed. This configuration thus prevents the degradation in the signal quality of a transmission signal in n77 of 5G-NR, and also attenuates the lowering of the receiving sensitivity of n77 of 5G-NR. 
     Also, for example, in the simultaneous transfer of signals in the second communication band (WLAN) and the third communication band (n79 of 5G-NR), for example, the frequency range of WLAN (5150 MHz to 7125 MHz band) includes the third-order intermodulation distortion (2f2-f1) of a transmission signal in n79 of 5G-NR (e.g., the center frequency of f1 MHz) and a transmission signal in WLAN (e.g., the center frequency of f2 MHz). In view of this, in radio frequency module  1 B according to Embodiment 3, two antennas  2 A and  2 B enable isolation between filter  12  that passes a signal in the second communication band and filter  21  that passes a signal in the third communication band. This configuration is thus capable of preventing the foregoing third-order intermodulation distortion from entering a signal path in which filter  12  is disposed. This configuration thus prevents the degradation in the signal quality of a transmission signal in WLAN, and also attenuates the lowering of the receiving sensitivity of WLAN. 
     Also, for example, in the simultaneous transfer of signals in the first communication band (n77 of 5G-NR) and the fourth communication band (n41 of 5G-NR), for example, the frequency range of n77 of 5G-NR (3300 MHz to 4200 MHz band) includes the third-order intermodulation distortion (2f2-f1) of a transmission signal in n77 of 5G-NR (e.g., the center frequency of f2 MHz) and a transmission signal in n41 of 5G-NR (e.g., the center frequency of f1 MHz). In view of this, in radio frequency module  1 B according to Embodiment 3, two antennas  2 A and  2 B enable isolation between filter  11  that passes a signal in the first communication band and filter  22  that passes a signal in the fourth communication band. This configuration is thus capable of preventing the foregoing third-order intermodulation distortion from entering a signal path in which filter  11  is disposed. This configuration thus prevents the degradation in the signal quality of a transmission signal in n77 of 5G-NR, and also attenuates the lowering of the receiving sensitivity of n77 of 5G-NR. 
     In radio frequency module  1 B according to Embodiment 3 and radio frequency module  1 C according to Embodiment 4, for example, the first frequency range may be 4400 MHz to 5000 MHz, the second frequency range may be 5925 MHz to 7125 MHz, the third frequency range may be 5150 MHz to 5850 MHz, and the fourth frequency range may be 3300 MHz to 4200 MHz or 3300 MHz to 3800 MHz. In this case, for example, n79 of 5G-NR is applied to the first communication band, WLAN 6 GHz band (5935 MHz to 7125 MHz) or NR-U is applied to the second communication band, WLAN 5 GHz band (5150 MHz to 5725 MHz) or NR-U is applied to the third communication band, and n77 or n78 of 5G-NR is applied to the fourth communication band. 
     Note that WLAN 5 GHz band and WLAN 6 GHz band are compliant with IEEE 802.11, which is a wireless LAN standard. 
     With this configuration, in the simultaneous transfer of signals in the second communication band (WLAN 6 GHz band) and the fourth communication band (n78 of 5G-NR), for example, the frequency range of WLAN 6 GHz band (5935 MHz to 7125 MHz) includes the frequency (6600 MHz) that is the second harmonic of a transmission signal in n78 of 5G-NR (e.g., the center frequency of 3300 MHz). In view of this, in radio frequency module  1 B according to Embodiment 3, two antennas  2 A and  2 B enable isolation between filter  12  that passes a signal in the second communication band and filter  22  that passes a signal in the fourth communication band. This configuration is thus capable of preventing the harmonic that is the second harmonic of a transmission signal in n78 of 5G-NR from entering a signal path in which filter  12  is disposed. This configuration thus prevents the degradation in the signal quality of a transmission signal in WLAN 6 GHz band, and also attenuates the lowering of the receiving sensitivity of WLAN 6 GHz band. 
