High frequency circuit and communication device

Abstract

This high frequency circuit (1) comprises: a 90° hybrid circuit (10) having output terminals (10b and 10c); a combination circuit (30) having input terminals (30b and 30c) and an output terminal (30a); power amplifiers (21 and 22); a switch (41) having common terminals (41a and 41b) and selection terminals (41c and 41d); and filters (51 and 52). The input end of the power amplifier (21) is connected to the output terminal (10b) and the output end is connected to the common terminal (41a). The input end of the power amplifier (22) is connected to the output terminal (10c) and the output end is connected to the common terminal (41b). The input end of the filter (51) is connected to the selection terminal (41c) and the output end is connected to the input terminal (30b). The input end of the filter (52) is connected to the selection terminal (41d) and the output end is connected to the input terminal (30c). The number of elastic wave resonators in the filter (52) is greater than the number of elastic wave resonators in the filter (51).

Description

High-frequency circuits and communication devices

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

[0002] Patent Document 1 discloses a power amplifier circuit configured to amplify an input signal, divide the amplified signal, transmit it through two filters, and finally combine it with a transformer. With this configuration, the divided amplified signal passes through each filter, so the power durability of each filter can be relaxed and filters with steep pass characteristics can be used.

[0003] International Publication No. 2022 / 080393

[0004] With the demand for higher output power in mobile communications, the demand for higher power durability and lower loss in high-frequency circuits having power amplifiers is becoming stricter. Furthermore, in the case of a balanced amplifier or a Doherty amplifier in which the output power of one of the two power amplifiers becomes extremely large, it is difficult to suppress deterioration of filter characteristics and prevent breakdown at high output power by simply distributing the amplified signal to two signal paths and transmitting it, as in the power amplifier circuit disclosed in Patent Document 1.

[0005] The present invention has been made to solve the above-mentioned problems, and has an object to provide a high-frequency circuit and a communication device that can suppress deterioration of filter characteristics and prevent breakdown at high output.

[0006] In order to achieve the above object, a high-frequency circuit according to one aspect of the present invention includes a 90° hybrid circuit having a first input terminal, a first output terminal, and a second output terminal; a combiner circuit having a second input terminal, a third input terminal, and a third output terminal; a first power amplifier and a second power amplifier; a switch having a first common terminal, a second common terminal, a first selection terminal, and a second selection terminal; a first filter including a plurality of acoustic wave resonators and having a passband including a first transmission band; and a second filter including a plurality of acoustic wave resonators and having a passband including the first transmission band. and a filter, wherein the input end of the first power amplifier is connected to the first output terminal, the output end of the first power amplifier is connected to the first common terminal, the input end of the second power amplifier is connected to the second output terminal, the output end of the second power amplifier is connected to the second common terminal, the input end of the first filter is connected to the first selection terminal, the output end of the first filter is connected to the second input terminal, the input end of the second filter is connected to the second selection terminal, and the output end of the second filter is connected to the third input terminal, and the number of elastic wave resonators of the second filter is greater than the number of elastic wave resonators of the first filter.

[0007] According to the present invention, it is possible to provide a high-frequency circuit and a communication device that can suppress deterioration of filter characteristics and prevent breakdown at high output.

[0008] FIG. 1 is a circuit configuration diagram of a high-frequency circuit and a communication device according to an embodiment. FIG. 2A is a diagram showing an example of a circuit configuration of a first filter according to an embodiment. FIG. 2B is a diagram showing an example of a circuit configuration of a second filter according to an embodiment. FIG. 3A is a diagram showing an example of a circuit configuration of a low-pass filter. FIG. 3B is a diagram showing an example of a circuit configuration of a high-pass filter. FIG. 4A is a diagram showing a first example of a circuit configuration of a combiner circuit according to an embodiment. FIG. 4B is a diagram showing a second example of a circuit configuration of a combiner circuit according to an embodiment. FIG. 5A is a circuit configuration diagram of a high-frequency circuit according to an embodiment in a first connection mode. FIG. 5B is a graph showing the relationship between the phase and output power of a power amplifier in the first connection mode. FIG. 6A is a circuit configuration diagram of a high-frequency circuit according to an embodiment in a second connection mode. FIG. 6B is a graph showing the relationship between the phase and output power of a power amplifier in the second connection mode. FIG. 7 is a circuit configuration diagram of a high-frequency circuit according to a first modification of the embodiment. FIG. 8 is a circuit configuration diagram of a high-frequency circuit according to a second modification of the embodiment. FIG. 9 is a plan view showing the component layout of a high-frequency circuit according to an embodiment.

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, arrangements and connection forms of the components shown in the following embodiments are merely examples and are not intended to limit the present invention.

[0010] It should be noted that the drawings are schematic diagrams in which emphasis, omission, or adjustment of proportions has been appropriately made to illustrate the present invention, and are not necessarily strictly illustrated, and may differ from the actual shapes, positional relationships, and proportions. In the drawings, the same reference numerals are used to denote substantially the same components, and redundant explanations may be omitted or simplified.

[0011] In the circuit configuration of the present disclosure, "connected" includes not only direct connection by connection terminals and / or wiring conductors, but also electrical connection via other circuit elements. "Connected between A and B" means connected to both A and B between A and B.

[0012] In addition, in this disclosure, a planar view of a board means that the board and the circuit elements mounted on the board are viewed by orthogonal projection onto a plane parallel to the main surface of the board.

[0013] Furthermore, in the component placement of the present disclosure, "a component is placed on a substrate" includes a component being placed on the main surface of the substrate and a component being placed within the substrate. "A component is placed on the main surface of the substrate" includes a component being placed in contact with the main surface of the substrate, as well as a component being placed above the main surface without contacting the main surface (for example, a component being stacked on another component placed in contact with the main surface). "A component is placed on the main surface of the substrate" may also include a component being placed in a recess formed in the main surface. "A component is placed within the substrate" includes a component being encapsulated within a module substrate, as well as a component being entirely placed between both main surfaces of the substrate but partially not covered by the substrate, and a component being only partially placed within the substrate.

[0014] In addition, in this disclosure, a "path" means a transmission line composed of a wiring through which a high-frequency signal propagates, an electrode directly connected to the wiring, and a terminal directly connected to the wiring or the electrode.

[0015] In addition, in this disclosure, "component A is arranged in series on path B" means that both the signal input terminal and the signal output terminal of component A are connected to wiring, electrodes, or terminals that make up path B.

[0016] In the present invention, the terms "terminal," "input end," and "output end" refer to the points at which conductors within elements terminate. However, if the impedance of the conductor between elements is sufficiently low, a terminal is interpreted as any point on the conductor between elements or the entire conductor, not just a single point.

[0017] Furthermore, terms indicating the relationship between elements, such as "parallel" and "perpendicular," terms indicating the shape of elements, such as "rectangle," and numerical ranges do not only represent strict meanings, but also include substantially equivalent ranges, for example, including an error of a few percent.

[0018] The "passband of a filter" is defined as the portion of the frequency spectrum transmitted by the filter over which the output power is not attenuated by more than 3 dB below the maximum output power. The upper and lower ends of the passband of a bandpass filter are therefore identified as the higher and lower frequencies of the two points at which the output power is attenuated by 3 dB below the maximum output power.

[0019] The term "transmission band" refers to a frequency band used for transmission in a communication device. The term "reception band" refers to a frequency band used for reception in a communication device. For example, in frequency division duplex (FDD), different frequency bands are used as the transmission band and the reception band, while in time division duplex (TDD), the same frequency band is used as the transmission band and the reception band. In particular, in FDD, when a communication device is implemented in a user equipment (UE) of a cellular network, an uplink operation band is used as the transmission band, and a downlink operation band is used as the reception band. Conversely, when a communication device is implemented as a base station (BS) of a cellular network, the downlink band is used as the transmission band, and the uplink band is used as the reception band.

[0020] The "passing phase" of a high frequency signal between two terminals can be obtained by applying a measurement RF probe to the two terminals and measuring the passing characteristic (S21 or S12) with a network analyzer.

[0021] In the present invention, the values ​​of the phase and passing phase of the high frequency signal do not only indicate the strict meaning, but also include a substantially equivalent range, and include a difference of, for example, about 30%.

