High-frequency circuit

Abstract

A high-frequency circuit (1) comprises: a transmission filter (31) that is connected to selection terminals (512 and 513) and has a passband including a transmission band of a band (A); a reception filter (33) that is connected to a selection terminal (516) and has a passband including a reception band of the band (A); and paths (P1 and P2) that respectively connect the transmission filter (31) to the selection terminals (512 and 513). The first reflection phase of the reception band of the band (A) when the transmission filter (31) is viewed from a common terminal (511) via the path (P1) differs from the second reflection phase of the reception band of the band (A) when the transmission filter (31) is viewed from the common terminal (511) via the path (P2). In the transmission band of the band (A), the phase fluctuation amount between the transmission filter (31) and the common terminal (511) via the path (P1) connection therebetween is smaller than the phase fluctuation amount between the transmission filter (31) and the common terminal (511) via the path (P2) connection therebetween.

Description

High-frequency circuits

[0001] The present invention relates to a high-frequency circuit.

[0002] Patent Document 1 discloses a high-frequency front-end circuit (high-frequency circuit) that can operate in both carrier aggregation mode and single mode and can suppress insertion loss caused by a multiplexer when operating in single mode.

[0003] JP 2019 / 154025 A

[0004] However, in conventional high-frequency circuits such as those disclosed in Patent Document 1, there are cases where the receiving sensitivity is reduced in the frequency division duplex (FDD) band.

[0005] Therefore, the present invention provides a high-frequency circuit that can suppress the decrease in reception sensitivity in the FDD band.

[0006] A high-frequency circuit according to one aspect of the present invention includes a first switch circuit including a first common terminal connected to an antenna connection terminal, and first, second, and third selection terminals; a first transmit filter connected to the first and second selection terminals and having a pass band including a transmit band of a first FDD band; a first receive filter connected to the third selection terminal and having a pass band including a receive band of the first FDD band; a first path connecting the first transmit filter to the first selection terminal; and a second path connecting the first transmit filter to the second selection terminal. A first reflection phase of the reception band of the first FDD band when the first transmission filter is viewed from the first common terminal via the first path in a state where the first common terminal is connected to the second selection terminal is different from a second reflection phase of the reception band of the first FDD band when the first transmission filter is viewed from the first common terminal via the second path in a state where the first common terminal is connected to the second selection terminal, and in the transmission band of the first FDD band, the amount of phase variation between the first common terminal and the first transmission filter connected via the first path is smaller than the amount of phase variation between the first common terminal and the first transmission filter connected via the second path.

[0007] A high-frequency circuit according to one aspect of the present invention comprises: a first switch circuit including a first common terminal connected to an antenna connection terminal, and a first selection terminal, a second selection terminal, and a third selection terminal; a first transmit filter connected to the first selection terminal and the second selection terminal and having a pass band that includes the transmit band of a first FDD band; a first receive filter connected to the third selection terminal and having a pass band that includes the receive band of the first FDD band; and a surface-mount inductor or a surface-mount capacitor connected between the second selection terminal and the first transmit filter, wherein the surface-mount inductor and the surface-mount capacitor are not connected between the first selection terminal and the first transmit filter.

[0008] a first transmit filter connected to the first selection terminal and having a pass band including the transmit band of a first FDD band; a first receive filter connected to the second selection terminal and having a pass band including the receive band of the first FDD band; an inductor or a capacitor connected between ground and a path connecting the first transmit filter to the first selection terminal; and a switch connected between the inductor or the capacitor and the path or the ground, wherein when a first power class defined by a first maximum output power is applied to the first FDD band, the first switch circuit connects the first common terminal to the first selection terminal and the switch is open, and when a second power class defined by a second maximum output power lower than the first maximum output power is applied to the first FDD band, the first switch circuit connects the first common terminal to the first selection terminal and the second selection terminal and the switch is closed.

[0009] According to the present invention, it is possible to suppress a decrease in reception sensitivity in the FDD band.

[0010] FIG. 1 is a circuit configuration diagram of a high-frequency circuit according to embodiment 1. FIG. 2A is an example of a circuit configuration diagram of a phase adjustment circuit according to embodiment 1. FIG. 2B is an example of a circuit configuration diagram of a phase adjustment circuit according to embodiment 1. FIG. 2C is an example of a circuit configuration diagram of a phase adjustment circuit according to embodiment 1. FIG. 2D is an example of a circuit configuration diagram of a phase adjustment circuit according to embodiment 1. FIG. 2E is an example of a circuit configuration diagram of a phase adjustment circuit according to embodiment 1. FIG. 2F is an example of a circuit configuration diagram of a phase adjustment circuit according to embodiment 1. FIG. 3 is a Smith chart for explaining phase adjustment by the phase adjustment circuit according to embodiment 1. FIG. 4 is a circuit configuration diagram showing a first communication mode of the high-frequency circuit according to embodiment 1. FIG. 5 is a circuit configuration diagram showing a second communication mode of the high-frequency circuit according to embodiment 1. FIG. 6 is a circuit configuration diagram showing a third communication mode of the high-frequency circuit according to embodiment 1. FIG. 7 is a circuit configuration diagram showing a fourth communication mode of the high-frequency circuit according to embodiment 1. FIG. 8 is a circuit configuration diagram of a high-frequency circuit according to embodiment 2. FIG. 9A is an example of a circuit configuration diagram of a phase adjustment circuit according to embodiment 2. Fig. 9B is an example of a circuit configuration diagram of a phase adjustment circuit according to embodiment 2. Fig. 10 is a circuit configuration diagram showing a first communication mode of the high-frequency circuit according to embodiment 2. Fig. 11 is a circuit configuration diagram showing a second communication mode of the high-frequency circuit according to embodiment 2. Fig. 12 is a circuit configuration diagram showing a third communication mode of the high-frequency circuit according to embodiment 2. Fig. 13 is a circuit configuration diagram showing a fourth communication mode of the high-frequency circuit according to embodiment 2.

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, arrangements and connection forms of the components shown in the following embodiments are merely examples and are not intended to limit the present invention.

[0012] It should be noted that the drawings are schematic diagrams in which emphasis, omission, or adjustment of proportions has been appropriately made to illustrate the present invention, and are not necessarily strictly illustrated, and may differ from the actual shapes, positional relationships, and proportions. In the drawings, the same reference numerals are used to denote substantially the same components, and redundant explanations may be omitted or simplified.

[0013] In this disclosure, "connected" includes not only direct connection by a connection terminal and / or wiring conductor, but also electrical connection via other circuit elements. "A is connected between B and C" means that A is connected in series to a path connecting B and C, specifically, one end of A is connected to B and the other end of A is connected to C. "Terminal" means a point where a conductor within an element terminates. Note that if the impedance of the conductor between elements is sufficiently low, a terminal can be interpreted as not only a single point, but also any point on the conductor between elements or the entire conductor.

[0014] The "passband of a filter" is defined as the portion of the frequency spectrum transmitted by the filter over which the output power is not attenuated by more than 3 dB below the maximum output power. The upper and lower ends of the passband of a bandpass filter are therefore identified as the higher and lower frequencies of the two points at which the output power is attenuated by 3 dB below the maximum output power.

[0015] The term "reception band" refers to a frequency band used for reception in a communication device, and the term "transmission band" refers to a frequency band used for transmission in a communication device. For example, in a band for frequency division duplex (FDD), different frequency bands (uplink band and downlink band) are used as the transmission band and the reception band. For example, in a band for time division duplex (TDD), the same frequency band is used as the transmission band and the reception band.

[0016] First Embodiment First, a first embodiment will be described. A communication device 5 according to this embodiment can be used to provide wireless connectivity. For example, the communication device 5 can be implemented in user equipment (UE) in a cellular network (also referred to as a mobile network), such as a mobile phone, a smartphone, a tablet computer, or a wearable device. In another example, the communication device 5 can be implemented to provide wireless connectivity to Internet of Things (IoT) sensor devices, medical / healthcare devices, cars, unmanned aerial vehicles (UAVs) (so-called drones), and automated guided vehicles (AGVs). In yet another example, the communication device 5 can be implemented to provide wireless connectivity in a wireless access point or a wireless hotspot.

[0017] The circuit configuration of a communication device 5 and a high-frequency circuit 1 according to this embodiment will be described with reference to Fig. 1. Fig. 1 is a circuit configuration diagram of a communication device 5 according to this embodiment.

[0018] 1 is an exemplary circuit configuration, and the communication device 5 and the radio frequency circuit 1 may be implemented using any of a wide variety of circuit implementations and circuit technologies. Therefore, the description of the communication device 5 and the radio frequency circuit 1 provided below should not be construed as limiting.

[0019] [1.1 Circuit Configuration of Communication Device 5] First, the circuit configuration of a communication device 5 according to this embodiment will be described with reference to Fig. 1. The communication device 5 includes a high-frequency circuit 1, an antenna 2, an RFIC (Radio Frequency Integrated Circuit) 3, and a BBIC (Baseband Integrated Circuit) 4.

[0020] The high-frequency circuit 1 can transmit high-frequency signals between the antenna 2 and the RFIC 3. The circuit configuration of the high-frequency circuit 1 will be described later.

[0021] The antenna 2 is connected to the antenna connection terminal 101 of the high-frequency circuit 1. The antenna 2 can receive a high-frequency signal from the high-frequency circuit 1 and output it to the outside of the communication device 5. The antenna 2 can also receive a high-frequency signal from the outside of the communication device 5 and output it to the high-frequency circuit 1. The antenna 2 does not have to be included in the communication device 5. The communication device 5 may also include one or more antennas in addition to the antenna 2.

[0022] The RFIC 3 is an example of a signal processing circuit that processes high-frequency signals. Specifically, the RFIC 3 can perform signal processing on a transmission signal input from the BBIC 4 by up-conversion or the like, and output the high-frequency transmission signal generated by the signal processing to the high-frequency circuit 1. Furthermore, the RFIC 3 can perform signal processing on a high-frequency reception signal input via the reception path of the high-frequency circuit 1 by down-conversion or the like, and output the reception signal generated by the signal processing to the BBIC 4. The RFIC 3 may also have a control unit that controls switches, power amplifiers, and the like included in the high-frequency circuit 1. Note that some or all of the functions of the RFIC 3 as a control unit may be included outside the RFIC 3, and may be included in, for example, the BBIC 4 or the high-frequency circuit 1.

[0023] The BBIC 4 is a baseband signal processing circuit that processes signals using an intermediate frequency band that is lower in frequency than the high-frequency signal transmitted by the high-frequency circuit 1. The signals processed by the BBIC 4 include, for example, image signals for image display and / or audio signals for calls via a speaker. The BBIC 4 does not necessarily have to be included in the communication device 5.