     Also, for example, in the simultaneous transfer of signals in the first communication band (n79 of 5G-NR) and the third communication band (WLAN 5 GHz band), for example, the frequency range of WLAN 5 GHz band (5150 MHz to 5725 MHz band) includes the third-order intermodulation distortion (2f2-f1) of a transmission signal in n79 of 5G-NR (e.g., the center frequency of f1 MHz) and a transmission signal in WLAN 5 GHz band (e.g., the center frequency of f2 MHz). In view of this, in radio frequency module  1 B according to Embodiment 3, two antennas  2 A and  2 B enable isolation between filter  11  that passes a signal in the first communication band and filter  21  that passes a signal in the third communication band. This configuration is thus capable of preventing the foregoing third-order intermodulation distortion from entering a signal path in which filter  21  is disposed. This configuration thus prevents the degradation in the signal quality of a transmission signal in WLAN 5 GHz band, and also attenuates the lowering of the receiving sensitivity of WLAN 5 GHz band. 
     Embodiment 5 
     While radio frequency module  1 C according to Embodiment 4 has the circuit configuration for transferring signals in the first through fourth communication bands, radio frequency module  1 D according to the present embodiment has a configuration that further includes a circuit for transferring signals in a fifth communication band. 
       FIG.  9    is a diagram showing the circuit configurations of radio frequency module  1 D and antenna module  5 D according to Embodiment 5. 
     Antenna module  5 D includes antenna  2  and radio frequency module  1 D. Antenna module  5 D according to the present embodiment is different from antenna module  5 C according to Embodiment 4 in that radio frequency circuit  20 D further includes filter  23  and in the connection of radio frequency circuits  10 D and  20 D. The following omits the descriptions of the same points as those of antenna module  5 C and radio frequency module  1 C according to Embodiment 4 and focuses on the differences to describe antenna module  5 D and radio frequency module  1 D according to the present embodiment. 
     Antenna  2  is connected to switch  47  of radio frequency module  1 D. Antenna  2  transmits a radio frequency signal output from radio frequency circuit  10 D or  20 D. Antenna  2  also receives a radio frequency signal from outside, and outputs the received radio frequency signal to radio frequency circuit  10 D or  20 D. 
     As shown in  FIG.  9   , radio frequency module  1 D includes antenna connection terminal  100 , radio frequency circuits  10 D and  20 D, and switch  47 . 
     As shown in  FIG.  9   , one end of filter  11  and one end of filter  12  are both connected to selection terminal  47   b , and one end of filter  21 , one end of filter  22 , and one end of filter  23  are all connected to selection terminal  47   c . Filters  11  and  12  are included in multiplexer  31 , and filters  21 ,  22 , and  23  are included in multiplexer  33 . 
     Radio frequency circuit  10 D includes filters  11  and  12 , power amplifiers  51 T and  52 T, low-noise amplifiers  51 R and  52 R, and switches  48  and  49 . Radio frequency circuit  20 D includes filters  21 ,  22 , and  23 , power amplifier  53 T, low-noise amplifier  53 R, and switch  43 . 
     Filter  23 , which is an exemplary fifth filter, is connected to selection terminal  47   c . Filter  23  is a radio frequency filter having a passband which is a fifth frequency range that includes the fifth communication band. 
     Radio frequency module  1 D and antenna module  5 D with the above configurations enable: (1) an independent transfer of a signal in the first communication band; (2) an independent transfer of a signal in the second communication band; (3) an independent transfer of a signal in the third communication band; (4) an independent transfer of a signal in the fourth communication band; (5) an independent transfer of a signal in the fifth communication band; (6) a simultaneous transfer of a signal in the first communication band and a signal in the second communication band; (7) a simultaneous transfer of a signal in the third communication band and a signal in the fourth communication band; (8) a simultaneous transfer of a signal in the third communication band and a signal in the fifth communication band; (9) a simultaneous transfer of a signal in the fourth communication band and a signal in the fifth communication band; and (10) a simultaneous transfer of a signal in the third communication band, a signal in the fourth communication band, and a signal in the fifth communication band. 
