High-frequency circuit

Abstract

This high-frequency circuit (1) comprises: a high-frequency input terminal (110) and an antenna connection terminal (100); power amplifiers (11 and 12); an orthogonal hybrid circuit (13) including an input terminal (131) connected to the high-frequency input terminal (110), an output terminal (132) connected to an input end of the power amplifier (11), and an output terminal (133) connected to an input end of the power amplifier (12); a synthesis circuit (14) including an input terminal (141) connected to an output end of the power amplifier (11), an input terminal (142) connected to an output end of the power amplifier (12), and an output terminal (143) connected to the antenna connection terminal (100); and a PA control circuit (60) having a first mode for operating the power amplifiers (11 and 12) and a second mode for selectively switching and operating the power amplifiers (11 and 12).

Description

High-frequency circuit

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

[0002] In Patent Document 1, a high-frequency signal is amplified by two power amplifiers in the high-power class, and the high-frequency signal is amplified by only one of the two power amplifiers in the non-high-power class, so that a small-sized high-frequency circuit capable of coping with a wide range of power classes is disclosed.

[0003] International Publication No. 2022 / 138001

[0004] However, in the above prior art, when the high-frequency signal is amplified by only one of the two power amplifiers, the power efficiency (power-added efficiency) may decrease due to load fluctuations.

[0005] Therefore, the present invention provides a high-frequency circuit capable of suppressing a decrease in power efficiency due to load fluctuations.

[0006] The high-frequency circuit according to one aspect of the present invention includes a high-frequency input terminal and an antenna connection terminal, a first power amplifier and a second power amplifier, a first input terminal connected to the high-frequency input terminal, a first output terminal connected to the input end of the first power amplifier, and a quadrature hybrid circuit including a second output terminal connected to the input end of the second power amplifier, a second input terminal connected to the output end of the first power amplifier, a third input terminal connected to the output end of the second power amplifier, and a third output terminal connected to the antenna connection terminal, and a first mode for operating the first power amplifier and the second power amplifier and a PA control circuit having a second mode for selectively switching and operating the first power amplifier and the second power amplifier.

[0007] According to the present invention, a decrease in power efficiency due to load fluctuations can be suppressed.

[0008] Figure 1 is a circuit diagram of a communication device according to Embodiment 1. Figure 2 is a diagram illustrating the first mode of the high-frequency circuit according to Embodiment 1. Figure 3 is a diagram illustrating the first connection state of the second mode of the high-frequency circuit according to Embodiment 1. Figure 4 is a diagram illustrating the second connection state of the second mode of the high-frequency circuit according to Embodiment 1. Figure 5 is a graph illustrating the switching between the first and second connection states in the second mode of the high-frequency circuit according to Embodiment 1. Figure 6 is a circuit diagram of a power amplifier circuit according to Modification 1 of Embodiment 1. Figure 7 is a circuit diagram of a power amplifier circuit according to Modification 2 of Embodiment 1. Figure 8 is a circuit diagram of a power amplifier circuit according to Modification 3 of Embodiment 1. Figure 9 is a circuit diagram of a communication device according to Modification 4 of Embodiment 1. Figure 10 is a circuit diagram of a power amplifier circuit according to Modification 5 of Embodiment 1. Figure 11 is a circuit diagram of a power amplifier circuit according to Modification 6 of Embodiment 1. Figure 12 is a circuit diagram of a power amplifier circuit according to Modification 7 of Embodiment 1. Figure 13 is a circuit diagram of a communication device according to Embodiment 2.

[0009] The embodiments of the present invention will be described in detail below with reference to the drawings. Note that the embodiments described below are all general or specific examples. The numerical values, shapes, materials, components, arrangement of components, and connection configurations shown in the following embodiments are examples only and are not intended to limit the present invention.

[0010] The figures are schematic diagrams that have been appropriately emphasized, omitted, or had their proportions adjusted to illustrate the present invention, and are not necessarily strictly accurate representations. Actual shapes, positional relationships, and proportions may differ. In each figure, substantially identical components are denoted by the same reference numerals, and redundant explanations may be omitted or simplified.

[0011] In the following explanation, "connected" includes not only cases where there is a direct connection via terminals and / or wiring conductors, but also cases where there is an electrical connection via other circuit elements. "C is connected between A and B" means that one end of C is connected to A and the other end of C is connected to B, and that C is arranged in series in the path between A and B. "Path between A and B" means a path consisting of conductors that electrically connect A to B.

[0012] "A is switchably connected to B" means that the connection and disconnection between A and B can be switched, and that A is connected to B via a switch. Note that "A is connected to B" includes "A is switchably connected to B".

[0013] A "terminal" refers to the point where a conductor within a circuit element ends. However, if the impedance of the conductors between circuit elements is sufficiently low, a terminal can be interpreted not only as a single point, but as any point on the conductor between circuit elements, or even the entire conductor.

[0014] A "node" refers to a point between circuit elements. However, if the impedance of the conductors between circuit elements is sufficiently low, a node can be interpreted not only as a single point, but as any point on the conductor between circuit elements, or even the entire conductor.

[0015] "Transmitting band" refers to the frequency band used for transmission in a communication device. "Receiving band" refers to the frequency band used for reception in a communication device. For example, in a frequency division duplex (FDD) band, different frequency bands (e.g., uplink band and downlink band) are used as the transmitting band and the receiving band. Also, for example, in a time division duplex (TDD) band, the same frequency band is used for both the transmitting and receiving bands.

[0016] "Power amplifier operating" means that the power amplifier is controlled to be in the ON state (i.e., in a state where the power amplifier can amplify high-frequency signals). Specifically, "power amplifier operating" means that the power amplifier is supplied with bias current and / or power supply voltage, causing it to amplify high-frequency signals. The ON / OFF state of the power amplifier can be controlled by supplying / not supplying bias current and / or power supply voltage.

[0017] "Power class" is a classification of the output power of user equipment (UE), defined by its maximum output power. A lower power class value indicates a higher maximum output power that is permitted. For example, the 3GPP (registered trademark) (3rd Generation Partnership Project) defines power classes 1, 1.5, 2, and 3. Specifically, power class 1 is defined as having a maximum output power of 31 dBm. Power class 1.5 is defined as having a maximum output power of 29 dBm. Power class 2 is defined as having a maximum output power of 26 dBm. Power class 3 is defined as having a maximum output power of 23 dBm.

[0018] The maximum output power of the UE is defined as the maximum output power at the antenna terminal. The output power of the UE is measured using methods defined by 3GPP, etc. For example, the output power is measured by measuring the radiated power at the antenna. Alternatively, instead of measuring the radiated power, the output power of the antenna can be measured by providing a terminal near the antenna and connecting a measuring instrument (such as a spectrum analyzer) to that terminal.

[0019] Terms indicating the relationship between elements, such as "parallel" and "perpendicular," and terms indicating the shape of elements, such as "straight line," as well as numerical ranges, do not represent only strict meanings but also include substantially equivalent ranges, such as errors of a few percent.

[0020] (Embodiment 1) Embodiment 1 will be described below.

[0021] [1.1. Circuit Configuration of Communication Device 5] Figure 1 is a circuit diagram of the communication device 5 according to this embodiment. Note that Figure 1 is an illustrative circuit diagram, and the communication device 5 can be implemented using any of the many different circuit implementations and circuit technologies. Therefore, the description of the communication device 5 provided below should not be interpreted as limiting.

[0022] The communication device 5 according to this embodiment can be used to provide wireless connectivity. For example, the communication device 5 can be implemented in a UE (User Interface) in a cellular network such as a mobile phone, smartphone, tablet computer, or wearable device. In another example, by implementing the communication device 5, wireless connectivity can be provided to IoT (Internet of Things) sensor devices, medical / healthcare devices, cars, unmanned aerial vehicles (UAVs) (so-called drones), and automated guided vehicles (AGVs). In yet another example, by implementing the communication device 5, wireless connectivity can also be provided in a wireless access point or wireless hotspot.

[0023] The communication device 5 comprises a high-frequency circuit 1, an antenna 2, an RFIC (Radio Frequency Integrated Circuit) 3, and a BBIC (Baseband Integrated Circuit) 4.

[0024] The high-frequency circuit 1 is connected between the antenna 2 and the RFIC 3. The high-frequency circuit 1 can transmit high-frequency signals between the antenna 2 and the RFIC 3. Details of the circuit configuration of the high-frequency circuit 1 will be described later.

[0025] Antenna 2 is connected to the high-frequency circuit 1. Antenna 2 can receive high-frequency signals from the high-frequency circuit 1 and transmit them to the outside of the communication device 5. Furthermore, antenna 2 may receive high-frequency signals from outside the communication device 5 and supply them to the high-frequency circuit 1. Note that antenna 2 does not have to be included in the communication device 5. In addition, the communication device 5 may have one or more antennas in addition to antenna 2.

[0026] RFIC3 is an example of a signal processing circuit that processes high-frequency signals. Specifically, RFIC3 processes the transmission signal input from BBIC4 by upconversion or the like, and outputs the high-frequency transmission signal generated by this signal processing to high-frequency circuit 1. Furthermore, RFIC3 may also process the high-frequency received signal input via the receiving path of high-frequency circuit 1 by downconversion or the like, and output the received signal generated by this signal processing to BBIC4. RFIC3 may also have a control unit that controls switches and power amplifiers, etc., of high-frequency circuit 1. Note that some or all of the control unit functions of RFIC3 may be included outside of RFIC3, for example, in BBIC4 and / or high-frequency circuit 1.

[0027] BBIC4 is a baseband signal processing circuit that processes signals using a frequency band lower than the high-frequency signal transmitted by the high-frequency circuit 1. Examples of signals processed by BBIC4 include image signals for image display and / or audio signals for communication via a speaker. Note that some or all of BBIC4 may not be included in the communication device 5.

[0028] [1.2. Circuit Configuration of High-Frequency Circuit 1] Next, the circuit configuration of high-frequency circuit 1 will be described with reference to Figure 1. Note that Figure 1 is an illustrative circuit configuration diagram, and high-frequency circuit 1 can be implemented using any of the many different circuit implementations and circuit technologies. Therefore, the description of high-frequency circuit 1 provided below should not be interpreted as restrictive.

[0029] The high-frequency circuit 1 includes a power amplifier circuit 10, matching circuits 21, 22 and 23, switch circuits 31 and 32, filters 41 and 42, a coupler 51, a PA control circuit 60, an antenna connection terminal 100, a high-frequency input terminal 110, a control terminal 120, and a power supply voltage terminal 130.

[0030] The antenna connection terminal 100 is an external connection terminal of the high-frequency circuit 1. The antenna connection terminal 100 is connected to the antenna 2 outside the high-frequency circuit 1 and to the coupler 51 inside the high-frequency circuit 1.

[0031] The high-frequency input terminal 110 is an external connection terminal of the high-frequency circuit 1 and is a terminal that receives high-frequency signals from the RFIC 3. The high-frequency input terminal 110 is connected to the RFIC 3 outside the high-frequency circuit 1 and to the power amplification circuit 10 inside the high-frequency circuit 1.

[0032] The control terminal 120 is an external connection terminal of the high-frequency circuit 1 and is a terminal that receives control signals from the RFIC 3. The control terminal 120 is connected to the RFIC 3 outside the high-frequency circuit 1 and to the PA control circuit 60 inside the high-frequency circuit 1.

[0033] The power supply voltage terminal 130 is an external connection terminal of the high-frequency circuit 1 and receives a power supply voltage (Vcc) from a power supply (not shown). The power supply voltage terminal 130 is connected to the power supply outside the high-frequency circuit 1 and connected to the power amplification circuit 10 inside the high-frequency circuit 1.

