The switch 52 is connected between the output end of the power amplifier 11 and the filter 61 and between the output end of the power amplifier 11 and the filter 62 and is connected between the input end of the low-noise amplifier 21 and the filter 62. The switch 52 includes terminals 521 to 524. The terminal 521 is connected to the filter 61 with the matching circuit 412 interposed therebetween. The terminal 522 is connected to the filter 62 with the matching circuit 422 interposed therebetween. The terminal 523 is connected to the output end of the power amplifier 11 with the matching circuit 413 interposed therebetween. The terminal 524 is connected to the input end of the low-noise amplifier 21 with the switch 53 and the matching circuit 433 interposed therebetween.

With this structure for connection, the switch 52 can connect the terminal 523 to at least the terminal 521 or 522, for example, based on a control signal from the RFIC 3 and can connect the terminal 522 to the terminal 523 or 524. That is, the switch 52 can switch connection and disconnection between the power amplifier 11 and the filter 61 and between the power amplifier 11 and the filter 62 and can change the connection destination of the filter 62 between the power amplifier 11 and the low-noise amplifier 21. For example, the switch 52 includes a multiconnection switch circuit.

The switch 53 is connected between the input end of the low-noise amplifier 21 and the filter 62 and between the input end of the low-noise amplifier 21 and the filter 63. The switch 53 includes terminals 531 to 533. The terminal 531 is connected to the input end of the low-noise amplifier 21 with the matching circuit 433 interposed therebetween. The terminal 532 is connected to the terminal 524 of the switch 52 and is connected to the filter 62 with the switch 52 and the matching circuit 422 interposed therebetween. The terminal 533 is connected to the filter 63 with the matching circuit 432 interposed therebetween.

With this structure for connection, the switch 53 can connect the terminal 531 to at least the terminal 532 or 533, for example, based on a control signal from the RFIC 3. That is, the switch 53 can switch connection and disconnection between the low-noise amplifier 21 and the filter 62 and between the low-noise amplifier 21 and the filter 63. For example, the switch 53 includes a multiconnection switch circuit.

The switch 54 is connected between the output end of the power amplifier 12 and the filter 64 and between the output end of the power amplifier 12 and the filter 65 and is connected between the input end of the low-noise amplifier 22 and the filter 65. The switch 54 includes terminals 541 to 544. The terminal 541 is connected to the filter 64 with the matching circuit 442 interposed therebetween. The terminal 542 is connected to the filter with the matching circuit 452 interposed therebetween. The terminal 543 is connected to the output end of the power amplifier 12 with the matching circuit 443 interposed therebetween. The terminal 544 is connected to the input end of the low-noise amplifier 22 with the switch 55 and the matching circuit 463 interposed therebetween.

With this structure for connection, the switch 54 can connect the terminal 543 to at least the terminal 541 or 542, for example, based on a control signal from the RFIC 3 and can connect the terminal 542 to the terminal 543 or 544. That is, the switch 54 can switch connection and disconnection between the power amplifier 12 and the filter 64 and between the power amplifier 12 and the filter 65 and can change the connection destination of the filter 65 between the power amplifier 12 and the low-noise amplifier 22. For example, the switch 54 includes a multiconnection switch circuit.

The switch 55 is connected between the input end of the low-noise amplifier 22 and the filter 65 and between the input end of the low-noise amplifier 22 and the filter 66. The switch 55 includes terminals 551 to 553. The terminal 551 is connected to the input end of the low-noise amplifier 22 with the matching circuit 463 interposed therebetween. The terminal 552 is connected to the terminal 544 of the switch 54 and is connected to the filter 65 with the switch 54 and the matching circuit 452 interposed therebetween. The terminal 553 is connected to the filter 66 with the matching circuit 462 interposed therebetween.

With this structure for connection, the switch 55 can connect the terminal 551 to at least the terminal 552 or 553, for example, based on a control signal from the RFIC 3. That is, the switch 55 can switch connection and disconnection between the low-noise amplifier 22 and the filter 65 and between the low-noise amplifier 22 and the filter 66. For example, the switch 55 includes a multiconnection switch circuit.

The filter 61 (A-Tx) is an example of a first filter and is connected between the power amplifier 11 and the antenna connection terminal 100. Specifically, an end of the filter 61 is connected to the antenna connection terminal 100 with the matching circuit 411, the switch 51, and the matching circuit 401 interposed therebetween. Another end of the filter 61 is connected to the output end of the power amplifier 11 with the matching circuit 412, the switch 52, and the matching circuit 413 interposed therebetween. The filter 61 has a pass band that includes an uplink operation band in the band A for frequency division duplex (FDD) and enables a transmission signal in the band A to pass.

