Patent Publication Number: US-2023155611-A1

Title: Radio frequency module and communication device

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This is a continuation of International Application No. PCT/JP2021/028535 filed on Aug. 2, 2021 which claims priority from Japanese Patent Application No. 2020-136565 filed on Aug. 13, 2020. The contents of these applications are incorporated herein by reference in their entireties. 
    
    
     BACKGROUND ART 
     Technical Field 
     The present disclosure relates to radio frequency modules and communication devices. 
     In mobile communication devices such as mobile phones and the like, particularly, with developments of multiband systems, the layout configuration of circuit elements making up a radio frequency front-end circuit becomes more complicated. 
     Patent Document 1 discloses a front-end circuit capable of performing communications using a plurality of communication bands (frequency bands). Specifically, the front-end circuit has a first transmit path in which a first power amplifier, a first band selection switch, a plurality of duplexers each corresponding to each communication band, and an antenna switch are connected in this order, and a second transmit path in which a second power amplifier, a second band selection switch, a plurality of duplexers each corresponding to each communication band, and the antenna switch are connected in this order. 
     Patent Document 1: U.S. Patent Application Publication No. 2019/190548 
     BRIEF SUMMARY 
     However, it is conceivable that the front-end circuit disclosed in Patent Document 1 has both a FDD signal path transmitting a signal of a communication band for frequency division duplex (FDD) and a TDD signal path transmitting a signal of a communication band for time division duplex (TDD), and includes different transmit power amplifiers for the FDD signal path and the TDD signal path and a same receive low noise amplifier. In this case, when transmitting and receiving a signal of the communication band for FDD, there is an issue of degrading receiver sensitivity in the FDD signal path because an unwanted wave from the transmit power amplifier flows into the receive low noise amplifier via the TDD signal path due to coupling between output matching circuits of the different transmit power amplifiers. 
     The present disclosure provides a radio frequency module and a communication device, in each of which the degradation of receiver sensitivity in the FDD signal path is suppressed. 
     A radio frequency module according to one aspect of the present disclosure includes: a first transmit filter having a pass band that includes an uplink operation band of a first communication band for FDD; a first receive filter having a pass band that includes a downlink operation band of the first communication band; a second filter having a pass band that includes a second communication band for TDD; a first power amplifier capable of amplifying a transmit signal of the first communication band; a second power amplifier capable of amplifying a transmit signal of the second communication band; a low noise amplifier capable of amplifying a receive signal of the first communication band and a receive signal of the second communication band; a first switch that switches between connecting the first receive filter to the low noise amplifier and connecting the second filter to the low noise amplifier; a second switch that switches between connecting the second filter to the second power amplifier and connecting the second filter to the low noise amplifier; a first impedance matching circuit connected between the first power amplifier and the first transmit filter; a second impedance matching circuit connected between the second power amplifier and the second switch; and a module board having a principal surface. The first power amplifier, the second power amplifier, the second switch, the first impedance matching circuit, and the second impedance matching circuit are arranged on the principal surface, and in a plan view of the module board, each of the first power amplifier, the second power amplifier, and the second switch is arranged in between the first impedance matching circuit and the second impedance matching circuit. 
     According to the present disclosure, it becomes possible to provide a radio frequency module and a communication device, in each of which the degradation of receiver sensitivity in the FDD path is suppressed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a circuit configuration diagram of a radio frequency module and a communication device according to an embodiment. 
         FIG.  2    is a diagram illustrating flows of signals of FDD transmission in the radio frequency module and the communication device according to the embodiment. 
         FIG.  3    is a plan view of the radio frequency module according to the embodiment. 
         FIG.  4    is a plan view of a radio frequency module according to a modified example 1 of the embodiment. 
         FIG.  5    is a plan view of a radio frequency module according to a modified example 2 of the embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the embodiments which will be described below each illustrates a comprehensive or specific example. Numeric values, shapes, materials, constituent elements, arrangements and connection modes of the constituent elements, and the like illustrated in the following embodiments are mere examples, and not intended to limit the present disclosure. 
     Note that each drawing is a schematic diagram in which emphasis, omission, or ratio adjustment is performed if appropriate to illustrate the present disclosure and is not precisely drawn, and in some cases, the shape, spatial relationship, and ratio are different from the actual ones. In all the drawing, same reference characters are attached to substantially the same constituent elements, and in some cases, an overlapping description is omitted or simplified. 