[0022] Furthermore, one acoustic wave resonator is defined as any one of (1) a resonator configured with a piezoelectric layer and one IDT electrode arranged on one main surface of the piezoelectric layer, (2) a resonator configured with a piezoelectric layer and a pair of IDT electrodes arranged on one main surface and the other main surface of the piezoelectric layer, and (3) a resonator configured with a laminate of a lower electrode, one piezoelectric layer, and an upper electrode. Note that a configuration in which multiple IDT electrodes are arranged on one main surface of the piezoelectric layer is defined as having multiple acoustic wave resonators arranged in a number corresponding to the number of IDT electrodes. Furthermore, a configuration in which multiple different piezoelectric layers are arranged between a lower electrode and an upper electrode is defined as having multiple acoustic wave resonators arranged in a number corresponding to the number of piezoelectric layers.

[0023] Furthermore, an elastic wave resonator (series arm resonator and parallel arm resonator) is defined as any one of the following: (1) a resonant circuit (a parallel connection circuit of an elastic wave resonator and a circuit (or circuit element)) configured with an elastic wave resonator and a circuit (or circuit element) connected in parallel to the elastic wave resonator; (2) a resonant circuit (a series connection circuit of an elastic wave resonator and a circuit (or circuit element)) configured with an elastic wave resonator and a circuit (or circuit element) connected to only one of the two input / output terminals of the elastic wave resonator, where a connection node connecting the elastic wave resonator and the circuit (or circuit element) is not connected to other circuits (and other circuit elements) or ground; (3) a resonant circuit (a parallel connection circuit of split resonators) configured with multiple elastic wave resonators connected in parallel; and (4) a resonant circuit (series connection circuit of split resonators) configured with multiple elastic wave resonators connected in series, where a connection node connecting the multiple elastic wave resonators is not connected to circuits (and circuit elements) other than the multiple elastic wave resonators or ground.

[0024] (Embodiment) [1. Circuit Configuration of High-Frequency Circuit 1 and Communication Device 4] The circuit configuration of a high-frequency circuit 1 and a communication device 4 according to an embodiment will be described with reference to Fig. 1. Fig. 1 is a circuit configuration diagram of the high-frequency circuit 1 and the communication device 4 according to an embodiment.

[0025] [1.1 Circuit Configuration of Communication Device 4] First, a description will be given of the circuit configuration of the communication device 4. As shown in Fig. 1 , the communication device 4 according to the embodiment includes a high-frequency circuit 1, an antenna 2, and an RF signal processing circuit (RFIC: Radio Frequency Integrated Circuit) 3.

[0026] The high-frequency circuit 1 transmits high-frequency signals between the antenna 2 and the RFIC 3. The detailed circuit configuration of the high-frequency circuit 1 will be described later.

[0027] The antenna 2 is connected to the antenna connection terminal 100 of the high frequency circuit 1 and transmits the high frequency signal output from the high frequency circuit 1. The antenna 2 may also receive a high frequency signal from the outside and output it to the high frequency circuit 1.

[0028] The RFIC 3 is an example of a signal processing circuit that processes high-frequency signals. Specifically, the RFIC 3 performs signal processing on a transmission signal input from a baseband signal processing circuit (BBIC, not shown) by up-conversion or the like, and outputs the transmission signal generated by the signal processing to the transmission path of the high-frequency circuit 1. The RFIC 3 may also perform signal processing on a reception signal input via the reception path of the high-frequency circuit 1 by down-conversion or the like, and output the reception signal generated by the signal processing to the BBIC. The RFIC 3 also has a control unit that controls the high-frequency circuit 1. Note that part or all of the functions of the RFIC 3 as the control unit may be implemented outside the RFIC 3, for example, may be implemented in the BBIC or the high-frequency circuit 1. The control circuit 70 included in the high-frequency circuit 1 may also be implemented in the RFIC 3.

[0029] The RFIC 3 may function as a control unit that controls the power supply voltage Vcc and bias voltage Vb supplied to the power amplifiers 21 and 22 included in the high-frequency circuit 1. Specifically, the RFIC 3 may output control signals to a power supply circuit (not shown) and a bias circuit (not shown). The power supply circuit and the bias circuit may be disposed in the high-frequency circuit 1. The power amplifiers 21 and 22 may be supplied with the power supply voltage Vcc controlled by the control signal from the power supply circuit, and may be supplied with the bias voltage Vb controlled by the control signal from the bias circuit.

[0030] In the communication device 4 according to this embodiment, the antenna 2 is not an essential component.

[0031] 1.2 Circuit Configuration of High-Frequency Circuit 1 Next, a description will be given of the circuit configuration of the high-frequency circuit 1. As shown in Fig. 1 , the high-frequency circuit 1 includes a 90° hybrid circuit 10, power amplifiers 21 and 22, a combining circuit 30, phase-shift circuits 57 and 58, a switch 41, a coupler 60, filters 51 and 52, a control circuit 70, an antenna connection terminal 100, and a signal input terminal 110.

[0032] The antenna connection terminal 100 is connected to the antenna 2. The signal input terminal 110 is connected to the RFIC 3. The antenna connection terminal 100 and the signal input terminal 110 do not necessarily have to be included in the high-frequency circuit 1.

[0033] The 90° hybrid circuit 10 has an input terminal 10a (first input terminal), an output terminal 10b (first output terminal), and an output terminal 10c (second output terminal), and is configured so that the phase difference between a first output signal output from the output terminal 10b and a second output signal output from the output terminal 10c is 90°. In this embodiment, the first output signal output from the output terminal 10b leads the second output signal output from the output terminal 10c by 90°.

[0034] The power amplifier 21 is an example of a first power amplifier and is capable of amplifying signals in the first band. The input terminal of the power amplifier 21 is connected to the output terminal 10b, and the output terminal of the power amplifier 21 is connected to the common terminal 41a of the switch 41 via the phase shift circuit 57.

[0035] The power amplifier 22 is an example of a second power amplifier and is capable of amplifying signals in the first band. The input terminal of the power amplifier 22 is connected to the output terminal 10c, and the output terminal of the power amplifier 22 is connected to the common terminal 41b of the switch 41 via the phase shift circuit 58.

[0036] Each of the power amplifiers 21 and 22 includes an amplifying transistor. The amplifying transistor may be, for example, a bipolar transistor such as a heterojunction bipolar transistor (HBT) or a field-effect transistor such as a metal-oxide-semiconductor field-effect transistor (MOSFET). If the amplifying transistor is a bipolar transistor, the input terminals of the power amplifiers 21 and 22 are, for example, the base terminals of the bipolar transistors, and the output terminals of the power amplifiers 21 and 22 are, for example, the collector terminals of the bipolar transistors. If the amplifying transistors are field-effect transistors, the input terminals of the power amplifiers 21 and 22 are, for example, the gate terminals of the field-effect transistors, and the output terminals of the power amplifiers 21 and 22 are, for example, the drain terminals of the field-effect transistors.

[0037] The filter 51 is an example of a first filter, includes a plurality of acoustic wave resonators, and has a pass band that includes the transmission band of the first band. The input terminal of the filter 51 is connected to the selection terminal 41 c of the switch 41, and the output terminal of the filter 51 is connected to the input terminal 30 b of the combining circuit 30.

[0038] The filter 52 is an example of a second filter, includes a plurality of acoustic wave resonators, and has a pass band that includes the transmission band of the first band. The input terminal of the filter 52 is connected to the selection terminal 41 d of the switch 41, and the output terminal of the filter 52 is connected to the input terminal 30 c of the combining circuit 30.

[0039] Fig. 2A is a diagram showing an example of the circuit configuration of a filter 51 according to an embodiment, and Fig. 2B is a diagram showing an example of the circuit configuration of a filter 52 according to an embodiment.

[0040] 2A , the filter 51 includes series arm resonators 511 and 512 and a parallel arm resonator 513. The series arm resonators 511 and 512 are each an example of an acoustic wave resonator and are arranged in series in a series arm path connecting the input terminal 51 a and the output terminal 51 b. The parallel arm resonator 513 is also an example of an acoustic wave resonator and is connected between the connection node of the series arm resonators 511 and 512 and ground. With the above configuration, the filter 51 forms a so-called T-type ladder acoustic wave filter.