The filter 62 (B-TRx) is an example of the first filter, is connected between the antenna connection terminal 100 and the power amplifier 11, and is connected between the antenna connection terminal 100 and the low-noise amplifier 21. Specifically, an end of the filter 62 is connected to the antenna connection terminal 100 with the switch 51 and the matching circuit 401 interposed therebetween. Another end of the filter 62 is connected to the output end of the power amplifier 11 with the matching circuit 422, the switch 52, and the matching circuit 413 interposed therebetween and is connected to the input end of the low-noise amplifier 21 with the matching circuit 422, the switches 52 and 53, and the matching circuit 433 interposed therebetween. The filter 62 has a pass band that includes the band B for time division duplex (TDD) and enables a transmission signal and a reception signal in the band B to pass.

The filter 63 (A-Rx) is an example of the first filter and is connected between the low-noise amplifier 21 and the antenna connection terminal 100. Specifically, an end of the filter 63 is connected to the antenna connection terminal 100 with the matching circuit 431, the switch 51, and the matching circuit 401 interposed therebetween. Another end of the filter 63 is connected to the input end of the low-noise amplifier 21 with the matching circuit 432, the switch 53, and the matching circuit 433 interposed therebetween. The filter 63 has a pass band that includes a downlink operation band in the band A for FDD and enables a reception signal in the band A to pass.

The filter 64 (C-Tx) is an example of the first filter and is connected between the power amplifier 12 and the antenna connection terminal 100. Specifically, an end of the filter 64 is connected to the antenna connection terminal 100 with the matching circuit 441, the switch 51, and the matching circuit 401 interposed therebetween. Another end of the filter 64 is connected to the output end of the power amplifier 12 with the matching circuit 442, the switch 54, and the matching circuit 443 interposed therebetween. The filter 64 has a pass band that includes an uplink operation band in the band C for FDD and enables a transmission signal in the band C to pass.

The filter 65 (D-TRx) is an example of the first filter, is connected between the antenna connection terminal 100 and the power amplifier 12, and is connected between the antenna connection terminal 100 and the low-noise amplifier 22. Specifically, an end of the filter 65 is connected to the antenna connection terminal 100 with the switch 51 and the matching circuit 401 interposed therebetween. Another end of the filter 65 is connected to the output end of the power amplifier 12 with the matching circuit 452, the switch 54, and the matching circuit 443 interposed therebetween, and is connected to the input end of the low-noise amplifier 22 with the matching circuit 452, the switches 54 and 55, and the matching circuit 463 interposed therebetween. The filter 65 has a pass band that includes the band D for TDD and enables a transmission signal and a reception signal in the band D to pass.

The filter 66 (C-Rx) is an example of the first filter and is connected between the low-noise amplifier 22 and the antenna connection terminal 100. Specifically, an end of the filter 66 is connected to the antenna connection terminal 100 with the matching circuit 461, the switch 51, and the matching circuit 401 interposed therebetween. Another end of the filter 66 is connected to the input end of the low-noise amplifier 22 with the matching circuit 462, the switch 55, and the matching circuit 463 interposed therebetween. The filter 66 has a pass band that includes a downlink operation band in the band C for FDD and enables a reception signal in the band C to pass.

The PA controller 71 can control the power amplifiers 11 and 12. The PA controller 71 receives a digital control signal from the RFIC 3 via the control terminal 131 and outputs a control signal to the power amplifiers 11 and 12.

The bands A to D are frequency bands for a communication system that is built by using radio access technology (RAT). The bands A to D are defined by, for example, standards organizations (such as 3GPP (3rd Generation Partnership Project) and IEEE (Institute of Electrical and Electronics Engineers)) in advance. Examples of the communication system include a 5GNR (5th Generation New Radio) system, a LTE (Long Term Evolution) system, and a WLAN (Wireless Local Area Network) system.

The bands A and B and the bands C and D may belong to different band groups or may belong to the same band group. A band group means a frequency range in which multiple bands are included. Examples of the band group can include an ultra-high band group (3300 to 5000 MHz), a high band group (2300 to 2690 MHz), a middle band group (1427 to 2200 MHz), and a low band group (698 to 960 MHz) but are not limited thereto. An example of the band group may be a band group that includes an unlicensed band of 5 GHz or more or a band group of a millimeter band.

For example, the bands A and B may be included in the high band group, and the bands C and D may be included in the middle band group. For example, the bands A and B may be included in the middle band group or the high band group, and the bands C and D may be included in the low band group.