[0034] The power amplifier circuit 10 is connected between the high-frequency input terminal 110 and the matching circuit 21, and further connected to the power supply voltage terminal 130. The power amplifier circuit 10 can amplify the high-frequency signal supplied from the RFIC 3. Details of the circuit configuration of the power amplifier circuit 10 will be described later.

[0035] The matching circuit (matching network) 21 (MN) is connected between the power amplifier circuit 10 and the switch circuit 31, and can achieve impedance matching between the power amplifier circuit 10 and the switch circuit 31. The matching circuit 21 includes, for example, an inductor and / or a capacitor. Note that the matching circuit 21 does not necessarily have to be included in the high-frequency circuit 1.

[0036] The matching circuit (matching network) 22 (MN) is connected between the filter 41 and the switch circuit 32, and can achieve impedance matching between the filter 41 and the switch circuit 32. The matching circuit 22 includes, for example, an inductor and / or a capacitor. Note that the matching circuit 22 does not necessarily have to be included in the high-frequency circuit 1.

[0037] The matching circuit (matching network) 23 (MN) is connected between the filter 42 and the switch circuit 32, and can achieve impedance matching between the filter 42 and the switch circuit 32. The matching circuit 23 includes, for example, an inductor and / or a capacitor. Note that the matching circuit 23 does not necessarily have to be included in the high-frequency circuit 1.

[0038] The switch circuit 31 is connected between the power amplifier circuit 10 and filters 41 and 42. The switch circuit 31 includes a common terminal 310 and select terminals 311 and 312. The common terminal 310 is connected to the power amplifier circuit 10 via the matching circuit 21. The select terminal 311 is connected to filter 41. The select terminal 312 is connected to filter 42. Note that the switch circuit 31 does not necessarily have to be included in the high-frequency circuit 1.

[0039] In this connection configuration, the switch circuit 31 can selectively connect the common terminal 310 to the selection terminals 311 and 312 based on a control signal from, for example, the RFIC 3 or the PA control circuit 60. In other words, the switch circuit 31 can switch the connection of the power amplifier circuit 10 between filters 41 and 42. Such a switch circuit 31 is composed of, for example, an SPDT (Single-Pole Double-Throw) type switch circuit.

[0040] The switch circuit 32 is connected between filters 41 and 42 and the antenna connection terminal 100. The switch circuit 32 includes a common terminal 320 and select terminals 321 and 322. The common terminal 320 is connected to the antenna connection terminal 100 via a coupler 51. The select terminal 321 is connected to filter 41 via a matching circuit 22. The select terminal 322 is connected to filter 42 via a matching circuit 23. Note that the switch circuit 32 does not necessarily have to be included in the high-frequency circuit 1.

[0041] In such a connection configuration, the switch circuit 32 can selectively connect the common terminal 320 to the selection terminals 321 and 322, for example, based on a control signal from the RFIC 3 or the PA control circuit 60. That is, the switch circuit 32 can switch the connection of the antenna connection terminal 100 between the filters 41 and 42. Such a switch circuit 32 is composed of, for example, a SPDT type switch circuit.

[0042] The switch circuits 31 and 32 can be mounted on a semiconductor integrated circuit. As the semiconductor material of the semiconductor integrated circuit, for example, single crystal silicon (Si), gallium nitride (GaN), or silicon carbide (SiC) can be used. At this time, some or all of the switch circuits 31 and 32 can be composed of field effect transistors (FETs: Field Effect Transistors). Note that bipolar transistors may be used instead of FETs. Also, the switch circuits 31 and 32 may be divided and mounted on a plurality of semiconductor integrated circuits.

[0043] The filter 41 is a bandpass filter having a passband including the transmission band of band A. The filter 41 is connected between the switch circuits 31 and 32. Specifically, one end of the filter 41 is connected to the selection terminal 311 of the switch circuit 31, and the other end of the filter 41 is connected to the selection terminal 321 of the switch circuit 32 via the matching circuit 22.

[0044] The filter 42 is a bandpass filter having a passband including the transmission band of band B. The filter 42 is connected between the switch circuits 31 and 32. Specifically, one end of the filter 42 is connected to the selection terminal 312 of the switch circuit 31, and the other end of the filter 42 is connected to the selection terminal 322 of the switch circuit 32 via the matching circuit 23.

[0045] For the filters 41 and 42, surface acoustic wave (SAW: Surface Acoustic Wave) filters, bulk acoustic wave (BAW: Bulk Acoustic Wave) filters, LC filters, dielectric filters, or any combination thereof may be used, and furthermore, they are not limited thereto.

[0046] Note that the filters 41 and / or 42 are not limited to band-pass filters. Part or all of the filters 41 and 42 may be band-elimination filters, or may be high-pass filters or low-pass filters. Also, the filters 41 and / or 42 may not be included in the high-frequency circuit 1.

[0047] Also, the high-frequency circuit 1 may further include an additional filter. For example, the high-frequency circuit 1 may include an additional filter connected between the switch circuits 31 and 32.

[0048] Bands A and B are frequency bands for a communication system constructed using a radio access technology (RAT: Radio Access Technology), and are predefined by a standardization organization or the like (e.g., 3GPP and IEEE (Institute of Electrical and Electronics Engineers), etc.). Examples of communication systems include 5GNR (5th Generation New Radio) systems, LTE (Long Term Evolution) systems, and WLAN (Wireless Local Area Network) systems.

[0049] The coupler 51 is a bi-directional coupler connected between the switch circuit 32 and the antenna connection terminal 100, and can feedback a part of the high-frequency signal transmitted between the switch circuit 32 and the antenna connection terminal 100 to the PA control circuit 60. The coupler 51 includes a main line 511 and a sub-line 512. One end of the main line 511 is connected to the common terminal 320 of the switch circuit 32, and the other end of the main line 511 is connected to the antenna connection terminal 100. One end and the other end of the sub-line 512 are connected to the PA control circuit 60. The coupler 51 can terminate one end of both ends of the sub-line 512 and extract a signal from the other end of both ends of the sub-line 512. Note that the configuration of the coupler 51 does not need to be particularly limited and is not limited to a bi-directional coupler.

[0050] The PA control circuit 60 can control the power amplifier circuit 10 based on the phase of the load impedance. Specifically, the PA control circuit 60 has a first mode in which power amplifiers 11 and 12 are operated, and a second mode in which power amplifiers 11 and 12 are selectively switched and operated. In this embodiment, in the second mode, the PA control circuit 60 can selectively switch and operate power amplifiers 11 and 12 based on the phase of the load impedance.

[0051] The phase of the load impedance is indicated by the output signal of the coupler 51. For example, the phase of the load impedance is determined from the bidirectional (forward and backward) feedback signals from the coupler 51. Therefore, in the second mode, the PA control circuit 60 may selectively switch between operating the power amplifiers 11 and 12 based on the output signal of the coupler 51.

[0052] [1.3. Circuit Configuration of Power Amplifier Circuit 10] Next, the circuit configuration of the power amplifier circuit 10 will be described with reference to Figure 1. Note that Figure 1 is an illustrative circuit configuration diagram, and the power amplifier circuit 10 can be implemented using any of the many different circuit implementations and circuit technologies. Therefore, the description of the power amplifier circuit 10 provided below should not be interpreted as restrictive.

[0053] The power amplification circuit 10 includes power amplifiers 11 and 12, an orthogonal hybrid circuit 13, a combining circuit 14, a low-pass filter 151, a high-pass filter 152, inductors 161 and 162, and a capacitor 163.

[0054] The orthogonal hybrid circuit 13, also known as a 90-degree hybrid coupler, can distribute a high-frequency signal (RFin) supplied from the RFIC 3 via the high-frequency input terminal 110 into two high-frequency signals with a 90-degree phase difference and supply them to power amplifiers 11 and 12, respectively. Specifically, the orthogonal hybrid circuit 13 includes an input terminal 131 and output terminals 132 and 133. Input terminal 131 is an example of a first input terminal and is connected to the high-frequency input terminal 110. Output terminal 132 is an example of a first output terminal and is connected to the input terminal of power amplifier 11. Output terminal 133 is an example of a second output terminal and is connected to the input terminal of power amplifier 12.

[0055] Power amplifier 11 is an example of a first power amplifier and is connected between the quadrature hybrid circuit 13 and the low-pass filter 151. Specifically, the input terminal of power amplifier 11 is connected to the output terminal 132 of the quadrature hybrid circuit 13, and the output terminal of power amplifier 11 is connected to the low-pass filter 151. When power amplifiers 11 and 12 are operating together, power amplifier 11 can amplify high-frequency signals with a phase lead of 45 degrees relative to it.

[0056] Power amplifier 12 is an example of a second power amplifier and is connected between the quadrature hybrid circuit 13 and the high-pass filter 152. Specifically, the input terminal of power amplifier 12 is connected to the output terminal 133 of the quadrature hybrid circuit 13, and the output terminal of power amplifier 12 is connected to the high-pass filter 152. When power amplifiers 11 and 12 are operating together, power amplifier 12 can amplify high-frequency signals with a phase lag of 45 degrees relative to each other.

[0057] Power amplifiers 11 and 12 can be composed of heterojunction bipolar transistors (HBTs) and can be manufactured using semiconductor materials. Examples of semiconductor materials include silicon germanium (SiGe) or gallium arsenide (GaAs). However, the amplification transistors of power amplifiers 11 and 12 are not limited to HBTs. For example, power amplifiers 11 and 12 may be composed of HEMTs (High Electron Mobility Transistors) or MESFETs (Metal-Semiconductor Field Effect Transistors). In this case, gallium nitride (GaN) or silicon carbide (SiC) may be used as the semiconductor material. Furthermore, some or all of the amplification transistors of power amplifiers 11 and 12 may be composed of CMOS (Complementary Metal Oxide Semiconductors) and may be manufactured by an SOI (Silicon on Insulator) process. In this case, silicon single crystal (Si) may be used as the semiconductor material.

[0058] The low-pass filter 151 is connected between the power amplifier 11 and the combining circuit 14. Specifically, one end of the low-pass filter 151 is connected to the output terminal of the power amplifier 11, and the other end of the low-pass filter 151 is connected to the input terminal 141 of the combining circuit 14. The low-pass filter 151 can advance the phase of the high-frequency signal amplified by the power amplifier 11 by 45 degrees. The low-pass filter 151 includes, for example, an inductor and / or a capacitor.

[0059] The high-pass filter 152 is connected between the power amplifier 12 and the combining circuit 14. Specifically, one end of the high-pass filter 152 is connected to the output terminal of the power amplifier 12, and the other end of the high-pass filter 152 is connected to the input terminal 142 of the combining circuit 14. The high-pass filter 152 can delay the phase of the high-frequency signal amplified by the power amplifier 12 by 45 degrees. The high-pass filter 152 includes, for example, an inductor and / or a capacitor.

[0060] The combining circuit 14 can combine two in-phase high-frequency signals that have passed through a low-pass filter 151 and a high-pass filter 152, respectively, and supply the combined high-frequency signal (RFout) to filters 41 and 42. Specifically, the combining circuit 14 includes input terminals 141 and 142 and an output terminal 143. Input terminal 141 is an example of a second input terminal and is connected to the output terminal of the power amplifier 11 via the low-pass filter 151. Input terminal 142 is an example of a third input terminal and is connected to the output terminal of the power amplifier 12 via the high-pass filter 152. Output terminal 143 is an example of a third output terminal and is switchably connected to filters 41 and 42 via a matching circuit 21 and a switching circuit 31.