       FIG.  10    is a diagram showing a relationship of the frequencies of the passbands of the filters included in radio frequency module  1 D according to Embodiment 5. The drawing shows the relationship of the frequencies of the first communication band, second communication band, third communication band, fourth communication band, and fifth communication band, and filters  11 ,  12 ,  21 ,  22 , and  23 . In the present embodiment, the fourth communication band, first communication band, third communication band, second communication band, and fifth communication band are located in the stated order from the lower frequency side. Accordingly, the fourth frequency range that includes the fourth communication band, the first frequency range that includes the first communication band, the third frequency range that includes the third communication band, the second frequency range that includes the second communication band, and the fifth frequency range that includes the fifth communication band are located in the stated order from the lower frequency side. Stated differently, the third frequency range is located between the first frequency range and the second frequency range. Note that the third frequency range may overlap the first frequency range and the second frequency range; at least part of the third frequency range is simply required to be located between the first frequency range and the second frequency range. Also, the fourth frequency range is lower than the first frequency range. Note that the fourth frequency range may overlap the first frequency range. Also, the fifth frequency range is higher than the second frequency range. Note that the fifth frequency range may overlap the second frequency range. Accordingly, at least part of the passband of filter  21  is located between the passband of filter  11  and the passband of filter  12 . Also, the passband of filter  22  is lower than the passband of filter  11 . Also, the passband of filter  23  is higher than the passband of filter  12 . 
     In radio frequency module  1 D according to the present embodiment, filters  11  and  12  are connected to selection terminal  47   b  of switch  47 , and filters  21 ,  22 , and  23  are connected to selection terminal  47   c  of switch  47 . Stated differently, filter  11  and filter  21  are not simultaneously connected because of the exclusive connection by switch  47 . This configuration thus achieves high isolation between filter  11  and filter  21 . Also, in this configuration, filter  12  and filter  21  are not simultaneously connected because of the exclusive connection by switch  47 . This configuration thus achieves high isolation between filter  12  and filter  21 . In this configuration, filter  11  and filter  22  are not simultaneously connected because of the exclusive connection by switch  47 . This configuration thus achieves high isolation between filter  11  and filter  22 . Also, in this configuration, filter  12  and filter  22  are not simultaneously connected because of the exclusive connection by switch  47 . This configuration thus achieves high isolation between filter  12  and filter  22 . In this configuration, filter  11  and filter  23  are not simultaneously connected because of the exclusive connection by switch  47 . This configuration thus achieves high isolation between filter  11  and filter  23 . Also, in this configuration, filter  12  and filter  23  are not simultaneously connected because of the exclusive connection by switch  47 . This configuration thus achieves high isolation between filter  12  and filter  23 . 
     The foregoing configuration also achieves high isolation between a signal path through which a signal in the fifth communication band is transferred and the signal path through which a signal in the first communication band is transferred in the independent transfer of a signal in the fifth communication band, thus enabling a low-loss signal transfer. The foregoing configuration also achieves high isolation between the signal paths through which signals in the third communication band, the fourth communication band, and the fifth communication band are transferred and the signal path through which a signal in the first communication band is transferred in the simultaneous transfer of a signal in the third communication band, a signal in the fourth communication band, and a signal in the fifth communication band, thus enabling a low-loss signal transfer. 
     In radio frequency module  1 D according to Embodiment 5, for example, n77 or n78 of 5G-NR is applied to the first communication band, WLAN (5150 MHz or greater) is applied to the second communication band, n79 of 5G-NR is applied to the third communication band, n78 of 5G-NR is applied to the fourth communication band, and WLAN (5470 MHz or greater) is applied to the fifth communication band. 
     The following describes circuit components other than the filters included in radio frequency circuits  10 D and  20 D. 
     Power amplifier  51 T is a transmission amplifier that amplifies a transmission signal in the first frequency range that includes the first communication band and a transmission signal in the fourth frequency range that includes the fourth communication band. The input terminal of power amplifier  51 T is connected to transmission input terminal  110 . Low-noise amplifier  51 R is a reception amplifier that amplifies a reception signal in the first frequency range that includes the first communication band and a reception signal in the fourth frequency range that includes the fourth communication band. The output terminal of low-noise amplifier  51 R is connected to reception output terminal  120 . 