The radio frequency circuit 1 is illustrated in FIG. 1 by way of example and is not limited thereto. For example, bands that are supported by the radio frequency circuit 1 are not limited to the bands A to D. For example, the radio frequency circuit 1 may support five or more bands. In this case, the radio frequency circuit 1 may include a filter for bands E, F, G, and so on. For example, the radio frequency circuit 1 may support only the bands A and B and does not necessarily need to support the bands C and D. In this case, the radio frequency circuit 1 does not necessarily need to include the power amplifier 12, the low-noise amplifier 22, the matching circuits 441 to 443, 452, and 461 to 463, the radio frequency input terminal 112, and the radio frequency output terminal 122. For example, the radio frequency circuit 1 may be a transmit-only circuit. In this case, the radio frequency circuit 1 does not necessarily need to include the low-noise amplifiers 21 and 22, the matching circuits 431 to 433 and 461 to 463, the switches 53 and 55, the filters 63 and 66, and the radio frequency output terminals 121 and 122. For example, the radio frequency circuit 1 may be a receive-only circuit. In this case, the radio frequency circuit 1 does not necessarily need to include the power amplifiers 11 and 12, the matching circuits 411 to 413 and 441 to 443, the switches 52 and 54, the filters 61 and 64, and the radio frequency input terminals 111 and 112.

The radio frequency circuit 1 does not necessarily need to include some of the matching circuits 401, 411 to 413, 422, 431 to 433, 441 to 443, 452, and 461 to 463. For example, the radio frequency circuit 1 may be connected to multiple antennas and may include multiple antenna connection terminals. The radio frequency circuit 1 may further include an additional radio frequency input terminal. In this case, a switch that can change the connection destination of a power amplifier between multiple radio frequency input terminals may be interposed between the power amplifier and the multiple radio frequency input terminals. The radio frequency circuit 1 may further include an additional radio frequency output terminal. In this case, a switch that can change the connection destination of a low-noise amplifier between multiple radio frequency output terminals may be interposed between the low-noise amplifier and the multiple radio frequency output terminals.

[2 Example of Radio Frequency Circuit 1]

2.1 First Example

A radio frequency module 1A that includes the radio frequency circuit 1 will be described as a first example of the radio frequency circuit 1 according to the exemplary embodiment described above with reference to FIG. 2 to FIG. 5.

[2.1.1 Arrangement of Components of Radio Frequency Module 1A]

FIG. 2 is a plan view of a main surface 91a of the radio frequency module 1A in the present example. FIG. 3 is a plan view of a main surface 91b of the radio frequency module 1A in the present example and illustrates the main surface 91b of a module substrate 91 viewed from a positive position on the z-axis. FIG. 4 is a plan view of a main surface 92b of the radio frequency module 1A in the present example and illustrates the main surface 92b of a module substrate 92 viewed in a positive position on the z-axis. FIG. 5 is a sectional view of the radio frequency module 1A in the present example. A section of the radio frequency module 1A in FIG. 5 is a section taken along line v-v in FIG. 2 to FIG. 4.

In FIG. 2 to FIG. 5, an illustration for wiring lines that connect multiple electronic components that are disposed in, on, or along the module substrates 91 and 92 is omitted. In FIG. 2 to FIG. 4, an illustration for resin members 93 to 95 that cover the multiple electronic components and a shield electrode layer 96 that covers surfaces of the resin members 93 to 95 is omitted.

The radio frequency module 1A includes the module substrates 91 and 92, the resin members 93 to 95, the shield electrode layer 96, multiple external connection terminals 150, and multiple inter-substrate connection terminals 151 in addition to multiple electronic components that include multiple circuit elements illustrated in FIG. 1.

The module substrate 91 is an example of a first module substrate and has the main surfaces 91a and 91b that face each other. The main surfaces 91a and 91b are examples of a first main surface and a second main surface.

The module substrate 92 is an example of a second module substrate and has a main surface 92a and the main surface 92b that face each other. The main surfaces 92a and 92b are examples of a third main surface and a fourth main surface.

The module substrates 91 and 92 are disposed such that the main surface 91b of the module substrate 91 faces the main surface 92a of the module substrate 92. The module substrates 91 and 92 are disposed so as to be separated from each other such that electronic components can be disposed between the main surfaces 91b and 92a. The multiple electronic components are disposed in, on, or along the two module substrates 91 and 92, specifically, between the main surfaces 91b and 92a, on or along the main surface 91a, and on or along the main surface 92b so as to be divided into three layers. As for the radio frequency module 1A, one or more electronic components can be disposed in the module substrate 91 and in the module substrate 92.

In FIG. 2 to FIG. 5, the module substrates 91 and 92 have a rectangular shape having the same size in a plan view but may have different sizes and/or different shapes. The shape of the module substrates 91 and 92 is not limited to a rectangular shape.

