Patent Publication Number: US-2023133510-A1

Title: Radio-frequency module and communication device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of U.S. patent application Ser. No. 17/233,542, filed Apr. 19, 2021, which claims priority to Japanese patent application JP2020-092582, filed May 27, 2020, the entire contents of each being incorporated herein by reference. 
    
    
     BACKGROUND 
     1. Field of the Disclosure 
     The present disclosure relates to a radio-frequency module and a communication device. 
     2. Description of the Related Art 
     Mobile communication apparatuses such as mobile phones incorporate power amplifiers that amplify radio-frequency transmission signals. Japanese Unexamined Patent Application Publication No. 2018-137522 discloses a front-end circuit (radio-frequency (RF) module) including a power-amplifier (PA) circuit (transmission amplifier circuit) for transmission of transmission signals and a low-noise amplifier (LNA) circuit (reception amplifier circuit) for transmission of reception signals. The transmission amplifier circuit includes a PA control unit configured to control amplification characteristics of power amplifiers, and the reception amplifier circuit includes an LNA control unit configured to control amplification characteristics of low-noise amplifiers. 
     The transmission amplifier circuit may be a power amplifier circuit in Doherty configuration, which is capable of providing high efficiency and high power but has a high part counts; that is, the power amplifier circuit includes multiple circuit elements, such as a carrier amplifier, a peaking amplifier, and a phase circuit. The use of a Doherty power amplifier circuit as the transmission amplifier circuit necessitates compromising the isolation of the reception amplifier circuit from the transmission amplifier circuit that transmits high-power transmission signals. 
     SUMMARY 
     The present disclosure therefore has been made to solve the problems described above, and it is an object of the present disclosure to provide a radio-frequency module and a communication device that achieve size reduction in a way that least compromises the isolation of a receiving circuit from a transmission power amplifier circuit in Doherty configuration. 
     According to an aspect of the present disclosure, a radio-frequency module including a module substrate having a first main surface and a second main surface on opposite sides; a low-noise amplifier disposed on the second main surface; and a power amplifier circuit in a Doherty configuration. The power amplifier including a first phase circuit; a second phase circuit; a carrier amplifier disposed on the first main surface and including an input terminal connected to a first end of the first phase circuit and an output terminal connected to a first end of the second phase circuit; and a peaking amplifier disposed on the first main surface and including an input terminal connected to a second end of the first phase circuit and an output terminal connected to a second end of the second phase circuit. 
     Other features, elements, characteristics and advantages of the present disclosure will become more apparent from the following detailed description of preferred embodiments of the present disclosure with reference to the attached drawings. 
    
    
     
       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 of the present disclosure; 
         FIG.  2 A  is a schematic diagram illustrating the planar configuration of a radio-frequency module according to Example 1; 
         FIG.  2 B  is a schematic diagram illustrating the sectional configuration of the radio-frequency module according to Example 1; 
         FIG.  2 C  is a schematic diagram illustrating the sectional configuration of a radio-frequency module according to a modification; 
         FIG.  3 A  is a schematic diagram illustrating the planar configuration of a radio-frequency module according to Example 2; and 
         FIG.  3 B  is a schematic diagram illustrating the sectional configuration of the radio-frequency module according to Example 2. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, an embodiment of the present disclosure will be described in detail. The following embodiment is a general or specific example. Details such as values, shapes, materials, constituent elements, and arrangements and connection patterns of the constituent elements in the following embodiment are provided merely as examples and should not be construed as limiting the present disclosure. Of the constituent elements in the following embodiment, examples, and modifications, those not mentioned in independent claims are described as optional constituent elements. The sizes and the relative proportions of the constituent elements illustrated in the drawings are not necessarily to scale. Redundant description of substantially the same constituent elements, which are denoted by the same reference signs in the drawings, will be omitted or brief description of the elements will be provided where appropriate. 
     The words (e.g., parallel, perpendicular) hereinafter used to describe the relationship between elements, the words (e.g., rectangular) hereinafter used to describe the shapes of elements, and numerical ranges hereinafter in the description should not necessarily be interpreted in the strict sense and can be understood as meaning that a margin of several percent is acceptable as substantial equivalence. 
     Regarding A, B, and C mounted on a substrate, the expression “when the substrate (or a main surface of the substrate) is viewed in a plan view, C is disposed between A and B” herein means that at least one of lines connecting freely selected points in A to freely selected points in B passes through C when the substrate is viewed in a plan view. The expression “the substrate is viewed in a plan view” herein means that the substrate and circuit elements on the substrate are viewed in such a manner that they are orthographically projected on a plane parallel to the main surface of the substrate. 
     The term “transmission path” hereinafter refers to a transmission line constructed of, for example, wiring through which radio-frequency transmission signals are propagated, an electrode connected directly to the wiring, and terminals connected directly to the wiring or to the electrode. The term “reception path” hereinafter refers to a transmission line constructed of, for example, wiring through which radio-frequency reception signals are propagated, an electrode connected directly to the wiring, and terminals connected directly to the wiring or to the electrode. The term “transmission-reception path” hereinafter refers to a transmission line constructed of, for example, wiring through which radio-frequency transmission signals and radio-frequency reception signals are propagated, an electrode connected directly to the wiring, and terminals connected directly to the wiring or to the electrode. 
     Embodiment 
     1. Circuit Configuration of Radio-Frequency Module  1  and Communication Device  5   
       FIG.  1    is a circuit configuration diagram of a radio-frequency module  1  and a communication device  5  according to the present embodiment. As illustrated in  FIG.  1   , the communication device  5  includes the radio-frequency module  1 , an antenna  2 , a radio-frequency integrated circuit (RFIC)  3 , and a baseband integrated circuit (BBIC)  4 . 
     The RFIC  3  is an RF signal processing circuit that processes radio-frequency signals transmitted via the antenna  2  and radio-frequency signals received via the antenna  2 . Specifically, the RFIC  3  performs signal processing such as down-conversion on radio-frequency signals input through reception paths of the radio-frequency module  1  and outputs the resultant reception signals to the BBIC  4 . The RFIC  3  performs signal processing such as up-conversion on transmission signals from the BBIC  4  and outputs the resultant transmission signals to transmission signal paths of the radio-frequency module  1 . 
     The BBIC  4  is a circuit that performs signal processing using intermediate frequency bands lower than the frequency bands of radio-frequency signals transmitted through the radio-frequency module  1 . The signals processed by the BBIC  4  are used, for example, as image signals for displaying an image or as audio signals for a telephone conversation through a speaker. 
     The RFIC  3  also functions as a control unit configured to control, in accordance with the communication band (frequency band) in use, connections in switches that are included in the radio-frequency module  1  and are denoted by  31 ,  32 ,  33 , and  34 , respectively. Specifically, the RFIC  3  causes, by using control signals (not illustrated), the individual switches  31  to  34  of the radio-frequency module  1  to perform connection switching. More specifically, the RFIC  3  outputs, to a power amplifier (PA) circuit  70 , digital control signals for controlling the switches  31  to  34 . In accordance with the digital control signals from the RFIC  3 , the PA control circuit  70  of the radio-frequency module  1  outputs digital control signals to the switches  31  to  34  so as to control switching between the connected state and the non-connected state in each of the switches  31  to  34 . 