     Power amplifier  53 T is a transmission amplifier that amplifies a transmission signal in the third frequency range that includes the third communication band. The input terminal of power amplifier  53 T is connected to transmission input terminal  210 . Low-noise amplifier  53 R is a reception amplifier that amplifies a reception signal in the third frequency range that includes the third communication band. The output terminal of low-noise amplifier  53 R is connected to reception output terminal  220 . 
     Switch  43  includes common terminal  43   a , and selection terminals  43   b  and  43   c . Switch  43  exclusively switches between connecting common terminal  43   a  and selection terminal  43   b  and connecting common terminal  43   a  and selection terminal  43   c . Common terminal  43   a  is connected to the other end of filter  21 , selection terminal  43   b  to the output terminal of power amplifier  53 T, and selection terminal  43   c  to the input terminal of low-noise amplifier  53 R. Switch  43  performs the switching operation to enable radio frequency circuit  20 D to transfer a transmission signal in the third communication band and a reception signal in the third communication band in different time slots. 
     Switch  48 , which is an example of the second switch, includes common terminal  48   a , selection terminal  48   b  (third selection terminal), selection terminal  48   c  (fourth selection terminal), selection terminal  48   d  (fifth selection terminal), and selection terminal  48   e  (fifth selection terminal). Selection terminal  48   b  is connected to filter  11 , selection terminal  48   c  to filter  22 , selection terminal  48   d  to the output terminal of power amplifier  51 T, and selection terminal  48   e  to the input terminal of low-noise amplifier  51 R. Switch  48  switches between connecting common terminal  48   a  and selection terminal  48   b  and connecting common terminal  48   a  and selection terminal  48   c , and switches between connecting common terminal  48   a  and selection terminal  48   d  and connecting common terminal  48   a  and selection terminal  48   e . Having this connection structure, switch  48  switches between connecting filter  11  and power amplifier  51 T and connecting filter  22  and power amplifier  51 T, and also switches between connecting filter  11  and low-noise amplifier  51 R and connecting filter  22  and low-noise amplifier  51 R. Switch  48  is, for example, a switch circuit that includes a single pole double throw (SPDT) sub-switch including common terminal  48   a , and selection terminals  48   b  and  48   c , and an SPDT sub-switch including common terminal  48   a , and selection terminals  48   d  and  48   e , where common terminals  48   a  of these two sub-switches are connected. 
     Switch  49  includes common terminal  49   a , and selection terminals  49   b ,  49   c ,  49   d , and  49   e . Selection terminal  49   b  is connected to filter  12 , selection terminal  49   c  to filter  23 , selection terminal  49   d  to the output terminal of power amplifier  52 T, and selection terminal  49   e  to the input terminal of low-noise amplifier  52 R. Switch  49  switches between connecting common terminal  49   a  and selection terminal  49   b  and connecting common terminal  49   a  and selection terminal  49   c , and switches between connecting common terminal  49   a  and selection terminal  49   d  and connecting common terminal  49   a  and selection terminal  49   e . Having this connection structure, switch  49  exclusively switches between connecting filter  12  and power amplifier  52 T and connecting filter  23  and power amplifier  52 T, and also exclusively switches between connecting filter  12  and low-noise amplifier  54 R and connecting filter  23  and low-noise amplifier  54 R. Switch  49  is, for example, a switch circuit that includes an SPDT sub-switch including common terminal  49   a , and selection terminals  49   b  and  49   c , and an SPDT sub-switch including common terminal  49   a , and selection terminals  49   d  and  49   e , where common terminals  49   a  of these two sub-switches are connected. 
       FIG.  11 A  is a diagram showing the circuit configuration of radio frequency module  1 D according to Embodiment 5 in a first connection status. As shown  FIG.  11 A , under a condition that common terminal  47   a  and selection terminal  47   b  are connected in switch  47 , one of the following operations is performed: (1) an independent transfer of a signal in the first communication band; (2) an independent transfer of a signal in the second communication band; and (6) a simultaneous transfer of a signal in the first communication band and a signal in the second communication band. For operation (1), common terminal  48   a  and selection terminal  48   b  are connected. For operation (2), common terminal  49   a  and selection terminal  49   b  are connected. For operation (6), common terminal  48   a  and selection terminal  48   b  are connected, and common terminal  49   a  and selection terminal  49   b  are connected. 
