High-frequency circuit and communication device

Abstract

The high-frequency circuit (1) includes a power amplifier (11) for communication band A and a power amplifier (12) for communication band B, and is capable of simultaneously using transmissions in communication band A, transmissions in communication band B, and receptions in communication band C. The frequency range of intermodulation distortion overlaps at least a part of the reception band of communication band C. The intermodulation distortion is generated between the second harmonic of the transmission signal in communication band A and the fundamental wave of the transmission signal in communication band B. The power amplifier (11) includes amplification elements (11A and 11B) and an output transformer (31) having coils (31a and 31b). One end of the coil (31a) is connected to the output of the amplification element (11A), the other end of the coil (31a) is connected to the output of the amplification element (11B), and one end of the coil (31b) is connected to the output terminal (116) of the power amplifier (11).

Description

Technical Field

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

[0002] In mobile communication devices such as mobile phones, with the development of multi-band, a front-end circuit capable of simultaneously transmitting high-frequency signals of different frequencies is required. For example, in Patent Document 1, the circuit structure of an electronic system (high-frequency front-end module) having a first transmission circuit and a second transmission circuit is disclosed.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2017-17691 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] However, in the above prior art, in the case of simultaneously transmitting and receiving multiple high-frequency signals, intermodulation distortion (IMD) between the multiple high-frequency signals may overlap with the reception band, resulting in a decrease in reception sensitivity.

[0008] Therefore, the present invention provides a high-frequency circuit and a communication device capable of suppressing a decrease in reception sensitivity caused by intermodulation distortion in the case of simultaneously transmitting and receiving multiple high-frequency signals.

[0009] Means for Solving the Problems

[0010] A high-frequency circuit according to one embodiment of the present invention includes: a first filter having a passband including a transmission band of a first communication band; a second filter having a passband including a transmission band of a second communication band different from the first communication band; a third filter having a passband including a reception band of a third communication band; a first power amplifier connected to the first filter; and a second power amplifier connected to the second filter, wherein transmission in the first communication band, transmission in the second communication band, and reception in the third communication band can be utilized simultaneously, at least a part of the frequency range of intermodulation distortion overlaps with at least a part of the reception band of the third communication band, the intermodulation distortion is generated between the second harmonic of the transmission signal in the first communication band and the fundamental wave of the transmission signal in the second communication band, the first power amplifier includes: a first amplifying element and a second amplifying element; and an output converter which is a first transformer having a first coil and a second coil, one end of the first coil is connected to the output of the first amplifying element, the other end of the first coil is connected to the output of the second amplifying element, and one end of the second coil is connected to the output terminal of the first power amplifier.

[0011] Effects of the Invention

[0012] According to the high-frequency circuit of one embodiment of the present invention, it is possible to suppress a decrease in reception sensitivity caused by intermodulation distortion in the case of simultaneously transmitting and simultaneously transmitting and receiving a plurality of high-frequency signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a circuit structure diagram of the high-frequency circuit and the communication device according to the embodiment.

[0014] Figure 2 It is a circuit structure diagram of the power amplifier included in the high-frequency circuit according to the embodiment.

[0015] Figure 3 It is a diagram showing the flow of signals in the communication device according to the embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0016] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, all of the embodiments described below represent general or specific examples. The numerical values, shapes, materials, constituent elements, arrangements of the constituent elements, connection methods, etc. shown in the following embodiments are examples, and the gist thereof is not intended to limit the present invention.

[0017] In addition, each drawing is a schematic diagram appropriately emphasized, omitted, or adjusted in ratio for representing the present invention, and is not necessarily strictly illustrated, and may be different from the actual shape, positional relationship, and ratio. In each drawing, substantially the same structures are denoted by the same reference numerals, and repeated descriptions may be omitted or simplified.

[0018] In the circuit structure of the present invention, "connection" means not only a case of direct connection through connection terminals and / or wiring conductors, but also a case of electrical connection via other circuit elements. "Connected between A and B" means connected to both A and B between A and B.

[0019] (Embodiment)

[0020] [1.1 Circuit Structure of High-Frequency Circuit 1 and Communication Device 5]

[0021] Refer to Figure 1 to describe the circuit structures of the high-frequency circuit 1 and the communication device 5 according to this embodiment. Figure 1 is the circuit structure diagram of the high-frequency circuit 1 and the communication device 5 according to the embodiment.