     In each of the following drawings, the x-axis and y-axis are axes orthogonal to each other on a plane parallel to a principal surface of a module board. Further, the z-axis is an axis vertical to the principal surface of the module board, the positive direction thereof indicates up direction, and the negative direction thereof indicates down direction. 
     Further, in the circuit configuration of the present disclosure, the term “being connected” is defined to include not only the case of being directly connected via a connection terminal and/or a wiring conductor but also include the case of being electrically connected via another circuit element. Further, the term “to be connected between A and B” means to be connected to both A and B in between A and B. 
     Further, in the module configuration of the present disclosure, a “plan view” means that an object is viewed using orthographic projection onto the x-y plane from the positive side of the z-axis. The term “a component is arranged on a principal surface of a board” is defined to include not only the case where a component is arranged on a principal surface of a board while the component is touching the principal surface of the board but also the case where the component is arranged above the principal surface of the board without necessarily touching the principal surface of the board and the case where the component is arranged on the board in such a way that part of the component is buried into the board from the principal surface side. The term “A is arranged between B and C” means that at least one of lines each connecting an arbitrary point in B and an arbitrary point in C goes through A. Further, terms indicating relationships among elements, such as “parallel”, “vertical”, and the like and terms indicating shapes of elements such as “rectangle” and the like are used not only to represent their precise meanings but also include their substantially equivalent ranges, for example, errors of about few %. 
     Embodiment 
     1 Circuit Configuration of Radio Frequency Module  1  and Communication Device  5   
     A circuit configuration of a radio frequency module  1  and a communication device  5  according to the present embodiment is described with reference to  FIG.  1   .  FIG.  1    is a circuit configuration diagram of the radio frequency module  1  and the communication device  5  according to the embodiment. 
     1.1 Circuit Configuration of Communication Device  5   
     First, the circuit configuration of the communication device  5  is described. As illustrated in  FIG.  1   , the communication device  5  according to the present embodiment includes the radio frequency module  1 , an antenna  2 , a RF signal processing circuit (RFIC)  3 , and a base band signal processing circuit (BBIC)  4 . 
     The radio frequency module  1  transmits radio frequency signals between the antenna  2  and the RFIC  3 . The radio frequency module  1  can be used as a module that can transmit and receive a radio frequency signal of TDD and that can transmit and receive a radio frequency signal of FDD. The circuit configuration of the radio frequency module  1  will be described later in detail. 
     The antenna  2  is connected to an antenna connection terminal  100  of the radio frequency module  1 , transmits a radio frequency signal output from the radio frequency module  1 , receives a radio frequency signal from outside, and outputs the received radio frequency signal to the radio frequency module  1 . 
     The RFIC  3  is one example of a signal processing circuit that performs processing on a radio frequency signal. Specifically, the RFIC  3  performs signal processing on a radio frequency receive signal input via a receive path of the radio frequency module  1  using down-converting and the like, and outputs a receive signal generated by this signal processing to the BBIC  4 . Further, the RFIC  3  performs signal processing on a transmit signal input from the BBIC  4  using up-converting and the like, and outputs a radio frequency transmit signal generated by this signal processing to a transmit path of the radio frequency module  1  via an amplifier circuit and the like. Further, the RFIC  3  includes a control part that controls switches, amplifiers, and the like included in the radio frequency module  1 . Note that part or all of the functions of the control part of the RFIC  3  may be installed outside of the RFIC  3 . For example, part or all of the functions of the control part of the RFIC  3  may be installed in the BBIC  4  or the radio frequency module  1 . 
     The BBIC  4  is a base band signal processing circuit that performs signal processing using an intermediate frequency band, which is lower in frequency than a radio frequency signal being transmitted by the radio frequency module  1 . As the signal to be processed in the BBIC  4 , for example, an image signal for image display and/or an audio signal for communication through a speaker is used. 
     Note that in the communication device  5  according to the present embodiment, the antenna  2  and the BBIC  4  are optional constituent elements. 
     1.2 Circuit Configuration of Radio Frequency Module  1   
     Next, the circuit configuration of the radio frequency module  1  is described. As illustrated in  FIG.  1   , the radio frequency module  1  includes a transmit filter  11 , a receive filter  12 , a filter  20 , power amplifiers  15  and  25 , a low noise amplifier  35 , switches  40 ,  41 , and  42 , matching circuits (MN)  13 ,  23 , and  33 , the antenna connection terminal  100 , transmit input terminals  110  and  120 , and a receive output terminal  130 . 