Examples of the module substrates 91 and 92 can include a high temperature co-fired ceramic (HTCC) substrate or a low-temperature co-fired ceramic (LTCC) substrate having a multilayer structure of multiple dielectric layers, a component-containing substrate, a substrate that includes a redistribution layer (RDL), and a printed circuit board but are not limited thereto.

A ground conductor 911 (a first planar ground conductor) that extends in parallel with the main surfaces 91a and 91b may be formed in the module substrate 91. This improves isolation between an electronic component that is disposed on or along the main surface 91a and an electronic component that is disposed on or along the main surface 91b. A ground conductor 921 (a second planar ground conductor) that extends in parallel with the main surfaces 92a and 92b may be formed in the module substrate 92. This improves isolation between an electronic component that is disposed on or along the main surface 92a and an electronic component that is disposed on or along the main surface 92b.

The module substrate 91 is thicker than the module substrate 92. More specifically, the thickness t1 of the module substrate 91 in a direction perpendicular to the main surfaces 91a and 91b (a z-axis direction) is greater than the thickness t2 of the module substrate 92 in a direction perpendicular to the main surfaces 92a and 92b (the z-axis direction).

The power amplifiers 11 and 12, the matching circuits 422 and 452, and the filters 61 and 64 are disposed on or along the main surface 91a (an upper layer).

The matching circuits 401, 411 to 413, 431 to 433, 441 to 443, and 461 to 463 are disposed in the module substrate 91.

For example, the power amplifiers 11 and 12 are composed of a CMOS (Complementary Metal Oxide Semiconductor) and may be specifically manufactured in a SOI (Silicon on Insulator) process. This enables the power amplifiers 11 and 12 to be manufactured at low costs. The power amplifiers 11 and 12 may be composed of at least gallium arsenide (GaAs), silicon germanium (SiGe), or gallium nitride (GaN). This enables the power amplifiers 11 and 12 to have high quality. A semiconductor material for the power amplifiers 11 and 12 is not limited to the materials described above.

The matching circuits 422 and 452 include respective chip inductors. Each chip inductor is a surface mount device (SMD) that is included in an inductor.

Each of the matching circuits 401, 411 to 413, 431 to 433, 441 to 443, and 461 to 463 is disposed in the module substrate 91 and includes a coil conductor in which multiple conductor patterns that are formed in parallel with the main surfaces 91a and 91b in the module substrate 91 are stacked in the direction perpendicular to the main surfaces 91a and 91b.

The matching circuits may include respective chip capacitors in addition to the chip inductors. The arrangement of the chip capacitors is not particularly limited.

The matching circuits 422 and 452 are not necessarily surface mount circuits but may be disposed in the module substrates 91 and 92 or the module substrate 91 or 92.

The matching circuits 401, 412, 413, 432, 433, 442, 443, 462, and 463 may be disposed on or along the main surfaces 91a, 91b, 92a, and 92b or the main surface 91a, 91b, 92a, or 92b.

Examples of the filters 61 and 64 may include a surface acoustic wave (SAW) filter, a bulk acoustic wave (BAW) filter, a LC resonance filter, and a dielectric filter but are not limited thereto.

The resin member 93 covers the main surface 91a and electronic components on or along the main surface 91a. The resin member 93 has a function of ensuring the reliability of, for example, the mechanical strength and humidity resistance of the electronic components on or along the main surface 91a. The radio frequency module 1A does not necessarily need to include the resin member 93.

The filters 62, 63, 65, and 66 and the multiple inter-substrate connection terminals 151 are disposed between the main surfaces 91b and 92a (an intermediate layer). The resin member 94 is injected between the main surfaces 91b and 92a and covers the electronic components that are disposed between the main surfaces 91b and 92a.

Examples of the filters 62, 63, 65, and 66 may include a SAW filter, a BAW filter, a LC resonance filter, and a dielectric filter but are not limited thereto.

The multiple electronic components (here, the filters 62, 63, 65, and 66) that are disposed between the main surfaces 91b and 92a are electrically connected to the module substrate 91 with electrodes that face the module substrate 91 interposed therebetween.

The multiple inter-substrate connection terminals 151 are electrodes for electrically connecting the module substrates 91 and 92. Some of the inter-substrate connection terminals 151 overlap the power amplifiers 11 and 12 in a plan view, are connected to the external connection terminals 150, and function as the heat dissipation electrodes of the power amplifiers 11 and 12. Examples of the inter-substrate connection terminals 151 include a copper post electrode, but shapes and materials are not limited thereto.

The resin member 94 covers the main surfaces 91b and 92a and the electronic components between the main surfaces 91b and 92a. The resin member 94 has a function of ensuring the reliability of, for example, the mechanical strength and humidity resistance of the electronic components between the main surfaces 91b and 92a. The radio frequency module 1A does not necessarily need to include the resin member 94.