     The RFIC  3  also functions as a control unit configured to control gains of a carrier amplifier  11 A, a peaking amplifier  11 B, and a preamplifier  11 C, which are included in the radio-frequency module  1  and may hereinafter also collectively referred to as power amplifiers, and to control a power supply voltage Vcc and a bias voltage Vbias, which are applied to the power amplifiers. Specifically, RFIC  3  outputs digital control signals such as mobile industry processor interface (MIPI) signals and general-purpose input/output (GPIO) signals to a control signal terminal  130 , which is provided to the radio-frequency module  1 . In accordance with the digital control signals input through the control signal terminal  130 , the PA control circuit  70  of the radio-frequency module  1  outputs control signals, the power supply voltage Vcc, or the bias voltage Vbias to the power amplifiers so as to adjust the gains of the power amplifiers. Different control signal terminals may be provided so that one of the control signal terminal receives, from the RFIC  3 , digital control signals for controlling the gains of the power amplifiers and the other control signal terminal receives, from the RFIC  3 , digital control signals for controlling the power supply voltage Vcc and the bias voltage Vbias that are to be applied to the power amplifiers. The control unit may be disposed outside the RFIC  3 . Specifically, the control unit may, for example, be disposed in the BBIC  4 . 
     The antenna  2  is connected to an antenna connection terminal  100  of the radio-frequency module  1  to radiate radio-frequency signals output by the radio-frequency module  1  and to enable the radio-frequency module  1  to receive radio-frequency signals from the outside. 
     The communication device  5  according to the present embodiment may optionally include the antenna  2  and the BBIC  4 . 
     The following describes, in detail, the configuration of the radio-frequency module  1 . 
     As illustrated in  FIG.  1   , the radio-frequency module  1  includes the antenna connection terminal  100 , a power amplifier circuit  10 , a low-noise amplifier  21 , transmitting filters  61 T and  62 T, receiving filters  61 R and  62 R, the PA control circuit  70 , matching circuits  12 A,  51 ,  52 , and  53 , the switches  31 ,  32 ,  33 , and  34 , and a diplexer  60 . 
     The antenna connection terminal  100  is connected to the antenna  2 . 
     The power amplifier circuit  10  is an amplifier circuit in Doherty configuration and amplifies transmission signals input through a transmission input terminal  111  and transmission signals input through a transmission input terminal  112 ; that is, the power amplifier circuit  10  amplifies transmission signals in a communication band A and transmission signals in a communication band B. The radio-frequency module  1  may include, in place of the power amplifier circuit  10 , a first amplifier circuit in Doherty configuration and a second amplifier circuit in Doherty configuration. The first amplifier circuit amplifies radio-frequency signals in the communication band A, and the second amplifier circuit amplifies radio-frequency signals in the communication band B. 
     The PA control circuit  70  adjusts the gains of the power amplifiers of the power amplifier circuit  10  in accordance with, for example, MIPI signals and GPIO signals that are digital control signals input through the control signal terminal  130 . The PA control circuit  70  may be a semiconductor integrated circuit (IC). The semiconductor IC is, for example, a complementary metal oxide semiconductor (CMOS). Specifically, the semiconductor IC is fabricated by means of a silicon on insulator (SOI) process. Such a semiconductor IC can thus be produced inexpensively. The semiconductor IC may be formed from at least one of GaAs, SiGe, and GaN such that the semiconductor IC can output radio-frequency signals with excellent amplification performance and excellent noise performance. 
     The low-noise amplifier  21  is an amplifier that amplifies radio-frequency signals in the communication band A and radio-frequency signals in the communication band B in a manner so as to ensure low noise and outputs the resultant signals to a reception output terminal  120 . The radio-frequency module  1  may include more than one low-noise amplifier. For example, the radio-frequency module  1  may include a first low-noise amplifier and a second low-noise amplifier. The first low-noise amplifier amplifies radio-frequency signals in the communication band A, and the second low-noise amplifier amplifies radio-frequency signals in the communication band B. 
     The transmitting filter  61 T is disposed on a transmission path AT, which connects the transmission input terminals  111  and  112  to the antenna connection terminal  100 . Of the transmission signals amplified by the power amplifier circuit  10 , transmission signals in the communication band A are allowed to pass through the transmitting filter  61 T. The transmitting filter  62 T is disposed on a transmission path BT, which connects the transmission input terminals  111  and  112  to the antenna connection terminal  100 . Of the transmission signals amplified by the power amplifier circuit  10 , transmission signals in the communication band B are allowed to pass through the transmitting filter  62 T. 
     The receiving filter  61 R is disposed on a reception path AR, which connects the reception output terminal  120  to the antenna connection terminal  100 . Of the reception signals input through the antenna connection terminal  100 , reception signals in the communication band A are allowed to pass through the receiving filter  61 R. The receiving filter  62 R is disposed on a reception path BR, which connects the reception output terminal  120  to the antenna connection terminal  100 . Of the reception signals input through the antenna connection terminal  100 , reception signals in the communication band B are allowed to pass through the receiving filter  62 R. 
     The transmitting filter  61 T and the receiving filter  61 R constitute a duplexer  61 , the pass band of which is the communication band A. The duplexer  61  operates in the frequency division duplex (FDD) mode to transmit transmission signals and reception signals in the communication band A. The transmitting filter  62 T and the receiving filter  62 R constitute a duplexer  62 , the pass band of which is the communication band B. The duplexer  62  operates in the FDD mode to transmit transmission signals and reception signals in the communication band B. 
     The duplexers  61  and  62  may each be a multiplexer including transmitting filters only, a multiplexer including receiving filters only, or a multiplexer constructed of duplexers. It is not required that the duplexer  61  including the transmitting filter  61 T and the receiving filter  61 R be provided. The duplexer  61  may be replaced with a filter that operates in the time division duplex (TDD) mode to transmit signals. In this case, a switch operable to switch between transmission and reception is disposed so as to precede or follow the filter, or the radio-frequency module  1  may include two such switches, one of which is disposed so as to precede the filter and the other one of which is disposed so as to follow the filter. Similarly, it is not required that the duplexer  62  including the transmitting filter  62 T and the receiving filter  62 R be provided. The duplexer  62  may be replaced with a filter that operates in the TDD mode to transmit signals. 
     The matching circuit  12 A is disposed on a transmission path connecting the power amplifier circuit  10  to the transmitting filters  61 T and  62 T and provides impedance matching between the power amplifier circuit  10  and the transmitting filter  61 T and impedance matching between the power amplifier circuit  10  and the transmitting filter  62 T. 
     The matching circuit  51  is disposed on a path connecting the switch  34  to the duplexer  61  and provides impedance matching between the switch  34  and the duplexer  61  and impedance matching between antenna  2  and the duplexer  61 . The matching circuit  52  is disposed on a path connecting the switch  34  to the duplexer  62  and provides impedance matching between the switch  34  and the duplexer  62  and impedance matching between the antenna  2  and the duplexer  62 . 
     The matching circuit  53  is disposed on a path connecting the low-noise amplifier  21  to the switch  32  and provides impedance matching between the low-noise amplifier  21  and the switch  32 , impedance matching between the low-noise amplifier  21  and the duplexer  61 , and impedance matching between the low-noise amplifier  21  and the duplexer  62 . 
     The switch  31  includes a common terminal  31   a  and selection terminals  31   b  and  31   c . The common terminal  31   a  is connected to an output terminal of the power amplifier circuit  10  via the matching circuit  12 A. The selection terminal  31   b  is connected to the transmitting filter  61 T, and the selection terminal  31   c  is connected to the transmitting filter  62 T. With the terminals being connected as above, the switch  31  performs switching between the state in which the power amplifier circuit  10  is connected to the transmitting filter  61 T and the state in which the power amplifier circuit  10  is connected to the transmitting filter  62 T. The switch  31  is, for example, a single-pole, double-throw (SPDT) switch circuit. 