[0061] Inductor 161 is a so-called choke inductor and is connected between the power supply voltage terminal 130 and the output terminal of the power amplifier 11. Specifically, one end of inductor 161 is connected to the power supply voltage terminal 130, and the other end of inductor 161 is connected to the output terminal (e.g., collector terminal) of the power amplifier 11. As a result, the power supply voltage (Vcc) is supplied to the power amplifier 11 via inductor 161. Note that inductor 161 does not necessarily have to be included in the power amplification circuit 10.

[0062] Inductor 162 is a so-called choke inductor and is connected between the power supply voltage terminal 130 and the output terminal of the power amplifier 12. Specifically, one end of inductor 162 is connected to the power supply voltage terminal 130, and the other end of inductor 162 is connected to the output terminal (e.g., collector terminal) of the power amplifier 12. As a result, the power supply voltage (Vcc) is supplied to the power amplifier 12 via inductor 162. Note that inductor 162 does not necessarily have to be included in the power amplification circuit 10.

[0063] Capacitor 163 is a so-called bypass capacitor and is connected between the path between the power supply voltage terminal 130 and the power amplifier 11 and ground, and between the path between the power supply voltage terminal 130 and the power amplifier 12 and ground. Specifically, one of the two electrodes of capacitor 163 is connected to the path between the power supply voltage terminal 130 and inductors 161 and 162, and the other of the two electrodes of capacitor 163 is connected to ground. Note that capacitor 163 does not necessarily have to be included in the power amplifier circuit 10.

[0064] The inductors and / or capacitors included in the low-pass filters 151 and 152, as well as inductors 161 and 162 and capacitor 163, may be implemented as chip inductors and chip capacitors. Chip inductors and chip capacitors refer to surface mount devices (SMDs) that constitute the inductors and capacitors, respectively. These inductors and capacitors are not limited to chip capacitors and chip inductors. For example, the implementation of these inductors and capacitors may involve wiring on a module board, or integrated passive devices (IPDs).

[0065] The power amplification circuit 10 may also include a coupler connected between the power amplifier 11 and the low-pass filter 151, and a coupler connected between the power amplifier 12 and the high-pass filter 152. In this case, the coupler 51 does not need to be included in the high-frequency circuit 1.

[0066] [1.4. Multiple Communication Modes] Next, the multiple communication modes of the high-frequency circuit 1 according to this embodiment will be described.

[0067] [1.4.1. First Mode] First, the first mode, which is included in the multiple communication modes of the high-frequency circuit 1, will be explained with reference to Figure 2. Figure 2 is a diagram showing the first mode of the high-frequency circuit 1 according to this embodiment. In Figure 2, dashed arrows represent signal paths.

[0068] The first mode is a communication mode for transmitting Band A signals in power class 2. Power class 2 is an example of a first power class defined by a higher maximum output power than the second power class. Note that the first power class is not limited to power class 2. For example, the first power class may be power class 1.5 or 1.

[0069] In the first mode, switch circuit 31 connects the common terminal 310 to the selection terminal 311, and switch circuit 32 connects the common terminal 320 to the selection terminal 321. As a result, the band A transmission signal is transmitted from RFIC 3 to antenna 2 via the high-frequency input terminal 110, power amplifier circuit 10, matching circuit 21, switch circuit 31, filter 41, matching circuit 22, switch circuit 32, coupler 51, and antenna connection terminal 100.

[0070] At this time, both power amplifiers 11 and 12 operate in the power amplification circuit 10. As a result, the transmission signal of band A is divided by the quadrature hybrid circuit 13 into two transmission signals with a phase difference of 90 degrees, which are then supplied to power amplifiers 11 and 12 respectively and amplified. The two amplified transmission signals pass through the low-pass filter 151 and the high-pass filter 152, respectively, and are combined by the combining circuit 14 and output. Note that the phase difference between the two transmission signals divided by the quadrature hybrid circuit 13 does not have to be exactly 90 degrees, and may be between 45 and 135 degrees.

[0071] Thus, in the first mode, the transmitted signal can be amplified using power amplifiers 11 and 12 at higher power classes. Therefore, the individual output power of power amplifiers 11 and 12 can be reduced compared to when the transmitted signal is amplified using only one power amplifier 11 or 12, and the size of power amplifiers 11 and 12 can be reduced.

[0072] [1.4.2. Second Mode (First Connection State)] Next, the first connection state of the second mode, which is included in the multiple communication modes of the high-frequency circuit 1, will be explained with reference to Figure 3. Figure 3 is a diagram showing the first connection state of the second mode of the high-frequency circuit 1 according to this embodiment. In Figure 3, dashed arrows represent signal paths.

[0073] The second mode is a communication mode for transmitting Band A signals in power class 3. Power class 3 is an example of a second power class defined by a lower maximum output power than the first power class. Note that the second power class is not limited to power class 3. For example, if the first power class is power class 1.5 or 1, the second power class may be power class 2. In the second mode, the first connection state and the second connection state, which will be described later, are switched based on the output signal of the coupler 51.

[0074] In the first connection state of the second mode, switch circuit 31 connects the common terminal 310 to the selection terminal 311, and switch circuit 32 connects the common terminal 320 to the selection terminal 321. As a result, the transmission signal for band A is transmitted from RFIC 3 to antenna 2 via the high-frequency input terminal 110, power amplifier circuit 10, matching circuit 21, switch circuit 31, filter 41, matching circuit 22, switch circuit 32, coupler 51, and antenna connection terminal 100.

[0075] At this time, in the power amplification circuit 10, power amplifier 11 operates, but power amplifier 12 does not. As a result, the transmission signal of band A is supplied to power amplifier 11 via the quadrature hybrid circuit 13 and amplified. The amplified transmission signal of band A is output via the low-pass filter 151 and the combining circuit 14.

[0076] Thus, in the first connection state of the second mode, the transmitted signal can be amplified using only the power amplifier 11 at a lower power class. Therefore, power efficiency at lower power classes can be improved compared to when the transmitted signal is amplified using both power amplifiers 11 and 12.

[0077] [1.4.3. Second Mode (Second Connection State)] Next, the second connection state of the second mode of the high-frequency circuit 1 will be described with reference to Figure 4. Figure 4 is a diagram showing the second connection state of the second mode of the high-frequency circuit 1 according to this embodiment. In Figure 4, dashed arrows represent signal paths.

[0078] In the second connection state of the second mode, switch circuit 31 connects the common terminal 310 to the selection terminal 311, and switch circuit 32 connects the common terminal 320 to the selection terminal 321. As a result, the transmission signal for band A is transmitted from RFIC 3 to antenna 2 via the high-frequency input terminal 110, power amplifier circuit 10, matching circuit 21, switch circuit 31, filter 41, matching circuit 22, switch circuit 32, coupler 51, and antenna connection terminal 100.

[0079] In this state, in the power amplification circuit 10, power amplifier 11 does not operate, while power amplifier 12 operates. As a result, the transmission signal for band A is supplied to power amplifier 12 via the quadrature hybrid circuit 13 and amplified. The amplified transmission signal for band A is output via the high-pass filter 152 and the combining circuit 14.

[0080] Thus, in the second connection state of the second mode, the transmitted signal can be amplified using only the power amplifier 12 at a lower power class. Therefore, power efficiency at lower power classes can be improved compared to when the transmitted signal is amplified using both power amplifiers 11 and 12.

[0081] Although the first and second modes of the high-frequency circuit 1 have been described with reference to Figures 2 to 4, the communication modes of the high-frequency circuit 1 are not limited to the first and second modes. For example, the communication modes of the high-frequency circuit 1 may include a mode for transmitting signals in band B. In this case, the switch circuit 31 may connect its common terminal 310 to the selection terminal 312, and the switch circuit 32 may connect its common terminal 320 to the selection terminal 322.

[0082] [1.5. Switching between the First and Second Connection States in the Second Mode] Here, the switching between the first and second connection states in the second mode will be explained with reference to Figure 5. Figure 5 is a graph illustrating the switching between the first and second connection states in the second mode of the high-frequency circuit 1 according to this embodiment. In Figure 5, the vertical axis represents the power efficiency of power amplifiers 11 and 12, and the horizontal axis represents the phase of the load impedance. Power efficiency PA1 (solid line) shows the power efficiency of power amplifier 11, and power efficiency PA2 (dashed line) shows the power efficiency of power amplifier 12.

[0083] As shown in Figure 5, the power efficiencies PA1 and PA2 of power amplifiers 11 and 12 change according to the phase of the load impedance. Therefore, the first connection state is selected when the phase of power efficiency PA1 is higher than that of power efficiency PA2. On the other hand, the second connection state is selected when the phase of power efficiency PA2 is higher than that of power efficiency PA1. In this way, in the second mode, by switching between the first and second connection states according to the phase of the load impedance obtained from the output signal of the coupler 51, the transmitted signal can be amplified using a more efficient power amplifier 11 or 12. Therefore, higher power efficiency can be achieved than when one of the power amplifiers 11 or 12 is operated in a fixed state.

[0084] [1.6. Summary] As described above, the high-frequency circuit 1 according to this embodiment comprises a high-frequency input terminal 110 and an antenna connection terminal 100, power amplifiers 11 and 12, an orthogonal hybrid circuit 13 including an input terminal 131 connected to the high-frequency input terminal 110, an output terminal 132 connected to the input terminal of the power amplifier 11, and an output terminal 133 connected to the input terminal of the power amplifier 12, a composite circuit 14 including an input terminal 141 connected to the output terminal of the power amplifier 11, an input terminal 142 connected to the output terminal of the power amplifier 12, and an output terminal 143 connected to the antenna connection terminal 100, and a PA control circuit 60 having a first mode for operating the power amplifiers 11 and 12 and a second mode for selectively switching between operating the power amplifiers 11 and 12.

[0085] According to this, high output power can be achieved by using the first mode in which power amplifiers 11 and 12 are operated, and power efficiency at low output power can be improved by using the second mode in which power amplifier 11 or 12 is operated. Furthermore, in the second mode, power amplifiers 11 and 12 can be selectively switched, so that power amplifier 11 or 12 capable of achieving higher power efficiency can be selected depending on the load condition. Therefore, the decrease in power efficiency due to load fluctuations can be suppressed more effectively than when only one of power amplifiers 11 or 12 is used in a fixed manner. In particular, since the two high-frequency signals supplied from the orthogonal hybrid circuit 13 to power amplifiers 11 and 12 have a phase difference of 90 degrees, the change in power efficiency in response to load fluctuations differs between power amplifiers 11 and 12. Therefore, selectively switching between power amplifiers 11 and 12 in the second mode has a significant effect in suppressing the decrease in power efficiency due to load fluctuations.

[0086] For example, in the high-frequency circuit 1 according to this embodiment, the PA control circuit 60 may selectively switch between power amplifiers 11 and 12 in the second mode based on the phase of the load impedance.

[0087] The power efficiency of power amplifiers 11 and 12, which amplify two high-frequency signals having a 90-degree phase difference, changes depending on the phase of the load impedance. Therefore, by selectively switching between power amplifiers 11 and 12 based on the phase of the load impedance, it is possible to select the power amplifier 11 or 12 with higher power efficiency, thereby suppressing the decrease in power efficiency due to load fluctuations.

[0088] For example, the high-frequency circuit 1 according to this embodiment may further include at least one coupler 51 connected between the output terminals of the power amplifiers 11 and 12 and the antenna connection terminal 100, and the PA control circuit 60 may selectively switch the operation of the power amplifiers 11 and 12 based on the output signal of at least one coupler 51.