[0024] [1.2 Circuit Configuration of High-Frequency Circuit 1] Next, the circuit configuration of the high-frequency circuit 1 according to this embodiment will be described with reference to Fig. 1. The high-frequency circuit 1 includes a power amplifier 11, low-noise amplifiers 21 and 22, transmit filters 31 and 32, receive filters 33 and 34, phase adjustment circuits 41 and 42, switch circuits 51 and 52, an antenna connection terminal 101, a high-frequency input terminal 111, and high-frequency output terminals 121 and 122.

[0025] The antenna connection terminal 101 is an external connection terminal of the high-frequency circuit 1. The antenna connection terminal 101 is connected to the antenna 2 outside the high-frequency circuit 1, and is connected to the switch circuit 51 inside the high-frequency circuit 1. This allows the high-frequency circuit 1 to supply a transmission signal to the antenna 2 and receive a reception signal from the antenna 2 via the antenna connection terminal 101.

[0026] The radio frequency input terminal 111 is an external connection terminal of the radio frequency circuit 1. The radio frequency input terminal 111 is connected to the RFIC 3 outside the radio frequency circuit 1, and is connected to the power amplifier 11 inside the radio frequency circuit 1. This allows the radio frequency circuit 1 to supply the transmission signals of bands A and B received from the RFIC 3 via the radio frequency input terminal 111 to the power amplifier 11.

[0027] The radio frequency output terminals 121 and 122 are external connection terminals of the radio frequency circuit 1. The radio frequency output terminals 121 and 122 are connected to the RFIC 3 outside the radio frequency circuit 1, and are connected to the low noise amplifiers 21 and 22, respectively, inside the radio frequency circuit 1. This allows the radio frequency circuit 1 to supply reception signals of bands A and B from the low noise amplifiers 21 and 22 to the RFIC 3 via the radio frequency output terminals 121 and 122.

[0028] The power amplifier 11 is connected between the radio frequency input terminal 111 and the switch circuit 52. Specifically, the input terminal of the power amplifier 11 is connected to the radio frequency input terminal 111, and the output terminal of the power amplifier 11 is connected to the switch circuit 52. The power amplifier 11 can amplify the transmission signals of bands A and B supplied from the RFIC 3 via the radio frequency input terminal 111, using power supplied from a power supply (not shown).

[0029] The power amplifier 11 may be configured with a heterojunction bipolar transistor (HBT) and may be manufactured using a semiconductor material. Examples of the semiconductor material that may be used include silicon germanium (SiGe) and gallium arsenide (GaAs). The amplifying transistor of the power amplifier 11 is not limited to an HBT. For example, the power amplifier 11 may be configured with a high electron mobility transistor (HEMT) or a metal-semiconductor field effect transistor (MESFET). In this case, gallium nitride (GaN) or silicon carbide (SiC) may be used as the semiconductor material.

[0030] Note that a part or all of the power amplifier 11 does not have to be included in the high-frequency circuit 1. In this case, a part or all of the power amplifier 11 may be connected between the RFIC 3 and the high-frequency input terminal 111, or may be included in the RFIC 3.

[0031] The low-noise amplifier 21 is connected between the receive filter 33 and the high-frequency output terminal 121. Specifically, the input terminal of the low-noise amplifier 21 is connected to the receive filter 33, and the output terminal of the low-noise amplifier 21 is connected to the high-frequency output terminal 121. The low-noise amplifier 21 can amplify the receive signal of band A that has passed through the receive filter 33, using power supplied from a power supply (not shown).

[0032] The low-noise amplifier 22 is connected between the receive filter 34 and the high-frequency output terminal 122. Specifically, the input terminal of the low-noise amplifier 22 is connected to the receive filter 34, and the output terminal of the low-noise amplifier 22 is connected to the high-frequency output terminal 122. The low-noise amplifier 22 can amplify the receive signal of band B that has passed through the receive filter 34, using power supplied from a power supply (not shown).

[0033] The low-noise amplifiers 21 and 22 may be configured with field-effect transistors (FETs) and may be manufactured using semiconductor materials. Examples of the semiconductor materials that may be used include single crystal silicon, gallium nitride (GaN), and silicon carbide (SiC). The amplifying transistors of the low-noise amplifiers 21 and 22 are not limited to FETs. For example, some or all of the low-noise amplifiers 21 and 22 may be configured with bipolar transistors.

[0034] Note that part or all of the low-noise amplifiers 21 and / or 22 may not be included in the high-frequency circuit 1. In this case, part or all of the low-noise amplifier 21 may be connected between the high-frequency output terminal 121 and the RFIC 3, and part or all of the low-noise amplifier 22 may be connected between the high-frequency output terminal 122 and the RFIC 3. Also, part or all of the low-noise amplifiers 21 and / or 22 may be included in the RFIC 3.

[0035] The transmit filter 31 is an example of a first transmit filter, and has a pass band that includes the transmit band of band A. The transmit filter 31 is connected between the switch circuits 51 and 52. Specifically, one end of the transmit filter 31 is connected to a selection terminal 512 of the switch circuit 51 via a path P1, and is connected to a selection terminal 513 of the switch circuit 51 via a path P2. The other end of the transmit filter 31 is connected to a selection terminal 522 of the switch circuit 52.

[0036] A bulk acoustic wave (BAW) filter can be used as the transmit filter 31. However, the transmit filter 31 may also be a surface acoustic wave (SAW) filter, an LC resonant filter, or a dielectric resonant filter, or any combination of a BAW filter, a SAW filter, an LC resonant filter, and a dielectric resonant filter, but is not limited to these.

[0037] The transmit filter 32 is an example of a second transmit filter, and has a pass band that includes the transmit band of band B. The transmit filter 32 is connected between the switch circuits 51 and 52. Specifically, one end of the transmit filter 32 is connected to a selection terminal 514 of the switch circuit 51 via a path P3, and is connected to a selection terminal 515 of the switch circuit 51 via a path P4. The other end of the transmit filter 32 is connected to a selection terminal 523 of the switch circuit 52.

[0038] A SAW filter can be used as the transmit filter 32. However, the transmit filter 32 may also be a BAW filter, an LC resonant filter, or a dielectric resonant filter, or any combination of a SAW filter, a BAW filter, an LC resonant filter, and a dielectric resonant filter, and is not limited to these.

[0039] The receive filter 33 is an example of a first receive filter, and has a pass band that includes the receive band of band A. The receive filter 33 is connected between the switch circuit 51 and the low-noise amplifier 21. Specifically, one end of the receive filter 33 is connected to the selection terminal 516 of the switch circuit 51, and the other end of the receive filter 33 is connected to the input end of the low-noise amplifier 21. A SAW filter can be used as the receive filter 33. Note that the receive filter 33 may also be a BAW filter, an LC resonant filter, or a dielectric resonant filter, or any combination of a SAW filter, a BAW filter, an LC resonant filter, and a dielectric resonant filter, but is not limited to these.

[0040] The receive filter 34 is an example of a second receive filter, and has a passband that includes the receive band of band B. The receive filter 34 is connected between the switch circuit 51 and the low-noise amplifier 22. Specifically, one end of the receive filter 34 is connected to the selection terminal 516 of the switch circuit 51, and the other end of the receive filter 34 is connected to the input terminal of the low-noise amplifier 22. The receive filter 34 does not have to be connected to the selection terminal 516, but may be connected to an additional selection terminal of the switch circuit 51. A SAW filter can be used as the receive filter 34. The receive filter 34 may be a BAW filter, an LC resonant filter, or a dielectric resonant filter, or any combination of a SAW filter, a BAW filter, an LC resonant filter, and a dielectric resonant filter, but is not limited to these.

[0041] The transmission filter 32 and / or the reception filter 34 do not have to be included in the high-frequency circuit 1. In other words, the high-frequency circuit 1 does not have to be capable of transmitting and / or receiving band B signals.

[0042] Bands A and B are frequency bands for communication systems built using radio access technologies (RATs). Bands A and B are predefined by standardization organizations (e.g., 3GPP (registered trademark) (3rd Generation Partnership Project) and IEEE (Institute of Electrical and Electronics Engineers)). Examples of communication systems include 5GNR (5th Generation New Radio) systems, LTE (Long Term Evolution) systems, and WLAN (Wireless Local Area Network) systems.

[0043] Bands A and B are examples of a first FDD band and a second FDD band, respectively. Each of bands A and B corresponds to a first power class. The first power class is defined by a first maximum output power that is higher than a second maximum output power of the second power class. Specifically, the first power class is, for example, power class 2, in which case the first maximum output power is 26 dBm. The second power class is, for example, power class 3, in which case the second maximum output power is 23 dBm. Note that the first power class and the second power class are not limited to power class 2 and power class 3. For example, the first power class may be power class 1.5, and the second power class may be power class 5.

[0044] An example of such a combination of bands A and B is a combination of n1 for Band 1 or 5G NR for LTE and n3 for Band 3 or 5G NR for LTE. Note that the combination of bands A and B is not limited to this. For example, the combination of bands A and B may be a combination of n1 for Band 1 or 5G NR for LTE and n40 for Band 40 or 5G NR for LTE. Also, for example, the combination of bands A and B may be a combination of n3 for Band 3 or 5G NR for LTE and n40 for Band 40 or 5G NR for LTE.

[0045] The power class is a classification of the terminal output power defined by the maximum output power, and the smaller the power class value, the higher the maximum output power allowed. For example, in 3GPP, the maximum output power of power class 1 is defined as 31 dBm, the maximum output power of power class 1.5 is defined as 29 dBm, the maximum output power of power class 2 is defined as 26 dBm, the maximum output power of power class 3 is defined as 23 dBm, and the maximum output power of power class 5 is defined as 20 dBm.

[0046] The maximum output power of a terminal is defined as the maximum output power at the antenna terminal. The maximum output power of a UE is measured using a method defined by 3GPP or the like. For example, in FIG. 1 , the maximum output power is measured by measuring the radiated power at antenna 2. Note that instead of measuring the radiated power, the maximum output power of antenna 2 can also be measured by providing a terminal near antenna 2 and connecting a measuring instrument (e.g., a spectrum analyzer) to the terminal. The power class is identified based on the maximum output power measured in this manner.