     The switch  32  includes a common terminal  32   a  and selection terminals  32   b  and  32   c . The common terminal  32   a  is connected to an input terminal of the low-noise amplifier  21  via the matching circuit  53 . The selection terminal  32   b  is connected to the receiving filter  61 R, and the selection terminal  32   c  is connected to the receiving filter  62 R. With the terminals being connected as above, the switch  32  performs switching between the state in which the low-noise amplifier  21  is connected to the receiving filter  61 R and the state in which the low-noise amplifier  21  is not connected to the  61 R and performs switching between the state in which the low-noise amplifier  21  is connected to the receiving filter  62 R and the state in which the low-noise amplifier  21  is not connected to the receiving filter  62 R. The switch  32  is, for example, an SPDT switch circuit. 
     The switch  34  is an example of an antenna switch and is connected to the antenna connection terminal  100  via the diplexer  60 . The switch  34  performs (1) switching between the state in which the antenna connection terminal  100  is connected to the duplexer  61  and the state in which the antenna connection terminal  100  is not connected to the duplexer  61  and (2) switching between the state in which the antenna connection terminal  100  is connected to the duplexer  62  and the state in which the antenna connection terminal  100  is not connected to the duplexer  62 . The switch  34  may be a multi-connection switching circuit capable of performing (1) and (2) at the same time, that is, capable of connecting the antenna connection terminal  100  to both the duplexers  61  and  62  at the same time. 
     The switch  33  includes a common terminal  33   a  and selection terminals  33   b  and  33   c . The common terminal  33   a  is connected to an input terminal of the power amplifier circuit  10 . The selection terminal  33   b  is connected to the transmission input terminal  111 , and the selection terminal  33   c  is connected to the transmission input terminal  112 . With the terminals being connected as mentioned above, the switch  33  performs switching between the state in which the power amplifier circuit  10  is connected to the transmission input terminal  111  and the state in which the power amplifier circuit  10  is connected to the transmission input terminal  112 . The switch  33  is, for example, an SPDT switch circuit. 
     For example, transmission signals in the communication band A are input through the transmission input terminal  111 , and transmission signals in the communication band B are input through the transmission input terminal  112 . Alternatively, transmission signals in the communication band A or B for the fourth-generation mobile communication system (4G) may be input through the transmission input terminal  111 , and transmission signals in the communication band A or B for the fifth-generation mobile communication system (5G) may be input through the transmission input terminal  112 . 
     The diplexer  60  is an example of a multiplexer and includes filters  60 L and  60 H. The pass band of the filter  60 L is a frequency range including the communication bands A and B, and the pass band of the filter  60 H is a frequency range different from the frequency range including the communication bands A and B. The filters  60 L and  60 H each include a terminal connected to the antenna connection terminal  100 . The filters  60 L and  60 H each include an inductor in chip form and/or a capacitor in chip form and may each be an inductor-capacitor (LC) filter. When the frequency range including the communication bands A and B is on the lower side than the other frequency range (i.e., the frequency range different from the frequency range including the communication bands A and B), the filter  60 L may be a low-pass filter, and the filter  60 H may be a high-pass filter. 
     The transmitting filters  61 T and  62 T and the receiving filters  61 R and  62 R may be acoustic wave filters using surface acoustic waves (SAWs), acoustic wave filters using bulk acoustic waves (BAWs), LC resonant filters, or dielectric filters but are not limited thereto. 
     The radio-frequency module  1  is configured as follows. The switch  33 , the power amplifier circuit  10 , the matching circuit  12 A, the switch  31 , the transmitting filter  61 T, the matching circuit  51 , and the switch  34  constitute a first transmitting circuit that transmits transmission signals in the communication band A to the antenna connection terminal  100 . The switch  34 , the matching circuit  51 , the receiving filter  61 R, the switch  32 , the matching circuit  53 , and the low-noise amplifier  21  constitute a first receiving circuit that transmits reception signals in the communication band A from the antenna  2  through the antenna connection terminal  100 . 
     The switch  33 , the power amplifier circuit  10 , the matching circuit  12 A, the switch  31 , the transmitting filter  62 T, the matching circuit  52 , and the switch  34  constitute a second transmitting circuit that transmits transmission signals in the communication band B to the antenna connection terminal  100 . The switch  34 , the matching circuit  52 , the receiving filter  62 R, the switch  32 , the matching circuit  53 , and the low-noise amplifier  21  constitute a second receiving circuit that transmits reception signals in the communication band B from the antenna  2  through the antenna connection terminal  100 . 
     The circuit configuration above enables the radio-frequency module  1  to transmit radio-frequency signals in the communication band A or B and/or to receive radio-frequency signals in the communication band A or B. The circuit configuration above also enables the radio-frequency module  1  to transmit radio-frequency signals in the communication band A and radio-frequency signals in the communication band B at the same time, to receive radio-frequency signals in the communication band A and radio-frequency signals in the communication band B at the same time, or to transmit and receive radio-frequency signals in the communication band A and radio-frequency signals in the communication band B at the same time. 
     It is not required that the two transmitting circuits and the two receiving circuits of the radio-frequency module according the present disclosure be connected to the antenna connection terminal  100  via the switch  34 . The two transmitting circuits and the two receiving circuits may be connected to the antenna  2  via their respective terminals. With regard to the circuit configuration illustrated in  FIG.  1   , it is only required that the power amplifier circuit  10  and the low-noise amplifier  21  be included in the radio-frequency module according to the present disclosure. 
     The low-noise amplifier  21  and at least one of the switches  31  to  34  may be incorporated in a semiconductor IC. The semiconductor IC is, for example, a CMOS. Specifically, the semiconductor IC is fabricated by means of an SOI process. Such a semiconductor IC can thus be produced inexpensively. The semiconductor IC may be formed from at least one of GaAs, SiGe, and GaN such that the semiconductor IC can output radio-frequency signals with excellent amplification performance and excellent noise performance. 
     The following describes, in detail, the circuit configuration of the power amplifier circuit  10 . 
     As illustrated in  FIG.  1   , the power amplifier circuit  10  includes the carrier amplifier  11 A, the peaking amplifier  11 B, the preamplifier  11 C, and phase circuits  11 D and  12 B. 
     The carrier amplifier  11 A, the peaking amplifier  11 B, the preamplifier  11 C, and the phase circuit  11 D constitute a power amplifier IC  11 . The power amplifier IC  11  is an example of a first semiconductor IC. The carrier amplifier  11 A, the peaking amplifier  11 B, the preamplifier  11 C, and the phase circuit  11 D may be mounted on a substrate or may be incorporated in a package. 
     The phase circuit  12 B and the matching circuit  12 A constitute a matching IC  12 . The phase circuit  12 B and the matching circuit  12 A of the matching IC  12  may be mounted on a substrate or may be incorporated in a package. 
     The preamplifier  11 C includes an input terminal connected to the common terminal  33   a  of the switch  33 . The carrier amplifier  11 A includes an input terminal connected to one end of the phase circuit  11 D, and the peaking amplifier  11 B includes an input terminal connected to the other end of the phase circuit  11 D. The carrier amplifier  11 A includes an output terminal connected to one end of the phase circuit  12 B, and the peaking amplifier  11 B includes an output terminal connected to the other end of the phase circuit  12 B. 