     The antenna connection terminal  100  is connected to the antenna  2 . 
     The transmit input terminal  110  is a terminal for receiving a transmit signal from outside of the radio frequency module  1 . Specifically, the transmit input terminal  110  is a terminal for receiving a transmit signal of a communication band A for FDD. The transmit input terminal  120  is a terminal for receiving a transmit signal from outside of the radio frequency module  1 . Specifically, the transmit input terminal  120  is a terminal for receiving a transmit signal of a communication band B for TDD. The receive output terminal  130  is a terminal for supplying a receive signal to outside of the radio frequency module  1 . Specifically, the receive output terminal  130  is a terminal for supplying receive signals of the communication bands A and B to the RFIC  3 . 
     Here, the communication bands mean frequency bands defined in advance by a standards group for a communication system (for example, 3GPP (3rd Generation Partnership Project), IEEE (Institute of Electrical and Electronics Engineers), and the like) or any other similar group. The communication system means a communication system constructed based on a radio access technology (RAT). As the communication system, for example, a 5GNR (5th Generation New Radio) system, an LTE (Long Term Evolution) system, a WLAN (Wireless Local Area Network) system, and the like can be used. However, the communication system is not limited thereto. 
     The communication band A is one example of a first communication band and is a communication band for FDD. The communication band B is one example of a second communication band and is a communication band for TDD. The communication band A and the communication band B can be used for simultaneous communication. 
     Note that the term “a plurality of communication bands can be used for simultaneous communication” means that a plurality of communication bands is allowed to be used for at least one of simultaneous transmission, simultaneous reception, and simultaneous transmission and reception. At that time, a single use of any one of the plurality of communication bands is not excluded. A combination of communication bands that can be used for simultaneous communication is defined in advance by, for example, a standards group for a communication system or any other similar group. 
     The transmit filter  11  (A-Tx) is one example of a first transmit filter and has a pass band that includes an uplink operation band (transmit band) of the communication band A. Because of this, the transmit filter  11  allows a transmit signal of the communication band A to pass through. An input terminal of the transmit filter  11  is connected to an output terminal of the power amplifier  15  via the matching circuit  13 , and an output terminal of the transmit filter  11  is connected to a selection terminal  40   b  of the switch  40 . 
     The receive filter  12  (A-Rx) is one example of a first receive filter and has a pass band that includes a downlink operation band (receive band) of the communication band A. Because of this, the receive filter  12  allows a receive signal of the communication band A to pass through. An input terminal of the receive filter  12  is connected to a selection terminal  40   b  of the switch  40 , and an output terminal of the receive filter  12  is connected to an input terminal of the low noise amplifier  35  via the switch  42  and the matching circuit  33 . 
     The transmit filter  11  and the receive filter  12  make up a duplexer  10  that allows a transmit signal and a receive signal of the communication band A to pass through. 
     The filter  20  (B-TRx) is one example of a second filter and has a pass band that includes the communication band B. Because of this, the filter  20  allows a transmit signal and a receive signal of the communication band B to pass through. One terminal of the filter  20  is connected to a selection terminal  40   c  of the switch  40 , and the other terminal of the filter  20  is connected to a common terminal  41   a  of the switch  41 . 
     The power amplifier  15  is one example of a first power amplifier and is connected between the transmit filter  11  and the transmit input terminal  110 . The power amplifier  15  can amplify a transmit signal of the communication band A input from the transmit input terminal  110 . 
     The power amplifier  25  is one example of a second power amplifier and is connected between the switch  41  and the transmit input terminal  120 . The power amplifier  25  can amplify a transmit signal of the communication band B input from the transmit input terminal  120 . 
     The low noise amplifier  35  is connected between the switch  42  and the receive output terminal  130 . The low noise amplifier  35  can amplify (1) a receive signal of the communication band A input from the antenna connection terminal  100  via the switch  40 , the receive filter  12 , the switch  42 , and the matching circuit  33  and (2) a receive signal of the communication band B input from the antenna connection terminal  100  via the switch  40 , the filter  20 , the switch  41 , the switch  42 , and the matching circuit  33 . The receive signals of the communication bands A and B amplified by the low noise amplifier  35  are output to the receive output terminal  130 . 
