High-frequency circuit and communication apparatus

Abstract

This high-frequency circuit (1) is capable of simultaneously transmitting two signals having the frequency of a band A and one signal having the frequency of a band B. The high-frequency circuit (1) comprises: a power amplifier (11); a filter (31) connected to an output terminal of the power amplifier (11) and having a passband including a transmission band of the band A; a power amplifier (12); a filter (32) connected to an output terminal of the power amplifier (12) and having a passband including a transmission band of the band B; a low-noise amplifier (22); a filter (33) connected to an input terminal of the low-noise amplifier (22) and having a passband including a reception band of the band B; a coupler (51) having a main line and a sub-line and connected between the filter (33) and the low-noise amplifier (22); a detection circuit (61) connected to the sub-line; and a variable phase shift circuit (62) connected to the detection circuit (61) and connected between the low-noise amplifier (22) and the main line.

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 high-frequency front-end module (high-frequency circuit) including two power amplifiers, a low-noise amplifier, and a diplexer. In this configuration, the diplexer connected to the input end of the low-noise amplifier is configured to remove high-frequency signals near the reception band in order to remove intermodulation distortion caused by the transmission signals output from the two power amplifiers.

[0003] Japanese Patent Application Laid-Open No. 2022-90612

[0004] In recent years, high-frequency circuits that communicate by simultaneously using a plurality of discontinuous component carriers (CCs) within a first band (intra-band non-contiguous carrier aggregation) have been studied.

[0005] However, when two CCs in the first band and one CC in the second band are transmitted simultaneously, triple beat distortion may occur. If the frequency of the triple beat distortion component overlaps with the reception band and the distortion component enters the reception path, a problem occurs in that reception sensitivity is degraded.

[0006] Therefore, the present invention has been made to solve the above problem, and provides a high-frequency circuit in which deterioration of receiving sensitivity is suppressed when three signals in two bands are transmitted simultaneously, and a communication device equipped with the same.

[0007] In order to achieve the above object, a high-frequency circuit according to one aspect of the present invention is a high-frequency circuit capable of simultaneously transmitting two signals having different frequencies in a first band and one signal having a frequency in a second band, and includes: a first power amplifier; a first filter connected to an output end of the first power amplifier and having a pass band including the transmission band of the first band; a second power amplifier; a second filter connected to an output end of the second power amplifier and having a pass band including the transmission band of the second band; a first low-noise amplifier; a third filter connected to an input end of the first low-noise amplifier and having a pass band including the reception band of a third band; a coupler having a main line and a sub-line and connected between the third filter and the first low-noise amplifier; a detection circuit connected to the sub-line; and a variable phase shift circuit connected to the detection circuit and connected between the first low-noise amplifier and the main line.

[0008] According to the present invention, it is possible to provide a high-frequency circuit and a communication device in which deterioration of reception sensitivity is suppressed when three signals in two bands are transmitted simultaneously.

[0009] Fig. 1 is a circuit diagram of a high-frequency circuit and a communication device according to an embodiment. Fig. 2 is a circuit diagram showing a signal transmission state of the high-frequency circuit according to the embodiment. Fig. 3 is a diagram illustrating the occurrence of a triple beat. Fig. 4 is a circuit diagram of a high-frequency circuit according to Example 1. Fig. 5 is a circuit diagram of a high-frequency circuit according to Example 2. Fig. 6 is a circuit diagram of a high-frequency circuit and a communication device according to a modified example of the embodiment.

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, component arrangements, and connection forms shown in the following embodiments are merely examples and are not intended to limit the present invention. Among the components in the following embodiments, components that are not recited in independent claims will be described as optional components. Furthermore, the sizes or size ratios of the components shown in the drawings are not necessarily strict.

[0011] 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.

[0012] In the circuit configurations of the present disclosure, "connected" includes not only direct connection by connection terminals and / or wiring conductors, but also electrical connection via matching elements or switch circuits. "Connected between A and B" means connected to both A and B between A and B.

[0013] In the present invention, a "terminal" means a point where a conductor within an element terminates. Note that a terminal is not limited to a single point, but may be any point (node) on the conductor between elements or the entire conductor, provided that the impedance of the conductor between elements is sufficiently low.

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

[0015] Furthermore, in the circuit element layout of the present disclosure, "circuit element A is arranged in series on path B" means that the signal input terminal and signal output terminal of circuit element A are connected to two wirings that form at least a part of path B, respectively. At least one of the two wirings may be an electrode or a terminal.

[0016] Also, in the following embodiments, the "filter passband" is the portion of the frequency spectrum transmitted by the filter, and is defined as the frequency band between two frequencies 3 dB above the minimum value of the power insertion loss.

[0017] In the present disclosure, the term "band" refers to at least one of an uplink operating band and a downlink operating band of a frequency band predefined by a standardization organization (e.g., 3GPP (registered trademark), IEEE (Institute of Electrical and Electronics Engineers)), etc., for a communication system built using a radio access technology (RAT). In this embodiment, examples of communication systems that can be used include, but are not limited to, an LTE (Long Term Evolution) system, a 5G (5th Generation)-NR (New Radio) system, and a WLAN (Wireless Local Area Network) system. Note that the uplink operating band of a frequency band refers to a frequency range designated for uplink within that frequency band. Furthermore, the downlink operating band of a frequency band refers to a frequency range designated for downlink within that frequency band.

[0018] (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 this 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 the embodiment.

[0019] [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 this embodiment includes a high-frequency circuit 1, antennas 2A and 2B, and an RF signal processing circuit (RFIC) 3.

[0020] The high-frequency circuit 1 transmits high-frequency signals between the antennas 2A and 2B and the RFIC 3. The detailed circuit configuration of the high-frequency circuit 1 will be described later.

[0021] Antenna 2A is connected to antenna connection terminal 101 of high frequency circuit 1, and transmits high frequency signals of band A output from high frequency circuit 1, and also receives high frequency signals from the outside and outputs them to high frequency circuit 1. Antenna 2B is connected to antenna connection terminal 102 of high frequency circuit 1, and transmits high frequency signals of band B output from high frequency circuit 1, and also receives high frequency signals from the outside and outputs them to high frequency circuit 1.