     The carrier amplifier  11 A is, for example, a Class A amplifier circuit or a Class AB amplifier circuit and is capable of providing high-efficiency amplification in the low power range and the middle power range. 
     The peaking amplifier  11 B is, for example, a Class C amplifier circuit and is capable of providing high-efficiency amplification in the high power range. 
     The phase circuit  11 D (first phase circuit) and the phase circuit  12 B (second phase circuit) are capable of shifting the phase of radio-frequency signals input to the respective circuits and may each be a λ/4 transmission line. 
     With the circuit elements of the power amplifier circuit  10  being connected as above, the output impedance of the peaking amplifier  11 B varies in accordance with the output level of the power amplifier circuit  10 . Thus, high-efficiency amplification in the low-to-middle power range (i.e., the normal output range) is achieved through the operation of the carrier amplifier  11 A, and high-efficiency amplification in the high power range is achieved through the operation of both the carrier amplifier  11 A and the peaking amplifier  11 B. The power amplifier circuit  10  in Doherty configuration achieves high-efficiency amplification in all of the power ranges by making combined use of the carrier amplifier  11 A and the peaking amplifier  11 B in accordance with the output level. 
     The power amplifier circuit  10  may optionally include the preamplifier  11 C. It is not required that the phase circuits  11 D and  12 B each be a λ/4 transmission line. 
     The carrier amplifier  11 A, the peaking amplifier  11 B, the preamplifier  11 C, and the low-noise amplifier  21  may each be a field-effect transistor (FET) or a heterojunction bipolar transistor (HBT) and may be formed from a silicon-based CMOS or GaAs. 
     The power amplifier circuit  10  in Doherty configuration has a large parts count; that is, the power amplifier circuit  10  includes multiple circuit elements such as the carrier amplifier  11 A, the peaking amplifier  11 B, the preamplifier  11 C, and the phase circuits  11 D and  12 B. The radio-frequency module  1  mounted on a single mounting substrate may thus be large in size. This configuration necessitates compromising the isolation of the receiving circuits from the power amplifier circuit  10  that transmits high-power transmission signals. 
     The radio-frequency module  1  according to the present embodiment achieves size reduction in a way that least compromises the isolation of the receiving circuits from the transmitting circuits including the power amplifier circuit  10 . The following describes the configuration of the radio-frequency module  1  that least compromises the isolation to achieve size reduction. 
     2. Layout of Circuit Elements of Radio-Frequency Module  1 A According to Example 1 
       FIG.  2 A  is a schematic diagram illustrating the planar configuration of a radio-frequency module  1 A according to Example 1.  FIG.  2 B  is a schematic diagram illustrating the sectional configuration of the radio-frequency module  1 A according to Example 1. More specifically,  FIG.  2 B  is a sectional view taken along line IIB-IIB in  FIG.  2 A . Part (a) of  FIG.  2 A  illustrates the layout of circuit elements on a module substrate  91  having main surfaces  91   a  and  91   b  on opposite sides, with the main surface  91   a  being seen from the positive side in the z-axis direction. Part (b) of  FIG.  2 A  illustrates the layout of the circuit elements, with the main surface  91   b  being seen through from the positive side in the z-axis direction. 
     The layout of the circuit elements of the radio-frequency module  1  according to the present embodiment will be specifically presented in the following description of the radio-frequency module  1 A according to Example 1. 
     As illustrated in  FIGS.  2 A and  2 B , the radio-frequency module  1 A according to Example 1 adopts the circuit configuration in  FIG.  1    and also includes the module substrate  91 , resin members  92  and  93 , and external connection terminals  150 . 
     The module substrate  91  has the main surface  91   a  (first main surface) and the main surface  91   b  (second main surface) on opposite sides. The transmitting circuits and the receiving circuits are mounted on the module substrate  91 . Substrates that may be used as the module substrate  91  include: a low-temperature co-fired ceramic (LTCC) substrate including dielectric layers stacked on one another; a high-temperature co-fired ceramic (HTCC) substrate including dielectric layers stacked on one another; a substrate with embedded components; a substrate provided with a redistribution layer (RDL); and a printed circuit board. The antenna connection terminal  100 , the transmission input terminals  111  and  112 , the reception output terminal  120 , and the control signal terminal  130  may be provided on the module substrate  91 . 
     The resin member  92  is disposed so as to cover the main surface  91   a  of the module substrate  91 . The transmitting circuits and the receiving circuits are each partially covered with the resin member  92 . The resin member  92  enables the circuit elements constituting the transmitting circuits and the circuit elements constituting the receiving circuits to maintain reliability in terms of, for example, mechanical strength and moisture resistance. The resin member  93  is disposed so as to cover the main surface  91   b  of the module substrate  91 . The transmitting circuits and the receiving circuits are each partially covered with the resin member  93 . The resin member  93  enables the circuit elements constituting the transmitting circuits and the circuit elements constituting the receiving circuits to maintain reliability in terms of, for example, mechanical strength and moisture resistance. The radio-frequency module according to the present disclosure may optionally include the resin members  92  and  93 . 
     Referring to  FIGS.  2 A and  2 B  illustrating the radio-frequency module  1 A according to Example 1, the power amplifier IC  11 , the matching IC  12 , the duplexers  61  and  62 , the matching circuit  51  and  52 , and the switches  33  and  34  are disposed on the main surface  91   a . The low-noise amplifier  21 , the PA control circuit  70 , the matching circuit  53 , the switches  31  and  32 , and the diplexer  60  are disposed on the main surface  91   b.    
     The transmission paths AT and BT and the reception paths AR and BR in  FIG.  1    include wiring (not illustrated in  FIG.  2 A ), which is provided in the module substrate  91  and on the main surfaces  91   a  and  91   b . The wiring may be constructed of bonding wires having ends each of which is bonded to the main surface  91   a , the main surface  91   b , or any one of the circuit elements of the radio-frequency module  1 A. Alternatively, the wiring may be constructed of terminals, electrodes, or traces on the surface of the circuit elements of the radio-frequency module  1 A. 
     In Example 1, the carrier amplifier  11 A and the peaking amplifier  11 B are disposed on the main surface  91   a , and the low-noise amplifier  21  is disposed on the main surface  91   b.    
     That is, the carrier amplifier  11 A and the peaking amplifier  11 B of the power amplifier circuit  10  are disposed opposite the low-noise amplifier  21 , with the module substrate  91  being located between the power amplifier circuit  10  and the low-noise amplifier  21 . Unlike the case where both the power amplifier circuit  10  and the low-noise amplifier  21  are disposed on one side of the module substrate  91 , the layout above enables the radio-frequency module  1 A to achieve size reduction in a way that least compromises the isolation of the receiving circuits from the transmission circuits, thus eliminating or reducing the possibility that transmission signals and harmonic waves of the signals will flow into the reception paths, and the degradation of reception sensitivity is inhibited accordingly. 
     The external connection terminals  150  are disposed on the main surface  91   b  of the module substrate  91 . Through the external connection terminals  150 , the radio-frequency module  1 A transmits electrical signals to an external substrate and receives electrical signals from the external substrate. The external substrate is disposed on the negative side in the z-axis direction of the radio-frequency module  1 A. As illustrated in part (b) of  FIG.  2 A , the antenna connection terminal  100 , the transmission input terminals  111  and  112 , the reception output terminal  120 , and the control signal terminal  130  are each one of the external connection terminals. External connection terminals  150   g , each of which is one of the external connection terminals  150 , are placed at the ground potential of the external substrate. 