[0089] According to this, power amplifiers 11 and 12 can be selectively switched and operated based on the phase of the load impedance obtained from the output signal of coupler 51.

[0090] For example, in the high-frequency circuit 1 according to this embodiment, the first mode may be a mode for transmitting a high-frequency signal in a first power class, and the second mode may be a mode for transmitting a high-frequency signal in a second power class defined by a maximum output power lower than that of the first power class.

[0091] According to this, by using a first mode in which two power amplifiers 11 and 12 are operated in a first power class where higher output power is permitted, the maximum output power of each power amplifier 11 and 12 can be suppressed more effectively than when only one power amplifier 11 or 12 is used. On the other hand, by using a second mode in which power amplifiers 11 and 12 are selectively switched and operated in a second power class where output power is limited, the decrease in power efficiency at lower output power can be suppressed more effectively than when both power amplifiers 11 and 12 are used.

[0092] For example, the high-frequency circuit 1 according to this embodiment may further include a low-pass filter 151 connected between the output terminal of the power amplifier 11 and the input terminal 141 of the combining circuit 14, and a high-pass filter 152 connected between the output terminal of the power amplifier 12 and the input terminal 142 of the combining circuit 14.

[0093] According to this, the phase of the high-frequency signal amplified by the power amplifier 11 can be delayed by 45 degrees by the low-pass filter 151, and the phase of the high-frequency signal amplified by the power amplifier 12 can be advanced by 45 degrees by the high-pass filter 152. Therefore, two in-phase high-frequency signals can be supplied to the combining circuit 14.

[0094] (Modification 1 of Embodiment 1) Next, Modification 1 of Embodiment 1 will be described. In this modification, the main difference from Embodiment 1 is that the combiner included in the power amplifier circuit is a Wilkinson-type combiner. Below, the high-frequency circuit 1 according to this modification will be described with reference to the drawings, focusing on the differences from Embodiment 1.

[0095] The high-frequency circuit 1 according to this modified example is the same as the high-frequency circuit 1 according to Embodiment 1, except that it includes a power amplifier circuit 10B instead of a power amplifier circuit 10. Therefore, the power amplifier circuit 10B will be described below, and the other components will not be explained.

[0096] [2.1. Circuit Configuration of Power Amplifier Circuit 10B] Figure 6 is a circuit configuration diagram of the power amplifier circuit 10B according to this modified example. Note that Figure 6 is an illustrative circuit configuration diagram, and the power amplifier circuit 10B can be implemented using any of the many different circuit implementations and circuit technologies. Therefore, the description of the power amplifier circuit 10B provided below should not be interpreted as restrictive.

[0097] The modified power amplification circuit 10B comprises power amplifiers 11 and 12, a quadrature hybrid circuit 13, a combining circuit 14B, a low-pass filter 151, a high-pass filter 152, inductors 161 and 162, and a capacitor 163.

[0098] The combining circuit 14B can combine two in-phase high-frequency signals that have passed through the low-pass filter 151 and the high-pass filter 152, respectively, and supply them to filters 41 and 42. Specifically, the combining circuit 14B includes input terminals 141 and 142, output terminal 143, quarter-wavelength transmission lines 144 and 145, switches 146, 147 and 148, and a resistor 149.

[0099] The quarter-wavelength transmission line 144 (λ / 4) is an example of a first transmission line and is connected between the input terminal 141 and the output terminal 143. Specifically, one end of the quarter-wavelength transmission line 144 is connected to the input terminal 141, and the other end of the quarter-wavelength transmission line 144 is connected to the output terminal 143.

[0100] The quarter-wavelength transmission line 145 (λ / 4) is an example of a second transmission line and is connected between the input terminal 142 and the output terminal 143. Specifically, one end of the quarter-wavelength transmission line 145 is connected to the input terminal 142, and the other end of the quarter-wavelength transmission line 145 is connected to the output terminal 143.

[0101] Furthermore, the line lengths of the quarter-wavelength transmission lines 144 and 145 do not need to strictly match the quarter-wavelength of the high-frequency signal, and may be between 1 / 8 and 3 / 8 wavelengths.

[0102] Switch 146 is an example of a third switch and is connected between the path connecting the input terminal 141 and the quarter-wavelength transmission line 144 and the ground. Specifically, one end of switch 146 is connected to the input terminal 141 and one end of the quarter-wavelength transmission line 144, and the other end of switch 146 is connected to the ground.

[0103] Switch 147 is an example of a fourth switch and is connected between the path connecting the input terminal 142 and the quarter-wavelength transmission line 145 and the ground. Specifically, one end of switch 147 is connected to the input terminal 142 and one end of the quarter-wavelength transmission line 145, and the other end of switch 147 is connected to the ground.

[0104] Switch 148 is an example of a fifth switch. Switch 148 and resistor 149 are connected in series between input terminals 141 and 142, and in parallel with quarter-wavelength transmission lines 144 and 145. Specifically, one end of the series connection of switch 148 and resistor 149 is connected to input terminal 141 and one end of quarter-wavelength transmission line 144, and the other end of the series connection of switch 148 and resistor 149 is connected to input terminal 142 and one end of quarter-wavelength transmission line 145.

[0105] [2.2. Multiple Communication Modes] The multiple communication modes of the high-frequency circuit 1 according to this modified example will be described below.

[0106] [2.2.1. First Mode] In the first mode, as in Embodiment 1, the common terminal 310 in the switch circuit 31 is connected to the selection terminal 311, and the common terminal 320 in the switch circuit 32 is connected to the selection terminal 321. In the power amplification circuit 10B, both power amplifiers 11 and 12 are in operation. Switches 146 and 147 are open, and switch 148 is closed. As a result, the combining circuit 14B functions as a Wilkinson coupler, and the transmission signal for band A is transmitted as in Figure 2.

[0107] [2.2.2. Second Mode (First Connection State)] In the first connection state of the second mode, similar to Embodiment 1, the common terminal 310 in the switch circuit 31 is connected to the selection terminal 311, and the common terminal 320 in the switch circuit 32 is connected to the selection terminal 321. In the power amplification circuit 10B, the power amplifier 11 operates, and the power amplifier 12 does not operate. Switches 146 and 148 are open, and switch 147 is closed. As a result, the transmission signal for band A is transmitted in the same manner as in Figure 3.

[0108] By closing the switch 147 in this way, the impedance when viewed from the output terminal 143 to the input terminal 142 is set to an open state, which suppresses leakage of the transmitted signal amplified by the power amplifier 11.

[0109] [2.2.3. Second Mode (Second Connection State)] In the second connection state of the second mode, similar to the first embodiment, the common terminal 310 in the switch circuit 31 is connected to the selection terminal 311, and the common terminal 320 in the switch circuit 32 is connected to the selection terminal 321. In the power amplification circuit 10B, the power amplifier 11 does not operate, and the power amplifier 12 operates. Switch 146 is closed, and switches 147 and 148 are open. As a result, the transmission signal for band A is transmitted in the same manner as in Figure 4.

[0110] When the switch 146 is closed in this way, the impedance when viewed from the output terminal 143 to the input terminal 141 is set to an open state, which suppresses leakage of the transmitted signal amplified by the power amplifier 12.

[0111] [2.3. [Summary] As described above, the high-frequency circuit 1 according to this modified example may further include a low-pass filter 151 connected between the output terminal of the power amplifier 11 and the input terminal 141 of the combining circuit 14B, and a high-pass filter 152 connected between the output terminal of the power amplifier 12 and the input terminal 142 of the combining circuit 14B. The combining circuit 14B may further include a quarter-wavelength transmission line 144 connected between the input terminal 141 and the output terminal 143, a quarter-wavelength transmission line 145 connected between the input terminal 142 and the output terminal 143, a switch 146 connected between the path connecting the input terminal 141 and the quarter-wavelength transmission line 144 and the ground, a switch 147 connected between the path connecting the input terminal 142 and the quarter-wavelength transmission line 145 and the ground, and a switch 148 and a resistor 149 connected in series between the input terminals 141 and 142 and connected in parallel with the quarter-wavelength transmission lines 144 and 145.

[0112] According to this, when switches 146 and 147 are open and switch 148 is closed, they can function as a Wilkinson coupler, improving the isolation between input terminals 141 and 142. On the other hand, when one of switches 146 and 147 and switch 148 are open and the other of switches 146 and 147 is closed, the impedance when viewed from output terminal 143 to one of input terminals 141 and 142 can be brought closer to an open state, suppressing signal leakage from output terminal 143 to one of input terminals 141 and 142.

[0113] For example, in the high-frequency circuit 1 according to this modified example, in the first mode, power amplifiers 11 and 12 may be turned on, switches 146 and 147 may be opened, and switch 148 may be closed; in the first connection state of the second mode, power amplifier 11 may be turned on, power amplifier 12 may be turned off, switches 146 and 148 may be opened, and switch 147 may be closed; in the second connection state of the second mode, power amplifier 11 may be turned off, power amplifier 12 may be turned on, switch 146 may be closed, and switches 147 and 148 may be opened.

[0114] According to this, in the first mode, the combining circuit 14B can function as a Wilkinson coupler, and in the first and second connection states of the second mode, signal leakage to the input terminal 141 or 142 to which the turned-off power amplifier 11 or 12 is connected can be suppressed.

[0115] (Modification 2 of Embodiment 1) Next, Modification 2 of Embodiment 1 will be described. In this modification, the position of the switch of the Wilkinson-type combiner included in the power amplifier circuit is mainly different from Modification 1 of Embodiment 1. Below, the high-frequency circuit 1 according to this modification will be described with reference to the drawings, focusing on the differences from Modification 1 of Embodiment 1.

[0116] The high-frequency circuit 1 according to this modified example is the same as the high-frequency circuit 1 according to Embodiment 1, except that it includes a power amplifier circuit 10C instead of a power amplifier circuit 10. Therefore, the power amplifier circuit 10C will be described below, and the other components will not be explained.

[0117] [3.1. Circuit Configuration of Power Amplifier Circuit 10C] Figure 7 is a circuit configuration diagram of the power amplifier circuit 10C according to this modified example. Note that Figure 7 is an illustrative circuit configuration diagram, and the power amplifier circuit 10C can be implemented using any of the many different circuit implementations and circuit technologies. Therefore, the description of the power amplifier circuit 10C provided below should not be interpreted as restrictive.

[0118] The power amplification circuit 10C according to this modified example comprises power amplifiers 11 and 12, an orthogonal hybrid circuit 13, a combining circuit 14C, a low-pass filter 151, a high-pass filter 152, inductors 161 and 162, and a capacitor 163.

[0119] The combining circuit 14C can combine two in-phase high-frequency signals that have passed through the low-pass filter 151 and the high-pass filter 152, respectively, and supply them to filters 41 and 42. Specifically, the combining circuit 14C includes input terminals 141 and 142, output terminal 143, quarter-wavelength transmission lines 144 and 145, switches 146C, 147C and 148, and a resistor 149.

[0120] Switch 146C is connected between the quarter-wavelength transmission line 144 and the output terminal 143. Specifically, one end of switch 146C is connected to the other end of the quarter-wavelength transmission line 144, and the other end of switch 146C is connected to the output terminal 143.

[0121] Switch 147C is connected between the quarter-wavelength transmission line 145 and the output terminal 143. Specifically, one end of switch 147C is connected to the other end of the quarter-wavelength transmission line 145, and the other end of switch 147C is connected to the output terminal 143.

[0122] [3.2. Multiple Communication Modes] The multiple communication modes of the high-frequency circuit 1 according to this modified example will be described below.