[0047] The phase adjustment circuit 41 is connected between the selection terminal 513 of the switch circuit 51 and the transmit filter 31. The phase adjustment circuit 41 includes an inductor and / or a capacitor. The phase adjustment circuit 41 can adjust the reflection phase of the receive band of band A when the transmit filter 31 is viewed from the common terminal 511 via path P2 in a state where the common terminal 511 is connected to the selection terminal 513. The reflection phase (second reflection phase) adjusted by the phase adjustment circuit 41 differs from the reflection phase (first reflection phase) of the receive band of band A when the transmit filter 31 is viewed from the common terminal 511 via path P1 in a state where the common terminal 511 is connected to the selection terminal 512 in the switch circuit 51.

[0048] The phase adjustment circuit 42 is connected between the selection terminal 515 of the switch circuit 51 and the transmit filter 32. The phase adjustment circuit 42 includes an inductor and / or a capacitor. The phase adjustment circuit 42 can adjust the reflection phase of the receive band of band B when the transmit filter 32 is viewed from the common terminal 511 via path P4 in a state where the common terminal 511 is connected to the selection terminal 515. The reflection phase (fourth reflection phase) adjusted by the phase adjustment circuit 42 differs from the reflection phase (third reflection phase) of the receive band of band B when the transmit filter 32 is viewed from the common terminal 511 via path P3 in a state where the common terminal 511 is connected to the selection terminal 514 in the switch circuit 51.

[0049] The inductors and / or capacitors included in the phase adjustment circuits 41 and 42 may be implemented as surface mount devices (SMDs) or may be implemented by wiring within or on a module substrate. Inductors and capacitors implemented on surface mount devices are referred to as surface mount inductors and surface mount capacitors, respectively. Note that the phase adjustment circuits 41 and / or 42 do not need to include inductors and capacitors and may be configured, for example, by transmission lines.

[0050] The switch circuit 51 is an example of a first switch circuit and may be referred to as an antenna switch. The switch circuit 51 is connected between the antenna connection terminal 101 and the transmit filters 31 and 32 and the receive filters 33 and 34. Specifically, the switch circuit 51 includes a common terminal 511 and selection terminals 512 to 516. The common terminal 511 is an example of a first common terminal and is connected to the antenna connection terminal 101. The selection terminal 512 is an example of a first selection terminal and is connected to the transmit filter 31 via path P1. The selection terminal 513 is an example of a second selection terminal and is connected to the transmit filter 31 via path P2. The selection terminal 514 is an example of a fourth selection terminal and is connected to the transmit filter 32 via path P3. The selection terminal 515 is an example of a fifth selection terminal and is connected to the transmit filter 32 via path P4. The selection terminal 516 is an example of a third selection terminal and is connected to the receive filters 33 and 34.

[0051] In such a connection configuration, the switch circuit 51 can connect the common terminal 511 to at least one of the selection terminals 512 to 516, for example, based on a control signal from the RFIC 3. That is, the switch circuit 51 can connect the common terminal 511 to any of the selection terminals 512 to 516, and can also simultaneously connect the common terminal 511 to at least two of the selection terminals 512 to 516. The switch circuit 51 is configured, for example, as a multi-connection type switch circuit.

[0052] The switch circuit 52 is an example of a second switch circuit and may be called a band select switch. The switch circuit 52 is connected between the power amplifier 11 and the transmit filters 31 and 32. Specifically, the switch circuit 52 includes a common terminal 521 and selection terminals 522 and 523. The common terminal 521 is an example of a second common terminal and is connected to the output end of the power amplifier 11. The selection terminal 522 is an example of a sixth selection terminal and is connected to the transmit filter 31. The selection terminal 523 is an example of a seventh selection terminal and is connected to the transmit filter 32.

[0053] In such a connection configuration, the switch circuit 52 can exclusively connect the common terminal 521 to the selection terminals 522 and 523, for example, based on a control signal from the RFIC 3. The switch circuit 52 is configured, for example, by an SPDT (Single-Pole Double-Throw) type switch circuit.

[0054] The switch circuits 51 and 52 may be implemented in a single integrated circuit including, for example, multiple MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors), but the method for implementing the switch circuits 51 and 52 is not limited to this. For example, the switch circuits 51 and 52 may be implemented separately in two integrated circuits. Furthermore, the switch circuit 51 may be implemented together with the phase adjustment circuits 41 and 42 in a single integrated circuit.

[0055] The path P1 is an example of a first path, and connects the selection terminal 512 and the transmission filter 31. The path P1 can connect the transmission filter 31 to the selection terminal 512 without passing through the phase adjustment circuit 41. In other words, the path P1 is a transmission path that bypasses the phase adjustment circuit 41.

[0056] The path P2 is an example of a second path, and connects the selection terminal 513 and the transmission filter 31. The path P2 can connect the transmission filter 31 to the selection terminal 513 via the phase adjustment circuit 41. In other words, the path P2 is a transmission path that passes through the phase adjustment circuit 41.

[0057] In this way, of paths P1 and P2, the phase adjustment circuit 41 is connected only to path P2. Therefore, in the transmission band of band A, the amount of phase variation between the common terminal 511 and the transmission filter 31 connected via path P1 is smaller than the amount of phase variation between the common terminal 511 and the transmission filter 31 connected via path P2. In other words, path P1 can suppress loss of the transmission signal of band A more effectively than path P2.

[0058] The path P3 is an example of a third path, and connects the selection terminal 514 and the transmission filter 32. The path P3 can connect the transmission filter 32 to the selection terminal 514 without passing through the phase adjustment circuit 42. In other words, the path P3 is a transmission path that bypasses the phase adjustment circuit 42.

[0059] The path P4 is an example of a fourth path, and connects the selection terminal 515 and the transmission filter 32. The path P4 can connect the transmission filter 32 to the selection terminal 515 via the phase adjustment circuit 42. In other words, the path P4 is a transmission path that passes through the phase adjustment circuit 42.

[0060] In this way, of paths P3 and P4, the phase adjustment circuit 42 is connected only to path P4. Therefore, in the transmission band of band B, the amount of phase variation between the common terminal 511 and the transmission filter 32 connected via path P3 is smaller than the amount of phase variation between the common terminal 511 and the transmission filter 32 connected via path P4. In other words, path P3 can suppress loss of the transmission signal of band B more effectively than path P4.

[0061] The phase variation amount means the phase difference between the input signal and the output signal. For example, the phase variation amount between the common terminal 511 and the transmit filter 31 connected via the path P1 is determined by the phase difference between the input signal from the output terminal of the transmit filter 31 to the path P1 and the output signal from the common terminal 511. The phase variation amount can be detected using a phase detector.

[0062] 2A to 2F, several examples of the circuit configuration of the phase adjustment circuits 41 and 42 will be described. Each of FIGS. 2A to 2F is an exemplary circuit configuration diagram of the phase adjustment circuits 41 and 42 according to this embodiment.

[0063] 2A-2F are exemplary circuit configurations, and the phase adjustment circuits 41 and 42 may be implemented using any of a wide variety of circuit implementations and circuit techniques. Therefore, the description of the phase adjustment circuits 41 and 42 provided below should not be construed as limiting.

[0064] First, Fig. 2A will be described. In Fig. 2A, the phase adjustment circuit 41 and / or 42 includes an inductor L1.

[0065] In the phase adjustment circuit 41, the inductor L1 is connected in series to the path P2. Specifically, in the phase adjustment circuit 41, one end of the inductor L1 is connected to the selection terminal 513 of the switch circuit 51, and the other end of the inductor L1 is connected to the transmit filter 31.

[0066] In the phase adjustment circuit 42, the inductor L1 is connected in series to the path P4. Specifically, in the phase adjustment circuit 42, one end of the inductor L1 is connected to the selection terminal 515 of the switch circuit 51, and the other end of the inductor L1 is connected to the transmit filter 32.

[0067] Next, referring to Fig. 2B, the phase adjustment circuit 41 and / or 42 includes a capacitor C1.

[0068] In the phase adjustment circuit 41, the capacitor C1 is connected in series to the path P2. Specifically, in the phase adjustment circuit 41, one end of the capacitor C1 is connected to the selection terminal 513 of the switch circuit 51, and the other end of the capacitor C1 is connected to the transmit filter 31.

[0069] In the phase adjustment circuit 42, the capacitor C1 is connected in series to the path P4. Specifically, in the phase adjustment circuit 42, one end of the capacitor C1 is connected to the selection terminal 515 of the switch circuit 51, and the other end of the capacitor C1 is connected to the transmit filter 32.

[0070] Next, referring to Fig. 2C, the phase adjustment circuit 41 and / or 42 includes an inductor L1, capacitors C1 and C2, and a switch S1.

[0071] In the phase adjustment circuit 41, the inductor L1 and the switch S1 are connected in series to the path P2, and the capacitors C1 and C2 are connected in parallel (shunt-connected) to the path P2. Specifically, in the phase adjustment circuit 41, one end of the inductor L1 is connected to a selection terminal 513 of the switch circuit 51, and the other end of the inductor L1 is switchably connected to the transmit filter 31 via the switch S1. The capacitor C1 is connected between a node on the path P2 between one end of the inductor L1 and the selection terminal 513 of the switch circuit 51 and ground, and the capacitor C2 is connected between a node on the path P2 between the other end of the inductor L1 and one end of the switch S1 and ground. One end of the switch S1 is connected to the other end of the inductor L1, and the other end of the switch S1 is connected to the transmit filter 31. When the common terminal 511 of the switch circuit 51 is connected to the selection terminal 513, the switch S1 is closed (turned on), and when the common terminal 511 of the switch circuit 51 is not connected to the selection terminal 513, the switch S1 is opened (turned off).

[0072] In the phase adjustment circuit 42, the inductor L1 and the switch S1 are connected in series to a path P4, and the capacitors C1 and C2 are connected in parallel to the path P4. Specifically, in the phase adjustment circuit 42, one end of the inductor L1 is connected to a selection terminal 515 of the switch circuit 51, and the other end of the inductor L1 is switchably connected to the transmit filter 32 via the switch S1. The capacitor C1 is connected between a node on the path P4 between one end of the inductor L1 and the selection terminal 515 of the switch circuit 51 and ground, and the capacitor C2 is connected between a node on the path P4 between the other end of the inductor L1 and one end of the switch S1 and ground. One end of the switch S1 is connected to the other end of the inductor L1, and the other end of the switch S1 is connected to the transmit filter 32. When the common terminal 511 of the switch circuit 51 is connected to the selection terminal 515, the switch S1 is closed, and when the common terminal 511 of the switch circuit 51 is not connected to the selection terminal 515, the switch S1 is opened.

[0073] Next, referring to Fig. 2D, the phase adjustment circuit 41 and / or 42 includes a capacitor C1, inductors L1 and L2, and a switch S1.