Integrated circuits 20 and 70, the switch 51, and the multiple external connection terminals 150 are disposed on or along the main surface 92b (a lower layer).

The integrated circuit 20 includes the low-noise amplifiers 21 and 22 and the switches 53 and 55. Circuit elements that are included in the low-noise amplifiers 21 and 22 and the switches 53 and 55 are formed on or along a circuit surface of the integrated circuit 20. An example of the circuit surface is a main surface of the integrated circuit 20 that faces the module substrate 92. The integrated circuit 70 includes the switches 52 and 54 and the PA controller 71. Circuit elements that are included in the switches 52 and 54 and the PA controller 71 are formed on or along a circuit surface of the integrated circuit 70. An example of the circuit surface is a main surface of the integrated circuit 70 that faces the module substrate 92. An integrated circuit 50 includes the switch 51. The switch 51 may be included in the integrated circuit 20 or 70.

For example, the integrated circuits 20, 50, and 70 are composed of a CMOS and may be specifically manufactured in a SOI process. The integrated circuits 20, 50, and 70 may be composed of at least GaAs, SiGe, or GaN. A semiconductor material for the integrated circuits 20, 50, and 70 is not limited to the materials described above.

A circuit element that is included in the switch 51 is formed on or along a circuit surface of a switch device. An example of the circuit surface is a main surface of the switch device that faces the module substrate 92. For example, the switch 51 is composed of a CMOS and may be specifically manufactured in a SOI process. The switch 51 may be composed of at least GaAs, SiGe, or GaN. A semiconductor material for the switch 51 is not limited to the materials described above. The integrated circuit 20 may include the switch 51.

A first electronic component (here, the integrated circuits 20 and 70 and the switch 51) that includes at least a transistor is disposed on or along the main surface 92b as described above, and a second electronic component (here, the filters 61 to 66 and the matching circuits 401, 411 to 413, 422, 431 to 433, 441 to 443, 452, and 461 to 463) that includes no transistor is not disposed on or along the main surface 92b. That is, among the multiple electronic components, only the first electronic component is disposed on or along the main surface 92b. This enables the lower surface of the radio frequency module 1A to be cut and enables the thicknesses of the resin member 95, the integrated circuits 20 and 70, and the switch 51 to be reduced.

The multiple external connection terminals 150 include a ground terminal in addition to the antenna connection terminal 100, the radio frequency input terminals 111 and 112, the radio frequency output terminals 121 and 122, and the control terminal 131 illustrated in FIG. 1. The multiple external connection terminals 150 are joined to, for example, input and output terminals and/or a ground terminal on or along a motherboard 1000 that is disposed at a negative position on the z-axis of the radio frequency module 1A. Examples of the multiple external connection terminals 150 can include a copper post electrode, but shapes and materials are not limited thereto. Some of the multiple external connection terminals 150 overlap the power amplifiers 11 and 12 in a plan view and function as the heat dissipation electrodes of the power amplifiers 11 and 12 together with the inter-substrate connection terminals 151 that are connected to the power amplifiers 11 and 12.

The resin member 95 covers the main surface 92b and the electronic components on or along the main surface 92b. The resin member 95 has a function of ensuring the reliability of, for example, the mechanical strength and humidity resistance of the electronic components on or along the main surface 92b. The radio frequency module 1A does not necessarily need to include the resin member 95.

The shield electrode layer 96 is a metal thin film that is formed by, for example, a spattering method and covers the upper surface of the resin member 93, the side surfaces of the resin members 93 to 95 and the module substrates 91 and 92. The shield electrode layer 96 is connected to the ground and inhibits an extraneous noise from being transmitted to the electronic components that are included in the radio frequency module 1A. The radio frequency module 1A does not necessarily need to include the shield electrode layer 96.

As for the radio frequency module 1A in the present example, the module substrate 91 that contains the matching circuits 401, 411 to 413, 431 to 433, 441 to 443, and 461 to 463 is farther than the module substrate 92 to the motherboard 1000. However, the module substrate 91 may be nearer than the module substrate 92 to the motherboard 1000. That is, the first module substrate that has a greater thickness may be nearer than the second module substrate that has a lesser thickness to the motherboard 1000.

[2.1.2 Effects of Radio Frequency Module 1A]

The radio frequency module 1A in the present example includes the module substrate 91 that has the main surfaces 91a and 91b that face each other, the module substrate 92 that has the main surfaces 92a and 92b that face each other, the main surface 92a facing the main surface 91b, the multiple electronic components that are disposed between the main surfaces 91b and 92a, on or along the main surface 91a, and on or along the main surface 92b, and the first inductor that is disposed in the module substrate 91, the multiple electronic components described above include the first filter and the switch 51 that switches connection and disconnection between the antenna connection terminal 100 and the first filter, and the first inductor is connected between the switch 51 and the first filter, and the module substrate 91 is thicker than the module substrate 92 as described above.