[0123] [3.2.1. First Mode] In the first mode, as in the first embodiment, the common terminal 310 in the switch circuit 31 is connected to the selection terminal 311, and the common terminal 320 in the switch circuit 32 is connected to the selection terminal 321. In the power amplification circuit 10C, both power amplifiers 11 and 12 are in operation. Switches 146C, 147C and switch 148 are closed. As a result, the combining circuit 14C functions as a Wilkinson coupler, and the transmission signal for band A is transmitted as in Figure 2.

[0124] [3.2.2. Second Mode (First Connection State)] In the first connection state of the second mode, similar to Embodiment 1, the common terminal 310 in the switch circuit 31 is connected to the selection terminal 311, and the common terminal 320 in the switch circuit 32 is connected to the selection terminal 321. In the power amplification circuit 10C, the power amplifier 11 operates, and the power amplifier 12 does not operate. Switch 146C is closed, and switches 147C and 148 are open. As a result, the transmission signal for band A is transmitted in the same manner as in Figure 3.

[0125] By opening the switch 147C in this way, the impedance when viewed from the output terminal 143 to the input terminal 142 is set to an open state, which suppresses leakage of the transmitted signal amplified by the power amplifier 11.

[0126] [3.2.3. Second Mode (Second Connection State)] In the second connection state of the second mode, similar to the first embodiment, the common terminal 310 in the switch circuit 31 is connected to the selection terminal 311, and the common terminal 320 in the switch circuit 32 is connected to the selection terminal 321. In the power amplification circuit 10C, the power amplifier 11 does not operate, and the power amplifier 12 operates. Switches 146C and 148 are open, and switch 147C is closed. As a result, the transmission signal for band A is transmitted in the same manner as in Figure 4.

[0127] By opening the switch 146C in this way, the impedance when viewed from the output terminal 143 to the input terminal 141 is set to an open state, which suppresses leakage of the transmitted signal amplified by the power amplifier 12.

[0128] [3.3. Summary] As described above, the high-frequency circuit 1 according to this modified example may further include a low-pass filter 151 connected between the output terminal of the power amplifier 11 and the input terminal 141 of the combining circuit 14C, and a high-pass filter 152 connected between the output terminal of the power amplifier 12 and the input terminal 142 of the combining circuit 14C. The combining circuit 14C may further include a quarter-wavelength transmission line 144 connected between the input terminal 141 and the output terminal 143, a quarter-wavelength transmission line 145 connected between the input terminal 142 and the output terminal 143, a switch 146C connected between the quarter-wavelength transmission line 144 and the output terminal 143, a switch 147C connected between the quarter-wavelength transmission line 145 and the output terminal 143, and a switch 148 and a resistor 149 connected in series between the input terminals 141 and 142 and connected in parallel with the quarter-wavelength transmission lines 144 and 145.

[0129] According to this, when switches 146C, 147C, and 148 are closed, they can function as a Wilkinson coupler, improving the isolation between input terminals 141 and 142. On the other hand, when one of switches 146C and 147C and switch 148 are open, and the other of switches 146C and 147C is closed, the impedance when viewed from output terminal 143 to one of input terminals 141 and 142 can be brought closer to an open state, thereby suppressing signal leakage from output terminal 143 to one of input terminals 141 and 142.

[0130] For example, in the high-frequency circuit 1 according to this modified example, in the first mode, power amplifiers 11 and 12 may be turned on and switches 146C, 147C and 148 may be closed; in the first connection state of the second mode, power amplifier 11 may be turned on, power amplifier 12 may be turned off, switch 146C may be closed, and switches 147C and 148 may be opened; in the second connection state of the second mode, power amplifier 11 may be turned off, power amplifier 12 may be turned on, switch 147C may be closed, and switches 146C and 148 may be opened.

[0131] According to this, in the first mode, the combining circuit 14C can function as a Wilkinson coupler, and in the first and second connection states of the second mode, signal leakage to the input terminal 141 or 142 to which the turned-off power amplifier 11 or 12 is connected can be suppressed.

[0132] (Modification 3 of Embodiment 1) Next, Modification 3 of Embodiment 1 will be described. In this modification, the main difference from Embodiment 1 is that the combiner included in the power amplifier circuit is a transformer. Below, the high-frequency circuit 1 according to this modification will be described with reference to the drawings, focusing on the differences from Embodiment 1.

[0133] The high-frequency circuit 1 according to this modified example is the same as the high-frequency circuit 1 according to Embodiment 1, except that it includes a power amplifier circuit 10D instead of a power amplifier circuit 10. Therefore, the power amplifier circuit 10D will be described below, and the other components will not be explained.

[0134] [4.1. Circuit Configuration of Power Amplifier Circuit 10D] Figure 8 is a circuit diagram of the power amplifier circuit 10D according to this modified example. Note that Figure 8 is an illustrative circuit diagram, and the power amplifier circuit 10D can be implemented using any of the many different circuit implementations and circuit technologies. Therefore, the description of the power amplifier circuit 10D provided below should not be interpreted as restrictive.

[0135] The modified power amplification circuit 10D comprises power amplifiers 11 and 12, an orthogonal hybrid circuit 13, a combining circuit 14D, a low-pass filter 151D, a high-pass filter 152D, inductors 161 and 162, a capacitor 163, and switches 173 and 174.

[0136] The low-pass filter 151D is connected between the power amplifier 12 and the combining circuit 14D. Specifically, one end of the low-pass filter 151D is connected to the output terminal of the power amplifier 12, and the other end of the low-pass filter 151D is connected to the input terminal 142 of the combining circuit 14D. The low-pass filter 151D can advance the phase of the high-frequency signal amplified by the power amplifier 12 by 45 degrees. The low-pass filter 151D includes, for example, an inductor and / or a capacitor.

[0137] The high-pass filter 152D is connected between the power amplifier 11 and the combining circuit 14D. Specifically, one end of the high-pass filter 152D is connected to the output terminal of the power amplifier 11, and the other end of the high-pass filter 152D is connected to the input terminal 141 of the combining circuit 14D. The high-pass filter 152D can delay the phase of the high-frequency signal amplified by the power amplifier 11 by 45 degrees. The high-pass filter 152D includes, for example, an inductor and / or a capacitor.

[0138] The combining circuit 14D is a transformer that can combine two out-of-phase high-frequency signals that have passed through the low-pass filter 151D and the high-pass filter 152D, respectively, and supply them to filters 41 and 42. Specifically, the combining circuit 14D includes input terminals 141 and 142, an output terminal 143, a primary coil 1401, and a secondary coil 1402.

[0139] The primary coil 1401 is connected between input terminals 141 and 142. Specifically, one end of the primary coil 1401 is connected to input terminal 141, and the other end of the primary coil 1401 is connected to input terminal 142.

[0140] The secondary coil 1402 is connectable to the primary coil 1401 and is connected between the output terminal 143 and ground. Specifically, one end of the secondary coil 1402 is connected to the output terminal 143, and the other end of the secondary coil 1402 is connected to ground.

[0141] Switch 173 is an example of a sixth switch and is connected between the path between the high-pass filter 152D and the input terminal 141 and the ground. Specifically, one end of switch 173 is connected to the other end of the high-pass filter 152D and the input terminal 141 of the combining circuit 14D, and the other end of switch 173 is connected to the ground.

[0142] Switch 174 is an example of a seventh switch and is connected between the path between the low-pass filter 151D and the input terminal 142 and the ground. Specifically, one end of switch 174 is connected to the other end of the low-pass filter 151D and the input terminal 142 of the combining circuit 14D, and the other end of switch 174 is connected to the ground.

[0143] [4.2. Multiple Communication Modes] The multiple communication modes of the high-frequency circuit 1 according to this modified example will be described below.

[0144] [4.2.1. First Mode] In the first mode, as in the first embodiment, the common terminal 310 in the switch circuit 31 is connected to the selection terminal 311, and the common terminal 320 in the switch circuit 32 is connected to the selection terminal 321. In the power amplification circuit 10D, both power amplifiers 11 and 12 are operated. Switches 173 and 174 are both open. As a result, the transmission signal for band A is transmitted as in Figure 2.

[0145] [4.2.2. Second Mode (First Connection State)] In the first connection state of the second mode, similar to Embodiment 1, the common terminal 310 in the switch circuit 31 is connected to the selection terminal 311, and the common terminal 320 in the switch circuit 32 is connected to the selection terminal 321. In the power amplification circuit 10D, the power amplifier 11 operates, and the power amplifier 12 does not operate. Switch 173 is open, and switch 174 is closed. As a result, the transmission signal for band A is transmitted in the same manner as in Figure 3.

[0146] [4.2.3. Second Mode (Second Connection State)] In the second connection state of the second mode, similar to the first embodiment, the common terminal 310 in the switch circuit 31 is connected to the selection terminal 311, and the common terminal 320 in the switch circuit 32 is connected to the selection terminal 321. In the power amplification circuit 10D, the power amplifier 11 does not operate, and the power amplifier 12 operates. Switch 173 is closed, and switch 174 is open. As a result, the transmission signal for band A is transmitted in the same manner as in Figure 4.

[0147] [4.3. Summary] As described above, the high-frequency circuit 1 according to this modified example may further include a high-pass filter 152D connected between the output terminal of the power amplifier 11 and the input terminal 141 of the combining circuit 14D, a low-pass filter 151D connected between the output terminal of the power amplifier 12 and the input terminal 142 of the combining circuit 14D, a switch 173 connected between the path connecting the high-pass filter 152D and the input terminal 141 and ground, and a switch 174 connected between the path connecting the low-pass filter 151D and the input terminal 142 and ground. The combining circuit 14D may further include a primary coil 1401 connected between the input terminals 141 and 142, and a secondary coil 1402 connected between the output terminal 143 and ground.

[0148] According to this, the phase of the high-frequency signal amplified by the power amplifier 11 can be advanced by 45 degrees by the high-pass filter 152D, and the phase of the high-frequency signal amplified by the power amplifier 12 can be delayed by 45 degrees by the low-pass filter 151D. Therefore, two high-frequency signals with opposite phases can be supplied to the combining circuit 14D, and a transformer can be used in the combining circuit 14D.

[0149] For example, in the high-frequency circuit 1 according to this modified example, in the first mode, power amplifiers 11 and 12 may be turned on and switches 173 and 174 may be opened; in the first connection state of the second mode, power amplifier 11 may be turned on, power amplifier 12 may be turned off, switch 173 may be opened and switch 174 may be closed; and in the second connection state of the second mode, power amplifier 11 may be turned off, power amplifier 12 may be turned on, switch 173 may be closed and switch 174 may be opened.

[0150] According to this, in the first mode, two high-frequency signals amplified by power amplifiers 11 and 12 can be combined and supplied to filters 41 and 42, and in the second mode, one high-frequency signal amplified by power amplifier 11 or 12 can be supplied to filters 41 and 42.

[0151] (Modification 4 of Embodiment 1) Next, Modification 4 of Embodiment 1 will be described. In this modification, the power amplifier circuit is a Doherty amplifier circuit, which is the main difference from Embodiment 1. Below, this modification will be described with reference to the drawings, focusing on the differences from Embodiment 1.

[0152] The high-frequency circuit 1 according to this modified example is the same as the high-frequency circuit 1 according to Embodiment 1, except that it includes a power amplifier circuit 10E instead of a power amplifier circuit 10. Therefore, the power amplifier circuit 10E will be described below, and the other components will not be explained.

[0153] [5.1. Circuit Configuration of Power Amplifier Circuit 10E] Figure 9 is a circuit configuration diagram of the power amplifier circuit 10E according to this modified example. Note that Figure 9 is an illustrative circuit configuration diagram, and the power amplifier circuit 10E can be implemented using any of the many different circuit implementations and circuit technologies. Therefore, the description of the power amplifier circuit 10E provided below should not be interpreted as restrictive.