[0074] In the phase adjustment circuit 41, the capacitor C1 and the switch S1 are connected in series to the path P2, and the inductors L1 and L2 are connected in parallel to the path P2. Specifically, in the phase adjustment circuit 41, one end of the capacitor C1 is connected to a selection terminal 513 of the switch circuit 51, and the other end of the capacitor C1 is switchably connected to the transmit filter 31 via the switch S1. In the phase adjustment circuit 41, the inductor L1 is connected between a node on the path P2 between one end of the capacitor C1 and the selection terminal 513 of the switch circuit 51 and ground, and the inductor L2 is connected between a node on the path P2 between the other end of the capacitor C1 and one end of the switch S1 and ground. In the phase adjustment circuit 41, one end of the switch S1 is connected to the other end of the capacitor C1, and the other end of the switch S1 is connected to the transmit filter 31. When the common terminal 511 of the switch circuit 51 is connected to the selection terminal 513, the switch S1 is closed, and when the common terminal 511 of the switch circuit 51 is not connected to the selection terminal 513, the switch S1 is opened.

[0075] In the phase adjustment circuit 42, the capacitor C1 and the switch S1 are connected in series to a path P4, and the inductors L1 and L2 are connected in parallel to the path P4. Specifically, in the phase adjustment circuit 42, one end of the capacitor C1 is connected to a selection terminal 515 of the switch circuit 51, and the other end of the capacitor C1 is switchably connected to the transmit filter 32 via the switch S1. In the phase adjustment circuit 42, the inductor L1 is connected between a node on the path P4 between one end of the capacitor C1 and the selection terminal 515 of the switch circuit 51 and ground, and the inductor L2 is connected between a node on the path P4 between the other end of the capacitor C1 and one end of the switch S1 and ground. In the phase adjustment circuit 42, one end of the switch S1 is connected to the other end of the capacitor C1, and the other end of the switch S1 is connected to the transmit filter 32. When the common terminal 511 of the switch circuit 51 is connected to the selection terminal 515, the switch S1 is closed, and when the common terminal 511 of the switch circuit 51 is not connected to the selection terminal 515, the switch S1 is opened.

[0076] Next, referring to Fig. 2E, the phase adjustment circuit 41 and / or 42 includes inductors L1 and L2, a capacitor C1, and a switch S1.

[0077] In the phase adjustment circuit 41, inductors L1 and L2 and a switch S1 are connected in series to a path P2, and a capacitor C1 is connected in parallel to the path P2. Specifically, in the phase adjustment circuit 41, one end of the inductor L1 is connected to a selection terminal 513 of the switch circuit 51, and the other end of the inductor L1 is connected to one end of an inductor L2. One end of the inductor L2 is connected to the other end of the inductor L1, and the other end of the inductor L2 is switchably connected to the transmit filter 31 via the switch S1. The capacitor C1 is connected between a node on the path P2 between the other end of the inductor L1 and one end of the inductor L2 and ground. One end of the switch S1 is connected to the other end of the inductor L2, and the other end of the switch S1 is connected to the transmit filter 31. When a common terminal 511 of the switch circuit 51 is connected to the selection terminal 513, the switch S1 is closed. When the common terminal 511 of the switch circuit 51 is not connected to the selection terminal 513, the switch S1 is opened.

[0078] In the phase adjustment circuit 42, inductors L1 and L2 and a switch S1 are connected in series to a path P4, and a capacitor C1 is connected in parallel to the path P4. Specifically, in the phase adjustment circuit 42, one end of the inductor L1 is connected to a selection terminal 515 of the switch circuit 51, and the other end of the inductor L1 is connected to one end of an inductor L2. One end of the inductor L2 is connected to the other end of the inductor L1, and the other end of the inductor L2 is switchably connected to the transmit filter 32 via the switch S1. The capacitor C1 is connected between a node on the path P4 between the other end of the inductor L1 and one end of the inductor L2 and ground. One end of the switch S1 is connected to the other end of the inductor L2, and the other end of the switch S1 is connected to the transmit filter 32. When a common terminal 511 of the switch circuit 51 is connected to the selection terminal 515, the switch S1 is closed, and when the common terminal 511 of the switch circuit 51 is not connected to the selection terminal 515, the switch S1 is opened.

[0079] Next, referring to Fig. 2F, the phase adjustment circuit 41 and / or 42 includes capacitors C1 and C2, an inductor L1, and a switch S1.

[0080] In the phase adjustment circuit 41, the capacitors C1 and C2 and the switch S1 are connected in series to a path P2, and the inductor L1 is connected in parallel to the path P2. Specifically, in the phase adjustment circuit 41, one end of the capacitor C1 is connected to a selection terminal 513 of the switch circuit 51, and the other end of the capacitor C1 is connected to one end of the capacitor C2. One end of the capacitor C2 is connected to the other end of the capacitor C1, and the other end of the capacitor C2 is switchably connected to the transmit filter 31 via the switch S1. The inductor L1 is connected between a node on the path P2 between the other end of the capacitor C1 and one end of the capacitor C2 and ground. One end of the switch S1 is connected to the other end of the capacitor C2, and the other end of the switch S1 is connected to the transmit filter 31. When the common terminal 511 of the switch circuit 51 is connected to the selection terminal 513, the switch S1 is closed, and when the common terminal 511 of the switch circuit 51 is not connected to the selection terminal 513, the switch S1 is opened.

[0081] In the phase adjustment circuit 42, the capacitors C1 and C2 and the switch S1 are connected in series to a path P4, and the inductor L1 is connected in parallel to the path P4. Specifically, in the phase adjustment circuit 42, one end of the capacitor C1 is connected to a selection terminal 515 of the switch circuit 51, and the other end of the capacitor C1 is connected to one end of the capacitor C2. One end of the capacitor C2 is connected to the other end of the capacitor C1, and the other end of the capacitor C2 is switchably connected to the transmit filter 32 via the switch S1. The inductor L1 is connected between a node on the path P4 between the other end of the capacitor C1 and one end of the capacitor C2 and ground. One end of the switch S1 is connected to the other end of the capacitor C2, and the other end of the switch S1 is connected to the transmit filter 32. When the common terminal 511 of the switch circuit 51 is connected to the selection terminal 515, the switch S1 is closed, and when the common terminal 511 of the switch circuit 51 is not connected to the selection terminal 515, the switch S1 is opened.

[0082] The circuit configurations of the phase adjustment circuits 41 and 42 may be different from each other. For example, the circuit configuration of the phase adjustment circuit 41 may be one of the circuit configurations shown in Figures 2A to 2F, and the circuit configuration of the phase adjustment circuit 42 may be another of the circuit configurations shown in Figures 2A to 2F. Furthermore, the circuit configurations of the phase adjustment circuits 41 and 42 may be the same.

[0083] [1.4 Phase Adjustment by Phase Adjustment Circuit 41] Next, the phase adjustment by the phase adjustment circuit 41 will be described with reference to Fig. 3. Fig. 3 is a Smith chart for explaining the phase adjustment by the phase adjustment circuit 41 according to this embodiment. The phase adjustment by the phase adjustment circuit 42 is similar to that of the phase adjustment circuit 41, and therefore its description will be omitted. Note that Fig. 3 is an exemplary Smith chart, and the following description of the phase adjustment by the phase adjustment circuit 41 should not be construed as limiting.

[0084] 3, impedance Z1 represents the impedance of the reception band of band A when the transmit filter 31 is viewed from the common terminal 511 via path P1 in a state where the common terminal 511 is connected to the selection terminal 512. Impedance Z2 represents the impedance of the reception band of band A when the transmit filter 31 is viewed from the common terminal 511 via path P2 in a state where the common terminal 511 is connected to the selection terminal 513.

[0085] 3, the phase of impedance Z2 (reflection phase) is adjusted by the phase adjustment circuit 41 so that it differs from the phase of impedance Z1 (reflection phase). Specifically, the phase of impedance Z2 is closer to 0 degrees than the phase of impedance Z1. This allows the impedance of the band A reception band when viewed from the common terminal 511 via path P2 toward the transmit filter 31 to approach an open state, thereby suppressing leakage of the band A reception signal from the common terminal 511 to the transmit filter 31 via path P2.

[0086] The reflection phase refers to the phase difference between a high-frequency signal and a reflected wave signal detected from a port to which the high-frequency signal is incident. The reflection phase of the reception band of band A when the transmit filter 31 is viewed from the common terminal 511 via path P1 in a state where the common terminal 511 is connected to the selection terminal 512, and the reflection phase of the reception band of band A when the transmit filter 31 is viewed from the common terminal 511 via path P2 in a state where the common terminal 511 is connected to the selection terminal 513, can be determined by measuring the impedance of band A using a network analyzer.

[0087] [1.5 Communication Modes of High-Frequency Circuit 1] Next, the communication modes of the high-frequency circuit 1 corresponding to the bands used for communication and the power classes applied to those bands will be described.

[0088] [1.5.1 First Communication Mode] First, the first communication mode of the high-frequency circuit 1 will be described with reference to Fig. 4. Fig. 4 is a circuit configuration diagram showing the first communication mode of the high-frequency circuit 1 according to this embodiment. In this figure and the following figures, dashed arrows indicate the flow of high-frequency signals.

[0089] The first communication mode is a communication mode for transmitting signals in Band A at a first power class (e.g., Power Class 2). In the first communication mode, transmission of signals in the transmit band of Band A does not occur simultaneously with reception of signals in the receive band of Band A.

[0090] In the first communication mode, the switch circuit 51 connects the common terminal 511 to the selection terminal 512, and does not connect it to the selection terminals 513 to 516. Furthermore, the switch circuit 52 connects the common terminal 521 to the selection terminal 522, and does not connect it to the selection terminal 523. As a result, one end of the transmit filter 31 is connected to the antenna connection terminal 101 via the path P1, and the other end of the transmit filter 31 is connected to the power amplifier 11.

[0091] As a result, the band A transmission signal is transmitted from the RFIC 3 to the antenna 2 via the high frequency input terminal 111, the power amplifier 11, the switch circuit 52, the transmit filter 31, the path P1, the switch circuit 51 and the antenna connection terminal 101.

[0092] [1.5.2 Second Communication Mode] Next, the second communication mode of the high-frequency circuit 1 will be described with reference to Fig. 5. Fig. 5 is a circuit configuration diagram showing the second communication mode of the high-frequency circuit 1 according to this embodiment.

[0093] The second communication mode is a communication mode for transmitting and receiving signals in Band A at a second power class (e.g., power class 3). In the second communication mode, transmission of signals in the transmission band of Band A occurs simultaneously with reception of signals in the reception band of Band A.