In this case, the multiple electronic components are disposed between the main surfaces 91b and 92a, on or along the main surface 91a, and on or along the main surface 92b so as to be divided into three layers, and the first inductor is disposed in the module substrate 91.

Accordingly, the area of the radio frequency module 1A in a plan view can be decreased, that is, the size of the radio frequency module 1A can be decreased. In addition, from the perspective that isolation between electronic components that are connected in front of and behind a matching circuit is ensured and that the transmission characteristics of the radio frequency module 1A are improved, the matching circuit (the first inductor) that is connected between the switch 51 and the first filter, among the matching circuits that are included in the radio frequency module 1A, needs to have the highest Q value. For this reason, the first inductor is preferably disposed in the module substrate 91 to decrease the size of the radio frequency module 1A, and in order to ensure a high Q value, it is preferable that the number of times (the number of stacked layers of the conductor patterns) a coil conductor that forms the first inductor is wound be increased and that the distance between a ground conductor pattern and the coil conductor in the module substrate 91 be increased. For this purpose, the thickness of the module substrate 91 that contains the first inductor is preferably increased. Since the module substrate 91 that contains the first inductor is thicker than the module substrate 92, the Q value of the first inductor can be increased. For this reason, the size of the radio frequency module 1A can be decreased, and the transmission characteristics can be inhibited from being degraded.

For example, the radio frequency module 1A in the present example may further include the multiple external connection terminals 150 that are disposed on or along the main surface 92b.

In this case, the module substrate 92 that is near the motherboard 1000 is thinner than the module substrate 91, and accordingly, the wiring lines that connect the motherboard 1000 and the electronic components that are disposed on or along the main surfaces 92a and 92b to each other can be shortened.

For example, the radio frequency module 1A in the present example may further include the second inductor that is disposed in the module substrate 91, the first filter may be a transmission filter that enables a transmission signal to pass, the multiple electronic components described above may further include the power amplifiers 11 and 12 or the power amplifier 11 or 12, and the second inductor may be connected between the power amplifier 11 and the first filter and between the power amplifier 12 and the first filter or between the power amplifier 11 or 12 and the first filter.

From the perspective that isolation between electronic components that are connected in front of and behind a matching circuit is ensured and that the transmission characteristics of the radio frequency module 1A are improved, the matching circuit (the second inductor) that is connected between the power amplifier 11 and the first filter and between the power amplifier 12 and the first filter or between the power amplifier 11 or 12 and the first filter, among the matching circuits that are included in the radio frequency module 1A, preferentially has a high Q value next to the first inductor. For this purpose, the module substrate 91 that contains the second inductor is thicker than the module substrate 92, and accordingly, the Q value of the second inductor can be increased. For this reason, the size of the radio frequency module 1A can be decreased, and the transmission characteristics can be inhibited from being degraded.

For example, as for the radio frequency module 1A in the present example, the power amplifiers 11 and 12 or the power amplifier 11 or 12 may be disposed on or along the main surface 91a.

In this case, the wiring lines that connect the power amplifier 11 and the second inductor to each other and the power amplifier 12 and the second inductor to each other or the wiring line that connects the power amplifier 11 or 12 and the second inductor to each other can be shortened, and accordingly, the transmission characteristics of the radio frequency module 1A can be inhibited from being degraded.

For example, the radio frequency module 1A in the present example may further include the third inductor that is disposed in the module substrate 91, and the third inductor may be connected between the antenna connection terminal 100 and the switch 51.

From the perspective that isolation between electronic components that are connected in front of and behind a matching circuit is ensured and that the transmission characteristics of the radio frequency module 1A are improved, the matching circuit (the third inductor) that is connected between the antenna connection terminal 100 and the switch 51, among the matching circuits that are included in the radio frequency module 1A, preferentially has a high Q value next to the first inductor. For this purpose, the module substrate 91 that contains the third inductor is thicker than the module substrate 92, and accordingly, the Q value of the third inductor can be increased. For this reason, the size of the radio frequency module 1A can be decreased, and the transmission characteristics can be inhibited from being degraded.

For example, as for the radio frequency module 1A in the present example, the switch 51 may be disposed on or along the main surface 92b.