     The switch  40  is one example of a third switch and is connected between the antenna connection terminal  100  and filters which are the duplexer  10  and the filter  20 . Specifically, the switch  40  has a common terminal  40   a  and the selection terminals  40   b  and  40   c.  The common terminal  40   a  is connected to the antenna connection terminal  100 , the selection terminal  40   b  is connected to the duplexer  10 , and the selection terminal  40   c  is connected to the filter  20 . 
     With this connection configuration, for example, based on a control signal from the RFIC  3 , the switch  40  can connect the common terminal  40   a  to at least one of the selection terminals  40   b  and  40   c.  That is to say, the switch  40  switches between connecting and disconnecting the antenna connection terminal  100  to/from the transmit filter  11  and the receive filter  12  and further switches between connecting and disconnecting the antenna connection terminal  100  to/from the filter  20 . The switch  40  is, for example, made up of a multi-connection type switch circuit and is sometimes referred to as an antenna switch. 
     The switch  41  is one example of a second switch and is connected between the filter  20  and amplifiers which are the power amplifier  25  and the low noise amplifier  35 . Specifically, the switch  41  has the common terminal  41   a  and selection terminals  41   b  and  41   c.  The common terminal  41   a  is connected to the other terminal of the filter  20 , the selection terminal  41   b  is connected to an output terminal of the power amplifier  25  via the matching circuit  23 , and the selection terminal  41   c  is connected to the receive output terminal  130  via the switch  42  and the matching circuit  33 . 
     With this connection configuration, for example, based on a control signal from the RFIC  3 , the switch  41  can connect the common terminal  41   a  to one of the selection terminals  41   b  and  41   c.  That is to say, the switch  41  can switch between connecting the filter  20  and the power amplifier  25  and connecting the filter  20  and the low noise amplifier  35 . The switch  41  is, for example, made up of a single pole double throw (SPDT) type switch circuit and is sometimes referred to as a TDD switch. 
     The switch  42  is one example of a first switch and is connected between filters, which are the receive filter  12  and the filter  20 , and the low noise amplifier  35 . Specifically, the switch  42  has a common terminal  42   a  and selection terminals  42   b  and  42   c.  The common terminal  42   a  is connected to an input terminal of the low noise amplifier  35  via the matching circuit  33 , the selection terminal  42   b  is connected to an output terminal of the receive filter  12 , and the selection terminal  42   c  is connected to the other terminal of the filter  20  via the switch  41 . 
     With this connection configuration, for example, based on a control signal from the RFIC  3 , the switch  42  can connect the common terminal  42   a  to one of the selection terminals  42   b  and  42   c.  That is to say, the switch  42  can switch between connecting the receive filter  12  to the low noise amplifier  35  and connecting the filter  20  to the low noise amplifier  35 . The switch  42  is, for example, made up of a SPDT type switch circuit and is sometimes referred to as a band selection switch. 
     The matching circuit  13  is one example of a first impedance matching circuit and is connected between the power amplifier  15  and the transmit filter  11 . The matching circuit  13  is, for example, made up of an inductor and/or a capacitor and can provide impedance matching between the power amplifier  15  and the transmit filter  11 . 
     The matching circuit  23  is one example of a second impedance matching circuit and is connected between the power amplifier  25  and the switch  41 . The matching circuit  23  is, for example, made up of an inductor and/or a capacitor and can provide impedance matching between the power amplifier  25  and the filter  20 . 
     The matching circuit  33  is connected between the low noise amplifier  35  and filters which are the receive filter  12  and the filter  20 . The matching circuit  33  is, for example, made up of an inductor and/or a capacitor and can provide impedance matching between the low noise amplifier  35  and the receive filter  12  and provide impedance matching between the low noise amplifier  35  and the filter  20 . 
     Note that some of circuit elements illustrated in  FIG.  1    are not necessarily included in the radio frequency module  1 . For example, the radio frequency module  1  only needs to include at least the duplexer  10 , the filter  20 , the power amplifiers  15  and  25 , the low noise amplifier  35 , the switches  41  and  42 , and the matching circuits  13  and  23 , and do not necessarily include other circuit elements. 
     Further, the radio frequency module  1  may include a signal path that transmits a radio frequency signal of a communication band different from the communication bands A and B. Note that in the signal path that transmits a radio frequency signal of the communication band different from the communication bands A and B, at least a filter whose pass band is the communication band different from the communication bands A and B is installed. 