[0094] In the second communication mode, the switch circuit 51 connects the common terminal 511 to the selection terminals 513 and 516, and does not connect it to the selection terminals 512, 514, and 515. Furthermore, the switch circuit 52 connects the common terminal 521 to the selection terminal 522, and does not connect it to the selection terminal 523. As a result, one end of the transmit filter 31 is connected to the antenna connection terminal 101 via the path P2, and the other end of the transmit filter 31 is connected to the power amplifier 11.

[0095] As a result, the transmission signal of band A is transmitted from the RFIC 3 to the antenna 2 via the radio frequency input terminal 111, the power amplifier 11, the switch circuit 52, the transmission filter 31, the path P2, the switch circuit 51, and the antenna connection terminal 101. The reception signal of band A is transmitted from the antenna 2 to the RFIC 3 via the antenna connection terminal 101, the switch circuit 51, the reception filter 33, the low noise amplifier 21, and the radio frequency output terminal 121.

[0096] [1.5.3 Third Communication Mode] First, the third communication mode of the high-frequency circuit 1 will be described with reference to Fig. 6. Fig. 6 is a circuit configuration diagram showing the third communication mode of the high-frequency circuit 1 according to this embodiment. In this figure and the following figures, dashed arrows indicate the flow of high-frequency signals.

[0097] The third communication mode is a communication mode for transmitting signals in Band B at a first power class (e.g., Power Class 2). In the third communication mode, transmission of signals in the transmission band of Band B does not occur simultaneously with reception of signals in the reception band of Band B.

[0098] In the third communication mode, the switch circuit 51 connects the common terminal 511 to the selection terminal 514, and does not connect it to the selection terminals 512, 513, 515, and 516. Furthermore, the switch circuit 52 connects the common terminal 521 to the selection terminal 523, and does not connect it to the selection terminal 522. As a result, one end of the transmit filter 32 is connected to the antenna connection terminal 101 via the path P3, and the other end of the transmit filter 32 is connected to the power amplifier 11.

[0099] As a result, the band B transmission signal is transmitted from the RFIC 3 to the antenna 2 via the high frequency input terminal 111, the power amplifier 11, the switch circuit 52, the transmit filter 32, the path P3, the switch circuit 51 and the antenna connection terminal 101.

[0100] [1.5.4 Fourth Communication Mode] Next, the fourth communication mode of the high-frequency circuit 1 will be described with reference to Fig. 7. Fig. 7 is a circuit configuration diagram showing the fourth communication mode of the high-frequency circuit 1 according to this embodiment.

[0101] The fourth communication mode is a communication mode for transmitting and receiving signals in Band B at a second power class (e.g., Power Class 3). In the fourth communication mode, transmission of signals in the transmission band of Band B is performed simultaneously with reception of signals in the reception band of Band B.

[0102] In the fourth communication mode, the switch circuit 51 connects the common terminal 511 to the selection terminals 515 and 516, and does not connect it to the selection terminals 512 to 514. Furthermore, the switch circuit 52 connects the common terminal 521 to the selection terminal 523, and does not connect it to the selection terminal 522. As a result, one end of the transmit filter 32 is connected to the antenna connection terminal 101 via the path P4, and the other end of the transmit filter 32 is connected to the power amplifier 11.

[0103] As a result, the transmission signal of band B is transmitted from the RFIC 3 to the antenna 2 via the radio frequency input terminal 111, the power amplifier 11, the switch circuit 52, the transmission filter 32, the path P4, the switch circuit 51, and the antenna connection terminal 101. The reception signal of band B is transmitted from the antenna 2 to the RFIC 3 via the antenna connection terminal 101, the switch circuit 51, the reception filter 34, the low noise amplifier 22, and the radio frequency output terminal 122.

[0104] [1.6 Summary] As described above, the high-frequency circuit 1 according to this embodiment includes the switch circuit 51 including the common terminal 511 connected to the antenna connection terminal 101 and the selection terminals 512, 513, and 516, the transmit filter 31 connected to the selection terminals 512 and 513 and having a pass band including the transmit band of band A, the receive filter 33 connected to the selection terminal 516 and having a pass band including the receive band of band A, a path P1 connecting the transmit filter 31 to the selection terminal 512, and a path P2 connecting the transmit filter 31 to the selection terminal 513. The first reflection phase of the reception band of band A when the transmit filter 31 is viewed from the common terminal 511 via path P1 when connected to terminal 512 is different from the second reflection phase of the reception band of band A when the transmit filter 31 is viewed from the common terminal 511 via path P2 when the common terminal 511 is connected to selection terminal 513, and in the transmission band of band A, the amount of phase variation between the common terminal 511 and the transmit filter 31 connected via path P1 is smaller than the amount of phase variation between the common terminal 511 and the transmit filter 31 connected via path P2.

[0105] This allows the high-frequency circuit 1 to selectively use two paths P1 and P2 for transmitting signals of band A. Therefore, for example, when only signals of band A are transmitted, path P1, which has a smaller amount of phase fluctuation in the transmission band of band A, can be selected to reduce loss of the transmitted signal of band A, thereby reducing loss of the transmitted signal. Furthermore, for example, when signals of band A are transmitted and received simultaneously, path P2, which has a more appropriate reflection phase for the receiving band, can be selected, thereby reducing leakage of the received signal into the transmitting path and improving receiving sensitivity.

[0106] Furthermore, for example, in the high-frequency circuit 1 according to this embodiment, the second reflection phase may be closer to 0 degrees than the first reflection phase.

[0107] As a result, the high-frequency circuit 1 can bring the impedance of the reception band of band A, when viewed from the common terminal 511 via path P2 to the transmission filter 31, closer to an open state, and can suppress leakage of the reception signal of band A from the common terminal 511 to the transmission filter 31 via path P2.

[0108] Furthermore, for example, in the high-frequency circuit 1 according to the present embodiment, when a first power class (e.g., power class 2) defined by a first maximum output power is applied to band A, the switch circuit 51 may connect the common terminal 511 to the selection terminal 512, and when a second power class (e.g., power class 3) defined by a second maximum output power lower than the first maximum output power is applied to band A, the switch circuit 51 may connect the common terminal 511 to the selection terminals 513 and 516.

[0109] According to this, in the first power class, the common terminal 511 is connected to the selection terminal 512, and the band A signal can be transmitted using the path P1, which has a smaller phase fluctuation. Therefore, the high-frequency circuit 1 can reduce loss of the transmission signal in band A. Meanwhile, in the second power class, the common terminal 511 is connected to the selection terminals 513 and 516, and the band A signal can be transmitted using the path P2, whose reflection phase in the reception band of band A is closer to 0 degrees. Therefore, the high-frequency circuit 1 can suppress leakage of the reception signal in band A to the transmission path, thereby improving reception sensitivity. In this way, the high-frequency circuit 1 can reduce loss of the transmission signal when transmitting the band A signal in the first power class, and can suppress leakage of the reception signal when transmitting and receiving the band A signal in the second power class. In particular, in the first power class, which allows a higher maximum output power, the power amplifier 11 has limited output capability, so the effect of reducing loss of the transmission signal is significant.

[0110] Furthermore, for example, in the high-frequency circuit 1 according to this embodiment, band A may be Band 1 or Band 3 for LTE, or n1 or n3 for 5G NR.

[0111] This allows the high frequency circuit 1 to support transmission and reception of signals of Band 1 or Band 3 for LTE, or n1 or n3 for 5G NR.

[0112] Furthermore, for example, the high-frequency circuit 1 according to the present embodiment may further include a power amplifier 11 connected to the transmission filter 31 .

[0113] This allows the high frequency circuit 1 to amplify the transmission signal of band A.

[0114] Furthermore, for example, the high-frequency circuit 1 according to this embodiment may further include a receiving filter 34 connected to the selection terminal 516 and having a pass band including the band B receiving band.

[0115] This allows the high frequency circuit 1 to support the reception of band B signals in addition to the transmission and reception of band A signals.

[0116] Furthermore, for example, in the high-frequency circuit 1 according to this embodiment, the switch circuit 51 may further include selection terminals 514 and 515, and the high-frequency circuit 1 may further include a transmit filter 32 connected to the selection terminals 514 and 515 and having a pass band that includes the transmit band of band B, a path P3 that connects the transmit filter 32 to the selection terminal 514, and a path P4 that connects the transmit filter 32 to the selection terminal 515, and the third reflection phase of the receive band of band B when the transmit filter 32 is viewed from the common terminal 511 via the path P3 with the common terminal 511 connected to the selection terminal 514 may be different from the fourth reflection phase of the receive band of band B when the transmit filter 32 is viewed from the common terminal 511 via the path P4 with the common terminal 511 connected to the selection terminal 515.

[0117] This allows the high-frequency circuit 1 to selectively use two paths P3 and P4 for transmitting signals of band B. Therefore, for example, when transmitting and receiving signals of band B simultaneously, a path (e.g., path P4) having a more suitable reflection phase for the reception band can be used, reducing leakage of the received signal to the transmission path and improving reception sensitivity. Conversely, for example, when only transmitting signals of band B, a path (e.g., path P3) suitable for transmitting signals of band B can be selected without considering the reflection phase for the reception band, reducing loss of the transmitted signal.

[0118] Furthermore, for example, in the high-frequency circuit 1 according to this embodiment, in the transmission band of band B, the amount of phase variation between the common terminal 511 and the transmission filter 32 connected via path P3 may be smaller than the amount of phase variation between the common terminal 511 and the transmission filter 32 connected via path P4.

[0119] According to this, the high-frequency circuit 1 can reduce the loss of the transmission signal of band B by selecting the path P3.

[0120] Furthermore, for example, in the high-frequency circuit 1 according to this embodiment, the fourth reflection phase may be closer to 0 degrees than the third reflection phase.

[0121] As a result, the high-frequency circuit 1 can bring the impedance of the reception band of band B, when viewed from the common terminal 511 to the transmission filter 32 via path P4, closer to an open state, and can suppress leakage of the reception signal of band B from the common terminal 511 to the transmission filter 32 via path P4.

[0122] Furthermore, for example, in the high-frequency circuit 1 according to the present embodiment, when a first power class defined by a first maximum output power is applied to band B, the switch circuit 51 may connect the common terminal 511 to the selection terminal 514, and when a second power class defined by a second maximum output power lower than the first maximum output power is applied to band B, the switch circuit 51 may connect the common terminal 511 to the selection terminals 515 and 516.