     When in the first connection status described above, for example, radio frequency module  1 D is capable of simultaneously transferring a radio frequency signal in n77 or n78 of 5G-NR and a radio frequency signal in WLAN (5150 MHz or greater) by use of multiplexer  31 , under a condition that n79 of 5G-NR is not in use. Here, n78 of 5G-NR, which is the fourth communication band, is also usable. 
       FIG.  11 B  is a diagram showing the circuit configuration of radio frequency module  1 D according to Embodiment 5 in a second connection status. As shown  FIG.  11 B , when common terminal  47   a  and selection terminal  47   c  are connected in switch  47 , one of the following operations is performed: (3) an independent transfer of a signal in the third communication band; (4) an independent transfer of a signal in the fourth communication band; (5) an independent transfer of a signal in the fifth communication band; (7) a simultaneous transfer of a signal in the third communication band and a signal in the fourth communication band; (8) a simultaneous transfer of a signal in the third communication band and a signal in the fifth communication band; (9) a simultaneous transfer of a signal in the fourth communication band and a signal in the fifth communication band; or (10) a simultaneous transfer of a signal in the third communication band, a signal in the fourth communication band, and a signal in the fifth communication band. For operations (4) and (7), common terminal  48   a  and selection terminal  48   c  are connected. For operations (5) and (8), common terminal  49   a  and selection terminal  49   c  are connected. For operations (9) and (10), common terminal  48   a  and selection terminal  48   c  are connected, and common terminal  49   a  and selection terminal  49   c  are connected. 
     When in the second connection status described above, for example, radio frequency module  1 D is capable of simultaneously transferring a radio frequency signal in n79 of 5G-NR, a radio frequency signal in n78 of 5G-NR, and a radio frequency signal in WLAN (5470 MHz or greater) by use of multiplexer  33 , under a condition that n79 of 5G-NR is in use. 
     Note that filters  21 ,  22 , and  23  included in multiplexer  33  may each be a single-chip LC filter. Also, multiplexer  33  may be a single-chip LC triplexer. Also, multiplexer  33  may include a single-chip LC diplexer and a single-chip LC filter. 
     Alternatively, multiplexer  33  may have a configuration as shown, for example, in  FIG.  12   . 
       FIG.  12    is a diagram showing the circuit configuration of radio frequency module  1 E according to a variation of Embodiment 5. As shown in  FIG.  12   , radio frequency module  1 E according to the present variation may include a first diplexer including filters  21  and  24 , and a second diplexer including filters  25  and  26 , instead of multiplexer  33  included in radio frequency module  1 D. One end of filter  21  and one end of filter  24  are connected to selection terminal  47   c , the other end of filter  24  is connected to one end of filter  25  and one end of filter  26 , the other end of filter  25  is connected to selection terminal  48   c , and the other end of filter  26  is connected to selection terminal  49   c.    
     Filter  21  is a filter having a passband which is the third frequency range that includes the third communication band. Filter  24  is a filter having passbands which are the fourth frequency range that includes the fourth communication band and the fifth frequency range that includes the fifth communication band. Also, Filter  25  is a filter having a passband which is the fourth frequency range that includes the fourth communication band, and filter  26  is a filter having a passband which is the fifth frequency range that includes the fifth communication band. 