[0022] 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 received signal input via the receive path of the high-frequency circuit 1, such as by down-conversion, and outputs the received signal generated by the signal processing to a baseband signal processing circuit (BBIC: not shown). The RFIC 3 also performs signal processing on a transmit signal input from the BBIC, such as by up-conversion, and outputs the transmit signal generated by the signal processing to the transmit path of the high-frequency circuit 1. The RFIC 3 also has a control unit that controls switches, amplifiers, and the like included in the high-frequency circuit 1. Note that some or all of the functions of the RFIC 3 as a control unit may be implemented outside the RFIC 3, such as in the BBIC or the high-frequency circuit 1.

[0023] In addition, in the communication device 4 according to this embodiment, the antennas 2A and 2B are not essential components.

[0024] [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 power amplifiers 11 and 12, low-noise amplifiers 21 and 22, filters 31, 32, and 33, a switch 41, a coupler 51, a detection circuit 61, a variable phase shift circuit 62, antenna connection terminals 101 and 102, signal input terminals 110 and 130, and signal output terminals 120 and 140.

[0025] The antenna connection terminal 101 is connected to the antenna 2A and the filter 31. The antenna connection terminal 102 is connected to the antenna 2B and the filters 32 and 33. The signal input terminal 110 is connected to the RFIC 3 and the input terminal of the power amplifier 11. The signal input terminal 130 is connected to the RFIC 3 and the input terminal of the power amplifier 12. The signal output terminal 120 is connected to the RFIC 3 and the output terminal of the low-noise amplifier 21. The signal output terminal 140 is connected to the RFIC 3 and the output terminal of the low-noise amplifier 22.

[0026] The power amplifier 11 is an example of a first power amplifier, and is capable of amplifying a high-frequency transmission signal (hereinafter referred to as a transmission signal) of band A (first band) output from the RFIC 3. An input end of the power amplifier 11 is connected to the RFIC 3 via a signal input terminal 110, and an output end of the power amplifier 11 is connected to the switch 41.

[0027] The power amplifier 12 is an example of a second power amplifier, and is capable of amplifying a transmission signal of band B (second band) output from the RFIC 3. An input end of the power amplifier 12 is connected to the RFIC 3 via a signal input terminal 130, and an output end of the power amplifier 12 is connected to the filter 32.

[0028] The low-noise amplifier 21 amplifies a high-frequency received signal of band A (hereinafter referred to as a received signal) input from the antenna connection terminal 101. The input terminal of the low-noise amplifier 21 is connected to the switch 41, and the output terminal of the low-noise amplifier 21 is connected to the RFIC 3 via a signal output terminal 120.

[0029] The low-noise amplifier 22 is an example of a first low-noise amplifier, and amplifies the received signal of band B input from the antenna connection terminal 102. The input terminal of the low-noise amplifier 22 is connected to the filter 33 via the variable phase shift circuit 62, and the output terminal of the low-noise amplifier 22 is connected to the RFIC 3 via the signal output terminal 140.

[0030] The switch 41 has a common terminal, a first selection terminal, and a second selection terminal, and switches between connection between the common terminal and the first selection terminal and connection between the common terminal and the second selection terminal. The common terminal is connected to one end of the filter 31, the first selection terminal is connected to the output terminal of the power amplifier 11, and the second selection terminal is connected to the input terminal of the low-noise amplifier 21.

[0031] The filter 31 is an example of a first filter, and is connected to the output terminal of the power amplifier 11 via the switch 41 and has a passband that includes the band A.

[0032] Band A is a band for time division duplex (TDD), but may also be a band for frequency division duplex (FDD). When band A is an FDD band, instead of filter 31, a transmission filter having a passband including the transmission band of band A is connected between the output end of power amplifier 11 and antenna connection terminal 101, and a reception filter having a passband including the reception band of band A is connected between the input end of low-noise amplifier 21 and antenna connection terminal 101.

[0033] The filter 32 is an example of a second filter, and is connected to the output terminal of the power amplifier 12 and has a pass band that includes the transmission band of band B.

[0034] The filter 33 is an example of a third filter, and is connected to the input terminal of the low-noise amplifier 22 via the variable phase shift circuit 62, and has a passband that includes the reception band of band B. Band B is a band for FDD.

[0035] The coupler 51 has a main line and a sub line, and is connected between the filter 33 and the low-noise amplifier 22. The main line of the coupler 51 is part of the signal path connecting the filter 33 and the low-noise amplifier 22.

[0036] The detection circuit 61 is connected to the secondary line of the coupler 51 and is configured to detect the high-frequency signal output from the secondary line and output a control signal corresponding to the power level of the high-frequency signal to the variable phase shift circuit 62.

[0037] The variable phase shift circuit 62 is connected to the detection circuit 61 and is connected between the low noise amplifier 22 and the main line of the coupler 51 .

[0038] The low-noise amplifier 22, the detector circuit 61, and the variable phase shift circuit 62 are included in a semiconductor IC 220 (first semiconductor IC). The semiconductor IC 220 may include at least one of the low-noise amplifier 22, the detector circuit 61, and the variable phase shift circuit 62. This allows the band B receiving circuit to be miniaturized, thereby enabling the high-frequency circuit 1 to be miniaturized. The semiconductor IC 220 may be configured using, for example, a complementary metal oxide semiconductor (CMOS), and specifically, may be manufactured using an SOI (silicon on insulator) process. The semiconductor IC 220 may also be configured of at least one of GaAs, SiGe, and GaN. The semiconductor material of the semiconductor IC 220 is not limited to the above-mentioned materials.

[0039] The high frequency circuit 1 having the above configuration can simultaneously transmit two signals having different frequencies in band A and one signal having a frequency in band B.

[0040] It should be noted that the low-noise amplifier 21 does not have to be included in the high-frequency circuit 1. Furthermore, the antennas 2A and 2B may be one antenna, in which case the antenna connection terminals 101 and 102 become one antenna connection terminal.

[0041] In the high-frequency circuit 1 according to this embodiment, band A is, for example, band B41 or band B40 for 4G-LTE, band n41 or band n40 for 5G-NR, and band B is, for example, band B3 or band B1 for 4G-LTE, band n3 or band n1 for 5G-NR.

[0042] 2 is a circuit diagram showing a signal transmission state of the high-frequency circuit 1 according to the embodiment, in which a first transmission signal in band A having a frequency f1, a second transmission signal in band A having a frequency f2, and a third transmission signal in band B having a frequency f3 are simultaneously transmitted.