For example, the radio frequency module 1A in the present example may further include the fourth inductor that is disposed in the module substrate 91, the first filter may be a reception filter that enables a reception signal to pass, the multiple electronic components may further include the low-noise amplifiers 21 and 22 or the low-noise amplifier 21 or 22, and the fourth inductor may be connected between the low-noise amplifier 21 and the first filter and between the low-noise amplifier 22 and the first filter or between the low-noise amplifier 21 or 22 and the first filter.

From the perspective that isolation between electronic components that are connected in front of and behind a matching circuit is ensured and that the transmission characteristics of the radio frequency module 1A are improved, the matching circuit (the fourth inductor) that is connected between the low-noise amplifier 21 and the first filter and between the low-noise amplifier 22 and the first filter or between the low-noise amplifier 21 or 22 and the first filter, among the matching circuits that are included in the radio frequency module 1A, preferentially has a high Q value next to the first inductor. For this purpose, the module substrate 91 that contains the fourth inductor is thicker than the module substrate 92, and accordingly, the Q value of the fourth inductor can be increased. For this reason, the size of the radio frequency module 1A can be decreased, and the transmission characteristics can be inhibited from being degraded.

For example, as for the radio frequency module 1A in the present example, the low-noise amplifiers 21 and 22 or the low-noise amplifier 21 or 22 may be disposed on or along the main surface 92b.

The communication device 5 in the present example includes the RFIC 3 that processes a radio frequency signal and the radio frequency module 1A that transmits the radio frequency signal between the RFIC 3 and the antenna 2.

This enables the communication device 5 to exert the effects of the radio frequency module 1A described above.

2.2 Second Example

A radio frequency module 1B that includes the radio frequency circuit 1 will now be described as a second example of the radio frequency circuit 1 according to the exemplary embodiment described above. The present example differs from the first example described above mainly in that a fifth inductor that is included in the first filter is disposed in the module substrate 92. Differences between the radio frequency module 1B in the present example and the first example described above will be mainly described with reference to FIG. 6 to FIG. 10.

[2.2.1 Arrangement of Components of Radio Frequency Module 1B]

FIG. 6 illustrates an example of a circuit structure of the filter 62 according to the example. As illustrated, the filter 62 is an example of the first filter and includes series arm resonators S1 and S2 that are disposed on a path that connects input and output terminals 101 and 102, parallel arm resonators P1, P2, and P3 that are connected between the path and the ground, and inductors L1 and L2.

Examples of the series arm resonators S1 to S2 and the parallel arm resonators P1 to P3 are elastic resonators. In this case, the filter 62 serves as a ladder acoustic wave filter.

The inductor L1 is an example of the fifth inductor and is connected between the parallel arm resonator P1 and the ground. The inductor L2 is an example of the fifth inductor and is connected between the parallel arm resonator P2 and the ground and between the parallel arm resonator P3 and the ground. The arrangement of the inductors L1 and L2 enables the pass band of the filter 62 to be expanded and enables attenuation characteristics to be improved.

As for the filter 62, the structure of connection between the series arm resonators and the parallel arm resonators and the number thereof, and the structure of connection between the inductors and the number thereof are not limited to those of the circuit structure illustrated in FIG. 6.

The filter 63 includes a circuit structure close to that of the filter 62. Specifically, the filter 63 is an example of the first filter and includes series arm resonators S3 and S4 that are disposed on a path that connects input and output terminals, parallel arm resonators P4, P5, and P6 that are connected between the path and the ground, and inductors L3 and L4.

FIG. 7 is a plan view of the main surface 91a of the radio frequency module 1B in the present example. FIG. 8 is a plan view of the main surface 92a of the radio frequency module 1B in the present example and illustrates the main surface 92a of the module substrate 92 viewed from a positive position on the z-axis. FIG. 9 is a plan view of the main surface 92b of the radio frequency module 1B in the present example and illustrates the main surface 92b of the module substrate 92 viewed in a positive position on the z-axis. FIG. 10 is a sectional view of the radio frequency module 1B in the present example. A section of the radio frequency module 1B in FIG. 10 is a section taken along line x-x in FIG. 7 to FIG. 9.

The module substrate 91 is thicker than the module substrate 92. More specifically, the thickness t1 of the module substrate 91 in the direction perpendicular to the main surfaces 91a and 91b (the z-axis direction) is greater than the thickness t2 of the module substrate 92 in the direction perpendicular to the main surfaces 92a and 92b (the z-axis direction).

The power amplifiers 11 and 12, the matching circuits 422 and 452, and the filters 61 and 64 are disposed on or along the main surface 91a (the upper layer).

The matching circuits 401, 411 to 413, 431 to 433, 441 to 443, and 461 to 463 are disposed in the module substrate 91.

The matching circuits 422 and 452 include respective chip inductors. Each chip inductor is a surface mount device (SMD) that is included in an inductor.