     Note that radio frequency module  1 E according to the variation of Embodiment 5 that eliminates switch  47  may also be included in the present disclosure. Stated differently, the radio frequency module according to the present disclosure may include: antenna connection terminal  100 ; antenna connection terminal  200  different from antenna connection terminal  100 ; filter  11  having a passband which is the first frequency range that includes the first communication band for TDD; filter  12  having a passband which is the second frequency range that includes the second communication band for TDD; filter  21  having a passband which is the third frequency range that includes the third communication band for TDD; filter  22  having a passband which is the fourth frequency range that includes the fourth communication band for TDD; filter  23  having a passband which is the fifth frequency range that includes the fifth communication band for TDD. Here, the fourth frequency range may be lower than the first frequency range, the second frequency range, and the third frequency range. The fifth frequency range may be higher than the first frequency range, the second frequency range, the third frequency range, and the fourth frequency range. Filters  11  and  12  may be connected to antenna connection terminal  100 , and filters  21 ,  22 , and  23  may be connected to antenna connection terminal  200 . 
     This configuration, in which filters  11  and  21  are not connected to the same antenna connection terminal, achieves high isolation between filters  11  and  21 . Also, this configuration, in which filters  12  and  21  are not connected to the same antenna connection terminal, achieves high isolation between filters  12  and  21 . Also, this configuration, in which filters  11  and  22  are not connected to the same antenna connection terminal, achieves high isolation between filters  11  and  22 . Also, this configuration, in which filters  12  and  22  are not connected to the same antenna connection terminal, achieves high isolation between filters  12  and  22 . Also, this configuration, in which filters  11  and  23  are not connected to the same antenna connection terminal, achieves high isolation between filters  11  and  23 . Also, this configuration, in which filters  12  and  23  are not connected to the same antenna connection terminal, achieves high isolation between filters  12  and  23 . 
     As described above, radio frequency modules  1  and  1 B each include: antenna connection terminal  100 ; antenna connection terminal  200  different from antenna connection terminal  100 ; filter  11  having a passband which is a first frequency range that includes a first communication band for TDD; filter  12  having a passband which is a second frequency range that includes a second communication band for TDD; and filter  21  having a passband which is a third frequency range that includes a third communication band for TDD. Here, at least part of the third frequency range is located between the first frequency range and the second frequency range, and filters  11  and  12  are both connected to one of antenna connection terminals  100  and  200 , and filter  21  is connected to a remaining one of antenna connection terminals  100  and  200 . 
     This configuration, in which filter  11  and filter  21  are connected to different antennas, achieves high isolation between a signal in the first communication band that passes through filter  11  and a signal in the third communication band that passes through filter  21 . Also, this configuration, in which filter  12  and filter  21  are connected to different antennas, achieves high isolation between a signal in the second communication band that passes through filter  12  and a signal in the third communication band that passes through filter  21 . 
     The foregoing configuration achieves high isolation between two signals to be simultaneously transferred, that is: a signal in the first communication band and a signal in the third communication band; or a signal in the second communication band and a signal in the third communication band. This configuration thus enables low-loss signal transfer. The foregoing configuration also enables low-loss signal transfer in the independent transfer of a signal in the first communication band, in the independent transfer of a signal in the second communication band, and in the independent transfer of a signal in the third communication band, and in the simultaneous transfer of a signal in the first communication band and a signal in the second communication band. 
     The radio frequency module according to a variation of Embodiment 1 may further include: switch  45  that includes common terminals  45   a  and  45   b  and selection terminals  45   c  and  45   d , and connects common terminal  45   a  exclusively to selection terminal  45   c  or  45   d , and connects common terminal  45   b  exclusively to selection terminal  45   c  or  45   d . Here, common terminal  45   a  may be connected to the one of antenna connection terminals  100  and  200 , common terminal  45   b  may be connected to the remaining one of antenna connection terminals  100  and  200 , selection terminal  45   c  may be connected to filters  11  and  12 , selection terminal  45   d  may be connected to filter  21 , and filters  11  and  12  may be both connected to one of antenna connection terminals  100  and  200  via selection terminal  45   c , and filter  21  may be connected to a remaining one of antenna connection terminals  100  and  200  via selection terminal  45   d.    
     This configuration, in which filter  11  and filter  21  are connected to different antennas, achieves high isolation between a signal in the first communication band that passes through filter  11  and a signal in the third communication band that passes through filter  21 . Also, this configuration, in which filter  12  and filter  21  are connected to different antennas, achieves high isolation between a signal in the second communication band that passes through filter  12  and a signal in the third communication band that passes through filter  21 . 