[0043] The first and second transmission signals (2CC: 2 Carrier Components) of band A, which are discontinuous with each other, are amplified by the power amplifier 11, passed through the switch 41, the filter 31, and the antenna connection terminal 101, and output from the antenna 2A. The third transmission signal (CC) of band B is amplified by the power amplifier 12, passed through the filter 32 and the antenna connection terminal 102, and output from the antenna 2B. Although not shown, simultaneously with the transmission of the first, second, and third transmission signals, the first reception signal of band B passes through the antenna 2B, the antenna connection terminal 102, the filter 33, and the variable phase shift circuit 62, is amplified by the low-noise amplifier 22, and is output from the signal output terminal 140.

[0044] At this time, the first transmission signal and the second transmission signal leak from the antenna connection terminal 101 and the antenna 2A to the antenna connection terminal 102 and the antenna 2B. It is assumed that these leaked first transmission signal and second transmission signal, as well as the third transmission signal that has passed through the filter 32, will invade the band B reception path connecting the filter 33 and the signal output terminal 140. The leaked components of the first transmission signal, the second transmission signal, and the third transmission signal that have invaded the reception path may cause triple beat intermodulation distortion in the low-noise amplifier 22. If the frequency of this triple beat distortion is included in the reception band of band B, the reception sensitivity of band B will be reduced.

[0045] FIG. 3 is a diagram illustrating the occurrence of triple beats. The diagram shows the relationship between the frequency and signal level of signals generated by the high-frequency circuit 1. Specifically, the diagram illustrates the spectra of triple beat distortions caused by (1) two first transmission signals (frequency f1 and f2) in band A output from the power amplifier 11, (2) one second transmission signal (frequency f3) in band B output from the power amplifier 12, and (3) two first transmission signals and one second transmission signal. An example of the frequency of triple beat distortion is expressed as f3±(m×f2−n×f1) (m and n are integers).

[0046] For example, if band A is band n41 (2496-2690 MHz) or band n40 (2300-2400 MHz) and band B is band n3 (transmit band: 1710-1785 MHz, receive band: 1805-1880 MHz), triple beat first-order distortion (m = n = 1: frequency f3 + f2 - f1) occurs in the receive band of band n3. Triple beat distortion can also occur in the receive band of band C, which is lower in frequency than band n3, and in the receive band of band D, which is higher in frequency than band n41 or n40.

[0047] In contrast, in the high-frequency circuit 1 according to this embodiment, at least one of the first transmission signal, the second transmission signal, and the third transmission signal that has entered the Band B reception path connecting the filter 33 and the low-noise amplifier 22 can be detected by the sub-line of the coupler 51. The at least one signal detected by the coupler 51 is detected by the detection circuit 61 and converted into a control signal corresponding to the power level of the at least one signal. The passing phase of the variable phase shift circuit 62 can be changed based on the control signal converted by the detection circuit 61. Changing the passing phase of the variable phase shift circuit 62 changes the input impedance of the low-noise amplifier 22. Due to the above-described functions of the coupler 51, the detection circuit 61, and the variable phase shift circuit 62, for example, when the power level of the at least one signal is equal to or greater than a predetermined threshold, it is possible to shift the impedance of at least one of the transmission bands of Band A and Band B toward the open side while minimizing the shift in the impedance of the reception band of Band B at the input end of the low-noise amplifier 22. This prevents the first transmission signal, the second transmission signal, and the third transmission signal that have entered the reception path of band B from entering the low-noise amplifier 22. This prevents triple-beat distortion components contained in the reception band of band B from occurring in the low-noise amplifier 22, and prevents deterioration of the reception sensitivity of band B.

[0048] [1.3 Configuration of the High-Frequency Circuit 1A of Example 1] Next, the high-frequency circuit 1A of Example 1 will be described. The high-frequency circuit 1A of Example 1 illustrates a specific circuit configuration example of the high-frequency circuit 1 according to the embodiment. FIG. 4 is a circuit configuration diagram of the high-frequency circuit 1A of Example 1. As shown in the figure, the high-frequency circuit 1A includes power amplifiers 11 and 12, low-noise amplifiers 21 and 22, filters 31, 32, and 33, a switch 41, a coupler 51, a detector circuit 61A, and a variable phase shift circuit 62A. Note that the power amplifiers 11 and 12, the low-noise amplifier 21, the filters 31 and 32, and the switch 41 are not illustrated in FIG. 4. The high-frequency circuit 1A of this example differs from the high-frequency circuit 1 according to the embodiment in that specific circuit configurations of the coupler 51, the detector circuit 61A, and the variable phase shift circuit 62A are shown. Therefore, the following description of the high-frequency circuit 1A of this example will omit a description of the same configuration as the high-frequency circuit 1 according to the embodiment, and will focus on the different configurations.

[0049] The variable phase shift circuit 62A has an inductor 621, a capacitor 622, and a switch 623. The inductor 621 and the capacitor 622 form a phase circuit that changes the phase of a signal propagating through a reception path that connects the filter 33 and the low-noise amplifier 22. The switch 623 is an example of a first switch, and is connected to the reception path to switch between connection and disconnection of the phase circuit and the low-noise amplifier 22.

[0050] In this embodiment, the phase circuit has a configuration in which an LC series resonant circuit including an inductor 621 and a capacitor 622 is connected between the reception path and ground, but the phase circuit is not limited to this. The phase circuit only needs to include at least one of an inductor and a capacitor, and may be arranged in series with the reception path. The phase circuit may be, for example, a so-called π-type LC resonant circuit having a capacitor arranged in series with the reception path, an inductor connected between one end of the capacitor and ground, and an inductor connected between the other end of the capacitor and ground.

[0051] The coupler 51 includes a main line 511, a sub-line 512, and a terminator 513. One end of the main line 511 is connected to the filter 33, and the other end is connected to the variable phase shift circuit 62A. One end of the sub-line 512 is connected to the terminator 513, and the other end is connected to the detection circuit 61A. With the above configuration, the coupler 51 can detect, via the sub-line 512, at least one of a signal in band A and a signal in the transmission band of band B propagating from one end of the main line 511 to the other end.

[0052] The detection circuit 61A includes a power detector 611 and a comparator 612, and outputs a control signal to a switch 623 of the variable phase shift circuit 62A based on the power level of the signal of band A output from the sub-line 512.

[0053] The power detector 611 includes, for example, a diode, and is configured to detect the signal of band A output from the sub-line 512 and detect the power level of the signal of band A.