     As illustrated in  FIG.  2 B , the radio-frequency module  1 A also includes via conductors  95   v   1 , via conductors  95   v   2 , a planar conductor  95   p   1 , a planar conductor  95   p   2 , and a planar conductor  95   p   3 , which are provided in the module substrate  91 . The via conductors  95   v   1 , the via conductors  95   v   2 , the planar conductor  95   p   1 , the planar conductor  95   p   2 , and the planar conductor  95   p   3  constitute an example of a heat-dissipating conductor portion that is provided in the module substrate  91  to form a connection between the main surface  91   a  and the main surface  91   b . On the main surface  91   a , the heat-dissipating conductor portion is connected to a ground electrode of the carrier amplifier  11 A and to a ground electrode of the peaking amplifier  11 B. On the main surface  91   b , the heat-dissipating conductor portion is connected to the external connection terminals  150   g  (first external connection terminals). 
     The via conductors  95   v   1  and the via conductors  95   v   2  extend perpendicularly to the main surfaces  91   a  and  91   b  (i.e., in the z-axis direction). The planar conductors  95   p   1 ,  95   p   2 , and  95   p   3  lie parallel to the main surfaces  91   a  and  91   b  and are in contact with neither the main surface  91   a  nor the main surface  91   b.    
     The via conductors  95   v   1  constitute an example of a first via conductor. The via conductors  95   v   1  each have an end connected, on the main surface  91   a , to the ground electrode of the carrier amplifier  11 A and each have an end connected, on the main surface  91   b , to the external connection terminals  150   g . Each via conductor  95   v   1  between the ends thereof is connected to the planar conductors  95   p   1 ,  95   p   2 , and  95   p   3 . 
     The via conductors  95   v   2  constitute an example of a second via conductor. The via conductors  95   v   2  each have an end connected, on the main surface  91   a , to the ground electrode of the peaking amplifier  11 B and each have an end connected to the planar conductor  95   p   1 . The via conductors  95   v   2  are not exposed at the main surface  91   b.    
     When the module substrate  91  is viewed in a plan view, the via conductors  95   v   1  overlap the carrier amplifier  11 A, and the via conductors  95   v   2  overlap the peaking amplifier  11 B. 
     The carrier amplifier  11 A is connected to the external connection terminals  150   g  through the via conductors  95   v   1  for heat dissipation. The peaking amplifier  11 B is connected to the external connection terminals  150   g  through the via conductors  95   v   2 , the planar conductor  95   p   1 , and the via conductors  95   v   1  for heat dissipation. 
     The power amplifier circuit  10  is a high heat-generating circuit component of the radio-frequency module  1 A. In order for the radio-frequency module  1 A to achieve enhanced dissipation of heat, it is important that heat generated in the power amplifier circuit  10  be transferred to the external substrate through heat transfer paths of low thermal resistance. However, the following problem may arise if the power amplifier circuit  10  is mounted on the main surface  91   b . In this case, electrode wiring connected to the power amplifier circuit  10  is disposed on the main surface  91   b , and a heat transfer path that passes through only a planar wiring pattern lying on the main surface  91   b  (in an x-y plane) is one of the heat transfer paths of the power amplifier circuit  10 . The planar wiring pattern is formed of a thin metal film and has a high thermal resistance accordingly. This means that the disadvantage of disposing the power amplifier circuit  10  on the main surface  91   b  is the degradation in heat dissipation characteristics. 
     As a workaround, the radio-frequency module  1 A according to Example 1 includes the via conductors  95   v   1  for heat dissipation that are connected, on the main surface  91   a , to the ground electrode of the power amplifier circuit  10  and extend from the main surface  91   a  to the main surface  91   b . The via conductors  95   v   1  are connected, on the main surface  91   b , to the external connection terminals  150   g  placed at the ground potential. 
     That is, the power amplifier circuit  10  is connected to the external connection terminals  150   g  through the via conductors  95   v   1  for heat dissipation. Heat generated in the power amplifier circuit  10  may be dissipated without having to use the heat transfer path that passes through only the planar wiring pattern lying in the x-y plane and having a thermal resistance higher than that of any other wiring path in the module substrate  91 . The via conductors  95   v   1 , which extend through the module substrate  91  perpendicularly to the main surfaces  91   a  and  91   b , have such low thermal resistance that heat generated in the power amplifier circuit  10  can be dissipated efficiently to the outside of the radio-frequency module  1 A. 
     The peaking amplifier  11 B operates in the high power range only, whereas the carrier amplifier  11 A continuously operates in low-to-high power ranges. When the amplification operation is continued for a given period of time, the amount of heat generated in the carrier amplifier  11 A is thus greater than the amount of heat generated in the peaking amplifier  11 B. 
     With this in view, the radio-frequency module  1 A according to Example 1 is configured such that heat generated in the carrier amplifier  11 A is dissipated through the via conductors  95   v   1  extending through the module substrate. That is, the heat generated in the carrier amplifier  11 A is dissipated with a high degree of efficiency through heat transfer paths of low thermal resistance. The heat generated in the peaking amplifier  11 B is dissipated through not only the via conductors  95   v   1  but also the planar conductor  95   p   1  and the via conductors  95   v   2 . That is, the heat generated in the peaking amplifier  11 B is dissipated less efficiently through the heat transfer paths whose thermal resistance is higher than the thermal resistance of the heat transfer paths for the heat generated in the carrier amplifier  11 A. However, the disparity in the heat dissipation efficiency can be offset by the fact that the amount of heat generated in the carrier amplifier  11 A is greater than the amount of heat generated in the peaking amplifier  11 B. The heat transfer paths enable well-balanced thermal dissipation accordingly. The structure of the heat-dissipating conductor portion in Example 1 enables the radio-frequency module  1 A to dissipate the heat of the power amplifier circuit  10  efficiently to the outside. 
     There is an overlap between the main surface  91   b  and the peaking amplifier  11 B when the module substrate  91  is viewed in a plan view. The via conductors for heat dissipation are not exposed at the main surface  91   b  in the overlapping region. The external connection terminals  150   g  are not disposed in the overlapping region. The overlapping region, in which the main surface  91   b  overlaps the peaking amplifier  11 B, can thus be a mounting place for a circuit element, such as the PA control circuit  70  as illustrated in part (b) of  FIG.  2 A  and in  FIG.  2 B . This leads to the enhanced efficiency in the layout of the circuit elements on the main surface  91   b , and space savings can be achieved accordingly. Another advantage of disposing the PA control circuit  70  in the overlapping region is a shortening of control wiring that connects the carrier amplifier  11 A, the peaking amplifier  11 B, and the PA control circuit  70  to each other. This enables a reduction in the digital noise in the control wiring. 
     It is not required that the PA control circuit  70  be disposed in the overlapping region, in which the main surface  91   b  overlaps the peaking amplifier  11 B. The advantage of disposing the switch  31  in the overlapping region is a shortening of transmission signal wiring that connects the power amplifier circuit  10  and the switch  31  to each other. This enables a reduction in the transmission loss for transmission signals. 