[0041] 2B , the filter 52 includes series arm resonators 521, 522, 523, and 524, and a parallel arm resonator 525. Each of the series arm resonators 521 to 524 is an example of an acoustic wave resonator, and is arranged in series in a series arm path connecting the input terminal 52a and the output terminal 52b. The parallel arm resonator 525 is an example of an acoustic wave resonator, and is connected between the connection node of the series arm resonators 522 and 523 and ground. With the above configuration, the filter 52 forms a so-called T-type ladder acoustic wave filter.

[0042] The filters 51 and 52 are designed to have substantially the same pass characteristics. Each of the series arm resonators 521 and 522 corresponds to a series split resonator of the series arm resonator 511, and the combined capacitance of the series arm resonators 521 and 522 is substantially equal to the capacitance of the series arm resonator 511. As a result, the total size of the series arm resonators 521 and 522 is approximately four times the size of the series arm resonator 511. Each of the series arm resonators 523 and 524 corresponds to a series split resonator of the series arm resonator 512, and the combined capacitance of the series arm resonators 523 and 524 is substantially equal to the capacitance of the series arm resonator 512. As a result, the total size of the series arm resonators 523 and 524 is approximately four times the size of the series arm resonator 512. As a result, the filter 52 is larger than the filter 51, and the filter 52 has better power handling performance than the filter 51.

[0043] Note that the filter 52 may have a configuration in which at least one of the series arm resonators 511, 512 and the parallel arm resonator 513 included in the filter 51 is split in series. Furthermore, the filter 52 does not need to have a split resonator, and it is sufficient that the number of elastic wave resonators included in the filter 52 is greater than the number of elastic wave resonators included in the filter 51. For example, the filter 51 shown in FIG. 2A has three elastic wave resonators, while the filter 52 shown in FIG. 2B has five elastic wave resonators, and the number of elastic wave resonators in the filter 52 is greater than the number of elastic wave resonators in the filter 51. This allows the filter 52 to have improved power handling performance compared to the filter 51.

[0044] In the present disclosure, the first band refers to a frequency band predefined by a standardization organization (e.g., 3GPP (registered trademark: 3rd Generation Partnership Project), IEEE (Institute of Electrical and Electronics Engineers), etc.) for a communication system built using radio access technology (RAT). In this embodiment, the communication system may be, for example, a 4G-LTE (Long Term Evolution) system, a 5G-NR (New Radio) system, and a WLAN (Wireless Local Area Network) system, but is not limited to these.

[0045] 1, the phase shift circuit 57 is connected between the output terminal of the power amplifier 21 and the common terminal 41a. The phase shift circuit 57 shifts the phase of the output signal output from the phase shift circuit 57 relative to the input signal input to the phase shift circuit 57. The phase shift circuit 57 is, for example, a low-pass filter or a high-pass filter.

[0046] 1, the phase shift circuit 58 is connected between the output end of the power amplifier 22 and the common terminal 41b. The phase shift circuit 58 shifts the phase of the output signal output from the phase shift circuit 58 relative to the input signal input to the phase shift circuit 58. The phase shift circuit 58 is, for example, a high-pass filter or a low-pass filter.

[0047] FIG. 3A is a diagram illustrating an example circuit configuration of the low-pass filter 31. The low-pass filter 31 (LPF) has, for example, a configuration in which an inductor 311 is connected in series to a series arm path connecting an input terminal 31a and an output terminal 31b, and a capacitor 312 is connected between the series arm path and ground. Note that the low-pass filter 31 may have either a configuration in which the inductor 311 is connected in series to the series arm path or a configuration in which the capacitor 312 is connected between the series arm path and ground. The low-pass filter 31 attenuates signals with frequencies higher than a predetermined frequency and transmits signals with low loss with frequencies lower than the predetermined frequency. The low-pass filter 31 is also configured to have a transmission phase of −45° (the phase at the output terminal lags behind the phase at the input terminal by 45°).

[0048] 3B is a diagram showing an example circuit configuration of the high-pass filter 32. The high-pass filter 32 (HPF) has, for example, a configuration in which a capacitor 321 is connected in series to a series arm path connecting an input terminal 32a and an output terminal 32b, and an inductor 322 is connected between the series arm path and ground. Note that the high-pass filter 32 may have either a configuration in which the capacitor 321 is connected in series to the series arm path or a configuration in which the inductor 322 is connected between the series arm path and ground. The high-pass filter 32 attenuates signals with frequencies lower than a predetermined frequency and transmits signals with high frequencies higher than the predetermined frequency with low loss. The high-pass filter 32 is also configured so that the passing phase is +45° (the phase at the output terminal leads the phase at the input terminal by 45°).

[0049] As shown in FIG. 1, the combining circuit 30 has an input terminal 30b (second input terminal), an input terminal 30c (third input terminal), and an output terminal 30a (third output terminal), and is configured to combine a first input signal input to the input terminal 30b and a second input signal input to the input terminal 30c, and output the combined output signal from the output terminal 30a.

[0050] FIG. 4A illustrates a first exemplary circuit configuration of the combining circuit 30 according to the embodiment. In the first exemplary circuit configuration, the input terminals 30b and 30c are directly connected to the output terminal 30a. In this case, a low-pass filter 31 is used as the phase-shift circuit 57, and a high-pass filter 32 is used as the phase-shift circuit 58. With the above configuration, for example, a first output signal of 90° is output from the output terminal 10b, a second output signal of 0° is output from the output terminal 10c, the first output signal passes through the low-pass filter 31, and becomes a first input signal of +45° phase at the input terminal 30b. The second output signal passes through the high-pass filter 32, and becomes a second input signal of +45° phase at the input terminal 30c. Then, the first input signal of +45° phase and the second input signal of +45° phase are in-phase combined at the output terminal 30a, and the combined output signal is output from the output terminal 30a. The combining circuit 30 may also include phase-shift circuits 57 and 58. That is, the phase shift circuit 57 may be connected between the input terminal 30b and the output terminal 30a, and the phase shift circuit 58 may be connected between the input terminal 30c and the output terminal 30a.

[0051] According to the above configuration, the high-frequency circuit 1 has a phase difference of 90° between the signal at the output end of power amplifier 21 and the signal at the output end of power amplifier 22, and a phase difference of 0° between the first input signal and the second input signal at output terminal 30 a, so that the high-frequency circuit 1 can operate as a current-combining balanced amplifier that is resistant to load fluctuations.

[0052] FIG. 4B illustrates a second exemplary circuit configuration of a combining circuit 30A according to an embodiment. In the second exemplary circuit configuration, the combining circuit 30A includes a transformer 33. The transformer 33 has an input coil and an output coil that are magnetically coupled to each other. One end of the input coil is connected to the input terminal 30b, and the other end of the input coil is connected to the input terminal 30c. One end of the output coil is connected to the output terminal 30a, and the other end of the output coil is connected to ground. In this case, a high-pass filter 32 is used as the phase shift circuit 57, and a low-pass filter 31 is used as the phase shift circuit 58. With the above configuration, for example, a first output signal of 90° is output from the output terminal 10b, and a second output signal of 0° is output from the output terminal 10c. The first output signal passes through the high-pass filter 32 to become a first input signal of +135° phase at the input terminal 30b, and the second output signal passes through the low-pass filter 31 to become a second input signal of -45° phase at the input terminal 30c. The transformer 33 then differentially combines (opposite phase) the first input signal with a phase of +135° and the second input signal with a phase of −45°, and the combined output signal is output from the output terminal 30a. The combining circuit 30A may include phase shift circuits 57 and 58. That is, the phase shift circuit 57 may be connected between the input terminal 30b and one end of the input coil, and the phase shift circuit 58 may be connected between the input terminal 30c and the other end of the input coil.

[0053] According to the above configuration, the high-frequency circuit 1 has a phase difference of 90° between the signal at the output end of the power amplifier 21 and the signal at the output end of the power amplifier 22, and a phase difference of approximately 180° between the first input signal and the second input signal at the input side coil, so it can operate as a voltage-combining type balanced amplifier that is resistant to load fluctuations.