[0054] The comparator 612 is configured to output a first control voltage that turns on the switch 623 of the variable phase shift circuit 62A when the power level of the signal of band A detected by the power detector 611 is equal to or greater than a predetermined value, and to output a second control voltage that turns off the switch 623 when the power level of the signal of band A detected by the power detector 611 is smaller than the predetermined value.

[0055] The low-noise amplifier 22, the detector circuit 61A, and the variable phase shift circuit 62A are included in a semiconductor IC 220A (first semiconductor IC). That is, the semiconductor IC 220A includes the diode and comparator that constitute the detector circuit 61A, as well as the inductor 621, capacitor 622, and switch 623 that constitute the variable phase shift circuit 62A. This allows the receiver circuit for Band B to be miniaturized, thereby enabling the high-frequency circuit 1A to be miniaturized. Furthermore, the wiring connecting the low-noise amplifier 22, the detector circuit 61A, and the variable phase shift circuit 62A can be shortened, allowing triple-beat distortion components included in the receive band of Band B to be suppressed with high precision. The semiconductor IC 220A is only required to include the low-noise amplifier 22 and at least one of the detector circuit 61A and the variable phase shift circuit 62A.

[0056] According to the above configuration, at least one of the first and second transmission signals of Band A that has entered the reception path can be detected by the sub-line 512. The at least one signal detected by the sub-line 512 is detected by the power detector 611, and a first control voltage or a second control voltage corresponding to the power level of the at least one signal is output from the comparator 612 to the switch 623. The variable phase shift circuit 62A can change the passing phase of the first and second transmission signals of Band A propagating through the variable phase shift circuit 62A based on the control voltage. Specifically, when the power level of the at least one signal detected by the power detector 611 is equal to or greater than a predetermined threshold, the comparator 612 outputs the first control voltage, and the phase shift circuit of the variable phase shift circuit 62A is connected to the reception path. As a result, the impedance of the transmission band of Band A at the input end of the low-noise amplifier 22 shifts to the open side, thereby preventing the first and second transmission signals that have entered the reception path from entering the low-noise amplifier 22. Therefore, it is possible to prevent the occurrence of triple beat distortion components included in the reception band of band B in the low noise amplifier 22, and to prevent deterioration of the reception sensitivity of band B.

[0057] [1.4 Configuration of the High-Frequency Circuit 1B According to Example 2] Next, the high-frequency circuit 1B according to Example 2 will be described. The high-frequency circuit 1B according to Example 2 illustrates a specific circuit configuration example of the high-frequency circuit 1 according to the embodiment. FIG. 5 is a circuit configuration diagram of the high-frequency circuit 1B according to Example 2. As shown in the figure, the high-frequency circuit 1B includes power amplifiers 11 and 12, low-noise amplifiers 21 and 22, filters 31, 32, and 33, a switch 41, a coupler 51, a detector circuit 61B, and a variable phase shift circuit 62B. Note that the power amplifiers 11 and 12, the low-noise amplifier 21, the filters 31 and 32, and the switch 41 are not illustrated in FIG. 5. The high-frequency circuit 1B according to this example differs from the high-frequency circuit 1 according to the embodiment in that specific circuit configurations of the coupler 51, the detector circuit 61B, and the variable phase shift circuit 62B are shown. Therefore, the following description of the high-frequency circuit 1B according to this example will omit a description of the same configuration as the high-frequency circuit 1 according to the embodiment, and will focus on the different configurations.

[0058] The low noise amplifier 22 includes an amplifying transistor having a signal input terminal, a signal output terminal, a power supply voltage input terminal, and a reference voltage terminal.

[0059] The variable phase shift circuit 62B includes a transistor 624. The transistor 624 has a first terminal, a second terminal, and a first control terminal. The first terminal is connected to a reference voltage terminal, the second terminal is connected to ground, and the first control terminal is connected to the detection circuit 61B. The transistor 624 is, for example, a p-type metal oxide semiconductor field effect transistor (MOSFET) with the first terminal serving as a source, the second terminal serving as a drain, and the first control terminal serving as a gate. The transistor 624 changes the conductance of the current flowing between the first and second terminals depending on the level of a control voltage applied to the first control terminal. This makes it possible to change the phase of the high-frequency signal input from the signal input terminal of the low-noise amplifier 22.

[0060] The coupler 51 includes a main line 511, a sub-line 512, and a terminator 513. One end of the main line 511 is connected to the filter 33, and the other end is connected to the input terminal of the low-noise amplifier 22. One end of the sub-line 512 is connected to the terminator 513, and the other end is connected to the detection circuit 61B. With the above configuration, the coupler 51 can detect, via the sub-line 512, at least one of a signal of band A and a signal of the transmission band of band B propagating from one end of the main line 511 to the other end.

[0061] The detection circuit 61B includes a power detector 611 and a voltage adjustment circuit 613, and is configured to output a control signal to a first control terminal of a transistor 624 of the variable phase shift circuit 62B based on the power level of the band A signal output from the sub-line 512.

[0062] The power detector 611 includes, for example, a diode, and is configured to detect the signal of band A output from the sub-line 512 and detect the power level of the signal of band A.

[0063] The voltage adjustment circuit 613 is configured to output a control voltage corresponding to the power level of the signal of band A detected by the power detector 611 to the first control terminal of the transistor 624 .

[0064] The low-noise amplifier 22, the detector circuit 61B, and the variable phase shift circuit 62B are included in a semiconductor IC 220B (first semiconductor IC). That is, the semiconductor IC 220B includes the diode and voltage adjustment circuit 613 that constitute the detector circuit 61B, and the transistor 624 that constitutes the variable phase shift circuit 62B. This allows the receiver circuit for Band B to be miniaturized, thereby enabling the high-frequency circuit 1B to be miniaturized. Furthermore, the wiring connecting the low-noise amplifier 22, the detector circuit 61B, and the variable phase shift circuit 62B can be shortened, allowing triple-beat distortion components included in the receive band of Band B to be suppressed with high precision. It is sufficient for the semiconductor IC 220B to include at least one of the low-noise amplifier 22, the detector circuit 61B, and the variable phase shift circuit 62B.