[0154] The power amplification circuit 10E according to this modified example comprises power amplifiers 11E and 12E, a quadrature hybrid circuit 13, a combining circuit 14, a quarter-wavelength transmission line 153, inductors 161 and 162, a capacitor 163, and a switch 175.

[0155] Power amplifier 11E is an example of a first power amplifier and is connected between the quadrature hybrid circuit 13 and the quarter-wavelength transmission line 153. Specifically, the input terminal of power amplifier 11E is connected to the output terminal 132 of the quadrature hybrid circuit 13, and the output terminal of power amplifier 11E is connected to the quarter-wavelength transmission line 153. Power amplifier 11E can amplify high-frequency signals with a phase lead of 45 degrees relative to power amplifiers 11E and 12E when both are operating, and can operate as a so-called carrier amplifier.

[0156] Power amplifier 12E is an example of a second power amplifier and is connected between the quadrature hybrid circuit 13 and the combining circuit 14. Specifically, the input terminal of power amplifier 12E is connected to the output terminal 133 of the quadrature hybrid circuit 13, and the output terminal of power amplifier 12E is connected to the input terminal 142 of the combining circuit 14. Power amplifier 12E can amplify high-frequency signals with a phase lag of 45 degrees relative to power amplifiers 11E and 12E when both are operating, and can operate as a so-called peak amplifier.

[0157] The quarter-wavelength transmission line 153 is an example of a third transmission line and is connected between the power amplifier 11E and the combining circuit 14. Specifically, one end of the quarter-wavelength transmission line 153 is connected to the output terminal of the power amplifier 11E, and the other end of the quarter-wavelength transmission line 153 is connected to the input terminal 141 of the combining circuit 14.

[0158] Switch 175 is an example of an eighth switch and is connected between the path connecting the power amplifier 11E and the quarter-wavelength transmission line 153 and the ground. Specifically, one end of switch 175 is connected to the output terminal of the power amplifier 11E and one end of the quarter-wavelength transmission line 153, and the other end of switch 175 is connected to the ground.

[0159] [5.2. Multiple Communication Modes] The multiple communication modes of the high-frequency circuit 1 according to this modified example will be described below.

[0160] [5.2.1. First Mode] In the first mode, as in Embodiment 1, the common terminal 310 in the switch circuit 31 is connected to the selection terminal 311, and the common terminal 320 in the switch circuit 32 is connected to the selection terminal 321. In the power amplification circuit 10E, both power amplifiers 11E and 12E operate. Specifically, power amplifier 11E operates as a carrier amplifier, and power amplifier 12E operates as a peak amplifier. Switch 175 is open. As a result, the transmission signal for band A is transmitted in the same manner as in Figure 2.

[0161] [5.2.2. Second Mode (First Connection State)] In the first connection state of the second mode, similar to Embodiment 1, the common terminal 310 in the switch circuit 31 is connected to the selection terminal 311, and the common terminal 320 in the switch circuit 32 is connected to the selection terminal 321. In the power amplification circuit 10E, the power amplifier 11E operates, and the power amplifier 12E does not operate. The switch 175 is open. As a result, the transmission signal for band A is transmitted in the same manner as in Figure 3.

[0162] [5.2.3. Second Mode (Second Connection State)] In the second connection state of the second mode, similar to the first embodiment, the common terminal 310 in the switch circuit 31 is connected to the selection terminal 311, and the common terminal 320 in the switch circuit 32 is connected to the selection terminal 321. In the power amplification circuit 10E, the power amplifier 11E does not operate, and the power amplifier 12E operates. The switch 175 is closed. As a result, the transmission signal for band A is transmitted in the same manner as in Figure 4.

[0163] [5.3. Summary] As described above, the high-frequency circuit 1 according to this modified example may further include a quarter-wavelength transmission line 153 connected between the output terminal of the power amplifier 11E and the input terminal 141 of the combining circuit 14, and a switch 175 connected between the path connecting the power amplifier 11E and the quarter-wavelength transmission line 153 and ground.

[0164] According to this, the power amplifiers 11E and 12E can be operated as the carrier amplifier and peak amplifier of the Doherty amplifier circuit.

[0165] For example, in the high-frequency circuit 1 according to this modified example, in the first mode, power amplifiers 11E and 12E may be turned on and switch 175 may be open; in the first connection state of the second mode, power amplifier 11E may be turned on, power amplifier 12E may be turned off, and switch 175 may be open; and in the second connection state of the second mode, power amplifier 11E may be turned off, power amplifier 12E may be turned on, and switch 175 may be closed.

[0166] According to this, in the first mode, the power amplifiers 11E and 12E can be operated as the carrier amplifier and peak amplifier of the Doherty amplifier circuit, and in the second mode, the power amplifiers 11E and 12E can be selectively switched and operated.

[0167] (Modification 5 of Embodiment 1) Next, Modification 5 of Embodiment 1 will be described. In this modification, the position of the switch included in the power amplifier circuit is the main difference from Modification 4 of Embodiment 1 described above. Below, this modification will be described with reference to the drawings, focusing on the differences from Modification 4 of Embodiment 1 described above.

[0168] The high-frequency circuit 1 according to this modified example is the same as the high-frequency circuit 1 according to Embodiment 1, except that it includes a power amplifier circuit 10F instead of a power amplifier circuit 10. Therefore, the power amplifier circuit 10F will be described below, and the other components will not be explained.

[0169] [6.1. Circuit Configuration of Power Amplifier Circuit 10F] Figure 10 is a circuit configuration diagram of the power amplifier circuit 10F according to this modified example. Note that Figure 10 is an illustrative circuit configuration diagram, and the power amplifier circuit 10F can be implemented using any of the many different circuit implementations and circuit technologies. Therefore, the description of the power amplifier circuit 10F provided below should not be interpreted as restrictive.

[0170] The power amplification circuit 10F according to this modified example comprises power amplifiers 11E and 12E, a quadrature hybrid circuit 13, a combining circuit 14, a quarter-wavelength transmission line 153, inductors 161 and 162, a capacitor 163, and a switch 175F.

[0171] Switch 175F is connected between the quarter-wavelength transmission line 153 and the combining circuit 14. Specifically, one end of switch 175F is connected to the other end of the quarter-wavelength transmission line 153, and the other end of switch 175F is connected to the input terminal 141 of the combining circuit 14.

[0172] [6.2. Multiple Communication Modes] The multiple communication modes of the high-frequency circuit 1 according to this modified example will be described below.

[0173] [6.2.1. First Mode] In the first mode, as in Embodiment 1, the common terminal 310 in the switch circuit 31 is connected to the selection terminal 311, and the common terminal 320 in the switch circuit 32 is connected to the selection terminal 321. In the power amplification circuit 10F, both power amplifiers 11E and 12E operate. Specifically, power amplifier 11E operates as a carrier amplifier, and power amplifier 12E operates as a peak amplifier. Switch 175F is closed. As a result, the transmission signal for band A is transmitted as in Figure 2.

[0174] [6.2.2. Second Mode (First Connection State)] In the first connection state of the second mode, similar to Embodiment 1, the common terminal 310 in the switch circuit 31 is connected to the selection terminal 311, and the common terminal 320 in the switch circuit 32 is connected to the selection terminal 321. In the power amplification circuit 10F, the power amplifier 11E operates, and the power amplifier 12E does not operate. The switch 175F is closed. As a result, the transmission signal for band A is transmitted in the same manner as in Figure 3.

[0175] [6.2.3. Second Mode (Second Connection State)] In the second connection state of the second mode, similar to the first embodiment, the common terminal 310 in the switch circuit 31 is connected to the selection terminal 311, and the common terminal 320 in the switch circuit 32 is connected to the selection terminal 321. In the power amplification circuit 10F, the power amplifier 11E does not operate, and the power amplifier 12E operates. The switch 175F is open. As a result, the transmission signal for band A is transmitted in the same manner as in Figure 4.

[0176] [6.3. Summary] As described above, the high-frequency circuit 1 according to this modified example may further include a quarter-wavelength transmission line 153 connected between the output terminal of the power amplifier 11E and the input terminal 141 of the combining circuit 14, and a switch 175F connected between the quarter-wavelength transmission line 153 and the combining circuit 14.

[0177] According to this, the power amplifiers 11E and 12E can be operated as the carrier amplifier and peak amplifier of the Doherty amplifier circuit.

[0178] For example, in the high-frequency circuit 1 according to this modified example, in the first mode, power amplifiers 11E and 12E may be turned on and switch 175F may be closed; in the first connection state of the second mode, power amplifier 11E may be turned on, power amplifier 12E may be turned off, and switch 175F may be closed; and in the second connection state of the second mode, power amplifier 11E may be turned off, power amplifier 12E may be turned on, and switch 175F may be opened.

[0179] According to this, in the first mode, the power amplifiers 11E and 12E can be operated as the carrier amplifier and peak amplifier of the Doherty amplifier circuit, and in the second mode, the power amplifiers 11E and 12E can be selectively switched and operated.

[0180] (Modification 6 of Embodiment 1) Next, Modification 6 of Embodiment 1 will be described. In this modification, the main difference from Modification 4 of Embodiment 1 is that the combining circuit is a transformer. Below, this modification will be described with reference to the drawings, focusing on the differences from Modification 4 of Embodiment 1.

[0181] The high-frequency circuit 1 according to this modified example is the same as the high-frequency circuit 1 according to Embodiment 1, except that it includes a power amplifier circuit 10G instead of a power amplifier circuit 10. Therefore, the power amplifier circuit 10G will be described below, and the other components will not be explained.

[0182] [7.1. Circuit Configuration of Power Amplifier Circuit 10G] Figure 11 is a circuit configuration diagram of the power amplifier circuit 10G according to this modified example. Note that Figure 11 is an illustrative circuit configuration diagram, and the power amplifier circuit 10G can be implemented using any of the many different circuit implementations and circuit technologies. Therefore, the description of the power amplifier circuit 10G provided below should not be interpreted as restrictive.

[0183] The power amplification circuit 10G according to this modified example comprises power amplifiers 11E and 12E, a quadrature hybrid circuit 13, a combining circuit 14D, a quarter-wavelength transmission line 154, inductors 161 and 162, a capacitor 163, and a switch 176.

[0184] The quarter-wavelength transmission line 154 is an example of a fourth transmission line and is connected between the power amplifier 12E and the combining circuit 14D. Specifically, one end of the quarter-wavelength transmission line 154 is connected to the output terminal of the power amplifier 12E, and the other end of the quarter-wavelength transmission line 154 is connected to the input terminal 142 of the combining circuit 14D.

[0185] Switch 176 is an example of a ninth switch and is connected between the path connecting the power amplifier 11E and the quarter-wavelength transmission line 154 and the ground. Specifically, one end of switch 176 is connected to the output terminal of the power amplifier 11E and one end of the quarter-wavelength transmission line 154, and the other end of switch 176 is connected to the ground.

[0186] [7.2. Multiple Communication Modes] The multiple communication modes of the high-frequency circuit 1 according to this modified example will be described below.

[0187] [7.2.1. First Mode] In the first mode, as in the first embodiment, the common terminal 310 in the switch circuit 31 is connected to the selection terminal 311, and the common terminal 320 in the switch circuit 32 is connected to the selection terminal 321. In the power amplification circuit 10G, both power amplifiers 11E and 12E operate. Specifically, power amplifier 11E operates as a carrier amplifier, and power amplifier 12E operates as a peak amplifier. Switch 176 is open. As a result, the transmission signal for band A is transmitted in the same manner as in Figure 2.