     The via conductors  95   v   1 , which extend through the module substrate  91  perpendicularly to the main surfaces  91   a  and  91   b  in Example 1, may each include columnar electrodes extending and cascade-connected perpendicularly to the main surfaces  91   a  and  91   b . There is an overlap between the columnar conductors of the via conductor  95   v   1  when the module substrate  91  is viewed in a plan view. The via conductors  95   v   1  structured as above may also be regarded as the via conductors extending through the module substrate  91  perpendicularly to the main surfaces  91   a  and  91   b.    
     Although the planar conductors  95   p   1 ,  95   p   2 , and  95   p   3  are provided in the example above, the module substrate  91  does not necessarily include three planar conductors. It is only required that at least one planar conductor be provided. 
     The other end of the via conductor  95   v   2  may be connected to the planar conductor  95   p   2  or  95   p   3  instead of being connected to the planar conductor  95   p   1 . 
     The radio-frequency module  1 A according to Example 1 is configured as follows. The carrier amplifier  11 A, the peaking amplifier  11 B, and the phase circuit  11 D are included in the power IC  11  (first semiconductor IC). The phase circuit  12 B and the matching circuit  12 A are included in the matching circuit IC  12 . 
     This means that the phase circuit  12 B is discretely separated from the power amplifier IC  11 . The phase circuit  12 B is preferably a low-loss transmission line having a high Q factor so that the phase circuit  12 B is capable of transmitting high-power transmission signals output by the carrier amplifier  11 A and high-power transmission signals output by the peaking amplifier  11 B. Similarly, in order for the matching circuit  12 A to be capable of transmitting high-power transmission signals, it preferably includes a circuit element such as an inductor having a high Q factor. Unlike the case with the power amplifier IC  11 , the matching circuit IC  12 , which is discretely separated from the power amplifier IC  11 , may be formed from a dielectric material selected with a view to achieving a high Q factor instead of being formed from a dielectric material selected with consideration given to amplification characteristics. This is conducive to reducing the transmission loss for transmission signals. 
     The matching IC  12  may be configured as an integrated passive device (IPD). The phase circuit  12 B may be configured as an IPD separate from the matching circuit  12 A. The miniaturization of the phase circuit  12 B enables the radio-frequency module  1 A to achieve a further reduction in size. 
     The phase circuit  12 B may be embedded in the module substrate  91 . 
     The carrier amplifier  11 A and the peaking amplifier  11 B of the radio-frequency module  1 A according to Example 1 are disposed between the phase circuit  11 D and the phase circuit  12 B when the module substrate  91  is viewed in a plan view as illustrated in part (a) of  FIG.  2 A . 
     This layout conforms to the flow of transmission signals that pass through the phase circuit  11 D, the carrier amplifier  11 A or the peaking amplifier  11 B, and the phase circuit  12 B in the stated order. This enables a shortening of wiring forming connections between these elements, and the transmission loss for transmission signals may be reduced accordingly. 
     The low-noise amplifier  21  and the switch  32  of the radio-frequency module  1 A in Example 1 may be configured as a semiconductor IC  80 . 
     As described above, the power amplifier IC  11 , the matching circuit IC  12 , the duplexers  61  and  62 , the matching circuits  51  and  52 , and the switches  33  and  34  are disposed on the main surface  91   a . The low-noise amplifier  21 , the PA control circuit  70 , the matching circuit  53 , the switches  31  and  32 , and the diplexer  60  are disposed on the main surface  91   b . However, circuit elements of the radio-frequency module  1 A according to Example 1 except for the power amplifier IC  11  on the main surface  91   a  and the low-noise amplifier  21  on the main surface  91   b  may be arranged differently. Specifically, circuit elements disposed on the main surface  91   b  may include at least one of the following: the duplexers  61  and  62 , the matching circuits  51  and  52 , and the switches  33  and  34 . Circuit elements disposed on the main surface  91   a  may include at least one of the following: the PA control circuit  70 , the matching circuit  53 , the switches  31  and  32 , and the diplexer  60 . 
     The module substrate  91  has a multilayer structure including dielectric layers stacked on each other. At least one of the dielectric layers preferably include a ground electrode pattern. This makes the module substrate  91  more capable of blocking electromagnetic fields. 
     The external connection terminals  150  may be columnar electrodes extending in the z-axis direction through the resin member  93  as illustrated in  FIGS.  2 A and  2 B . Alternatively, the external connection terminals  150  (and the external connection terminals  150   g ) may be bump electrodes on the main surface  91   b  and may be denoted by  160  as in  FIG.  2 C , which illustrates the radio-frequency module  1 B according to a modification. In this case, the resin member  93  on the main surface  91   b  is optional. 
     3. Layout of Circuit Elements of Radio-Frequency Module  1 C According to Example 2 
       FIG.  3 A  is a schematic diagram illustrating the planar configuration of a radio-frequency module  1 C according to Example 2.  FIG.  3 B  is a schematic diagram illustrating the sectional configuration of the radio-frequency module  1 C according to Example 2. More specifically,  FIG.  3 B  is a sectional view taken along line IIIB-IIIB in  FIG.  3 A . Part (a) of  FIG.  3 A  illustrates the layout of circuit elements on the module substrate  91  having the main surfaces  91   a  and  91   b  on opposite sides, with the main surface  91   a  being seen from the positive side in the z-axis direction. Part (b) of  FIG.  3 A  illustrates the layout of the circuit elements, with the main surface  91   b  being seen through from the positive side in the z-axis direction. 
     The layout of the circuit elements of the radio-frequency module  1  according to the present embodiment will be specifically presented in the following description of the radio-frequency module  1 C according to Example 2. 
     The layout of the circuit elements of the radio-frequency module  1 C according to Example 2 is different from the layout of the circuit elements of the radio-frequency module  1 A according to Example 1. Configurations common to the radio-frequency module  1 C according to Example 2 and the radio-frequency module  1 A according to Example 1 will be omitted from the following description, which will be given while focusing on distinctive features of the radio-frequency module  1 C. 
     Referring to  FIGS.  3 A and  3 B  illustrating the radio-frequency module  1 C according to Example 2, the power amplifier IC  11 , the matching IC  12 , the PA control circuit  70 , the duplexers  61  and  62 , the matching circuit  51  and  52 , and the switch  33  are disposed on the main surface  91   a  of the module substrate  91 . The low-noise amplifier  21 , the matching circuit  53 , the switches  31 ,  32 , and  34 , and the diplexer  60  are disposed on the main surface  91   b  of the module substrate  91 . 
     The carrier amplifier  11 A and the peaking amplifier  11 B in Example 2 are disposed on the main surface  91   a . The low-noise amplifier  21  is disposed on the main surface  91   b.    
     This layout enables the radio-frequency module  1 C to achieve size reduction in a way that least compromises the isolation of the receiving circuits from the transmission circuits, thus eliminating or reduces the possibility that transmission signals and harmonic waves of the signals will flow into the reception paths, and the degradation of reception sensitivity is inhibited accordingly. 
     As illustrated in  FIG.  3 B , the radio-frequency module  1 C also includes a via conductor  95   v   3  and a via conductor  95   v   4 , which are disposed in the module substrate  91 . The via conductors  95   v   3  and  95   v   4  constitute an example of the heat-dissipating conductor portion that is provided in the module substrate  91  to form a connection between the main surface  91   a  and the main surface  91   b . On the main surface  91   a , the heat-dissipating conductor portion is connected to the ground electrode of the carrier amplifier  11 A and to the ground electrode of the peaking amplifier  11 B. On the main surface  91   b , the heat-dissipating conductor portion is connected to the external connection terminals  150   g  (first external connection terminals). 