[0065] According to the above configuration, at least one of the first and second transmission signals of Band A that has entered the reception path can be detected by the sub-line 512. The at least one signal detected by the sub-line 512 is detected by the power detector 611, and a control voltage corresponding to the power level of the at least one signal is output from the voltage adjustment circuit 613 to the first control terminal of the transistor 624. The variable phase shift circuit 62B changes the conductance of the current flowing between the first and second terminals of the transistor 624 based on the control voltage, thereby changing the passing phase of the first and second transmission signals of Band A that are input to the input terminal of the low-noise amplifier 22. Specifically, the higher the power level of the at least one signal detected by the power detector 611, the larger the control voltage output from the voltage adjustment circuit 613, and the lower the conductance of the current flowing between the first and second terminals of the transistor 624. As a result, the impedance of the transmission band of Band A at the input end of the low-noise amplifier 22 can be shifted toward the open side as the power level of the at least one signal increases, and the first transmission signal and the second transmission signal that have entered the reception path are prevented from entering the low-noise amplifier 22. Therefore, it is possible to prevent triple-beat distortion components contained in the reception band of Band B from occurring in the low-noise amplifier 22, and to prevent deterioration of the reception sensitivity of Band B.

[0066] The circuit configuration of the variable phase shift circuit 62 of the high-frequency circuit 1 according to this embodiment is not limited to the variable phase shift circuit 62A according to the first embodiment and the variable phase shift circuit 62B according to the second embodiment. For example, the switch 623 of the variable phase shift circuit 62A may be omitted, and the capacitor 622 may be a variable capacitance capacitor. In this case, the detection circuit 61B is used as the detection circuit, and a control voltage corresponding to the power level of the at least one signal is supplied from the voltage adjustment circuit 613 to the variable capacitance capacitor, thereby changing the capacitance value of the capacitor. This makes it possible to change the passing phases of the first transmission signal and the second transmission signal of band A passing through the reception path.

[0067] [2 Circuit Configuration of High-Frequency Circuit 5 and Communication Device 6 According to Modification] The circuit configuration of the high-frequency circuit 5 and communication device 6 according to a modification of the embodiment will be described with reference to Fig. 6. Fig. 6 is a circuit configuration diagram of the high-frequency circuit 5 and communication device 6 according to a modification of the embodiment.

[0068] 2.1 Circuit Configuration of Communication Device 6 First, a description will be given of the circuit configuration of the communication device 6. As shown in FIG. 6 , the communication device 6 according to this modification includes a high-frequency circuit 5, antennas 2A, 2B, and 2C, and an RFIC 3.

[0069] The high frequency circuit 5 transmits high frequency signals between the antennas 2A to 2C and the RFIC 3.

[0070] Antenna 2A is connected to antenna connection terminal 101 of high frequency circuit 5, and transmits high frequency signals of band A output from high frequency circuit 5, and also receives high frequency signals from the outside and outputs them to high frequency circuit 5. Antenna 2B is connected to antenna connection terminal 102 of high frequency circuit 5, and transmits high frequency signals of band B output from high frequency circuit 5, and also receives high frequency signals from the outside and outputs them to high frequency circuit 5. Antenna 2C is connected to antenna connection terminal 103 of high frequency circuit 5, and transmits high frequency signals of band C output from high frequency circuit 5, and also receives high frequency signals from the outside and outputs them to high frequency circuit 5.

[0071] In the communication device 6 according to this embodiment, the antennas 2A to 2C are not essential components.

[0072] [2.2 Circuit Configuration of High-Frequency Circuit 5] Next, the circuit configuration of the high-frequency circuit 5 will be described. As shown in FIG. 6 , the high-frequency circuit 5 includes power amplifiers 11 and 12, low-noise amplifiers 21, 22, and 23, filters 31, 32, 33, and 34, a switch 41, a coupler 52, a detector circuit 63, a variable phase shift circuit 64, antenna connection terminals 101, 102, and 103, signal input terminals 110 and 130, and signal output terminals 120, 140, and 150. The high-frequency circuit 5 according to this modification differs from the high-frequency circuit 1 according to the embodiment in that a circuit for transmitting a band C reception signal is added, and the coupler 52, the detector circuit 63, and the variable phase shift circuit 64 are arranged in the band C reception path rather than the band B reception path. Therefore, the following description of the high-frequency circuit 5 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.

[0073] The antenna connection terminal 103 is connected to the antenna 2C and the filter 34. The signal output terminal 150 is connected to the RFIC 3 and the output end of the low-noise amplifier 23.

[0074] The low-noise amplifier 23 is an example of a first low-noise amplifier, and amplifies the received signal of band C input from the antenna connection terminal 103. The input end of the low-noise amplifier 23 is connected to the filter 34 via the variable phase shift circuit 64, and the output end of the low-noise amplifier 23 is connected to the RFIC 3 via the signal output terminal 150.

[0075] The filter 34 is an example of a third filter, and is connected to the input terminal of the low-noise amplifier 23 via a variable phase shift circuit 64, and has a pass band that includes the band C reception band.

[0076] The coupler 52 has a main line and a sub line, and is connected between the filter 34 and the low-noise amplifier 23. The main line of the coupler 52 is part of the signal path connecting the filter 34 and the low-noise amplifier 23.

[0077] The detection circuit 63 is connected to the secondary line of the coupler 52, and is configured to detect the high-frequency signal output from the secondary line and output a control signal corresponding to the power level of the high-frequency signal to the variable phase shift circuit 64.

[0078] The variable phase shift circuit 64 is connected to the detection circuit 63 and is connected between the low noise amplifier 23 and the main line of the coupler 52 .

[0079] The low-noise amplifier 23, the detection circuit 63, and the variable phase shift circuit 64 are included in a semiconductor IC 230 (first semiconductor IC). The semiconductor IC 230 only needs to include the low-noise amplifier 23 and at least one of the detection circuit 63 and the variable phase shift circuit 64. This allows the receiver circuit for band C to be miniaturized, and therefore the high-frequency circuit 5 to be miniaturized.

[0080] The high-frequency circuit 5 having the above configuration is capable of simultaneously transmitting two signals having different frequencies in band A (first band), one signal having a frequency in band B (second band), and one signal having a frequency in band C (third band).

[0081] It should be noted that the low-noise amplifiers 21 and 22 do not necessarily have to be included in the high-frequency circuit 5. Furthermore, the antennas 2A to 2C may be one or two antennas, in which case at least two of the antenna connection terminals 101, 102, and 103 become one antenna connection terminal.

[0082] In the high-frequency circuit 5 according to this modification, band A is, for example, band B41 or band B40 for 4G-LTE, or band n41 or band n40 for 5G-NR. Band B is, for example, one of band B3 and band B1 for 4G-LTE, or one of band n3 and band n1 for 5G-NR. Band C is, for example, the other of band B3 and band B1 for 4G-LTE, or the other of band n3 and band n1 for 5G-NR.