[0188] [7.2.2. Second Mode (First Connection State)] In the first connection state of the second mode, similar to Embodiment 1, the common terminal 310 in the switch circuit 31 is connected to the selection terminal 311, and the common terminal 320 in the switch circuit 32 is connected to the selection terminal 321. In the power amplification circuit 10G, the power amplifier 11E operates, and the power amplifier 12E does not operate. The switch 176 is open. As a result, the transmission signal for band A is transmitted in the same manner as in Figure 3.

[0189] [7.2.3. Second Mode (Second Connection State)] In the second connection state of the second mode, similar to the first embodiment, the common terminal 310 in the switch circuit 31 is connected to the selection terminal 311, and the common terminal 320 in the switch circuit 32 is connected to the selection terminal 321. In the power amplification circuit 10G, the power amplifier 11E does not operate, and the power amplifier 12E operates. The switch 176 is closed. As a result, the transmission signal for band A is transmitted in the same manner as in Figure 4.

[0190] [7.3. Summary] As described above, the high-frequency circuit 1 according to this modified example may further include a quarter-wavelength transmission line 154 connected between the output terminal of the power amplifier 12E and the input terminal 142 of the combining circuit 14D, and a switch 176 connected between the path connecting the output terminal and input terminal 141 of the power amplifier 11E and ground. The combining circuit 14D may further include a primary coil 1401 connected between input terminals 141 and 142, and a secondary coil 1402 connected between the third output terminal and ground.

[0191] According to this, power amplifiers 11E and 12E can be operated as carrier amplifier and peak amplifier of a Doherty amplifier circuit. Furthermore, by connecting a quarter-wavelength transmission line 154 between the output terminal of power amplifier 12E and the input terminal 142 of the combining circuit 14D, two out-of-phase high-frequency signals can be supplied to the combining circuit 14D. Therefore, a transformer can be used in the combining circuit 14D.

[0192] For example, in the high-frequency circuit 1 according to this modified example, in the first mode, power amplifiers 11E and 12E may be turned on and switch 176 may be open; in the first connection state of the second mode, power amplifier 11E may be turned on, power amplifier 12E may be turned off, and switch 176 may be open; and in the second connection state of the second mode, power amplifier 11E may be turned off, power amplifier 12E may be turned on, and switch 176 may be closed.

[0193] According to this, in the first mode, two high-frequency signals amplified by power amplifiers 11E and 12E can be combined and supplied to filters 41 and 42, and in the second mode, one high-frequency signal amplified by power amplifier 11E or 12E can be supplied to filters 41 and 42.

[0194] (Modification 7 of Embodiment 1) Next, Modification 7 of Embodiment 1 will be described. In this modification, the power supply voltage is supplied to the midpoint of the primary coil, which is the main difference from Modification 4 of Embodiment 1 described above. Below, this modification will be described with reference to the drawings, focusing on the differences from Modification 4 of Embodiment 1 described above.

[0195] The high-frequency circuit 1 according to this modified example is the same as the high-frequency circuit 1 according to Embodiment 1, except that it includes a power amplifier circuit 10H instead of a power amplifier circuit 10. Therefore, the power amplifier circuit 10H will be described below, and the other components will not be explained.

[0196] [8.1. Circuit Configuration of Power Amplifier Circuit 10H] Figure 12 is a circuit configuration diagram of the power amplifier circuit 10H according to this modified example. Note that Figure 12 is an illustrative circuit configuration diagram, and the power amplifier circuit 10H can be implemented using any of the many different circuit implementations and circuit technologies. Therefore, the description of the power amplifier circuit 10H provided below should not be interpreted as limiting.

[0197] The modified power amplification circuit 10H comprises power amplifiers 11E and 12E, an orthogonal hybrid circuit 13, a combining circuit 14D, a quarter-wavelength transmission line 154, an inductor 164, a capacitor 165, and switches 177, 178, and 179.

[0198] The inductor 164 is connected between the power supply voltage terminal 130 and switches 177 to 179. Specifically, one end of the inductor 164 is connected to the power supply voltage terminal 130, and the other end of the inductor 164 is connected to one end of switches 177, 178, and 179, respectively.

[0199] Capacitor 165 is connected between the path connecting inductor 164 and switches 177-179 and ground. Specifically, one of the two electrodes of capacitor 165 is connected to the other end of inductor 164 and one end of each of switches 177, 178, and 179, while the other electrode of capacitor 165 is connected to ground.

[0200] Switch 177 is an example of a tenth switch and is connected between the power supply voltage terminal 130 and one end of the primary coil 1401. Specifically, one end of switch 177 is connected to the power supply voltage terminal 130 via an inductor 164, and the other end of switch 177 is connected to one end of the primary coil 1401 via an input terminal 141.

[0201] Switch 178 is an example of a 11th switch and is connected between the power supply voltage terminal 130 and the other end of the primary coil 1401. Specifically, one end of switch 178 is connected to the power supply voltage terminal 130 via inductor 164, and the other end of switch 178 is connected to the other end of the primary coil 1401 via input terminal 142.

[0202] Switch 179 is an example of a twelfth switch and is connected between the power supply voltage terminal 130 and the intermediate node of the primary coil 1401. Specifically, one end of switch 179 is connected to the power supply voltage terminal 130 via inductor 164, and the other end of switch 179 is connected to the intermediate node of the primary coil 1401. The intermediate node of the primary coil 1401 refers to any node between one end and the other end of the primary coil 1401, and may be the midpoint between one end and the other end of the primary coil 1401.

[0203] [8.2. Multiple Communication Modes] The multiple communication modes of the high-frequency circuit 1 according to this modified example will be described below.

[0204] [8.2.1. First Mode] In the first mode, as in the first embodiment, the common terminal 310 in the switch circuit 31 is connected to the selection terminal 311, and the common terminal 320 in the switch circuit 32 is connected to the selection terminal 321. In the power amplification circuit 10H, both power amplifiers 11E and 12E operate. Specifically, power amplifier 11E operates as a carrier amplifier, and power amplifier 12E operates as a peak amplifier. Switches 177 and 178 are open, and switch 179 is closed. As a result, the transmission signal for band A is transmitted as in Figure 2.

[0205] [8.2.2. Second Mode (First Connection State)] In the first connection state of the second mode, similar to the first embodiment, the common terminal 310 in the switch circuit 31 is connected to the selection terminal 311, and the common terminal 320 in the switch circuit 32 is connected to the selection terminal 321. In the power amplification circuit 10H, the power amplifier 11E operates, and the power amplifier 12E does not operate. Switches 177 and 179 are open, and switch 178 is closed. As a result, the transmission signal for band A is transmitted in the same manner as in Figure 3.

[0206] [8.2.3. Second Mode (Second Connection State)] In the second connection state of the second mode, similar to the first embodiment, the common terminal 310 in the switch circuit 31 is connected to the selection terminal 311, and the common terminal 320 in the switch circuit 32 is connected to the selection terminal 321. In the power amplification circuit 10H, the power amplifier 11E does not operate, and the power amplifier 12E operates. Switches 178 and 179 are open, and switch 177 is closed. As a result, the transmission signal for band A is transmitted in the same manner as in Figure 4.

[0207] [8.3. Summary] As described above, in the high-frequency circuit 1 according to this modified example, the combining circuit 14D may further include a primary coil 1401 connected between input terminals 141 and 142, and a secondary coil 1402 connected between output terminal 143 and ground. The high-frequency circuit 1 may further include a switch 177 connected between the power supply and one end of the primary coil 1401, a switch 178 connected between the power supply and the other end of the primary coil 1401, a switch 179 connected between the power supply and an intermediate node of the primary coil 1401, an inductor 164 connected between the power supply and switches 177, 178 and 179, and a capacitor 165 connected between the path connecting the inductor 164 and switches 177, 178 and 179 and ground.

[0208] According to this, the power supply voltage (Vcc) can be supplied to the intermediate node of the primary coil 1401, so the number of choke inductors (inductors 164) can be reduced compared to when the power supply voltage (Vcc) is supplied to the power amplifiers 11E and 12E individually.

[0209] For example, in the high-frequency circuit 1 according to this modified example, in the first mode, power amplifiers 11E and 12E may be turned on, switches 177 and 178 may be opened, and switch 179 may be closed; in the first connection state of the second mode, power amplifier 11E may be turned on, power amplifier 12E may be turned off, switches 177 and 179 may be opened, and switch 178 may be closed; in the second connection state of the second mode, power amplifier 11E may be turned off, power amplifier 12E may be turned on, switches 178 and 179 may be opened, and switch 177 may be closed.

[0210] According to this, in the first mode, two high-frequency signals amplified by power amplifiers 11E and 12E can be combined and supplied to filters 41 and 42, and in the second mode, one high-frequency signal amplified by power amplifier 11E or 12E can be supplied to filters 41 and 42.

[0211] (Embodiment 2) Next, Embodiment 2 will be described. This embodiment differs from Embodiment 1 in that the power amplifier is controlled based on the power efficiency of the power amplifier instead of the phase of the load impedance. Below, this embodiment will be described with reference to the drawings, focusing on the differences from Embodiment 1.

[0212] Furthermore, the communication device 5J is the same as the communication device 5, except that it is equipped with a high-frequency circuit 1J instead of the high-frequency circuit 1. Therefore, the high-frequency circuit 1J will be described below, and the other components will not be described.

[0213] [9.1. Circuit Configuration of High-Frequency Circuit 1J] Figure 13 is a circuit configuration diagram of the communication device 5J according to this embodiment. Note that Figure 13 is an illustrative circuit configuration diagram, and the high-frequency circuit 1J can be implemented using any of the many different circuit implementations and circuit technologies. Therefore, the description of the high-frequency circuit 1J provided below should not be interpreted as limiting.

[0214] The high-frequency circuit 1J according to this embodiment includes a power amplifier circuit 10J, matching circuits 21, 22, and 23, switch circuits 31 and 32, filters 41 and 42, a PA control circuit 60J, an antenna connection terminal 100, a high-frequency input terminal 110, a control terminal 120, and a power supply voltage terminal 130. In other words, the high-frequency circuit 1J includes a power amplifier circuit 10J and a PA control circuit 60J instead of a power amplifier circuit 10 and a PA control circuit 60, and does not include a coupler 51.

[0215] The PA control circuit 60J can control the power amplifier circuit 10J based on the power efficiency of the power amplifiers 11 and 12. Specifically, the PA control circuit 60J has a first mode for operating the power amplifiers 11 and 12 and a second mode for selectively switching between operating the power amplifiers 11 and 12, similar to the first embodiment. In this embodiment, the PA control circuit 60J can selectively switch between operating the power amplifiers 11 and 12 based on the output signal of the temperature sensor 19 in the second mode.

[0216] The temperatures of power amplifiers 11 and 12 depend on their power efficiency. Specifically, if the power efficiency of power amplifiers 11 and 12 is low, their temperatures will be high. Conversely, if the power efficiency of power amplifiers 11 and 12 is high, their temperatures will be low. Therefore, by selectively switching the operation of power amplifiers 11 and 12 based on the temperatures of power amplifiers 11 and 12 indicated by the output signal of the temperature sensor 19, it is possible to select a power amplifier capable of achieving higher power efficiency. For example, in the second mode, if the temperature of power amplifier 11 is higher than the threshold temperature, the PA control circuit 60J may switch from the first connection state to the second connection state. Also, for example, if the temperature of power amplifier 12 is higher than the threshold temperature, the PA control circuit 60J may switch from the second connection state to the first connection state.