[0123] According to this, in the first power class, the common terminal 511 is connected to the selection terminal 514, and the band B signal can be transmitted using the path P3, which has a smaller phase fluctuation. Therefore, the high-frequency circuit 1 can reduce loss of the band B transmission signal. Meanwhile, in the second power class, the common terminal 511 is connected to the selection terminals 515 and 516, and the band B signal can be transmitted using the path P4, whose reflection phase in the reception band of band B is closer to 0 degrees. Therefore, the high-frequency circuit 1 can suppress leakage of the band B reception signal to the transmission path and improve reception sensitivity. In this way, the high-frequency circuit 1 can reduce transmission signal loss when transmitting band B signals in the first power class, and can suppress reception signal leakage when transmitting and receiving band B signals in the second power class. In particular, in the first power class, which allows a higher maximum output power, the power amplifier 11 has limited output capability, so the effect of reducing transmission signal loss is significant.

[0124] Also, for example, in the high-frequency circuit 1 according to this embodiment, the combination of Band A and Band B may be a combination of Band 1 for LTE or n1 for 5G NR and Band 3 for LTE or n3 for 5G NR.

[0125] According to this, the high frequency circuit 1 can support the transmission and reception of n1 signals for Band 1 for LTE or 5G NR, and the transmission and reception of n3 signals for Band 3 for LTE or 5G NR.

[0126] Furthermore, for example, in the high-frequency circuit 1 according to this embodiment, the transmit filter 31 may be a bulk acoustic wave filter, and the transmit filter 32 may be a surface acoustic wave filter.

[0127] According to this, by using a BAW filter for the transmit filter 31 corresponding to the first power class, it is possible to improve the power durability of the transmit filter 31. On the other hand, by using a SAW filter for the receive filter 33, it is possible to reduce the size and cost of the receive filter 33.

[0128] For example, the high-frequency circuit 1 according to this embodiment may further include a power amplifier 11, and a switch circuit 52 including a common terminal 521 connected to the power amplifier 11, a selection terminal 522 connected to the transmit filter 31, and a selection terminal 523 connected to the transmit filter 32.

[0129] This allows the power amplifier 11 to be used in common to amplify the transmission signals of bands A and B, thereby reducing the circuit scale of the high-frequency circuit 1 compared to when separate power amplifiers are provided for bands A and B.

[0130] Moreover, the high-frequency circuit 1 according to this embodiment includes a switch circuit 51 including a common terminal 511 connected to the antenna connection terminal 101 and selection terminals 512, 513, and 516; a transmit filter 31 connected to the selection terminals 512 and 513 and having a pass band that includes the transmit band of band A; a receive filter 33 connected to the selection terminal 516 and having a pass band that includes the receive band of band A; and a surface-mount inductor (L1) or a surface-mount capacitor (C1) connected between the selection terminal 513 and the transmit filter 31; and no surface-mount inductor or surface-mount capacitor is connected between the selection terminal 512 and the transmit filter 31.

[0131] According to this, by connecting the common terminal 511 of the switch circuit 51 to the selection terminal 512, the high-frequency circuit 1 can connect the transmit filter 31 to the common terminal 511 without passing through a surface-mount inductor or a surface-mount capacitor. Furthermore, by connecting the common terminal 511 of the switch circuit 51 to the selection terminal 513, the high-frequency circuit 1 can connect the transmit filter 31 to the common terminal 511 via a surface-mount inductor (L1) or a surface-mount capacitor (C1). Therefore, when only band A signals are transmitted, signal loss due to surface-mount inductors and surface-mount capacitors can be avoided by connecting the transmit filter 31 to the common terminal 511 without passing through a surface-mount inductor or a surface-mount capacitor. On the other hand, when transmission and reception of band A signals are performed simultaneously, by connecting the transmit filter 31 to the common terminal 511 via a surface-mounted inductor (L1) or a surface-mounted capacitor (C1), the impedance of the receive band of band A when viewing the transmit filter 31 from the common terminal 511 can be made closer to an open state by the surface-mounted inductor (L1) or the surface-mounted capacitor (C1), and leakage of the receive signal of band A into the transmit path can be suppressed.

[0132] (Embodiment 2) Next, embodiment 2 will be described. In this embodiment, the main difference from embodiment 1 is that the phase adjustment circuit is shunt-connected to the transmission path, and each transmission filter is connected to a single selection terminal of the antenna switch. Below, this embodiment will be described with reference to the drawings, focusing on the differences from embodiment 1.

[0133] The communication device 5A according to this embodiment can be used to provide wireless connectivity, similar to the first embodiment.

[0134] The circuit configuration of a communication device 5A and a high-frequency circuit 1A according to this embodiment will be described with reference to Fig. 8. Fig. 8 is a circuit configuration diagram of a communication device 5A according to this embodiment.

[0135] 8 is an exemplary circuit configuration, and the communication device 5A and the high-frequency circuit 1A can be implemented using any of a wide variety of circuit implementations and circuit technologies. Therefore, the following description of the communication device 5A and the high-frequency circuit 1A should not be construed as limiting.

[0136] [2.1 Circuit Configuration of Communication Device 5A] The communication device 5A is the same as that of the first embodiment except that it includes a high-frequency circuit 1A instead of the high-frequency circuit 1, and therefore detailed description thereof will be omitted.

[0137] [2.2 Circuit Configuration of High-Frequency Circuit 1A] The circuit configuration of the high-frequency circuit 1A according to this embodiment will be described with reference to Fig. 8. The high-frequency circuit 1A includes a power amplifier 11, low-noise amplifiers 21 and 22, transmit filters 31 and 32, receive filters 33 and 34, phase adjustment circuits 41A and 42A, switch circuits 51A and 52, an antenna connection terminal 101, a high-frequency input terminal 111, and high-frequency output terminals 121 and 122.

[0138] The phase adjustment circuit 41A is connected between ground and a path P5 that connects the selection terminal 512A of the switch circuit 51A and the transmit filter 31, and includes an inductor or capacitor and a switch. By opening and closing the switch, the phase adjustment circuit 41A can adjust the reflection phase of the Band A receive band when the transmit filter 31 is viewed from the common terminal 511A with the common terminal 511A connected to the selection terminal 512A. The reflection phase when the switch of the phase adjustment circuit 41A is closed is closer to 0 degrees than the reflection phase when the switch is open. Therefore, by closing the switch, the impedance of the Band A receive band when the transmit filter 31 is viewed from the common terminal 511A can be brought closer to an open state, thereby suppressing leakage of the Band A receive signal from the common terminal 511A to the transmit filter 31.

[0139] The phase adjustment circuit 42A is connected between ground and a path P6 that connects the selection terminal 513A of the switch circuit 51A and the transmit filter 32, and includes an inductor or capacitor and a switch. By opening and closing the switch, the phase adjustment circuit 42A can adjust the reflection phase of the Band B receive band when the transmit filter 32 is viewed from the common terminal 511A with the common terminal 511A connected to the selection terminal 513A. The reflection phase when the switch of the phase adjustment circuit 42A is closed is closer to 0 degrees than the reflection phase when the switch is open. Therefore, closing the switch can bring the impedance of the Band B receive band when the transmit filter 32 is viewed from the common terminal 511A closer to an open state, thereby suppressing leakage of the Band B receive signal from the common terminal 511A to the transmit filter 32.

[0140] The switch circuit 51A is an example of a first switch circuit and may be called an antenna switch. The switch circuit 51A is connected between the antenna connection terminal 101 and the transmit filters 31 and 32 and the receive filters 33 and 34. Specifically, the switch circuit 51A includes a common terminal 511A and selection terminals 512A to 514A. The common terminal 511A is an example of a first common terminal and is connected to the antenna connection terminal 101. The selection terminal 512A is an example of a first selection terminal and is connected to the transmit filter 31. The selection terminal 513A is connected to the transmit filter 32. The selection terminal 514A is an example of a second selection terminal and is connected to the receive filters 33 and 34.

[0141] In this connection configuration, the switch circuit 51A can connect the common terminal 511A to at least one of the selection terminals 512A to 514A, for example, based on a control signal from the RFIC 3. In other words, the switch circuit 51A can connect the common terminal 511A to any of the selection terminals 512A to 514A, and can also connect the common terminal 511A to at least two of the selection terminals 512A to 514A simultaneously. The switch circuit 51A is configured, for example, as a multi-connection type switch circuit.

[0142] 2.3 Circuit Configuration of Phase Adjustment Circuits 41A and 42A Next, several examples of the circuit configuration of the phase adjustment circuits 41A and 42A will be described with reference to FIGS. 9A and 9B. Each of FIGS. 9A and 9B is an exemplary circuit configuration diagram of the phase adjustment circuits 41A and 42A according to this embodiment.

[0143] 9A and 9B are exemplary circuit configurations, and the phase adjustment circuits 41A and 42A may be implemented using any of a wide variety of circuit implementations and circuit techniques, and therefore the description of the phase adjustment circuits 41A and 42A provided below should not be construed as limiting.

[0144] First, Fig. 9A will be described. In Fig. 9A, the phase adjustment circuit 41A and / or 42A includes an inductor L1 and a switch S1.

[0145] In the phase adjustment circuit 41A, the inductor L1 is connected between a path P5 that connects the selection terminal 512A of the switch circuit 51A and the transmit filter 31 and ground. Specifically, in the phase adjustment circuit 41A, one end of the inductor L1 is connected to the path P5, and the other end of the inductor L1 is connected to ground via a switch S1. The switch S1 is connected between the inductor L1 and ground. Note that the switch S1 may also be connected between the inductor L1 and the path P5.

[0146] In the phase adjustment circuit 42A, the inductor L1 is connected between a path P6 that connects the selection terminal 513A of the switch circuit 51A and the transmit filter 32 and ground. Specifically, in the phase adjustment circuit 42A, one end of the inductor L1 is connected to the path P6, and the other end of the inductor L1 is connected to ground via a switch S1. The switch S1 is connected between the inductor L1 and ground. Note that the switch S1 may also be connected between the inductor L1 and the path P6.

[0147] Next, referring to Fig. 9B, the phase adjustment circuit 41A and / or 42A includes a capacitor C1 and a switch S1.

[0148] In the phase adjustment circuit 41A, the capacitor C1 is connected between ground and a path P5 that connects the selection terminal 512A of the switch circuit 51A and the transmit filter 31. Specifically, in the phase adjustment circuit 41A, one end of the capacitor C1 is connected to the path P5, and the other end of the capacitor C1 is connected to ground via a switch S1. The switch S1 is connected between the capacitor C1 and ground. Note that the switch S1 may also be connected between the capacitor C1 and the path P5.

[0149] In the phase adjustment circuit 42A, the capacitor C1 is connected between a path P6 that connects the selection terminal 513A of the switch circuit 51A and the transmit filter 32 and ground. Specifically, in the phase adjustment circuit 42A, one end of the capacitor C1 is connected to the path P6, and the other end of the capacitor C1 is connected to ground via a switch S1. The switch S1 is connected between the capacitor C1 and ground. Note that the switch S1 may also be connected between the capacitor C1 and the path P6.