     2 Flow of Signal Transmission in Communication Device  5   
     Next, the flow of signal transmission in the radio frequency module  1  and the communication device  5 , which are configured as above, is described with reference to the  FIG.  2   .  FIG.  2    is a diagram illustrating flows of signals of FDD transmission in the radio frequency module  1  and the communication device  5  according to the embodiment. 
     As illustrated in  FIG.  2   , in the radio frequency module  1  and the communication device  5  according to the present embodiment, for example, a transmit signal of the communication band A and a receive signal of the communication band A are being transmitted simultaneously. Specifically, a transmit signal of the communication band A is output from the antenna  2  via the transmit input terminal  110 , the matching circuit  13 , the transmit filter  11 , the switch  40 , and the antenna connection terminal  100 . Further, a receive signal of the communication band A is output from the receive output terminal  130  via the antenna  2 , the antenna connection terminal  100 , the receive filter  12 , the switch  42 , the matching circuit  33 , and the low noise amplifier  35 . 
     At that time, when electromagnetic coupling is established between the matching circuit  13  and the matching circuit  23 , a high power transmit signal output from the power amplifier  15  flows into a transmit path of the communication band B via the matching circuit  13  and the matching circuit  23  as an unwanted wave signal. This unwanted wave signal leaks from the selection terminal  41   b  to the selection terminal  41   c  of the switch  41  through an off capacitance. Moreover, a leaked unwanted wave signal further leaks from the selection terminal  42   c  of the switch  42 , which is in the electrically disconnected state, to the selection terminal  42   b  and the common terminal  42   a  through an off capacitance. Finally, a leaked unwanted wave signal flows into the low noise amplifier  35  and degrades the receiver sensitivity for a receive signal of the communication band A, which is being transmitted simultaneously with a transmit signal of the communication band A. 
     In the communication band A for FDD, in the case where a transmit signal and a receive signal are being transmitted simultaneously, the duplexer  10  is installed in order to prevent a transmit signal output from the power amplifier  15  and a receive band noise from flowing into the receive path. However, when the total value of the isolation at the time the switch  41  for TDD is electrically disconnected and the isolation at the time the switch  42  for band selection is electrically disconnected becomes substantially equal to a level of the isolation between transmission and reception of the duplexer  10 , degradation of receiver sensitivity such as the one described above occurs. 
     In contrast, the radio frequency module  1  according to the present embodiment has the configuration that suppresses the formation of electromagnetic coupling between the matching circuit  13  and the matching circuit  23 . In the following section, the foregoing configuration of the radio frequency module  1  according to the present embodiment that suppresses the electromagnetic coupling is described. 
     3 Component Layout of Radio Frequency Module 
     Next, a component layout of the radio frequency module  1  configured as above is described specifically with reference to  FIG.  3   . 
       FIG.  3    is a plan view of the radio frequency module  1  according to an embodiment. Specifically,  FIG.  3    is a diagram illustrating a principal surface  91   a  of a module board  91  seen from the positive side of the z-axis. As illustrated in  FIG.  3   , the radio frequency module  1  further includes the module board  91 , in addition to circuit components that make up the circuits illustrated in  FIG.  1   . 
     The module board  91  has the principal surface  91   a  whose normal is the z-axis. As the module board  91 , for example, a low temperature co-fired ceramics (LTCC) board, a high temperature co-fired ceramics (HTCC) board, a board including components, a board including a redistribution layer (RDL), a printed board, or the like, each of which has a multilayer structure including a plurality of dielectric layers, can be used, but the module board  91  is not limited thereto. Note that on the module board  91 , the antenna connection terminal  100 , the transmit input terminals  110  and  120 , and the receive output terminal  130  may be formed. 
     As illustrated in  FIG.  3   , on the principal surface  91   a,  the duplexer  10 , the filter  20 , the power amplifiers  15  and  25 , the low noise amplifier  35 , the switches  40 ,  41 , and  42 , and the matching circuits (MN)  13 ,  23 , and  33  are arranged. 
     Note that although it is not illustrated in the drawing, wiring lines that make up signal paths including the transmit path and the receive path illustrated in  FIG.  1    are formed in the inside of the module board  91  and on the principal surface  91   a.  Further, the foregoing wiring line may be a bonding wire whose two end portions are bonded on the principal surface  91   a  and one of circuit components that make up the radio frequency module  1  or may be a terminal, an electrode, or a wiring line, which is formed on a surface of a circuit component included in the radio frequency module  1 . 