[0083] 6 , the first and second transmission signals of band A are amplified by power amplifier 11, pass through switch 41, filter 31, and antenna connection terminal 101, and are output from antenna 2A. At the same time, the third transmission signal of band B is amplified by power amplifier 12, pass through filter 32 and antenna connection terminal 102, and are output from antenna 2B. At the same time, the first reception signal of band C passes through antenna 2C, antenna connection terminal 103, filter 34, and variable phase shift circuit 64, is amplified by low-noise amplifier 23, and is output from signal output terminal 150.

[0084] At this time, the first transmission signal and the second transmission signal leak from the antenna connection terminal 101 and the antenna 2A to the antenna connection terminal 103 and the antenna 2C. Furthermore, the third transmission signal leaks from the antenna connection terminal 102 and the antenna 2B to the antenna connection terminal 103 and the antenna 2C. It is expected that these leaked first transmission signal, second transmission signal, and third transmission signal will enter the band C reception path connecting the filter 34 and the signal output terminal 150. The leaked components of the first transmission signal, second transmission signal, and third transmission signal that have entered the reception path may cause triple beat intermodulation distortion in the low-noise amplifier 23. If the frequency of this triple beat distortion is included in the reception band of band C, the reception sensitivity of band C will be reduced.

[0085] For example, in FIG. 3, if band A is band n41 (2496-2690 MHz) or band n40 (2300-2400 MHz), band B is band n1 (transmit band: 1920-1980 MHz, receive band: 2110-2170 MHz), and band C is band n3 (transmit band: 1710-1785 MHz, receive band: 1805-1880 MHz), then triple beat first-order distortion (m=n=1: frequency f3-f2+f1) will occur in the receive band of band n3.

[0086] In contrast, in the high-frequency circuit 5 according to this modification, at least one of the first, second, and third transmission signals that has entered the band C reception path connecting the filter 34 and the low-noise amplifier 23 can be detected by the sub-line of the coupler 52. The at least one signal detected by the coupler 52 is detected by the detection circuit 63 and converted into a control signal corresponding to the power level of the at least one signal. The passing phase of the variable phase shift circuit 64 can be changed based on the control signal converted by the detection circuit 63. Changing the passing phase of the variable phase shift circuit 64 changes the input impedance of the low-noise amplifier 23. Due to the above-described functions of the coupler 52, the detection circuit 63, and the variable phase shift circuit 64, for example, when the power level of the at least one signal is equal to or greater than a predetermined threshold, it is possible to shift the impedance of at least one of the transmission bands of bands A and B toward the open side while minimizing the shift in the impedance of the reception band of band C at the input end of the low-noise amplifier 23. This prevents the first transmission signal, the second transmission signal, and the third transmission signal that have entered the reception path of band C from entering the low-noise amplifier 23. This prevents the low-noise amplifier 23 from generating triple-beat distortion components contained in the reception band of band C, thereby preventing deterioration of the reception sensitivity of band C.

[0087] In the high-frequency circuit 5 according to this modification, the coupler 51, the detection circuit 61, and the variable phase shift circuit 62 included in the high-frequency circuit 1 according to the embodiment may be arranged in the reception path of band B connecting the filter 33 and the low-noise amplifier 22.

[0088] [3 Effects, etc.] As described above, the high-frequency circuit 1 according to this embodiment (the high-frequency circuit 5 according to the modified example) can simultaneously transmit two signals having different frequencies in band A and one signal having a frequency in band B, and includes a power amplifier 11, a filter 31 connected to the output terminal of the power amplifier 11 and having a pass band that includes the transmission band of band A, a power amplifier 12, a filter 32 connected to the output terminal of the power amplifier 12 and having a pass band that includes the transmission band of band B, a low-noise amplifier 22 (23), a filter 33 (34) connected to the input terminal of the low-noise amplifier 22 (23) and having a pass band that includes the reception band of band B (band C), a coupler 51 (52) having a main line and a sub-line and connected between the filter 33 (34) and the low-noise amplifier 22 (23), a detection circuit 61 (63) connected to the sub-line, and a variable phase shift circuit 62 (64) connected to the detection circuit 61 (63) and connected between the low-noise amplifier 22 (23) and the main line.

[0089] This allows at least one of the first, second, and third transmission signals that have entered the band B (band C) receiving path connecting the filter 33 (34) and the low-noise amplifier 22 (23) to be detected by the sub-line of the coupler 51 (52). The at least one signal detected by the coupler 51 (52) is detected by the detection circuit 61 (63) and converted into a control signal corresponding to the power level of the at least one signal. The passing phase of the variable phase shift circuit 62 (64) can be changed based on the control signal converted by the detection circuit 61 (63). Changing the passing phase of the variable phase shift circuit 62 (64) changes the input impedance of the low-noise amplifier 22 (23). The above functions of the coupler 51 (52), the detection circuit 61 (63), and the variable phase shift circuit 62 (64) make it possible, for example, when the power level of the at least one signal is equal to or higher than a predetermined threshold, to shift the impedance of at least one of the transmission bands of Band A and Band B at the input end of the low-noise amplifier 22 (23) to the open side. This prevents the first transmission signal, the second transmission signal, and the third transmission signal that have entered the reception path of Band B (Band C) from entering the low-noise amplifier 22 (23), thereby preventing triple-beat distortion components included in the reception band of Band B (Band C) from occurring in the low-noise amplifier 22 (23), and suppressing deterioration of the reception sensitivity of Band B (Band C).

[0090] For example, in the high-frequency circuit 1 (5), two first transmission signals having different frequencies in band A, one second transmission signal having a frequency in band B, and one first reception signal having a frequency in band B (band C) can be transmitted simultaneously, and the frequency of the triple beat distortion generated by the two first transmission signals and one second transmission signal is included in the reception band of band B (band C).

[0091] According to this, even if the frequency of the triple beat distortion generated by the two first transmission signals and one second transmission signal is included in the reception band of band B (band C), the two first transmission signals and one second transmission signal can be prevented from entering the low-noise amplifier 22 (23), thereby suppressing deterioration of the reception sensitivity of band B (band C).