[0217] [9.2. Circuit Configuration of Power Amplifier Circuit 10J] Next, the circuit configuration of the power amplifier circuit 10J will be described with reference to Figure 13. Note that Figure 13 is an illustrative circuit configuration diagram, and the power amplifier circuit 10J can be implemented using any of the many different circuit implementations and circuit technologies. Therefore, the description of the power amplifier circuit 10J provided below should not be interpreted as restrictive.

[0218] The power amplification circuit 10J includes power amplifiers 11 and 12, an orthogonal hybrid circuit 13, a combining circuit 14, a low-pass filter 151, a high-pass filter 152, inductors 161 and 162, a capacitor 163, and a temperature sensor 19.

[0219] The temperature sensor 19 can detect the temperatures of the power amplifiers 11 and 12 and output a sensor signal to the PA control circuit 60J. For example, a semiconductor temperature sensor such as a silicon diode can be used as the temperature sensor 19.

[0220] [9.3. Summary] As described above, in the high-frequency circuit 1J according to this embodiment, the PA control circuit 60J may selectively switch between operating the power amplifiers 11 and 12 based on the power efficiency of the power amplifiers 11 and 12 in the second mode.

[0221] According to this, by selectively switching between power amplifiers 11 and 12 based on their power efficiency, it is possible to select the power amplifier 11 or 12 with higher power efficiency, thereby suppressing the decrease in power efficiency due to load fluctuations.

[0222] For example, the high-frequency circuit 1 according to this modified example may further include a temperature sensor 19 configured to detect the temperatures of the power amplifiers 11 and 12, and the PA control circuit 60J may selectively switch the operation of the power amplifiers 11 and 12 based on the output signal of the temperature sensor 19.

[0223] According to this, the power amplifiers 11 and 12 can be selectively switched and operated based on the power efficiency of the power amplifiers 11 and 12 estimated from the output signal of the temperature sensor 19.

[0224] (Other Embodiments) The high-frequency circuit according to the present invention has been described above based on embodiments, but the high-frequency circuit according to the present invention is not limited to the above embodiments. Other embodiments realized by combining any of the components in the above embodiments, modified versions obtained by applying various modifications to the above embodiments that a person skilled in the art can conceive of without departing from the spirit of the present invention, and various devices incorporating the above high-frequency circuit are also included in the present invention.

[0225] For example, in the circuit configuration of the high-frequency circuit according to each of the above embodiments, other circuit elements and wiring may be inserted between the paths connecting the circuit elements and signal paths disclosed in the drawings. For example, a capacitor may be connected between the power amplifier 11 and the low-pass filter 151, or between the power amplifier 12 and the high-pass filter 152.

[0226] Furthermore, for example, each variation of Embodiment 1 may be applied to Embodiment 2. Moreover, Embodiment 1 and Embodiment 2 may be combined. In this case, the high-frequency circuit may include a coupler and a temperature sensor, and the PA control circuit may selectively switch between two power amplifiers based on the phase of the load impedance and the power efficiency of the power amplifiers.

[0227] In the above embodiment 1, the coupler 51 may be connected between the power amplifier 11 and the low-pass filter 151, and between the power amplifier 12 and the high-pass filter 152, respectively. Even in this case, the phase of the load impedance can be estimated based on the output signals of the two couplers 51.

[0228] In each of the above embodiments, the high-frequency circuit may support the reception of signals in band A and / or B. In this case, the high-frequency circuit may include a filter having a passband that includes the reception band of band A and a filter having a passband that includes the reception band of band B, and may also include a low-noise amplifier circuit. Furthermore, the high-frequency circuit may support the transmission and / or reception of signals in bands other than bands A and B.

[0229] This invention can be widely used in communication devices such as mobile phones as a high-frequency circuit placed in the front end.

[0230] 1, 1J High-frequency circuit 2 Antenna 3 RFIC 4 BBIC 5, 5J Communication device 10, 10B, 10C, 10D, 10E, 10F, 10G, 10H, 10J Power amplifier circuit 11, 11E, 12, 12E Power amplifier 13 Quadrature hybrid circuit 14, 14B, 14C, 14D Combination circuit 19 Temperature sensor 21, 22, 23 Matching circuit 31, 32 Switch circuit 41, 42 Filter 51 Coupler 60, 60J PA control circuit 100 Antenna connection terminal 110 High-frequency input terminal 120 Control terminal 130 Power supply voltage terminal 131, 141, 142 Input terminal 132, 133, 143 Output terminal 144, 145, 153, 154 Quarter wavelength transmission line 146, 146C, 147, 147C, 148 Switches 149 Resistors 151, 151D Low-pass filters 152, 152D High-pass filters 161, 162, 164 Inductors 163, 165 Capacitors 173, 174, 175, 175F, 176, 177, 178, 179 Switches 310, 320 Common terminals 311, 312, 321, 322 Select terminals 511 Main line 512 Sub-line 1401 Primary coil 1402 Secondary coil

Claims

1. A high-frequency circuit comprising: a high-frequency input terminal and an antenna connection terminal; a first power amplifier and a second power amplifier; an orthogonal hybrid circuit including a first input terminal connected to the high-frequency input terminal, a first output terminal connected to the input terminal of the first power amplifier, and a second output terminal connected to the input terminal of the second power amplifier; a combining circuit including a second input terminal connected to the output terminal of the first power amplifier, a third input terminal connected to the output terminal of the second power amplifier, and a third output terminal connected to the antenna connection terminal; and a PA control circuit having a first mode for operating the first power amplifier and the second power amplifier and a second mode for selectively switching between operating the first power amplifier and the second power amplifier.

2. The high-frequency circuit according to claim 1, wherein the PA control circuit selectively switches between operating the first power amplifier and the second power amplifier based on the phase of the load impedance in the second mode.

3. The high-frequency circuit according to claim 2, further comprising at least one coupler connected between the output terminals of the first power amplifier and the second power amplifier and the antenna connection terminal, wherein the PA control circuit selectively switches and operates the first power amplifier and the second power amplifier based on the output signal of the at least one coupler.

4. The high-frequency circuit according to claim 1, wherein the PA control circuit selectively switches between operating the first power amplifier and the second power amplifier based on the power efficiency of the first power amplifier and the second power amplifier in the second mode.

5. The high-frequency circuit according to claim 4, further comprising a temperature sensor configured to detect the temperatures of the first power amplifier and the second power amplifier, wherein the PA control circuit selectively switches and operates the first power amplifier and the second power amplifier based on the output signal of the temperature sensor.

6. The high-frequency circuit according to any one of claims 1 to 5, wherein the first mode is a mode for transmitting a high-frequency signal in a first power class, and the second mode is a mode for transmitting a high-frequency signal in a second power class defined by a maximum output power lower than that of the first power class.

7. The high-frequency circuit according to any one of claims 1 to 6, further comprising: a low-pass filter connected between the output terminal of the first power amplifier and the second input terminal of the combining circuit; and a high-pass filter connected between the output terminal of the second power amplifier and the third input terminal of the combining circuit.

8. The high-frequency circuit according to any one of claims 1 to 6, further comprising: a low-pass filter connected between the output terminal of the first power amplifier and the second input terminal of the combining circuit; and a high-pass filter connected between the output terminal of the second power amplifier and the third input terminal of the combining circuit, wherein the combining circuit further comprises: a first transmission line connected between the second input terminal and the third output terminal; a second transmission line connected between the third input terminal and the third output terminal; a third switch connected between the path connecting the second input terminal and the first transmission line and ground; a fourth switch connected between the path connecting the third input terminal and the second transmission line and ground; and a fifth switch and resistor connected in series between the second input terminal and the third input terminal and connected in parallel with the first transmission line and the second transmission line.

9. The high-frequency circuit according to claim 8, wherein in the first mode, the first power amplifier and the second power amplifier are turned on, the third switch and the fourth switch are open, and the fifth switch is closed; in the first connection state of the second mode, the first power amplifier is turned on, the second power amplifier is turned off, the third switch and the fifth switch are open, and the fourth switch is closed; and in the second connection state of the second mode, the first power amplifier is turned off, the second power amplifier is turned on, the third switch is closed, and the fourth switch and the fifth switch are open.

10. The high-frequency circuit according to any one of claims 1 to 6, further comprising: a high-pass filter connected between the output terminal of the first power amplifier and the second input terminal of the combining circuit; a low-pass filter connected between the output terminal of the second power amplifier and the third input terminal of the combining circuit; a sixth switch connected between the path connecting the high-pass filter and the second input terminal and ground; and a seventh switch connected between the path connecting the low-pass filter and the third input terminal and ground, wherein the combining circuit further comprises: a primary coil connected between the second input terminal and the third input terminal; and a secondary coil connected between the third output terminal and ground.

11. In the first mode, the first power amplifier and the second power amplifier are turned on, and the sixth switch and the seventh switch are open; in the first connection state of the second mode, the first power amplifier is turned on, the second power amplifier is turned off, the sixth switch is open, and the seventh switch is closed; in the second connection state of the second mode, the first power amplifier is turned off, the second power amplifier is turned on, the sixth switch is closed, and the seventh switch is open; the high-frequency circuit according to claim 10.

12. The high-frequency circuit according to any one of claims 1 to 6, further comprising: a third transmission line connected between the output terminal of the first power amplifier and the second input terminal of the combining circuit; and an eighth switch connected between the path connecting the first power amplifier and the third transmission line and ground.

13. The high-frequency circuit according to claim 12, wherein in the first mode, the first power amplifier and the second power amplifier are turned on and the eighth switch is open; in the first connection state of the second mode, the first power amplifier is turned on, the second power amplifier is turned off, and the eighth switch is open; and in the second connection state of the second mode, the first power amplifier is turned off, the second power amplifier is turned on, and the eighth switch is closed.

14. The high-frequency circuit according to any one of claims 1 to 6, further comprising: a fourth transmission line connected between the output terminal of the second power amplifier and the third input terminal of the combining circuit; and a ninth switch connected between a path connecting the output terminal of the first power amplifier and the second input terminal and ground; and the combining circuit further comprising: a primary coil connected between the second input terminal and the third input terminal; and a secondary coil connected between the third output terminal and ground.

15. The high-frequency circuit according to claim 14, wherein in the first mode, the first power amplifier and the second power amplifier are turned on and the ninth switch is open; in the first connection state of the second mode, the first power amplifier is turned on, the second power amplifier is turned off, and the ninth switch is open; and in the second connection state of the second mode, the first power amplifier is turned off, the second power amplifier is turned on, and the ninth switch is closed.

16. The high-frequency circuit according to any one of claims 1 to 6, further comprising: a primary coil connected between the second input terminal and the third input terminal; a secondary coil connected between the third output terminal and ground; and the high-frequency circuit further comprising: a tenth switch connected between a power supply and one end of the primary coil; an eleventh switch connected between the power supply and the other end of the primary coil; a twelfth switch connected between the power supply and an intermediate node of the primary coil; an inductor connected between the power supply and the tenth switch, the eleventh switch and the twelfth switch; and a capacitor connected between the path connecting the inductor and the tenth switch, the eleventh switch and the twelfth switch and ground.

17. The high-frequency circuit according to claim 16, wherein in the first mode, the first power amplifier and the second power amplifier are turned on, the 10th switch and the 11th switch are open, and the 12th switch is closed; in the first connection state of the second mode, the first power amplifier is turned on, the second power amplifier is turned off, the 10th switch and the 12th switch are open, and the 11th switch is closed; and in the second connection state of the second mode, the first power amplifier is turned off, the second power amplifier is turned on, the 11th switch and the 12th switch are open, and the 10th switch is closed.

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