     Radio frequency module  1 B according to Embodiment 3 may further include: filter  22  having a passband which is a fourth frequency range that includes a fourth communication band, filter  22  being connected to the remaining one of antenna connection terminals  100  and  200 . Here, the fourth frequency range may be lower or higher than the first frequency range, the second frequency range, and the third frequency range. 
     This configuration, in which filter  21  and filter  11  are connected to different antennas, achieves high isolation between a signal in the third communication band that passes through filter  21  and a signal in the first communication band that passes through filter  11 . Also, this configuration, in which filter  21  and filter  12  are connected to different antennas, achieves high isolation between a signal in the third communication band that passes through filter  21  and a signal in the second communication band that passes through filter  12 . Also, this configuration, in which filter  22  and filter  11  are connected to different antennas, achieves high isolation between a signal in the fourth communication band that passes through filter  22  and a signal in the first communication band that passes through filter  11 . Also, this configuration, in which filter  22  and filter  12  are connected to different antennas, achieves high isolation between a signal in the fourth communication band that passes through filter  22  and a signal in the second communication band that passes through filter  12 . 
     The foregoing configuration achieves high isolation between two signals to be simultaneous transferred, that is: a signal in the first communication band and a signal in the third communication band; a signal in the first communication band and a signal in the fourth communication band; a signal in the second communication band and a signal in the third communication band; or a signal in the second communication band and a signal in the fourth communication band. This configuration thus enables low-loss signal transfer. The foregoing configuration also enables low-loss signal transfer in the independent transfer of a signal in the first communication band, in the independent transfer of a signal in the second communication band, in the independent transfer of a signal in the third communication band, in the independent transfer of a signal in the fourth communication band, in the simultaneous transfer of a signal in the first communication band and a signal in the second communication band, and in the simultaneous transfer of a signal in the third communication band and a signal in the fourth communication band. 
     Also, each of radio frequency modules  1  and  1 B may further include: antenna  2 A connected to antenna connection terminal  100 ; and antenna  2 B connected antenna connection terminal  200 . 
     Also, radio frequency module  1 A according to Embodiment 3 may further include: antenna connection terminal  100 ; switch  40  that includes selection terminals  40   b  and  40   c  and common terminal  40   a  that is connected to antenna connection terminal  100 , and exclusively switches between connecting common terminal  40   a  and selection terminal  40   b  and connecting common terminal  40   a  and selection terminal  40   c ; filter  11  having a passband which is a first frequency range that includes a first communication band for TDD, filter  11  being connected to selection terminal  40   b ; filter  12  having a passband which is a second frequency range that includes a second communication band for TDD, filter  12  being connected to selection terminal  40   b ; and filter  21  having a passband which is a third frequency range that includes a third communication band for TDD, filter  21  being connected to selection terminal  40   c . Here, at least part of the third frequency range may be located between the first frequency range and the second frequency range. 
     In this configuration, filter  11  and filter  21  are not simultaneously connected because of the exclusive connection by switch  40 . This configuration thus achieves high isolation between filter  11  and filter  21 . Also, in this configuration, filter  12  and filter are not simultaneously connected because of the exclusive connection by switch  40 . This configuration thus achieves high isolation between filter  12  and filter  21 . 
     The foregoing configuration thus enables low-loss signal transfer in the independent transfer of a signal in the first communication band, in the independent transfer of a signal in the second communication band, and in the independent transfer of a signal in the third communication band. The foregoing configuration also achieves high isolation between the signal paths through which signals in the first communication band and the second communication band are transferred and the signal path through which a signal in the third communication band is transferred in the simultaneous transfer of a signal in the first communication band and a signal in the second communication band, thus enabling a low-loss signal transfer. 
     Also, radio frequency module  1 C according to Embodiment 4 may further include: filter  22  having a passband which is a fourth frequency range that includes a fourth communication band, filter  22  being connected to selection terminal  47   c . Here, the fourth frequency range may be lower or higher than the first frequency range, the second frequency range, and the third frequency range. 