[0092] Furthermore, for example, in the high-frequency circuit 1A according to the first embodiment, the variable phase shift circuit 62A includes a phase circuit including at least one of an inductor and a capacitor, and a switch 623 that switches between connection and disconnection between the phase circuit and the low-noise amplifier 22, and the detection circuit 61A is configured to output a control signal to the switch 623 based on the power level of the signal of band A output from the sub-line 512.

[0093] This makes it possible to change the passing phase of the variable phase shift circuit 62A in accordance with the power level of the band A signal passing through the band B receiving path connecting the filter 33 and the low-noise amplifier 22, thereby shifting the impedance of band A at the input end of the low-noise amplifier 22.

[0094] Also, for example, in the high-frequency circuit 1A, the detection circuit 61A includes a power detector 611 that detects the power level of the signal of band A output from the sub-line 512, and a comparator 612 that is configured to output a first control voltage that turns on the switch 623 when the power level detected by the power detector 611 is equal to or greater than a predetermined value, and to output a second control voltage that turns off the switch 623 when the power level is smaller than the predetermined value.

[0095] This allows the passing phase of the variable phase shift circuit 62A to be changed depending on whether the power level of the band A signal passing through the band B receiving path is high or low, and makes it possible to shift the impedance of band A at the input end of the low-noise amplifier 22 to the open side when the power level of the band A signal is high.

[0096] Furthermore, for example, in the high-frequency circuit 1B according to the second embodiment, the low-noise amplifier 22 includes an amplifying transistor having a signal input terminal, a signal output terminal, a power supply voltage input terminal, and a reference voltage terminal, and the variable phase shift circuit 62B includes a first terminal, a second terminal, and a first control terminal, and includes a transistor 624 having the first terminal connected to the reference voltage terminal, the second terminal connected to ground, and the first control terminal connected to the detection circuit 61B, and the detection circuit 61B is configured to output a control signal to the first control terminal based on the power level of band A output from the sub-line 512.

[0097] This causes the conductance of the current flowing between the first and second terminals of the transistor 624 of the variable phase shift circuit 62B to change depending on the power level of the band A signal passing through the band B reception path connecting the filter 33 and the low-noise amplifier 22, thereby shifting the impedance of the band A transmission band at the input end of the low-noise amplifier 22.

[0098] Also, for example, in the high-frequency circuit 1B, the detection circuit 61B has a power detector 611 that detects the power level of band A output from the sub-line 512, and a voltage adjustment circuit 613 that is configured to output a control voltage corresponding to the power level detected by the power detector 611 to a first control terminal.

[0099] This allows the conductance of the current flowing between the first and second terminals of the transistor 624 to change depending on whether the power level of the band A signal passing through the band B reception path is high or low, thereby changing the passing phase of the variable phase shift circuit 62B, and makes it possible to shift the impedance of band A at the input end of the low-noise amplifier 22 to the open side when the power level of the band A signal is high.

[0100] Also, for example, in the high frequency circuit 1 (5), the low noise amplifier 22 (23) is included in the semiconductor IC 220 (230), and the variable phase shift circuit 62 (64) is included in the semiconductor IC 220 (230).

[0101] This allows the receiver circuit for band B to be made smaller, and therefore the high frequency circuit 1 (5) can be made smaller.

[0102] Also, for example, in the high frequency circuit 1 (5), the detection circuit 61 (63) is included in the semiconductor IC 220 (230).

[0103] This allows the receiver circuit for band B to be made smaller, and therefore the high frequency circuit 1 (5) can be made smaller.

[0104] Also, for example, in the high frequency circuit 1, band A is a band for TDD, and band B is a band for FDD.

[0105] This makes it possible to suppress deterioration of the receiving sensitivity of band B when the first and second transmission signals having the frequency of band A and the third transmission signal of band B are transmitted simultaneously.

[0106] For example, in the high-frequency circuit 1, band A is band B41, band B40 for 4G-LTE, band n41 for 5G-NR, or band n40, and band B is band B3, band B1 for 4G-LTE, band n3 for 5G-NR, or band n1.

[0107] 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 antennas 2A and 2B.

[0108] This allows the effects of the high frequency circuit 1 to be realized in the communication device 4.

[0109] (Other Embodiments) While the high-frequency circuit and communication device according to the present invention have been described above based on the embodiments, examples, and modifications, the high-frequency circuit and communication device according to the present invention are not limited to the above-described embodiments, examples, and modifications. The present invention also includes other embodiments realized by combining any of the components in the above-described embodiments, examples, and modifications, modifications obtained by applying various modifications to the above-described embodiments, examples, and modifications that would occur to a person skilled in the art without departing from the spirit of the present invention, and various devices incorporating the above-described high-frequency circuit.

[0110] For example, in the circuit configurations of the high-frequency circuits according to the above-described embodiments, examples, and modifications, other circuit elements, wiring, etc. may be inserted between the paths connecting the circuit elements and signal paths shown in the drawings.

[0111] The following describes the features of the high-frequency circuit and communication device described based on the above-mentioned embodiment, example, and modified example.

[0112] <1> A high-frequency circuit capable of simultaneously transmitting two signals having different frequencies in a first band and one signal having a frequency in a second band, comprising: a first power amplifier; a first filter connected to an output end of the first power amplifier and having a pass band including a transmission band of the first band; a second power amplifier; a second filter connected to an output end of the second power amplifier and having a pass band including the transmission band of the second band; a first low-noise amplifier; a third filter connected to an input end of the first low-noise amplifier and having a pass band including a reception band of a third band; a coupler having a main line and a sub-line and connected between the third filter and the first low-noise amplifier; a detection circuit connected to the sub-line; and a variable phase shift circuit connected to the detection circuit and connected between the first low-noise amplifier and the main line.

[0113] <2> The high-frequency circuit according to <1>, wherein two first transmission signals having different frequencies in the first band, one second transmission signal having a frequency in the second band, and one first reception signal having a frequency in the third band can be transmitted simultaneously, and a frequency of triple beat distortion occurring in the two first transmission signals and the one second transmission signal is included in a reception band of the third band.

[0114] <3> The high-frequency circuit according to <1> or <2>, wherein the third band is the second band, and the third filter has a pass band that includes a reception band of the second band.

[0115] <4> The high-frequency circuit according to any one of <1> to <3>, wherein the variable phase shift circuit comprises: a phase circuit including at least one of an inductor and a capacitor; and a first switch that switches between connection and disconnection between the phase circuit and the first low-noise amplifier; and the detection circuit is configured to output a control signal to the first switch based on a power level of the first band signal output from the sub-line.