Each of the matching circuits 401, 411 to 413, 431 to 433, 441 to 443, and 461 to 463 is disposed in the module substrate 91 and includes a coil conductor in which multiple conductor patterns that are formed in parallel with the main surfaces 91a and 91b in the module substrate 91 are stacked in the direction perpendicular to the main surfaces 91a and 91b.

The matching circuits may include respective chip capacitors in addition to the chip inductors. The arrangement of the chip capacitors is not particularly limited.

The matching circuits 422 and 452 are not necessarily surface mount circuits but may be disposed in the module substrates 91 and 92 or the module substrate 91 or 92.

The matching circuits 401, 412, 413, 432, 433, 442, 443, 462, and 463 may be disposed on or along the main surfaces 91a, 91b, 92a, and 92b or the main surface 91a, 91b, 92a, or 92b.

The filters 62, 63, 65, and 66 and the multiple inter-substrate connection terminals 151 are disposed between the main surfaces 91b and 92a (the intermediate layer).

The inductors L1 and L2 that are included in the filter 62 and the inductors L3 and L4 that are included in the filter 63 are disposed in the module substrate 92.

Each of the inductors L1 to L4 is disposed in the module substrate 92 and includes a coil conductor in which multiple conductor patterns that are formed in parallel with the main surfaces 92a and 92b in the module substrate 92 are stacked in the direction perpendicular to the main surfaces 92a and 92b.

As for the matching circuit 411, the number of times a coil that forms the first inductor (the matching circuits 411, 431, 441, and 461) is wound is larger than the number of times a coil that forms the fifth inductor (L1, L2, L3, and L4) is wound.

The distance between the first inductor (the matching circuits 411, 431, 441, and 461) and the ground conductor 911 (the first planar ground conductor) is longer than the distance between the fifth inductor (L1, L2, L3, and L4) and the ground conductor 921 (the second planar ground conductor).

The series arm resonators S1 to S2 and the parallel arm resonators P1 to P3 of the filter 62 and the series arm resonators S3 to S4 and the parallel arm resonators P4 to P6 of the filter 63, among the multiple electronic components (here, the filters 62, 63, 65, and 66) that are disposed between the main surfaces 91b and 92a, are electrically connected to the module substrate 92 with electrodes that face the module substrate 92 (the main surface 92a) interposed therebetween.

The integrated circuits 20 and 70, the switch 51, and the multiple external connection terminals 150 are disposed on or along the main surface 92b (the lower layer).

The integrated circuit 20 includes the low-noise amplifiers 21 and 22 and the switches 53 and 55.

The fifth inductor that is disposed in the module substrate 92 is not limited to the inductors L1 to L4 that are included in the filters 62 and 63 but may be an inductor other than the first inductor (the matching circuits 411, 431, 441, and 461).

[2.2.2 Effects of Radio Frequency Module 1B]

The radio frequency module 1B in the present example includes the module substrate 91 that has the main surfaces 91a and 91b that face each other, the module substrate 92 that has the main surfaces 92a and 92b that face each other, the main surface 92a facing the main surface 91b, the multiple electronic components that are disposed between the main surfaces 91b and 92a, on or along the main surface 91a, and on or along the main surface 92b, and the first inductor that is disposed in the module substrate 91, the multiple electronic components described above include the first filter and the switch 51 that switches connection and disconnection between the antenna connection terminal 100 and the first filter, and the first inductor is connected between the switch 51 and the first filter, and the module substrate 91 is thicker than the module substrate 92 as described above.

In this case, the multiple electronic components are disposed between the main surfaces 91b and 92a, on or along the main surface 91a, and on or along the main surface 92b so as to be divided into three layers, and the first inductor is disposed in the module substrate 91. Accordingly, the area of the radio frequency module 1B in a plan view can be decreased, that is, the size of the radio frequency module 1B can be decreased. Since the module substrate 91 that contains the first inductor is thicker than the module substrate 92, the Q value of the first inductor can be increased. For this reason, the size of the radio frequency module 1B can be decreased, and the transmission characteristics can be inhibited from being degraded.

For example, the radio frequency module 1B in the present example may further include the fifth inductor that is disposed in the module substrate 92.

In this case, the fifth inductor is disposed in the module substrate 92. Accordingly, the area of the radio frequency module 1B in a plan view can be decreased, that is, the size of the radio frequency module 1B can be decreased.

For example, as for the radio frequency module 1B in the present example, the number of times the coil that forms the first inductor is wound may be larger than the number of times the coil that forms the fifth inductor is wound.

In this case, the Q value of the first inductor can be larger than that of the fifth inductor. For this reason, the transmission characteristics of the radio frequency module 1B can be inhibited from being degraded.