     The via conductor  95   v   3  and the via conductor  95   v   4  extend perpendicularly to the main surfaces  91   a  and  91   b  (i.e., in the z-axis direction). 
     The via conductor  95   v   3  has an end connected, on the main surface  91   a , to the ground electrode of the carrier amplifier  11 A and has an end connected, on the main surface  91   b , to the external connection terminals  150   g.    
     The via conductor  95   v   4  has an end connected, on the main surface  91   a , to the ground electrode of peaking amplifier  11 B and an end connected, on the main surface  91   b , to the external connection terminals  150   g.    
     The carrier amplifier  11 A is connected to the external connection terminals  150   g  through the via conductor  95   v   3  for heat dissipation. The peaking amplifier  11 B is connected to the external connection terminals  150   g  through the via conductor  95   v   4  for heat dissipation. That is, the power amplifier circuit  10  is connected to the external connection terminals  150   g  through the via conductors  95   v   3  and  95   v   4  for heat dissipation. This configuration enables the radio-frequency module  1 C to dissipate the heat of the power amplifier circuit  10  efficiently to the outside. 
     Referring to  FIG.  3 B  illustrating the radio-frequency module  1 C in Example 2, the PA control circuit  70  is stacked on the power amplifier IC  11  on the main surface  91   a . As illustrated in part (a) of  FIG.  3 A , the PA control circuit  70  overlaps neither the carrier amplifier  11 A nor the peaking amplifier  11 B when the module substrate  91  is viewed in a plan view. 
     This layout eliminates the need to leave a space for the PA control circuit  70  on the main surface of the module substrate  91  and thus enables the radio-frequency module  1 C to achieve size reduction. The PA control circuit  70  is not disposed on the upper side (i.e., on the positive side in the y-axis direction) of the carrier amplifier  11 A and the peaking amplifier  11 B, in which the amount of heat generated is greater than the amount of heat generated in any other circuit element of the power amplifier IC  11 . This layout eliminates or reduces the possibility that the heat generated in the power amplifier IC  11  will raise the temperature of the PA control circuit  70  and will degrade the control performance of the PA control circuit  70  accordingly. 
     When the module substrate  91  is viewed in a plan view, the PA control circuit  70  does not overlap the carrier amplifier  11 A although the PA control circuit  70  may overlap the peaking amplifier  11 B. 
     When the amplification operation is continued for a given period of time, the amount of heat generated in the carrier amplifier  11 A is greater than the amount of heat generated in the peaking amplifier  11 B. The PA control circuit  70  is not disposed on the upper side (i.e., on the positive side in the y-axis direction) of the carrier amplifier  11 A, in which the amount of heat generated is greater than the amount of heat generated in the peaking amplifier  11 B. This layout eliminates or reduces the possibility that the heat generated in the carrier amplifier  11 A will raise the temperature of the PA control circuit  70  and will degrade the control performance of the PA control circuit  70  accordingly. 
     The phase circuit  12 B and the switch  34  of the radio-frequency module  1 C according to Example 2, respectively, are disposed on the main surfaces  91   a  and  91   b . That is, the phase circuit  12 B and the switch  34  are disposed on opposite sides with the module substrate  91  therebetween. 
     This layout eliminates or reduces the possibility that transmission signals, harmonic waves, or intermodulation distortion from the power amplifier circuit  10  will be electromagnetically coupled to the switch  34 . For example, a transmission signal in the communication band A or B is kept from bypassing the transmitting filter  61 T or  62 T and the switch  31  and flowing into the reception path AR or BR. Owing to the improved isolation of the receiving circuits from the transmitting circuits, spurious waves associated with the transmission signals, harmonic waves, or intermodulation distortion are kept from flowing into the reception paths. This eliminates or reduces the possibility that the reception sensitivity will degrade. 
     The low-noise amplifier  21  and the switches  32  and  34  of the radio-frequency module  1 C in Example 2 may be configured as a semiconductor IC  81 . 
     As described above, the power amplifier IC  11 , the matching circuit IC  12 , the PA control circuit  70 , the duplexers  61  and  62 , the matching circuits  51  and  52 , and the switch  33  are disposed on the main surface  91   a . The low-noise amplifier  21 , the matching circuit  53 , the switches  31 ,  32 , and  34 , and the diplexer  60  are disposed on the main surface  91   b . However, circuit elements of the radio-frequency module  1 C according to Example 2 except for the power amplifier IC  11  and the PA control circuit  70  on the main surface  91   a  and the low-noise amplifier  21  on the main surface  91   b  may be arranged differently. Specifically, circuit elements disposed on the main surface  91   b  may include at least one of the following: the duplexers  61  and  62 , the matching circuits  51  and  52 , and the switch  33 . Circuit elements disposed on the main surface  91   a  may include at least one of the following: the matching circuit  53 , the switches  31 ,  32 , and  34 , and the diplexer  60 . 
     4. Effects 
     The radio-frequency module  1  according to the present embodiment includes the module substrate  91 , the power amplifier circuit  10  in Doherty configuration, and the low-noise amplifier  21 . The module substrate  91  has the main surface  91   a  and the main surface  91   b  on opposite sides. The power amplifier circuit  10  includes the carrier amplifier  11 A, the peaking amplifier  11 B, and the phase circuits  11 D and  12 B. The carrier amplifier  11 A includes an input terminal connected to one end of the phase circuit  11 D. The peaking amplifier  11 B includes an input terminal connected to the other end of the phase circuit  11 D. The carrier amplifier  11 A includes an output terminal connected to one end of the phase circuit  12 B. The peaking amplifier  11 B includes an output terminal connected to the other end of the phase circuit  12 B. The carrier amplifier  11 A and the peaking amplifier  11 B are disposed on the main surface  91   a . The low-noise amplifier  21  is disposed on the main surface  91   b.    
     That is, the carrier amplifier  11 A and the peaking amplifier  11 B of the power amplifier circuit  10  are disposed opposite the low-noise amplifier  21 , with the module substrate  91  being located between the power amplifier circuit  10  and the low-noise amplifier  21 . Unlike the case where both the power amplifier circuit  10  and the low-noise amplifier  21  are disposed on one side of the module substrate  91 , the layout above enables the radio-frequency module  1  to achieve size reduction in a way that least compromises the isolation of the receiving circuits from the transmission circuits, thus eliminating or reducing the possibility that transmission signals and harmonic waves of the signals will flow into the reception paths, and the degradation of reception sensitivity is inhibited accordingly. 
     The radio-frequency module  1  also includes the heat-dissipating conductor portion and the external connection terminals  150 . The heat-dissipating conductor portion is provided in the module substrate  91  to form a connection between the main surface  91   a  and the main surface  91   b . The external connection terminals  150  are disposed on the main surface  91   b . The heat-dissipating conductor portion is connected, on the main surface  91   a , to the ground electrode of the carrier amplifier  11 A and to the ground electrode of the peaking amplifier  11 B and is connected, on the main surface  91   b , to the external connection terminals  150   g  placed at the ground potential. Each of the external connection terminals  150   g  is one of the external connection terminals  150 . 
     That is, the power amplifier circuit  10  is connected to the external connection terminals  150   g  through the heat-dissipating conductor portion. This configuration enables the radio-frequency module  1  to dissipate the heat of the power amplifier circuit  10  efficiently to the outside. 