     Further, a resin member may be arranged in such a manner as to cover the foregoing circuit components arranged on the principal surface  91   a.  Moreover, a metal shield layer in contact with an outer surface of the foregoing resin member and side surfaces of the module board  91  may also be formed. 
     Here, in a plan view of the module board  91 , each of the power amplifiers  15  and  25  and the switch  41  is arranged in between the matching circuit  13  and the matching circuit  23 . 
     According to this, the power amplifiers  15  and  25  and the switch  41  are arranged in between the matching circuit  13  and the matching circuit  23 , and thus a long distance can be secured between the matching circuit  13  and the matching circuit  23 . Further, the power amplifiers  15  and  25  and the switch  41 , which are conductive components, are present in between the matching circuit  13  and the matching circuit  23 . Because of this, the electromagnetic coupling between the matching circuit  13  and the matching circuit  23  can be suppressed, and thus it becomes possible to suppress a flow of an unwanted wave signal of a transmit signal of the communication band A into the receive path of the communication band A through the foregoing electromagnetic coupling, the switch  41 , and the switch  42 . Accordingly, the isolation between transmission and reception of the communication band A for FDD can be improved, and the degradation of receiver sensitivity can be suppressed. 
     Note that the duplexer  10 , the filter  20 , the low noise amplifier  35 , the matching circuit  33 , and the switches  40  and  42  may be arranged on a principal surface opposite the principal surface  91   a  or may be buried in the module board  91 . 
     Note that in the plan view of the module board  91 , the matching circuit  13  and the power amplifier  15  are arranged next to each other with no conductive component interposed therebetween. 
     According to this, the wiring line connecting the matching circuit  13  and the power amplifier  15  can be shortened, and thus the transmission loss of a transmit signal of the communication band A can be reduced. 
     Further, in the plan view of the module board  91 , the matching circuit  23  and the power amplifier  25  are arranged next to each other with no conductive component interposed therebetween. 
     According to this, the wiring line connecting the matching circuit  23  and the power amplifier  25  can be shortened, and thus the transmission loss of a transmit signal of the communication band B can be reduced. 
     Note that the conductive component is an electronic component having a conductive member such as an electrode for signal retrieval or the like and is, for example, at least a chip resistor, a chip capacitor, a chip inductor, a filter, a switch, or an active element, such as an amplifier, a control circuit, or the like. 
       FIG.  4    is a plan view of a radio frequency module  1 A according to a modified example 1 of the embodiment. As illustrated in  FIG.  4   , in the radio frequency module  1 A according to the present modified example, the duplexer  10 , the filter  20 , the power amplifiers  15  and  25 , the low noise amplifier  35 , the switches  40 ,  41 , and  42 , and the matching circuits (MN)  13 ,  23 , and  33  are arranged on the principal surface  91   a.  Compared with the radio frequency module  1  according to the embodiment, the radio frequency module  1 A according to the present modified example is different in the layout configuration of the matching circuits  13  and  23 , the power amplifiers  15  and  25 , and the switch  41  and in additionally having a metal shield layer  95 . Hereinafter, the radio frequency module  1 A according to the present modified example is described with the emphasis on points different from the radio frequency module  1  according to the embodiment, and the description for the same point as the radio frequency module  1  according to the embodiment is omitted. 
     The metal shield layer  95  is formed in such a manner as to be in contact with an outer surface of a resin member covering the foregoing circuit components arranged on the principal surface  91   a  and side surfaces of the module board  91 . Note that in the present modified example, the metal shield layer  95  and the resin member are not necessarily included. 
     Here, in the plan view of the module board  91 , each of the power amplifiers  15  and  25  and the switch  41  is arranged in between the matching circuit  13  and the matching circuit  23 . 
     According to this, the power amplifiers  15  and  25  and the switch  41  are arranged in between the matching circuit  13  and the matching circuit  23 , and thus a long distance can be secured between the matching circuit  13  and the matching circuit  23 . Because of this, the electromagnetic coupling between the matching circuit  13  and the matching circuit  23  can be suppressed, and thus it becomes possible to suppress a flow of an unwanted wave signal of a transmit signal of the communication band A into the receive path of the communication band A through the foregoing electromagnetic coupling, the switch  41 , and the switch  42 . Accordingly, the isolation between transmission and reception of the communication band A for FDD can be improved, and the degradation of receiver sensitivity can be suppressed. 