[0022] [1.1.1 Circuit Structure of Communication Device 5]

[0023] First, describe the circuit structure of the communication device 5. As Figure 1 shown, the communication device 5 according to this embodiment includes a high-frequency circuit 1, an antenna 2, an RFIC 3, and a BBIC 4.

[0024] The high-frequency circuit 1 transmits high-frequency signals between the antenna 2 and the RFIC 3. The circuit structure of the high-frequency circuit 1 will be described later.

[0025] The antenna 2 is connected to the antenna connection terminal 100 of the high-frequency circuit 1, and after receiving a high-frequency signal from the outside, outputs it to the high-frequency circuit 1.

[0026] The RFIC 3 is an example of a signal processing circuit that processes high-frequency signals. Specifically, the RFIC 3 performs signal processing on the high-frequency reception signal input via the reception path of the high-frequency circuit 1 through down-conversion or the like, and outputs the reception signal generated after this signal processing to the BBIC 4. In addition, the RFIC 3 has a control unit that controls switches and amplifiers etc. possessed by the high-frequency circuit 1. Furthermore, part or all of the functions of the control unit of the RFIC 3 can be installed outside the RFIC 3, for example, can be installed in the BBIC 4 or the high-frequency circuit 1.

[0027] The BBIC 4 is a baseband signal processing circuit that performs signal processing using an intermediate frequency band lower than the high-frequency signal transmitted by the high-frequency circuit 1. As the signals processed by the BBIC 4, for example, an image signal for displaying an image and / or a voice signal for making a call via a speaker are used.

[0028] In addition, in the communication device 5 according to this embodiment, the antenna 2 and the BBIC 4 are not essential constituent elements.

[0029] [1.1.2 Circuit Structure of High-Frequency Circuit 1]

[0030] Next, the circuit structure of high-frequency circuit 1 will be described. As Figure 1 shown, high-frequency circuit 1 includes power amplifiers 11 and 12, a low-noise amplifier 21, a switch 51, filters 61 to 63, an antenna connection terminal 100, high-frequency input terminals 111 and 112, and a high-frequency output terminal 121.

[0031] The antenna connection terminal 100 is connected to the antenna 2.

[0032] The high-frequency input terminals 111 and 112 are respectively terminals for receiving high-frequency transmission signals from outside high-frequency circuit 1. In high-frequency input terminal 111, a transmission signal in communication band A can be received from RFIC 3. In high-frequency input terminal 112, a transmission signal in communication band B can be received from RFIC 3. In this embodiment, the transmission signals received by high-frequency input terminals 111 and 112 are both unbalanced signals.

[0033] The high-frequency output terminal 121 is a terminal for providing a high-frequency reception signal to the outside of high-frequency circuit 1. Specifically, the high-frequency output terminal 121 is a terminal for providing a reception signal in communication band C to RFIC 3.

[0034] The communication band refers to a band for a communication system predefined by a standardization organization etc. (such as 3GPP (3rd Generation Partnership Project) and IEEE (Institute of Electrical and Electronics Engineers) etc.).

[0035] Here, the communication system refers to a communication system constructed using radio access technology (RAT). As the communication system, for example, 5GNR (5th Generation New Radio) system, LTE (Long Term Evolution) system, and WLAN (Wireless Local Area Network) system etc. can be used, but it is not limited to these systems.

[0036] Communication frequency band A is an example of the first communication frequency band. Communication frequency band B is an example of the second communication frequency band and is a frequency band different from communication frequency band A. Communication frequency band C is an example of the third communication frequency band. Communication frequency band C can be the same as either of communication frequency bands A and B or different from communication frequency bands A and B. Communication frequency bands A, B, and C can also be any of the communication frequency bands for frequency division duplex (FDD) and time division duplex (TDD).

[0037] Here, it is possible to simultaneously utilize the transmission of communication frequency band A, the transmission of communication frequency band B, and the reception of communication frequency band C. Simultaneously utilizing the transmission of communication frequency band A, the transmission of communication frequency band B, and the reception of communication frequency band C means allowing the simultaneous transmission and reception of the transmission signal of communication frequency band A, the transmission signal of communication frequency band B, and the reception signal of communication frequency band C. At this time, separate and individual utilization of the transmission and reception of multiple communication frequency bands is not excluded. The combination of communication frequency bands that can be simultaneously utilized is predefined by a standardization organization or the like, for example.