     The radio-frequency module  1 A may be configured as follows. The heat-dissipating conductor portion includes the via conductors  95   v   1 , the via conductors  95   v   2 , and the planar conductor  95   p   1 . The via conductors  95   v   1  and  95   v   2  extend perpendicularly to the main surfaces  91   a  and  91   b . The planar conductor  95   p   1  lies parallel to the main surfaces  91   a  and  91   b  and is in contact with neither the main surface  91   a  nor the main surface  91   b . When the module substrate  91  is viewed in a plan view, the via conductors  95   v   1  overlap the carrier amplifier  11 A, and the via conductors  95   v   2  overlap the peaking amplifier  11 B. The via conductors  95   v   1  each have an end connected, on the main surface  91   a , to the ground electrode of the carrier amplifier  11 A and each have an end connected, on the main surface  91   b , to the external connection terminals  150   g . Each via conductor  95   v   1  between the ends thereof is connected to the planar conductor  95   p   1 . The via conductors  95   v   2  each have an end connected, on the main surface  91   a , to the ground electrode of the peaking amplifier  11 B and each have an end connected to the planar conductor  95   p   1 . 
     The heat generated in the carrier amplifier  11 A of the radio-frequency module  1 A is dissipated with a high degree of efficiency through heat transfer paths of low thermal resistance. The heat generated in the peaking amplifier  11 B is dissipated less efficiently through the heat transfer paths whose thermal resistance is higher than the thermal resistance of the heat transfer paths for the heat generated in the carrier amplifier  11 A. However, the disparity in the heat dissipation efficiency can be offset by the fact that the amount of heat generated in the carrier amplifier  11 A is greater than the amount of heat generated in the peaking amplifier  11 B. The heat transfer paths enable well-balanced thermal dissipation accordingly. There is an overlap between the main surface  91   b  and the peaking amplifier  11 B when the module substrate  91  is viewed in a plan view. The via conductors for heat dissipation are not exposed at the main surface  91   b  in the overlapping region. The external connection terminals  150   g  are not disposed in the overlapping region, which can thus be a mounting place for a circuit component. This leads to the enhanced efficiency in the layout of the circuit components on the main surface  91   b , and space savings can be achieved accordingly. 
     The carrier amplifier  11 A and the peaking amplifier  11 B of the radio-frequency module  1  may be disposed between the phase circuit  11 D and the phase circuit  12 B when the module substrate  91  is viewed in a plan view. 
     This layout conforms to the flow of transmission signals that pass through the phase circuit  11 D, the carrier amplifier  11 A or the peaking amplifier  11 B, and the phase circuit  12 B in the stated order. This enables a shortening of wiring forming connections between these elements, and the transmission loss for transmission signals may be reduced accordingly. 
     The radio-frequency module  1  may be configured as follows: the carrier amplifier  11 A, the peaking amplifier  11 B, and the phase circuit  11 D of the radio-frequency module  1  are included in the power amplifier IC  11 , whereas the phase circuit  12 B is not included in the power amplifier IC  11 . 
     The phase circuit  12 B is preferably a low-loss transmission line having a high Q factor so that the phase circuit  12 B is capable of transmitting high-power transmission signals output by the carrier amplifier  11 A and high-power transmission signals output by the peaking amplifier  11 B. The phase circuit  12 B, which is not included in the power amplifier IC  11 , may be formed from a dielectric material selected with a view to achieving a high Q factor instead of being formed from a dielectric material selected with consideration given to amplification characteristics. This is conducive to reducing the transmission loss for transmission signals. 
     The radio-frequency module  1 C may include the PA control circuit  70  that controls the carrier amplifier  11 A and the peaking amplifier  11 B. The PA control circuit  70  is stacked on the power amplifier IC  11  on the main surface  91   a . The PA control circuit  70  does not overlap the carrier amplifier  11 A when the module substrate  91  is viewed in a plan view. 
     This layout eliminates the need to leave a space for the PA control circuit  70  on the main surface of the module substrate  91  and thus enables the radio-frequency module  1 C to achieve size reduction. The PA control circuit  70  is not disposed on the upper side (i.e., on the positive side in the y-axis direction) of the carrier amplifier  11 A, in which the amount of heat generated is greater than the amount of heat generated in any other circuit element of the power amplifier IC  11 . This layout eliminates or reduces the possibility that the heat generated in the carrier amplifier  11 A will raise the temperature of the PA control circuit  70  and will degrade the control performance of the PA control circuit  70  accordingly. 
     The radio-frequency module  1 C may be configured in such a manner that the PA control circuit  70  does not overlap the peaking amplifier  11 B when the module substrate is viewed in a plan view. 
     This eliminates or reduces the possibility that the heat generated in the carrier amplifier  11 A and the heat generated in the peaking amplifier  11 B will raise the temperature of the PA control circuit  70  and will degrade the control performance of the PA control circuit  70  accordingly. 
     The radio-frequency module  1 C may also include the antenna connection terminal  100 , the transmitting filter  61 T, and the switch  34 . The transmitting filter  61 T allows a transmission signal from the power amplifier circuit  10  to pass therethrough. The switch  34  performs switching between the state in which the antenna connection terminal  100  is connected to the transmitting filter  61 T and the state in which the antenna connection terminal  100  is not connected to the transmitting filter  61 T. The phase circuit  12 B may be disposed on the main surface  91   a . The switch may be disposed on the main surface  91   b.    
     This configuration eliminates or reduces the possibility that transmission signals, harmonic waves, or intermodulation distortion from the power amplifier circuit  10  will be electromagnetically coupled to the switch  34 . A transmission signal in the communication band A or B is kept from bypassing, for example, the transmitting filter  61 T and flowing into the reception path AR or BR. That is, spurious waves associated with the transmission signals, harmonic waves, or intermodulation distortion are kept from flowing into the reception paths. This eliminates or reduces the possibility that the reception sensitivity will degrade. 
     The phase circuit  12 B of the radio-frequency module  1  may be an integrated passive device. 
     The miniaturization of the phase circuit  12 B enables the radio-frequency module  1  to achieve a further reduction in size. 
     The communication device  5  includes the antenna  2 , the RFIC  3 , and the radio-frequency module  1 . The RFIC  3  process radio-frequency signals transmitted via the antenna  2  and radio-frequency signals received via the antenna  2 . The radio-frequency module  1  transmits the radio-frequency signals between the antenna  2  and the RFIC  3 . 
     This enables a reduction in the size of the communication device  5  in a way that least compromises the isolation of the receiving circuits from the transmission power amplifier circuit in Doherty configuration. 
     Other Embodiments 
     The radio-frequency module and the communication device according to the present disclosure are not limited to the embodiment, the examples, and the modifications that have been described so far. The present disclosure embraces other embodiments implemented by varying combinations of constituent elements of the embodiment above and the modifications thereof, other modifications achieved through various alterations to the embodiment above and modifications thereof that may be conceived by those skilled in the art within a range not departing from the spirit of the present disclosure, and various types of apparatuses including the radio-frequency module and the communication device. 
     In each of the radio-frequency modules and the communication devices according to the embodiment, the examples, and the modifications, the paths forming connections between the circuit elements and the signal paths illustrated in the drawings may have, for example, other circuit elements and wiring disposed thereon. 
     INDUSTRIAL APPLICABILITY 
     The present disclosure, or more specifically, a radio-frequency module including high-power transmission circuits has wide applicability to communication apparatuses such as mobile phones. 
     While preferred embodiments of the disclosure have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the disclosure. The scope of the disclosure, therefore, is to be determined solely by the following claims.