     Note that the difference between the layout configuration of the radio frequency module  1 A according to the present modified example and the layout configuration of the radio frequency module  1  according to the embodiment is that the power amplifier  15  is arranged on the x-axis negative direction side of the matching circuit  13 . 
     According to this, the layout area for the matching circuits  13  and  23 , the power amplifiers  15  and  25 , and the switch  41  can be reduced, and thus the radio frequency module  1 A can be downsized. 
       FIG.  5    is a plan view of a radio frequency module  1 B according to a modified example 2 of the embodiment. As illustrated in  FIG.  5   , in the radio frequency module  1 B according to the present modified example, the duplexer  10 , the filter  20 , the power amplifiers  15  and  25 , the low noise amplifier  35 , the switches  40 ,  41 , and  42 , and the matching circuits (MN)  13 ,  23 , and  33  are arranged on the principal surface  91   a.  The radio frequency module  1 B according to the present modified example is different from the radio frequency module  1  according to the embodiment in the layout configuration of the matching circuits  13  and  23 , the power amplifiers  15  and  25 , and the switch  41  and in additionally having the metal shield layer  95 . Hereinafter, the radio frequency module  1 B according to the present modified example is described with the emphasis on points different from the radio frequency module  1  according to the embodiment, and the description for the same point as the radio frequency module  1  according to the embodiment is omitted. 
     The metal shield layer  95  is formed in such a manner as to be in contact with an outer surface of a resin member covering the foregoing circuit components arranged on the principal surface  91   a  and side surfaces of the module board  91 . Note that in the present modified example, the metal shield layer  95  and the resin member are not necessarily included. 
     Here, in the plan view of the module board  91 , each of the power amplifiers  15  and  25  and the switch  41  is arranged in between the matching circuit  13  and the matching circuit  23 . 
     According to this, the power amplifiers  15  and  25  and the switch  41  are arranged in between the matching circuit  13  and the matching circuit  23 , and thus a long distance can be secured between the matching circuit  13  and the matching circuit  23 . Because of this, the electromagnetic coupling between the matching circuit  13  and the matching circuit  23  can be suppressed, and thus it becomes possible to suppress a flow of an unwanted wave signal of a transmit signal of the communication band A into the receive path of the communication band A through the foregoing electromagnetic coupling, the switch  41 , and the switch  42 . Accordingly, the isolation between transmission and reception of the communication band A for FDD can be improved, and the degradation of receiver sensitivity can be suppressed. 
     Note that the difference between the layout configuration of the radio frequency module  1 B according to the present modified example and the layout configuration of the radio frequency module  1  according to the embodiment is that the power amplifier  25  is arranged on the x-axis negative direction side of the matching circuit  23 . 
     According to this, the layout area for the matching circuits  13  and  23 , the power amplifiers  15  and  25 , and the switch  41  can be reduced, and thus the radio frequency module  1 B can be downsized. 
     4 Effects and the Like 
     As described above, the radio frequency module  1  according to the present embodiment includes the transmit filter  11  having a pass band that includes the uplink operation band of the communication band A for FDD, the receive filter  12  having a pass band that includes the downlink operation band of the communication band A, the filter  20  having a pass band that includes the communication band B for TDD, the power amplifier  15  capable of amplifying a transmit signal of the communication band A, the power amplifier  25  capable of amplifying a transmit signal of the communication band B, the low noise amplifier  35  capable of amplifying receive signals of the communication bands A and B, the switch  42  that switches between connecting the receive filter  12  to the low noise amplifier  35  and connecting the filter  20  to the low noise amplifier  35 , the switch  41  that switches between connecting the filter  20  to the power amplifier  25  and connecting the filter  20  to the low noise amplifier  35 , the matching circuit  13  connected between the power amplifier  15  and the transmit filter  11 , the matching circuit  23  connected between the power amplifier  25  and the switch  41 , and the module board  91  having the principal surfaces  91   a.  The power amplifiers  15  and  25 , the switch  41 , and the matching circuits  13  and  23  are arranged on the principal surface  91   a,  and in the plan view of the module board  91 , each of the power amplifiers  15  and  25  and the switch  41  is arranged in between the matching circuit  13  and the matching circuit  23 . 