[0054] 1 , the switch 41 has a common terminal 41 a (first common terminal), a common terminal 41 b (second common terminal), a selection terminal 41 c (first selection terminal), and a selection terminal 41 d (second selection terminal). The common terminal 41 a is connected to the output terminal of the power amplifier 21 via a phase shift circuit 57, the common terminal 41 b is connected to the output terminal of the power amplifier 22 via a phase shift circuit 58, the selection terminal 41 c is connected to the input terminal of the filter 51, and the selection terminal 41 d is connected to the input terminal of the filter 52.

[0055] In this connection configuration, the switch 41 is configured to be switchable between a first connection mode in which the common terminal 41a is connected to the selection terminal 41c and the common terminal 41b is connected to the selection terminal 41d, and a second connection mode in which the common terminal 41a is connected to the selection terminal 41d and the common terminal 41b is connected to the selection terminal 41c.

[0056] Because there is a phase difference of 90° between the first output signal of power amplifier 21 and the second output signal of power amplifier 22, there is a phase difference of approximately 180° between the impedance seen from the output terminal of power amplifier 21 toward combiner circuit 30 and the impedance seen from the output terminal of power amplifier 22 toward combiner circuit 30. Therefore, when one of power amplifiers 21 and 22 has a high impedance, the other has a low impedance. With the above-described configuration of high-frequency circuit 1, by switching switch 41 to connect high-power-tolerant filter 52 to the output terminal of one of the power amplifiers that has a low impedance, it is possible to suppress deterioration of the pass characteristics of filters 51 and 52 and prevent their breakdown at high output power.

[0057] The coupler 60 is a directional coupler and is arranged on a common signal path connecting the antenna connection terminal 100 and the output terminal 30a. This allows a single coupler 60 to detect a signal obtained by combining the first output signal of the power amplifier 21 and the second output signal of the power amplifier 22, thereby enabling the high-frequency circuit 1 to be miniaturized. The coupler 60 can detect a forward-direction high-frequency signal traveling along the common signal path from the output terminal 30a to the antenna connection terminal 100, and a reflected signal traveling in the reverse direction from the antenna connection terminal 100 to the output terminal 30a. The circuit configuration of the coupler 60 is not particularly limited, and examples thereof include a branch-line coupler, a rat-race coupler, and a coupled-line coupler.

[0058] The control circuit 70 is connected between the coupler 60 and the switch 41. The control circuit 70 is connected to the coupler 60 via a high-frequency transmission line and to the switch 41 via a control wiring. This allows the control circuit 70 to output a control signal to the switch 41 based on a detection signal detected by the coupler 60. The control circuit 70 is included in, for example, a semiconductor IC. The semiconductor IC may include, for example, a control circuit that controls the power supply voltage Vcc and bias voltage Vb supplied to the power amplifiers 21 and 22. The semiconductor IC may be configured using, for example, a complementary metal oxide semiconductor (CMOS) and, more specifically, may be manufactured using an SOI (silicon-on-insulator) process. The semiconductor IC may also be configured of at least one of GaAs, SiGe, and GaN. Note that the semiconductor material of the semiconductor IC is not limited to the above-mentioned materials. The control circuit 70 does not necessarily have to be included in the high-frequency circuit 1, but may instead be included in the RFIC 3.

[0059] Control circuit 70 receives signals corresponding to the forward-direction (forward mode) high-frequency signal and the reverse-direction (reverse mode) reflected signal detected by coupler 60, and calculates the output impedance of power amplifiers 21 and 22 based on the VSWR (voltage standing wave ratio) and phase difference. This makes it possible to match the output impedance of power amplifiers 21 and 22 with the switching of switch 41.

[0060] 5A is a circuit configuration diagram of the high-frequency circuit 1 according to the embodiment in the first connection mode. The control circuit 70 operates the switch 41 in the first connection mode when the calculated output impedance of the power amplifier 22 is smaller than the calculated output impedance of the power amplifier 21. In other words, when the calculated output impedance of the power amplifier 22 is smaller than the calculated output impedance of the power amplifier 21, the control circuit 70 determines that the output power P2 of the power amplifier 22 is greater than the output power P1 of the power amplifier 21, and operates the switch 41 in the first connection mode.

[0061] 5B is a graph showing the relationship between the phase and output power of the power amplifier in the first connection mode. The horizontal axis of FIG. 5B represents the phase of the impedance seen from the output terminal 30a toward the antenna 2, while the vertical axis represents the output power P1 of the power amplifier 21, the output power P2 of the power amplifier 22, and the output power P3 of the output terminal 30a. The impedance seen from the output terminal 30a toward the antenna 2 (hereinafter referred to as the antenna terminal impedance), the impedance seen from the output terminal of the power amplifier 21 toward the combining circuit 30 (hereinafter referred to as the output impedance of the power amplifier 21), and the impedance seen from the output terminal of the power amplifier 22 toward the combining circuit 30 (hereinafter referred to as the output impedance of the power amplifier 22) are calculated from the forward-mode high-frequency signal and the reverse-mode reflected signal detected by the coupler 60. Depending on the phase of the antenna terminal impedance, the output impedances of the power amplifiers 21 and 22 change while maintaining a phase difference of 180°. The output power P1 of the power amplifier 21 increases as the output impedance of the power amplifier 21 decreases, and the output power P2 of the power amplifier 22 increases as the output impedance of the power amplifier 22 decreases. As a result, as shown in Fig. 5B, the output power P1 of the power amplifier 21 and the output power P2 of the power amplifier 22 fluctuate periodically and complementarily with respect to the phase change of the antenna end impedance, and the output power P3 of the output terminal 30a does not change much with respect to the phase change of the antenna end impedance and remains stable.

[0062] The circuit state (first connection mode) of Figure 5A is, for example, the circuit state when the phase of the antenna end impedance in Figure 5B is 200°, and is a state in which the output power P2 of the power amplifier 22 is greater than the output power P1 of the power amplifier 21.

[0063] According to the connection configuration (first connection mode) of the high-frequency circuit 1 shown in FIG. 5A , the filter 52 with high power durability is connected to the output end of the power amplifier 22, which has a relatively high output, and therefore, it is possible to suppress deterioration of the pass characteristics of the filter 52 and prevent damage to the filter 52 when a high-output signal is input.

[0064] 6A is a circuit configuration diagram of the high-frequency circuit 1 according to the embodiment in the second connection mode. The control circuit 70 operates the switch 41 in the second connection mode when the calculated output impedance of the power amplifier 21 is smaller than the calculated output impedance of the power amplifier 22. In other words, when the calculated output impedance of the power amplifier 21 is smaller than the calculated output impedance of the power amplifier 22, the control circuit 70 determines that the output power P1 of the power amplifier 21 is greater than the output power P2 of the power amplifier 22, and operates the switch 41 in the second connection mode.

[0065] 6B is a graph showing the relationship between the phase and output power of the power amplifier in the second connection mode. The horizontal axis of Fig. 6B represents the phase of the impedance when viewed from output terminal 30a toward antenna 2, and the vertical axis represents output power P1 of power amplifier 21, output power P2 of power amplifier 22, and output power P3 of output terminal 30a.

[0066] The circuit state (second connection mode) of Figure 6A is, for example, the circuit state when the phase of the antenna end impedance in Figure 6B is 35°, and is a state in which the output power P1 of the power amplifier 21 is greater than the output power P2 of the power amplifier 22.

[0067] According to the connection configuration (second connection mode) of the high-frequency circuit 1 shown in FIG. 6A , the filter 52 with high power durability is connected to the output end of the power amplifier 21, which has a relatively high output, so that it is possible to suppress deterioration of the pass characteristics of the filter 52 and prevent damage to the filter 52 when a high-output signal is input.

[0068] At least one of the coupler 60 and the control circuit 70 does not have to be included in the high-frequency circuit 1 .