[0150] [2.4 Communication Modes of High-Frequency Circuit 1A] Next, communication modes of the high-frequency circuit 1A corresponding to the bands used and the power classes applied to the bands will be described.

[0151] [2.4.1 First Communication Mode] First, the first communication mode of the high-frequency circuit 1A will be described with reference to Fig. 10. Fig. 10 is a circuit configuration diagram showing the first communication mode of the high-frequency circuit 1A according to this embodiment. Note that in Fig. 10 and the following figures, the phase adjustment circuit 41A of Fig. 9A is used as the phase adjustment circuit 41A, but the phase adjustment circuit 41A of Fig. 9B may also be used.

[0152] The first communication mode is a communication mode for transmitting signals in Band A at a first power class (e.g., Power Class 2). In the first communication mode, transmission of signals in the transmit band of Band A does not occur simultaneously with reception of signals in the receive band of Band A.

[0153] In the first communication mode, the switch circuit 51A connects the common terminal 511A to the selection terminal 512A but does not connect it to the selection terminal 514A. The switch circuit 52 connects the common terminal 521 to the selection terminal 522 but does not connect it to the selection terminal 523. The phase adjustment circuit 41A opens the switch S1. As a result, one end of the transmit filter 31 is connected to the antenna connection terminal 101, and the other end of the transmit filter 31 is connected to the power amplifier 11. Furthermore, the path P5 is not connected to ground via the inductor L1 or the capacitor C1 of the phase adjustment circuit 41A.

[0154] As a result, the band A transmission signal is transmitted from the RFIC 3 to the antenna 2 via the high frequency input terminal 111, the power amplifier 11, the switch circuit 52, the transmit filter 31, the path P5, the switch circuit 51A and the antenna connection terminal 101.

[0155] [2.4.2 Second Communication Mode] Next, the second communication mode of the high-frequency circuit 1A will be described with reference to Fig. 11. Fig. 11 is a circuit configuration diagram showing the second communication mode of the high-frequency circuit 1A according to this embodiment.

[0156] The second communication mode is a communication mode for transmitting and receiving signals in Band A at a second power class (e.g., power class 3). In the second communication mode, transmission of signals in the transmission band of Band A occurs simultaneously with reception of signals in the reception band of Band A.

[0157] In the second communication mode, the switch circuit 51A connects the common terminal 511A to the selection terminals 512A and 514A. The switch circuit 52 connects the common terminal 521 to the selection terminal 522 and does not connect it to the selection terminal 523. The phase adjustment circuit 41A closes the switch S1. As a result, one end of the transmit filter 31 is connected to the antenna connection terminal 101, and the other end of the transmit filter 31 is connected to the power amplifier 11. Furthermore, the path P5 is connected to ground via the inductor L1 or capacitor C1 of the phase adjustment circuit 41A, and the reflection phase when the transmit filter 31 is viewed from the common terminal 511A is adjusted by the phase adjustment circuit 41A.

[0158] As a result, the transmission signal of band A is transmitted from the RFIC 3 to the antenna 2 via the radio frequency input terminal 111, the power amplifier 11, the switch circuit 52, the transmission filter 31, the path P5, the switch circuit 51A, and the antenna connection terminal 101. The reception signal of band A is transmitted from the antenna 2 to the RFIC 3 via the antenna connection terminal 101, the switch circuit 51A, the reception filter 33, the low noise amplifier 21, and the radio frequency output terminal 121.

[0159] [2.4.3 Third Communication Mode] First, the third communication mode of the high-frequency circuit 1A will be described with reference to Fig. 12. Fig. 12 is a circuit configuration diagram showing the third communication mode of the high-frequency circuit 1A according to this embodiment.

[0160] The third communication mode is a communication mode for transmitting signals in Band B at a first power class (e.g., Power Class 2). In the third communication mode, transmission of signals in the transmission band of Band B does not occur simultaneously with reception of signals in the reception band of Band B.

[0161] In the third communication mode, the switch circuit 51A connects the common terminal 511A to the selection terminal 513A but does not connect it to the selection terminal 514A. The switch circuit 52 connects the common terminal 521 to the selection terminal 523 but does not connect it to the selection terminal 522. The phase adjustment circuit 42A opens the switch S1. As a result, one end of the transmit filter 32 is connected to the antenna connection terminal 101, and the other end of the transmit filter 32 is connected to the power amplifier 11. Furthermore, the path P6 is not connected to ground via the inductor L1 or the capacitor C1 of the phase adjustment circuit 42A.

[0162] As a result, the band B transmission signal is transmitted from the RFIC 3 to the antenna 2 via the high frequency input terminal 111, the power amplifier 11, the switch circuit 52, the transmit filter 32, the path P6, the switch circuit 51A and the antenna connection terminal 101.

[0163] [2.4.4 Fourth Communication Mode] Next, the fourth communication mode of the high-frequency circuit 1A will be described with reference to Fig. 13. Fig. 13 is a circuit configuration diagram showing the fourth communication mode of the high-frequency circuit 1A according to this embodiment.

[0164] The fourth communication mode is a communication mode for transmitting and receiving signals in Band B at a second power class (e.g., Power Class 3). In the fourth communication mode, transmission of signals in the transmission band of Band B is performed simultaneously with reception of signals in the reception band of Band B.

[0165] In the fourth communication mode, the switch circuit 51A connects the common terminal 511A to the selection terminals 513A and 514A. The switch circuit 52 connects the common terminal 521 to the selection terminal 523 and does not connect it to the selection terminal 522. The phase adjustment circuit 42A closes the switch S1. As a result, one end of the transmit filter 32 is connected to the antenna connection terminal 101, and the other end of the transmit filter 32 is connected to the power amplifier 11. Furthermore, the path P6 is connected to ground via the inductor L1 or capacitor C1 of the phase adjustment circuit 42A, and the reflection phase when the transmit filter 32 is viewed from the common terminal 511A is adjusted by the phase adjustment circuit 42A.

[0166] As a result, the transmission signal of band B is transmitted from the RFIC 3 to the antenna 2 via the radio frequency input terminal 111, the power amplifier 11, the switch circuit 52, the transmission filter 32, the path P6, the switch circuit 51A, and the antenna connection terminal 101. The reception signal of band B is transmitted from the antenna 2 to the RFIC 3 via the antenna connection terminal 101, the switch circuit 51A, the reception filter 34, the low noise amplifier 22, and the radio frequency output terminal 122.

[0167] [2.5 Summary] As described above, the high-frequency circuit 1A according to this embodiment includes the switch circuit 51A including the common terminal 511A connected to the antenna connection terminal 101 and the selection terminals 512A and 514A, the transmit filter 31 connected to the selection terminal 512A and having a pass band including the transmit band of band A, the receive filter 33 connected to the selection terminal 514A and having a pass band including the receive band of band A, the inductor L1 or capacitor C1 connected between the path P5 connecting the transmit filter 31 to the selection terminal 512A and ground, and the inductor L1 or capacitor C1. and a switch S1 connected between L1 or capacitor C1 and path P5 or ground, wherein when a first power class defined by a first maximum output power is applied to band A, switch circuit 51A connects common terminal 511A to selection terminal 512A and switch S1 is opened, and when a second power class defined by a second maximum output power lower than the first maximum output power is applied to band A, switch circuit 51A connects common terminal 511A to selection terminals 512A and 514A and switch S1 is closed.

[0168] According to this, in the first power class, the common terminal 511A is connected to the selection terminal 512A, and the switch S1 is opened. Therefore, the high-frequency circuit 1A can suppress an increase in loss in the transmission path due to the inductor L1 or the capacitor C1, and can reduce loss of the transmission signal in Band A. Meanwhile, in the second power class, the common terminal 511A is connected to the selection terminals 512A and 514A, and the switch S1 is closed. Therefore, the high-frequency circuit 1A can adjust the reflection phase of the reception band of Band A when viewed from the common terminal 511A toward the transmission filter 31, using the inductor L1 or the capacitor C1, and can suppress leakage of the reception signal in Band A into the transmission path. In this way, the high-frequency circuit 1A can reduce loss of the transmission signal when transmitting a signal in Band A in the first power class, and can suppress leakage of the reception signal when transmitting and receiving signals in Band A in the second power class.

[0169] (Other Embodiments) While the high-frequency circuit according to the present invention has been described above based on the embodiments, the high-frequency circuit according to the present invention is not limited to the above embodiments. The present invention also includes other embodiments realized by combining any of the components in the above embodiments, modifications obtained by applying various modifications to the above embodiments that would occur to those skilled in the art without departing from the spirit of the present invention, and various devices incorporating the above-mentioned high-frequency circuit.

[0170] For example, in the circuit configuration of the high-frequency circuit according to each of the above embodiments, other circuit elements, wiring, etc. may be inserted between the paths connecting the circuit elements and signal paths disclosed in the drawings. For example, an impedance matching circuit may be inserted between the filter and the switch circuit.

[0171] For example, the high-frequency circuits according to the above embodiments may further include one or more transmit filters and / or receive filters. In this case, the switch circuits 51 and 51A may further include one or more additional selection terminals to which the one or more transmit filters and / or receive filters are connected.

[0172] The features of the high-frequency circuits described based on the above embodiments will be described below.

[0173] <1> A first switch circuit including a first common terminal connected to an antenna connection terminal, and first, second, and third selection terminals; a first transmit filter connected to the first and second selection terminals and having a pass band including a transmit band of a first FDD band; a first receive filter connected to the third selection terminal and having a pass band including a receive band of the first FDD band; a first path connecting the first transmit filter to the first selection terminal; and a second path connecting the first transmit filter to the second selection terminal, wherein a first reflection phase of the receive band of the first FDD band when the first transmit filter is viewed from the first common terminal via the first path in a state where the first common terminal is connected to the first selection terminal differs from a second reflection phase of the receive band of the first FDD band when the first transmit filter is viewed from the first common terminal via the second path in a state where the first common terminal is connected to the second selection terminal, a phase variation between the first common terminal and the first transmit filter connected via the first path in a transmission band of the first FDD band is smaller than a phase variation between the first common terminal and the first transmit filter connected via the second path.

[0174] <2> The high-frequency circuit according to <1>, wherein the second reflection phase is closer to 0 degrees than the first reflection phase.