     According to this, the power amplifiers  15  and  25  and the switch  41  are arranged in between the matching circuit  13  and the matching circuit  23 , and thus a long distance can be secured between the matching circuit  13  and the matching circuit  23 . Further, the power amplifiers  15  and  25  and the switch  41 , which are conductive components, are present in between the matching circuit  13  and the matching circuit  23 . Because of this, the electromagnetic coupling between the matching circuit  13  and the matching circuit  23  can be suppressed, and thus it becomes possible to suppress a flow of an unwanted wave signal of a transmit signal of the communication band A into the receive path of the communication band A through the foregoing electromagnetic coupling, the switch  41 , and the switch  42 . Accordingly, the isolation between transmission and reception of the communication band A for FDD can be improved, and the degradation of receiver sensitivity can be suppressed. 
     Further, in the radio frequency module  1 , in the plan view of the module board  91 , the matching circuit  13  and the power amplifier  15  may be arranged next to each other with no conductive component interposed therebetween. 
     According to this, the wiring line connecting the matching circuit  13  and the power amplifier  15  can be shortened, and thus the transmission loss of a transmit signal of the communication band A can be reduced. 
     Further, in the radio frequency module  1 , in the plan view of the module board  91 , the matching circuit  23  and the power amplifier  25  may be arranged next to each other with no conductive component interposed therebetween. 
     According to this, the wiring line connecting the matching circuit  23  and the power amplifier  25  can be shortened, and thus the transmission loss of a transmit signal of the communication band B can be reduced. 
     Further, the radio frequency module  1  may further include the switch  40  that switches between connecting and disconnecting the antenna connection terminal  100  to/from the transmit filter  11  and the receive filter  12  and further switches between connecting and disconnecting the antenna connection terminal  100  to/from the filter  20 . 
     According to this, isolation between the signal path of the communication band A and the signal path of the communication band B can be improved. 
     Further, the communication device  5  according to the present embodiment includes the RFIC  3  that performs processing on a radio frequency signal and the radio frequency module  1  that transmits radio frequency signals between the RFIC  3  and the antenna  2 . 
     According to this, the communication device  5  can produce substantially the same effects as the radio frequency module  1 . 
     Other Embodiments 
     The radio frequency modules and the communication devices according to the present disclosure have been described using the embodiment and the modified examples. However, the radio frequency module and the communication device according to the present disclosure are not limited to the foregoing embodiment and modified examples. Other embodiments realized by combining optional constituent elements of the foregoing embodiment and modified examples, modified examples obtained by applying various modifications conceivable to those skilled in the art to the foregoing embodiment and modified examples without necessarily departing the scope of the present disclosure, and various devices incorporating the foregoing radio frequency modules and communication devices may also be included in the present disclosure. 
     For example, in the component layout configurations of the radio frequency modules according to the foregoing embodiment, the circuit components that make up the radio frequency module are arranged on one of the principal surfaces of the module board  91 . However, the circuit components that make up the radio frequency module may be divided and arranged on a first principal surface and a second principal surface of the module board  91 , which face each other. That is to say, the circuit components that make up the foregoing radio frequency module may be mounted on one surface of the module board  91  or may be mounted on both surfaces of the module board  91 . 
     For example, in the circuit configurations of the radio frequency modules and the communication devices according to the foregoing embodiment and modified examples, another circuit element, a wiring line, or the like may be inserted in a path connecting each circuit element and a signal path represented in the drawings. 
     For example, in the foregoing embodiment and modified examples, a filter or a matching circuit may be inserted between the antenna connection terminal  100  and the switch  40 . 
     INDUSTRIAL APPLICABILITY 
     The present disclosure can be widely used in communication devices such as mobile phones and the like as a radio frequency circuit to be installed in a front-end unit. 
     REFERENCE SIGNS LIST 
       1 ,  1 A,  1 B Radio frequency module 
       2  Antenna 
       3  RF signal processing circuit (RFIC) 
       4  Base band signal processing circuit (BBIC) 
       5  Communication device 
       10  Duplexer 
       11  Transmit filter 
       12  Receive filter 
       13 ,  23 ,  33  Matching circuit 
       15 ,  25  Power amplifier 
       20  Filter 
       35  Low noise amplifier 
       40 ,  41 ,  42  Switch 
       40   a,    41   a,    42   a  Common terminal 
       40   b,    40   c,    41   b,    41   c,    42   b,    42   c  Selection terminal 
       91  Module board 
       91   a  Principal surface 
       95  Metal shield layer 
       100  Antenna connection terminal 
       110 ,  120  Transmit input terminal 
       130  Receive output terminal