[0069] Furthermore, the high-frequency circuit 1 according to this embodiment operates as a balanced amplifier, but can also operate as a Doherty amplifier. In this case, for example, the second output signal output from the output terminal 10c of the 90° hybrid circuit 10 is delayed in phase by 90° from the first output signal output from the output terminal 10b. The power amplifier 21 is, for example, a carrier amplifier, and the power amplifier 22 is, for example, a peaking amplifier. The phase shift circuits 57 and 58 are not provided, and the combining circuit 30 includes, for example, a phase shift line connected between the output end of the power amplifier 21 and the output terminal 30a. The phase shift line is configured to delay the output signal of the power amplifier 21 by 90° and is, for example, a quarter-wave transmission line. For example, one end of the quarter-wave transmission line is connected to a signal path connecting the output end of the power amplifier 21 and the input terminal 30b, the other end of the quarter-wave transmission line is connected to the output terminal 30a, and the input terminal 30c is connected to the output terminal 30a. As a result, the first output signal of the power amplifier 21 and the second output signal of the power amplifier 22 are combined in phase at the output terminal 30a. Alternatively, the phase shift circuits 57 and 58 are not provided, and the combining circuit 30 includes, for example, a transformer having an input coil and an output coil, and a phase shift line. One end of the input coil is connected to the output end of the power amplifier 21. The phase shift line is connected between the output end of the power amplifier 22 and the other end of the input coil. One end of the output coil is connected to the output terminal 30a, and the other end of the output coil is connected to ground. The phase shift line is configured to delay the output signal of the power amplifier 22 by 90° and is, for example, a quarter-wave transmission line. As a result, the first output signal of the power amplifier 21 and the second output signal of the power amplifier 22 are combined differentially (out of phase) at the output terminal 30a. This makes it possible to suppress deterioration of the pass characteristics of the filters 51 and 52 and prevent breakdown at high output power in the Doherty high-frequency circuit 1.

[0070] [2 Configuration of High-Frequency Circuit 1A According to Modification 1] Next, the configuration of the high-frequency circuit 1A according to Modification 1 will be described. FIG. 7 is a circuit configuration diagram of the high-frequency circuit 1A according to Modification 1. As shown in the figure, the high-frequency circuit 1A includes a 90° hybrid circuit 10, power amplifiers 21 and 22, a combining circuit 30, phase-shift circuits 57 and 58, a switch 41, couplers 61 and 62, filters 51 and 52, a control circuit 70, an antenna connection terminal 100, and a signal input terminal 110. The high-frequency circuit 1A according to Modification 1 differs from the high-frequency circuit 1 according to the embodiment in the arrangement of the couplers 61 and 62. Therefore, the following description of the high-frequency circuit 1A according to this modification will omit a description of the same configuration as the high-frequency circuit 1 according to the embodiment, and will focus on the different configuration.

[0071] The coupler 61 is a directional coupler and is disposed on a first signal path connecting the output end of the power amplifier 21 and the input terminal 30b. The coupler 61 can detect a high-frequency signal traveling in the forward direction along the first signal path from the power amplifier 21 to the combining circuit 30.

[0072] The coupler 62 is a directional coupler and is arranged on a second signal path connecting the output end of the power amplifier 22 and the input terminal 30c. The coupler 62 can detect a high-frequency signal traveling in the forward direction along the second signal path from the power amplifier 22 to the combining circuit 30.

[0073] The control circuit 70 is connected between the couplers 61 and 62 and the switch 41. The control circuit 70 is connected to the couplers 61 and 62 via high-frequency transmission lines, and to the switch 41 via control wiring. This allows the control circuit 70 to output a control signal to the switch 41 based on the detection signals detected by the couplers 61 and 62.

[0074] Control circuit 70 receives a signal corresponding to the forward direction (forward mode) high frequency signal detected by coupler 61, and also receives a signal corresponding to the forward direction (forward mode) high frequency signal detected by coupler 62, and calculates the output impedance of power amplifiers 21 and 22.

[0075] With this, the first output signal of power amplifier 21 and the second output signal of power amplifier 22 are detected individually by couplers 61 and 62, respectively, allowing control circuit 70 to calculate the output impedances of power amplifiers 21 and 22 with high accuracy. Furthermore, only forward mode detection by couplers 61 and 62 is required, simplifying the detection process by couplers 61 and 62. This makes it possible to suppress deterioration of the pass characteristics of filters 51 and 52 and prevent breakdown at high output power.

[0076] [3 Configuration of High-Frequency Circuit 1B According to Modification 2] Next, the configuration of the high-frequency circuit 1B according to Modification 2 will be described. FIG. 8 is a circuit configuration diagram of the high-frequency circuit 1B according to Modification 2. As shown in the figure, the high-frequency circuit 1B includes a 90° hybrid circuit 10, power amplifiers 21 and 22, a combining circuit 30, phase-shift circuits 57 and 58, a switch 41, a coupler 62, filters 51 and 52, a control circuit 70, an antenna connection terminal 100, and a signal input terminal 110. The high-frequency circuit 1B according to Modification 2 differs from the high-frequency circuit 1A according to Modification 1 in that the coupler 61 is not provided. Therefore, the following description of the high-frequency circuit 1B according to this modification will omit a description of the same configuration as the high-frequency circuit 1A according to Modification 1, and will focus on the different configuration.

[0077] The coupler 62 is a directional coupler and is arranged on a second signal path connecting the output end of the power amplifier 22 and the input terminal 30c. The coupler 62 can detect a high-frequency signal traveling in the forward direction along the second signal path from the power amplifier 22 to the combining circuit 30.

[0078] The control circuit 70 is connected between the coupler 62 and the switch 41. The control circuit 70 is connected to the coupler 62 via a high-frequency transmission line, and to the switch 41 via a control wiring. This allows the control circuit 70 to output a control signal to the switch 41 based on the detection signal detected by the coupler 62.

[0079] The control circuit 70 receives a signal corresponding to the forward direction (forward mode) high frequency signal detected by the coupler 62 and calculates the output impedance of the power amplifiers 21 and 22 .

[0080] Because there is a phase difference of 180° between the output impedance of power amplifier 21 and the output impedance of power amplifier 22, calculating the output impedance of one of power amplifiers 21 and 22 makes it possible to estimate the output impedance of the other. Therefore, by detecting the second output signal of power amplifier 22 with coupler 62, it becomes possible to calculate not only the output impedance of power amplifier 22 but also the output impedance of power amplifier 21. In this way, since the output impedances of both power amplifiers 21 and 22 can be calculated, it is possible to suppress deterioration of the pass characteristics of filters 51 and 52 and prevent breakdown at high output.

[0081] Note that, instead of arranging the coupler 62 in the second signal path, the coupler 61 may be arranged in the first signal path.

[0082] [4 Component Layout of High-Frequency Circuit 1] Next, the component layout of the high-frequency circuit 1 according to this embodiment will be described. Fig. 9 is a plan view showing the component layout of the high-frequency circuit 1 according to this embodiment. Fig. 9 shows the layout of circuit components when the main surface of a module substrate 90 is viewed from the positive z-axis direction. Note that Fig. 9 does not show the module substrate 90 and the wiring connecting the circuit components. Also, Fig. 9 includes marks indicating the functions of the circuit components to facilitate understanding of their layout relationships, but these marks are not attached to the actual circuit components.

[0083] The high-frequency circuit 1 shown in FIG. 9 further comprises a module substrate 90 and a shielding metal layer 95 in addition to the components of the high-frequency circuit 1 shown in FIG.

[0084] The module substrate 90 is a substrate on which circuit components that constitute the high-frequency circuit 1 are mounted. Examples of the module substrate 90 that can be used include a substrate made of a ceramic element formed by low-temperature co-fired ceramics (LTCC) having a laminated structure of multiple dielectric layers, a substrate made of a ceramic element formed by high-temperature co-fired ceramics (HTCC), a component-embedded substrate, a substrate having a redistribution layer (RDL), a printed circuit board, etc.

[0085] 9, power amplifiers 21 and 22, filters 51 and 55, switch 41, and phase shift circuits 57 and 58 are arranged on the main surface of module substrate 90. Note that in Fig. 9, power amplifiers 21 and 22, filters 51 and 55, switch 41, and phase shift circuits 57 and 58 are each arranged on the main surface of module substrate 90 on the positive side of the z axis, but at least a portion of them may be arranged on the main surface of module substrate 90 on the negative side of the z axis, or inside module substrate 90.

[0086] Although not shown in FIG. 9, the 90° hybrid circuit 10, the combining circuit 30, the coupler 60, the control circuit 70, the antenna connection terminal 100, and the signal input terminal 110 may be disposed on the module substrate 90.

[0087] According to the above configuration, the circuit elements that make up the high frequency circuit 1 are mounted on one module substrate 90, so that the high frequency circuit 1 can be made smaller.