[0116] <5> The high-frequency circuit according to <4>, wherein the detection circuit includes: a power detector that detects a power level of the first band signal output from the sub-line; and a comparator configured to output a first control voltage that makes the first switch conductive when the power level detected by the power detector is equal to or greater than a predetermined value, and to output a second control voltage that makes the first switch non-conductive when the power level is smaller than the predetermined value.

[0117] <6> The high-frequency circuit according to any one of <1> to <3>, wherein the first low-noise amplifier includes an amplifying transistor having a signal input terminal, a signal output terminal, a power supply voltage input terminal, and a reference voltage terminal; the variable phase shift circuit includes a field-effect transistor having a first terminal, a second terminal, and a first control terminal, the first terminal being connected to the reference voltage terminal, the second terminal being connected to ground, and the first control terminal being connected to the detection circuit; and the detection circuit is configured to output a control signal to the first control terminal based on the power level of the first band output from the sub-line.

[0118] <7> The high-frequency circuit according to <6>, wherein the detection circuit includes: a power detector that detects a power level of the first band output from the sub-line; and a voltage adjustment circuit configured to output a control voltage corresponding to the power level detected by the power detector to the first control terminal.

[0119] <8> The high-frequency circuit according to any one of <1> to <7>, wherein the first low-noise amplifier is included in a first semiconductor IC, and the variable phase shift circuit is included in the first semiconductor IC.

[0120] <9> The high-frequency circuit according to <8>, wherein the detection circuit is included in the first semiconductor IC.

[0121] <10> The high-frequency circuit according to any one of <1> to <9>, wherein the first band is a time-division duplex band, and the second band is a frequency-division duplex band.

[0122] <11> The first band is band B41, band B40 for 4G-LTE, band n41, or band n40 for 5G-NR, and the second band is band B3, band B1 for 4G-LTE, band n3, or band n1 for 5G-NR. The high-frequency circuit according to <10>.

[0123] <12> 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 <11> that transmits the high-frequency signal between the signal processing circuit and an antenna.

[0124] The present invention can be widely used in communication devices such as mobile phones as a high-frequency circuit and a communication device disposed in a front end portion.

[0125] 1, 1A, 1B, 5 High frequency circuit 2A, 2B, 2C Antenna 3 RF signal processing circuit (RFIC) 4, 6 Communication device 11, 12 Power amplifier 21, 22, 23 Low noise amplifier 31, 32, 33, 34 Filter 41 Switch 51, 52 Coupler 61, 61A, 61B, 63 Detector circuit 62, 62A, 62B, 64 Variable phase shift circuit 101, 102, 103 Antenna connection terminal 110, 130 Signal input terminal 120, 140, 150 Signal output terminal 220, 220A, 220B, 230 Semiconductor IC 511 Main line 512 Sub line 513 Terminator 611 Power detector 612 Comparator 613 Voltage adjustment circuit 621 Inductor 622 Capacitor 623 Switch 624 Transistor

Claims

1. A high-frequency circuit capable of simultaneously transmitting two signals having different frequencies in a first band and one signal having a frequency in a second band, comprising: a first power amplifier; a first filter connected to the output end of the first power amplifier and having a passband including the transmission band of the first band; a second power amplifier; a second filter connected to the output end of the second power amplifier and having a passband including the transmission band of the second band; a first low-noise amplifier; a third filter connected to the input end of the first low-noise amplifier and having a passband including the reception band of a third band; a coupler having a main line and a sub-line and connected between the third filter and the first low-noise amplifier; a detection circuit connected to the sub-line; and a variable phase shift circuit connected to the detection circuit and connected between the first low-noise amplifier and the main line.

2. The high frequency circuit according to claim 1, wherein two first transmission signals having different frequencies in the first band, one second transmission signal having a frequency in the second band, and one first reception signal having a frequency in the third band can be transmitted simultaneously, and the frequency of triple beat distortion occurring in the two first transmission signals and the one second transmission signal is included in the reception band of the third band.

3. The high-frequency circuit according to claim 1 or 2, wherein the third band is the second band, and the third filter has a pass band that includes a reception band of the second band.

4. The high-frequency circuit according to any one of claims 1 to 3, wherein the variable phase shift circuit comprises: a phase circuit including at least one of an inductor and a capacitor; and a first switch that switches between connection and disconnection of the phase circuit and the first low-noise amplifier; and the detection circuit is configured to output a control signal to the first switch based on the power level of the first band signal output from the sub-line.

5. The high-frequency circuit according to claim 4, wherein the detection circuit comprises: a power detector that detects the power level of the first band signal output from the sub-line; and a comparator configured to output a first control voltage that makes the first switch conductive when the power level detected by the power detector is equal to or greater than a predetermined value, and to output a second control voltage that makes the first switch non-conductive when the power level is less than the predetermined value.

6. The high-frequency circuit according to any one of claims 1 to 3, wherein the first low-noise amplifier comprises an amplifying transistor having a signal input terminal, a signal output terminal, a power supply voltage input terminal and a reference voltage terminal; the variable phase shift circuit comprises a field-effect transistor having a first terminal, a second terminal and a first control terminal, the first terminal being connected to the reference voltage terminal, the second terminal being connected to ground, and the first control terminal being connected to the detection circuit; and the detection circuit is configured to output a control signal to the first control terminal based on the power level of the first band output from the sub-line.

7. The high-frequency circuit according to claim 6, wherein the detection circuit comprises: a power detector that detects the power level of the first band output from the sub-line; and a voltage adjustment circuit configured to output a control voltage corresponding to the power level detected by the power detector to the first control terminal.

8. The high-frequency circuit according to any one of claims 1 to 7, wherein the first low-noise amplifier is included in a first semiconductor IC, and the variable phase shift circuit is included in the first semiconductor IC.

9. The high frequency circuit according to claim 8, wherein the detection circuit is included in the first semiconductor IC.

10. The high-frequency circuit according to any one of claims 1 to 9, wherein the first band is a time-division duplex band, and the second band is a frequency-division duplex band.

11. The radio frequency circuit according to claim 10, wherein the first band is band B41 or band B40 for 4G-LTE, or band n41 or band n40 for 5G-NR, and the second band is band B3 or band B1 for 4G-LTE, or band n3 or band n1 for 5G-NR.

12. 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 11 that transmits a high-frequency signal between the signal processing circuit and an antenna.

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