     In this configuration, filter  11  and filter  22  are not simultaneously connected because of the exclusive connection by switch  47 . This configuration thus achieves high isolation between filter  11  and filter  22 . Also, in this configuration, filter  12  and filter are not simultaneously connected because of the exclusive connection by switch  47 . This configuration thus achieves high isolation between filter  12  and filter  22 . 
     The foregoing configuration thus enables a low-loss signal transfer in the independent transfer of a signal in the first communication band, in the independent transfer of a signal in the second communication band, in the independent transfer of a signal in the third communication band, and in the independent transfer of a signal in the fourth communication band. The foregoing configuration also achieves high isolation between the signal paths through signals in the third communication band and the fourth communication band are transferred and the signal path through which a signal in the first communication band is transferred in the simultaneous transfer of a signal in the third communication band and a signal in the fourth communication band, thus enabling a low-loss signal transfer. 
     Also, each of radio frequency modules  1 A and  1 C may further include: antenna  2  connected to antenna connection terminal  100 . 
     Also, radio frequency module  1 D according to Embodiment 5 may further include: filter  23  having a passband which is a fifth frequency range that includes a fifth communication band, filter  23  being connected to selection terminal  47   c ; power amplifier  51 T that amplifies radio frequency signals in the first communication band and the fourth communication band; and switch  48  that includes selection terminal  48   b  connected to filter  11 , selection terminal  48   c  connected to filter  22 , and selection terminal  48   d  connected to power amplifier  51 T, and exclusively switches between connecting selection terminal  48   d  and selection terminal  48   b  and connecting selection terminal  48   d  and selection terminal  48   c . Here, the fourth frequency range may be lower than the first frequency range, the second frequency range, and the third frequency range, and the fifth frequency range may be higher than the first frequency range, the second frequency range, the third frequency range, and the fourth frequency range. 
     Here, filters  11 ,  12 , and  21  may be disposed on the same board or inside of the same package. 
     This configuration achieves the downsizing of radio frequency modules  1 ,  1 A,  1 B, and  1 C. 
     Here, filters  11  and  12  may be disposed on a different board or inside of a different package from a board or a package on which or inside of which filter  21  is disposed. 
     This configuration further enhances the isolation between the signal paths of the first communication band and the second communication band and the signal path of the third communication band. 
     Also, communication device  6  includes: one of radio frequency modules  1 ,  1 A,  1 B, and  1 C; and RFIC  3  that processes a radio frequency signal transferred by such radio frequency module. 
     This configuration provides communication device  6  that enables low-loss transfer of signals in TDD communication bands. 
     Another Embodiment 
     The radio frequency module and the communication device according to the present disclosure have been described above using embodiments and variations thereof, but the present disclosure is not limited to the foregoing embodiments and variations. The present disclosure also includes: another embodiment achieved by freely combining structural elements in the foregoing embodiments and variations; variations achieved by making various modifications to the foregoing embodiments that can be conceived by those skilled in the art without departing from the essence of the present disclosure; and various devices that include the radio frequency module and the communication device according to the present disclosure. 
     In the multiplexer, front-end circuit, and communication device in the foregoing embodiments and variations, for example, a matching element such as an inductor and a capacitor, and a switch circuit may be connected between circuit elements. Note that the inductor may include a wiring inductor implemented as wiring that connects circuit elements. 
     Note that filters  11 ,  12 ,  21 , and  22  according to the foregoing embodiments and variations are, for example, acoustic wave filters and LC filters having any filter structures. Here, an acoustic wave filter is a filter having an acoustic wave resonator. Also, an LC filter is defined as a filter having a passband which includes one or more inductors and one or more capacitors. Such LC filter may thus include an acoustic wave resonator for forming an attenuation pole that is present outside of the passband. 
     Although only some exemplary embodiments of the present disclosure have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of the present disclosure. Accordingly, all such modifications are intended to be included within the scope of the present disclosure. 
     The present disclosure is widely applicable for use in communication equipment, such as a mobile phone, as a multiplexer, a front-end circuit, and a communication device that can be applied in a multiband system that includes 5G-NR communication bands.