[0088] Although the filters 51 and 52 are formed on different substrates, they may also be formed on a common substrate. For example, if the filters 51 and 52 are surface acoustic wave filters, the filters 51 and 52 may be formed on a common piezoelectric substrate, or if the filters 51 and 52 are bulk acoustic wave filters, the filters 51 and 52 may be formed on a common silicon substrate.

[0089] The power amplifiers 21 and 22 are included in a semiconductor IC 81. The switch 41 and the phase shift circuits 57 and 58 are included in a semiconductor IC .

[0090] The semiconductor ICs 81 and 82 may be configured using, for example, a complementary metal oxide semiconductor (CMOS), and more specifically, may be manufactured using an SOI (silicon on insulator) process. The semiconductor ICs 81 and 82 may also be configured using at least one of GaAs, SiGe, and GaN. The semiconductor materials of the semiconductor ICs 81 and 82 are not limited to the above-mentioned materials.

[0091] Note that power amplifiers 21 and 22 do not necessarily have to be included in semiconductor IC 81, and may be individually arranged on the main surface of module substrate 90. Furthermore, power amplifiers 21 and 22 may be included in different semiconductor ICs.

[0092] Furthermore, the switch 41 and the phase shift circuits 57 and 58 do not have to be included in the semiconductor IC 82, and may be individually arranged on the main surface of the module substrate 90. The switch 41 and the phase shift circuits 57 and 58 may be included in different semiconductor ICs.

[0093] When the module substrate 90 is viewed from above, the shielding metal layer 95 is disposed so as to surround the module substrate 90. The shielding metal layer 95 may be set to ground potential, which improves the electromagnetic wave shielding effect.

[0094] A resin member may be disposed on the module substrate 90 so as to cover the circuit components described above. When a resin member is disposed on the module substrate 90, the shield metal layer 95 is disposed so as to cover the resin member.

[0095] As shown in FIG. 9, the distance D between the filter 52 and the power amplifiers 21 and 22 is Ｐ２ is the distance D between the filter 51 and the power amplifiers 21 and 22. Ｐ１This makes it possible to prevent the heat generated from power amplifiers 21 and 22 from flowing into filter 52, thereby improving the power durability of filter 52.

[0096] As shown in FIG. 9, the distance D between the filter 52 and the shield metal layer 95 Ｇ２ is the distance D between the filter 51 and the shield metal layer 95 Ｇ１ This improves heat dissipation from the filter 52 to the shield metal layer 95, thereby improving the power durability of the filter 52.

[0097] When filters 51 and 52 are mounted on a common substrate, the distance between filter 51 or 52 and the circuit elements is defined as the distance between the circuit elements and an area including the IDT electrodes and the wiring electrodes connected to the IDT electrodes if filter 51 or 52 has an IDT electrode. Also, when filter 51 or 52 has a laminate of an upper electrode, a piezoelectric layer, and a lower electrode, the distance is defined as the distance between the circuit elements and an area including the laminate and the wiring electrodes connected to the upper electrode and the lower electrode.

[0098] Furthermore, when power amplifiers 21 and 22 are included in semiconductor IC 81, the distance between power amplifiers 21 and 22 and the circuit elements is defined as the distance between semiconductor IC 81 and the circuit elements. Furthermore, when power amplifiers 21 and 22 are arranged separately, the distance between power amplifiers 21 and 22 and the circuit elements is defined as the smaller of the distance between power amplifier 21 and the circuit elements and the distance between power amplifier 22 and the circuit elements.

[0099] The shield metal layer 95 may include a shield top surface portion arranged to sandwich the filters 51 and 52 between itself and the main surface of the module substrate 90, and a shield side surface portion arranged to surround the module substrate 90 when the module substrate 90 is viewed in plan. In this case, the filter 52 may be in contact with the shield top surface portion. This improves heat dissipation from the filter 52 to the shield metal layer 95, thereby improving the power durability of the filter 52.

[0100] [5. Effects, etc.] As described above, the high-frequency circuit 1 according to the embodiment includes: 90° hybrid circuit 10 having input terminal 10a and output terminals 10b and 10c; combiner circuit 30 having input terminals 30b and 30c and output terminal 30a; power amplifiers 21 and 22; switch 41 having common terminals 41a and 41b and selection terminals 41c and 41d; filter 51 including a plurality of acoustic wave resonators and having a pass band that includes a first transmission band; and filter 52 including a plurality of acoustic wave resonators and having a pass band that includes the first transmission band. an input terminal of the power amplifier 21 connected to the output terminal 10b, an output terminal of the power amplifier 21 connected to the common terminal 41a, an input terminal of the power amplifier 22 connected to the output terminal 10c, an output terminal of the power amplifier 22 connected to the common terminal 41b, an input terminal of the filter 51 connected to the selection terminal 41c, an output terminal of the filter 51 connected to the input terminal 30b, an input terminal of the filter 52 connected to the selection terminal 41d, an output terminal of the filter 52 connected to the input terminal 30c, and the number of elastic wave resonators of the filter 52 is greater than the number of elastic wave resonators of the filter 51.

[0101] According to this, by switching switch 41 and connecting filter 52 with high power resistance to the output terminal of one of the power amplifiers that has low impedance, it is possible to suppress deterioration of the pass characteristics of filters 51 and 52 and prevent breakdown at high output.

[0102] For example, the high-frequency circuit 1 further includes an antenna connection terminal 100 connected to the output terminal 30a, a coupler 60 arranged in at least one of a first signal path connecting the output terminal of the power amplifier 21 and the antenna connection terminal 100 and a second signal path connecting the output terminal of the power amplifier 22 and the antenna connection terminal 100, and a control circuit 70 connected between the coupler 60 and the switch 41.

[0103] This allows the control circuit 70 to output a control signal to the switch 41 based on the detection signal detected by the coupler 60 .

[0104] Furthermore, for example, in the high-frequency circuit 1, the coupler 60 is disposed on a common signal path connecting the output terminal 30a and the antenna connection terminal 100.

[0105] According to this, the signal obtained by combining the first output signal of the power amplifier 21 and the second output signal of the power amplifier 22 is detected by one coupler 60, so that the high frequency circuit 1 can be made smaller.

[0106] Furthermore, for example, in the high-frequency circuit 1B according to the second modification, the coupler 62 is disposed in the second signal path connecting the output end of the power amplifier 22 and the input terminal 30c.

[0107] Because the output impedance of power amplifier 21 and the output impedance of power amplifier 22 have a phase difference of 180°, calculating the output impedance of one of power amplifiers 21 and 22 allows the output impedance of the other to be estimated. Therefore, by detecting the output signal of power amplifier 22 using coupler 62, it is possible to calculate not only the output impedance of power amplifier 22 but also the output impedance of power amplifier 21. Furthermore, only forward mode detection by coupler 62 is required, simplifying the detection process by coupler 62. Since the output impedances of both power amplifiers 21 and 22 can be calculated, it is possible to suppress deterioration in the pass characteristics of filters 51 and 52 and prevent breakdown at high output power.

[0108] Also, for example, in the high-frequency circuit 1, the coupler 60 detects a forward signal traveling from the output terminal 30a to the antenna connection terminal 100 and a reverse reflected signal traveling from the antenna connection terminal 100 to the output terminal 30a, and the control circuit 70 calculates the output impedance of the power amplifiers 21 and 22 from the forward signal and the reverse reflected signal detected by the coupler 60.

[0109] This allows the output impedance of the power amplifiers 21 and 22 to correspond to the switching of the switch 41 .

[0110] For example, in the high-frequency circuit 1, the switch 41 is configured to be switchable between a first connection mode in which the common terminal 41a is connected to the selection terminal 41c and the common terminal 41b is connected to the selection terminal 41d, and a second connection mode in which the common terminal 41a is connected to the selection terminal 41d and the common terminal 41b is connected to the selection terminal 41c.

[0111] Also, for example, in the high-frequency circuit 1, the control circuit 70 operates the switch 41 in the first connection mode when the calculated output impedance of the power amplifier 22 is smaller than the calculated output impedance of the power amplifier 21, and operates the switch 41 in the second connection mode when the calculated output impedance of the power amplifier 21 is smaller than the calculated output impedance of the power amplifier 22.