[0175] <3> The radio frequency circuit according to <1> or <2>, wherein, when a first power class defined by a first maximum output power is applied to the first FDD band, the first switch circuit connects the first common terminal to the first selection terminal, and when a second power class defined by a second maximum output power lower than the first maximum output power is applied to the first FDD band, the first switch circuit connects the first common terminal to the second selection terminal and the third selection terminal.

[0176] <4> The radio frequency circuit according to any one of <1> to <3>, wherein the first FDD band is Band 1 or Band 3 for LTE, or n1 or n3 for 5G NR.

[0177] <5> The high-frequency circuit according to any one of <1> to <4>, further comprising a power amplifier connected to the first transmission filter.

[0178] <6> The radio frequency circuit according to any one of <1> to <4>, further comprising a second reception filter connected to the third selection terminal and having a pass band including a reception band of a second FDD band.

[0179] <7> The high-frequency circuit according to <6>, wherein the first switch circuit further includes a fourth selection terminal and a fifth selection terminal, and the high-frequency circuit further includes: a second transmit filter connected to the fourth selection terminal and the fifth selection terminal and having a passband including a transmit band of the second FDD band; a third path connecting the second transmit filter to the fourth selection terminal; and a fourth path connecting the second transmit filter to the fifth selection terminal, wherein a third reflection phase of the receive band of the second FDD band when the second transmit filter is viewed from the first common terminal via the third path in a state where the first common terminal is connected to the fourth selection terminal is different from a fourth reflection phase of the receive band of the second FDD band when the second transmit filter is viewed from the first common terminal via the fourth path in a state where the first common terminal is connected to the fifth selection terminal.

[0180] <8> The high-frequency circuit according to <7>, wherein, in a transmission band of the first FDD band, a phase variation between the first common terminal and the second transmission filter connected via the third path is smaller than a phase variation between the first common terminal and the second transmission filter connected via the fourth path.

[0181] <9> The high-frequency circuit according to <7> or <8>, wherein the fourth reflection phase is closer to 0 degrees than the third reflection phase.

[0182] <10> The radio frequency circuit according to any one of <7> to <9>, wherein when a first power class defined by a first maximum output power is applied to the second FDD band, the first switch circuit connects the first common terminal to the fourth selection terminal, and when a second power class defined by a second maximum output power lower than the first maximum output power is applied to the second FDD band, the first switch circuit connects the first common terminal to the third selection terminal and the fifth selection terminal.

[0183] <11> The radio frequency circuit according to any one of <7> to <10>, wherein the combination of the first FDD band and the second FDD band is a combination of Band1 for LTE or n1 for 5G NR and Band3 for LTE or n3 for 5G NR.

[0184] <12> The high-frequency circuit according to any one of <7> to <11>, wherein the first transmit filter is a bulk acoustic wave filter, and the second transmit filter is a surface acoustic wave filter.

[0185] <13> The radio frequency circuit according to any one of <7> to <12>, further comprising: a power amplifier; and a second switch circuit including a second common terminal connected to the power amplifier, a sixth selection terminal connected to the first transmit filter, and a seventh selection terminal connected to the second transmit filter.

[0186] <14> A high-frequency circuit comprising: a first switch circuit including a first common terminal connected to an antenna connection terminal, and a first selection terminal, a second selection terminal, and a third selection terminal; a first transmit filter connected to the first selection terminal and the second selection terminal and having a pass band including a transmit band of a first FDD band; a first receive filter connected to the third selection terminal and having a pass band including a receive band of the first FDD band; and a surface-mount inductor or a surface-mount capacitor connected between the second selection terminal and the first transmit filter, wherein no surface-mount inductor or surface-mount capacitor is connected between the first selection terminal and the first transmit filter.

[0187] <15> A radio frequency circuit comprising: a first switch circuit including a first common terminal connected to an antenna connection terminal, and a first selection terminal and a second selection terminal; a first transmission filter connected to the first selection terminal and having a pass band including a transmission band of a first FDD band; a first reception filter connected to the second selection terminal and having a pass band including a reception band of the first FDD band; an inductor or a capacitor connected between a path connecting the first transmission filter to the first selection terminal and ground; and a switch connected between the inductor or the capacitor and the path or ground, wherein, when a first power class defined by a first maximum output power is applied to the first FDD band, the first switch circuit connects the first common terminal to the first selection terminal and the switch is opened; and when a second power class defined by a second maximum output power lower than the first maximum output power is applied to the first FDD band, the first switch circuit connects the first common terminal to the first selection terminal and the second selection terminal and the switch is closed.

[0188] The present invention can be widely used as a high-frequency circuit disposed in the front end of communication devices such as mobile phones.

[0189] REFERENCE SIGNS LIST 1, 1A High frequency circuit 2 Antenna 3 RFIC 4 BBIC 5, 5A Communication device 11 Power amplifier 21, 22 Low noise amplifier 31, 32 Transmit filter 33, 34 Receiving filter 41, 41A, 42, 42A Phase adjustment circuit 51, 51A, 52 Switch circuit 101 Antenna connection terminal 111 High frequency input terminal 121, 122 High frequency output terminal 511, 511A, 521 Common terminal 512, 512A, 513, 513A, 514, 514A, 515, 516, 522, 523 Selection terminal C1, C2 Capacitor L1, L2 Inductor P1, P2, P3, P4, P5, P6 Path S1 Switch

Claims

1. A first switch circuit including a first common terminal connected to an antenna connection terminal, and a first selection terminal, a second selection terminal, and a third selection terminal; a first transmission filter connected to the first selection terminal and the second selection terminal and having a pass band including a transmission band of a first FDD band; a first reception filter connected to the third selection terminal and having a pass band including a reception band of the first FDD band; a first path connecting the first transmission filter to the first selection terminal; and a second path connecting the first transmission filter to the second selection terminal, wherein a first reflection phase of the reception band of the first FDD band when the first transmission filter is viewed from the first common terminal via the first path in a state in which the first common terminal is connected to the first selection terminal is different from a second reflection phase of the reception band of the first FDD band when the first transmission filter is viewed from the first common terminal via the second path in a state in which the first common terminal is connected to the second selection terminal, a phase variation between the first common terminal and the first transmission filter connected via the first path in a transmission band of the first FDD band is smaller than a phase variation between the first common terminal and the first transmission filter connected via the second path.

2. The high-frequency circuit according to claim 1, wherein the second reflection phase is closer to 0 degrees than the first reflection phase.

3. The radio frequency circuit according to claim 1 or 2, wherein, when a first power class defined by a first maximum output power is applied to the first FDD band, the first switch circuit connects the first common terminal to the first selection terminal, and when a second power class defined by a second maximum output power lower than the first maximum output power is applied to the first FDD band, the first switch circuit connects the first common terminal to the second selection terminal and the third selection terminal.

4. The high-frequency circuit according to any one of claims 1 to 3, wherein the first FDD band is Band 1 or Band 3 for LTE, or n1 or n3 for 5G NR.

5. The high frequency circuit according to any one of claims 1 to 4, further comprising a power amplifier connected to the first transmission filter.

6. The high frequency circuit according to any one of claims 1 to 4, further comprising a second receive filter connected to the third selection terminal and having a pass band including a receive band of the second FDD band.

7. The radio frequency circuit according to claim 6, wherein the first switch circuit further comprises a fourth selection terminal and a fifth selection terminal; and the radio frequency circuit further comprises: a second transmission filter connected to the fourth selection terminal and the fifth selection terminal and having a pass band including the transmission band of the second FDD band; a third path connecting the second transmission filter to the fourth selection terminal; and a fourth path connecting the second transmission filter to the fifth selection terminal; and a third reflection phase of the reception band of the second FDD band when the second transmission filter is viewed from the first common terminal via the third path in a state in which the first common terminal is connected to the fourth selection terminal is different from a fourth reflection phase of the reception band of the second FDD band when the second transmission filter is viewed from the first common terminal via the fourth path in a state in which the first common terminal is connected to the fifth selection terminal.

8. The high-frequency circuit according to claim 7, wherein, in the transmission band of the first FDD band, the amount of phase variation between the first common terminal and the second transmission filter connected via the third path is smaller than the amount of phase variation between the first common terminal and the second transmission filter connected via the fourth path.

9. The high-frequency circuit according to claim 7 or 8, wherein the fourth reflection phase is closer to 0 degrees than the third reflection phase.

10. The radio frequency circuit according to any one of claims 7 to 9, wherein when a first power class defined by a first maximum output power is applied to the second FDD band, the first switch circuit connects the first common terminal to the fourth selection terminal, and when a second power class defined by a second maximum output power lower than the first maximum output power is applied to the second FDD band, the first switch circuit connects the first common terminal to the third selection terminal and the fifth selection terminal.

11. The radio frequency circuit according to any one of claims 7 to 10, wherein a combination of the first FDD band and the second FDD band is a combination of Band1 for LTE or n1 for 5G NR and Band3 for LTE or n3 for 5G NR.

12. The high-frequency circuit according to any one of claims 7 to 11, wherein the first transmit filter is a bulk acoustic wave filter, and the second transmit filter is a surface acoustic wave filter.

13. The radio frequency circuit according to any one of claims 7 to 12, further comprising: a power amplifier; and a second switch circuit including a second common terminal connected to the power amplifier, a sixth selection terminal connected to the first transmit filter, and a seventh selection terminal connected to the second transmit filter.

14. A high-frequency circuit comprising: a first switch circuit including a first common terminal connected to an antenna connection terminal, and a first selection terminal, a second selection terminal, and a third selection terminal; a first transmission filter connected to the first selection terminal and the second selection terminal and having a pass band including a transmission band of a first FDD band; a first reception filter connected to the third selection terminal and having a pass band including a reception band of the first FDD band; and a surface-mounted inductor or a surface-mounted capacitor connected between the second selection terminal and the first transmission filter, wherein no surface-mounted inductor or surface-mounted capacitor is connected between the first selection terminal and the first transmission filter.

15. A radio frequency circuit comprising: a first switch circuit including a first common terminal connected to an antenna connection terminal, and a first selection terminal and a second selection terminal; a first transmission filter connected to the first selection terminal and having a pass band including a transmission band of a first FDD band; a first reception filter connected to the second selection terminal and having a pass band including a reception band of the first FDD band; an inductor or a capacitor connected between a path connecting the first transmission filter to the first selection terminal and ground; and a switch connected between the inductor or the capacitor and the path or ground, wherein when a first power class defined by a first maximum output power is applied to the first FDD band, the first switch circuit connects the first common terminal to the first selection terminal and the switch is opened, and when a second power class defined by a second maximum output power lower than the first maximum output power is applied to the first FDD band, the first switch circuit connects the first common terminal to the first selection terminal and the second selection terminal and the switch is closed.

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