[0112] According to this, in the first connection mode, the filter 52 with high power durability is connected to the output terminal of the power amplifier 22, which has a relatively high output, and in the second connection mode, the filter 52 with high power durability is connected to the output terminal of the power amplifier 21, which has a relatively high output. This makes it possible to suppress deterioration of the pass characteristics of the filter 52 and prevent damage to the filter 52 when a high-output signal is input.

[0113] For example, in the high-frequency circuit 1, the first output signal output from the output terminal 10b is 90° ahead in phase with the second output signal output from the output terminal 10c, and the synthesis circuit 30 includes a low-pass filter 31 connected between the input terminal 30b and the output terminal 30a, and a high-pass filter 32 connected between the input terminal 30c and the output terminal 30a.

[0114] According to this, in the high-frequency circuit 1, the phase difference between the signal at the output end of power amplifier 21 and the signal at the output end of power amplifier 22 is 90°, and the phase difference between the first input signal and the second input signal at output terminal 30 a is 0°, so it is possible for the circuit to operate as a current-combining type balanced amplifier that is resistant to load fluctuations.

[0115] For example, in the high-frequency circuit 1, the first output signal output from the output terminal 10b is 90° ahead in phase with the second output signal output from the output terminal 10c, and the combining circuit 30A includes a transformer 33 having an input coil and an output coil, a high-pass filter 32 connected between the input terminal 30b and one end of the input coil, and a low-pass filter 31 connected between the input terminal 30c and the other end of the input coil, and one end of the output coil is connected to the output terminal 30a and the other end of the output coil is connected to ground.

[0116] According to this, the high-frequency circuit 1 has a phase difference of 90° between the signal at the output end of power amplifier 21 and the signal at the output end of power amplifier 22, and a phase difference of approximately 180° between the first input signal and the second input signal at output terminal 30 a, so it can operate as a voltage-combining type balanced amplifier that is resistant to load fluctuations.

[0117] For example, in the high-frequency circuit 1, the first output signal output from the output terminal 10b is 90° ahead in phase with the second output signal output from the output terminal 10c, and the combining circuit 30 includes a quarter-wave transmission line, one end of which is connected to the input terminal 30b, the other end of which is connected to the output terminal 30a, and the input terminal 30c is connected to the output terminal 30a.

[0118] This makes it possible to provide a Doherty-type high-frequency circuit 1 in which the power amplifier 21 is a carrier amplifier, the power amplifier 22 is a peak amplifier, the first output signal of the power amplifier 21 and the second output signal of the power amplifier 22 are combined in phase at the output terminal 30 a, and deterioration of the pass characteristics of the filters 51 and 52 is suppressed and breakdown is prevented at high output.

[0119] For example, the high-frequency circuit 1 further includes a module substrate 90 on which the filters 51 and 52 and the power amplifiers 21 and 22 are arranged, and a shielding metal layer 95 arranged to surround the module substrate 90 when the module substrate 90 is viewed in a plane.

[0120] This allows the circuit elements that make up the high-frequency circuit 1 to be mounted on a single module substrate 90, thereby making it possible to reduce the size of the high-frequency circuit 1. Furthermore, the arrangement of the shielding metal layer 95 improves the electromagnetic wave shielding effect.

[0121] For example, in the high-frequency circuit 1, the distance D between the filter 52 and the power amplifiers 21 and 22 is Ｐ２ is the distance D between the filter 51 and the power amplifiers 21 and 22. Ｐ１ is greater than.

[0122] This can prevent heat generated from power amplifiers 21 and 22 from flowing into filter 52, thereby improving the power durability of filter 52.

[0123] In addition, for example, in the high frequency circuit 1, the distance D between the filter 52 and the shield metal layer 95 is Ｇ２ is the distance D between the filter 51 and the shield metal layer 95 Ｇ１ is smaller than.

[0124] This improves heat dissipation from the filter 52 to the shield metal layer 95, thereby improving the power durability of the filter 52.

[0125] For example, in the high-frequency circuit 1, the shield metal layer 95 includes a shield top surface portion arranged to sandwich the filters 51 and 52 with the main surface of the module substrate 90, and a shield side surface portion arranged to surround the module substrate 90 when the module substrate 90 is viewed in a plane, and the filter 52 comes into contact with the shield top surface portion.

[0126] This improves heat dissipation from the filter 52 to the shield metal layer 95, thereby improving the power durability of the filter 52.

[0127] The communication device 4 according to this embodiment also includes an RFIC 3 that processes high-frequency signals, and a high-frequency circuit 1 that transmits high-frequency signals between the RFIC 3 and the antenna 2 .

[0128] This allows the effects of the high frequency circuit 1 to be realized in the communication device 4.

[0129] (Other Embodiments, etc.) While the high-frequency circuits and communication devices according to the embodiments of the present invention have been described above with reference to the embodiments and modifications thereof, the high-frequency circuits and communication devices according to the present invention are not limited to the above-described embodiments and modifications. The present invention also includes other embodiments realized by combining any of the components in the above-described embodiments and modifications, modifications obtained by applying various modifications to the above-described embodiments and modifications that would occur to those skilled in the art without departing from the spirit of the present invention, and various devices incorporating the above-described high-frequency circuits.

[0130] For example, in the high-frequency circuits and communication devices according to the above-described embodiments and modifications, other circuit elements, wiring, etc. may be inserted between the paths connecting the circuit elements and signal paths disclosed in the drawings.

[0131] The following describes the features of the high-frequency circuit and communication device described based on the above embodiment and modifications.

[0132] <1> A 90° hybrid circuit having a first input terminal, a first output terminal, and a second output terminal; a combiner circuit having a second input terminal, a third input terminal, and a third output terminal; a first power amplifier and a second power amplifier; a switch having a first common terminal, a second common terminal, a first selection terminal, and a second selection terminal; a first filter including a plurality of acoustic wave resonators and having a pass band including a first transmission band; and a second filter including a plurality of acoustic wave resonators and having a pass band including the first transmission band, wherein an input end of the first power amplifier is connected to the first output terminal, and an output end of the first power amplifier is connected to the first common terminal; an input end of the second power amplifier is connected to the second output terminal, and an output end of the second power amplifier is connected to the second common terminal; an input end of the first filter is connected to the first selection terminal, and an output end of the first filter is connected to the second input terminal; an input end of the second filter is connected to the second selection terminal, and an output end of the second filter is connected to the third input terminal; a number of acoustic wave resonators in the second filter being greater than a number of acoustic wave resonators in the first filter;

[0133] <2> The high-frequency circuit according to <1>, further comprising: an antenna connection terminal connected to the third output terminal; a coupler arranged in at least one of a first signal path connecting an output end of the first power amplifier and the antenna connection terminal and a second signal path connecting an output end of the second power amplifier and the antenna connection terminal; and a control circuit connected between the coupler and the switch.

[0134] <3> The high-frequency circuit according to <2>, wherein the coupler is disposed on a common signal path connecting the third output terminal and the antenna connection terminal.

[0135] <4> The high-frequency circuit according to <2>, wherein the coupler is arranged in either a first signal path connecting an output end of the first power amplifier and the second input terminal or a second signal path connecting an output end of the second power amplifier and the third input terminal.

[0136] <5> The radio-frequency circuit according to <2> or <3>, wherein the coupler detects a forward signal traveling from the third output terminal to the antenna connection terminal and a reverse reflected signal traveling from the antenna connection terminal to the third output terminal, and the control circuit calculates output impedances of the first power amplifier and the second power amplifier from the forward signal and the reverse reflected signal detected by the coupler.

[0137] <6> The high-frequency circuit according to <5>, wherein the switch is configured to be switchable between a first connection mode in which the first common terminal and the first selection terminal are connected and the second common terminal and the second selection terminal are connected, and a second connection mode in which the first common terminal and the second selection terminal are connected and the second common terminal and the first selection terminal are connected.

[0138] <7> The radio-frequency circuit according to <6>, wherein the control circuit operates the switch in the first connection mode when the calculated output impedance of the second power amplifier is smaller than the calculated output impedance of the first power amplifier, and operates the switch in the second connection mode when the calculated output impedance of the first power amplifier is smaller than the calculated output impedance of the second power amplifier.

[0139] <8> The high-frequency circuit according to any one of <1> to <7>, wherein a first output signal output from the first output terminal is 90° ahead in phase with a second output signal output from the second output terminal, and the combining circuit includes: a low-pass filter connected between the second input terminal and the third output terminal; and a high-pass filter connected between the third input terminal and the third output terminal.

[0140] <9> The high-frequency circuit according to any one of <1> to <7>, wherein a first output signal output from the first output terminal is 90° ahead in phase with a second output signal output from the second output terminal, the combining circuit includes: a transformer having an input coil and an output coil; a high-pass filter connected between the second input terminal and one end of the input coil; and a low-pass filter connected between the third input terminal and the other end of the input coil, one end of the output coil being connected to the third output terminal, and the other end of the output coil being connected to ground.

[0141] <10> The high-frequency circuit according to any one of <1> to <7>, wherein a first output signal output from the first output terminal is 90° ahead in phase with a second output signal output from the second output terminal, the combining circuit includes a quarter-wave transmission line, one end of the quarter-wave transmission line is connected to the second input terminal and the other end of the quarter-wave transmission line is connected to the third output terminal, and the third input terminal is connected to the third output terminal.

[0142] <11> The high-frequency circuit according to any one of <1> to <10>, further including: a module substrate on which the first filter, the second filter, the first power amplifier, and the second power amplifier are arranged; and a shielding metal layer arranged to surround the module substrate when the module substrate is viewed from above.

[0143] <12> The high-frequency circuit according to <11>, wherein a distance between the second filter and the first power amplifier and the second power amplifier is greater than a distance between the first filter and the first power amplifier and the second power amplifier.

[0144] <13> The high-frequency circuit according to <11> or <12>, wherein the distance between the second filter and the shielding metal layer is shorter than the distance between the first filter and the shielding metal layer.

[0145] <14> The high-frequency circuit according to any one of <11> to <13>, wherein the shield metal layer includes: a shield top surface portion arranged to sandwich the first filter and the second filter between the shield metal layer and a main surface of the module substrate; and a shield side surface portion arranged to surround the module substrate when the module substrate is viewed in a plane, and the second filter is in contact with the shield top surface portion.

[0146] <15> A communication device comprising: a signal processing circuit that processes a high-frequency signal; and the high-frequency circuit according to any one of <1> to <14> that transmits the high-frequency signal between the signal processing circuit and an antenna.

[0147] The present invention can be widely used as an amplifier circuit disposed in a front end portion of communication devices such as mobile phones.

[0148] REFERENCE SIGNS LIST 1, 1A, 1B High frequency circuit 2 Antenna 3 RFIC 4 Communication device 10 90° hybrid circuit 10a, 30b, 30c, 31a, 32a Input terminal 10b, 10c, 30a, 31b, 32b Output terminal 21, 22 Power amplifier 30, 30A Combiner circuit 31 Low pass filter 32 High pass filter 33 Transformer 41 Switch 41a, 41b Common terminal 41c, 41d Selection terminal 51, 52 Filter 51a, 52a Input terminal 51b, 52b Output terminal 57, 58 Phase shift circuit 60, 61, 62 Coupler 70 Control circuit 81, 82 Semiconductor IC 90 Module substrate 95 Shield metal layer 100 Antenna connection terminal 110 Signal input terminal 311, 322 Inductor 312, 321 Capacitors 511, 512, 521, 522, 523, 524 Series arm resonators 513, 525 Parallel arm resonators

Claims

1. A 90° hybrid circuit having a first input terminal, a first output terminal, and a second output terminal; a combiner circuit having a second input terminal, a third input terminal, and a third output terminal; a first power amplifier and a second power amplifier; a switch having a first common terminal, a second common terminal, a first selection terminal, and a second selection terminal; a first filter including a plurality of acoustic wave resonators and having a pass band including a first transmission band; and a second filter including a plurality of acoustic wave resonators and having a pass band including the first transmission band, wherein an input terminal of the first power amplifier is connected to the first output terminal, and an output terminal of the first power amplifier is connected to the first common terminal; an input terminal of the second power amplifier is connected to the second output terminal, and an output terminal of the second power amplifier is connected to the second common terminal; an input terminal of the first filter is connected to the first selection terminal, and an output terminal of the first filter is connected to the second input terminal; an input terminal of the second filter is connected to the second selection terminal, and an output terminal of the second filter is connected to the third input terminal; the number of acoustic wave resonators in the second filter is greater than the number of acoustic wave resonators in the first filter.

2. The high-frequency circuit according to claim 1, further comprising: an antenna connection terminal connected to said third output terminal; a coupler arranged in at least one of a first signal path connecting the output end of said first power amplifier and said antenna connection terminal and a second signal path connecting the output end of said second power amplifier and said antenna connection terminal; and a control circuit connected between said coupler and said switch.

3. The high-frequency circuit according to claim 2, wherein the coupler is disposed on a common signal path connecting the third output terminal and the antenna connection terminal.

4. The high-frequency circuit according to claim 2, wherein the coupler is arranged in either a first signal path connecting the output end of the first power amplifier and the second input terminal, or a second signal path connecting the output end of the second power amplifier and the third input terminal.

5. The radio frequency circuit according to claim 2 or 3, wherein the coupler detects a forward signal traveling from the third output terminal to the antenna connection terminal and a reflected signal traveling in a reverse direction from the antenna connection terminal to the third output terminal, and the control circuit calculates the output impedance of the first power amplifier and the second power amplifier from the forward signal and the reflected signal traveling in a reverse direction detected by the coupler.

6. The high-frequency circuit according to claim 5, wherein the switch is configured to be switchable between a first connection mode in which the first common terminal and the first selection terminal are connected and the second common terminal and the second selection terminal are connected, and a second connection mode in which the first common terminal and the second selection terminal are connected and the second common terminal and the first selection terminal are connected.

7. The radio frequency circuit according to claim 6, wherein the control circuit operates the switch in the first connection mode when the calculated output impedance of the second power amplifier is smaller than the calculated output impedance of the first power amplifier, and operates the switch in the second connection mode when the calculated output impedance of the first power amplifier is smaller than the calculated output impedance of the second power amplifier.

8. The high-frequency circuit according to any one of claims 1 to 7, wherein the first output signal output from the first output terminal is 90° ahead in phase with the second output signal output from the second output terminal, and the combining circuit includes a low-pass filter connected between the second input terminal and the third output terminal, and a high-pass filter connected between the third input terminal and the third output terminal.

9. The high frequency circuit according to any one of claims 1 to 7, wherein the first output signal output from the first output terminal is 90° ahead in phase with the second output signal output from the second output terminal, and the combining circuit includes: a transformer having an input coil and an output coil; a high pass filter connected between the second input terminal and one end of the input coil; and a low pass filter connected between the third input terminal and the other end of the input coil, one end of the output coil being connected to the third output terminal, and the other end of the output coil being connected to ground.

10. The high-frequency circuit according to any one of claims 1 to 7, wherein the first output signal output from the first output terminal is 90° ahead in phase with the second output signal output from the second output terminal, the combining circuit includes a quarter-wave transmission line, one end of the quarter-wave transmission line is connected to the second input terminal and the other end of the quarter-wave transmission line is connected to the third output terminal, and the third input terminal is connected to the third output terminal.

11. The radio frequency circuit according to any one of claims 1 to 10, further comprising: a module substrate on which the first filter, the second filter, the first power amplifier, and the second power amplifier are arranged; and a shielding metal layer arranged to surround the module substrate when the module substrate is viewed in plan.

12. The high-frequency circuit according to claim 11, wherein the distance between the second filter and the first and second power amplifiers is greater than the distance between the first filter and the first and second power amplifiers.

13. The high-frequency circuit according to claim 11 or 12, wherein the distance between the second filter and the shielding metal layer is smaller than the distance between the first filter and the shielding metal layer.

14. The high-frequency circuit according to any one of claims 11 to 13, wherein the shield metal layer includes a shield top surface portion arranged to sandwich the first filter and the second filter between itself and the main surface of the module substrate, and a shield side surface portion arranged to surround the module substrate when the module substrate is viewed in a plane, and the second filter is in contact with the shield top surface portion.

15. A communication device comprising: a signal processing circuit that processes a high-frequency signal; and a high-frequency circuit according to any one of claims 1 to 14 that transmits a high-frequency signal between the signal processing circuit and an antenna.

Images