[0038] Power amplifier 11 is an example of the first power amplifier. The input terminal 115 of power amplifier 11 is connected to the high-frequency input terminal 111, and the output terminal 116 of power amplifier 11 is connected to the filter 61. Power amplifier 11 can amplify the transmission signal of communication frequency band A received by the high-frequency input terminal 111. At this time, power amplifier 11 can amplify the unbalanced signal received by the high-frequency input terminal 111 after converting it into a balanced signal. Such a power amplifier 11 is sometimes also referred to as a differential amplification type amplifier. Use Figure 2 The detailed structure of power amplifier 11 will be described later.

[0039] In addition, a balanced signal refers to a group of signals having opposite phases to each other. A balanced signal is sometimes also referred to as a differential signal. On the other hand, an unbalanced signal refers to a signal represented by the potential difference from the ground. An unbalanced signal is sometimes also referred to as a single-ended signal.

[0040] Power amplifier 12 is an example of the second power amplifier. The input terminal 125 of power amplifier 12 is connected to the high-frequency input terminal 112, and the output terminal 126 of power amplifier 12 is connected to the filter 62. Power amplifier 12 is a multi-stage structure amplifier and includes two amplification elements 12A and 12B connected in series. Amplification element 12A corresponds to the input stage of the multi-stage structure amplifier. Amplification element 12B corresponds to the output stage of the multi-stage structure amplifier.

[0041] The power amplifier 12 can amplify the transmission signal in communication band B received by the high-frequency input terminal 112. At this time, the power amplifier 12 can amplify the transmission signal in communication band B while maintaining it in an unbalanced signal state. That is to say, the power amplifier 12 can amplify the unbalanced signal in communication band B received by the high-frequency input terminal 111 without converting it into a balanced signal. Such a power amplifier 12 is sometimes also referred to as a non-differential amplification type amplifier.

[0042] In addition, the structure of the power amplifier 12 is not limited to Figure 1 the structure of. For example, the power amplifier 12 can also be a single-stage structure amplifier. In addition, the power amplifier 12 can be either a differential amplification type amplifier or a Doherty type amplifier.

[0043] In addition, the power amplifiers 11 and 12 respectively correspond to a high-power class and a non-high-power class. The power class is a classification of the output power of the terminal defined by the maximum output power, etc., indicating that the smaller the value representing the power class, the higher the power output corresponding to it. The maximum output power of the high-power class is larger than the maximum output power of the non-high-power class. The maximum output power is defined by the output power at the antenna terminal of the terminal. The measurement of the maximum output power is performed, for example, by the method defined by 3GPP, etc. For example, in Figure 1 the maximum output power is measured by measuring the radiation power at antenna 2. In addition, instead of measuring the radiation power, it is also possible to measure the output power of antenna 2 by setting a terminal near antenna 2 and connecting a measuring device (such as a spectrum analyzer, etc.) to this terminal.

[0044] The high-power class is an example of the first power class and is represented by a value less than a specified value. The non-high-power class is an example of the second power class and is represented by a value equal to or greater than the specified value. As the specified value, for example, 3 can be used. In this case, the high-power class includes power classes 1, 1.5, and 2, and the non-high-power class includes power classes 3 and 4.

[0045] The input of the low-noise amplifier 21 is connected to the filter 63, and the output of the low-noise amplifier 21 is connected to the high-frequency output terminal 121. The low-noise amplifier 21 can amplify the received signal in communication band C received by the antenna connection terminal 100. The received signal in communication band C amplified by the low-noise amplifier 21 is output to the high-frequency output terminal 121.

[0046] The amplifying elements included in the power amplifiers 11 and 12 and the low-noise amplifier 21 can be constituted by, for example, field effect transistors (FETs) or heterojunction bipolar transistors (HBTs) made of Si-based CMOS (Complementary Metal Oxide Semiconductor) or GaAs.

[0047] The switch 51 is connected between the antenna connection terminal 100 and the filters 61 to 63. The switch 51 has terminals 511 to 514. The terminal 511 is connected to the antenna connection terminal 100. The terminal 512 is connected to the filter 61, the terminal 513 is connected to the filter 62, and the terminal 514 is connected to the filter 63.

[0048] In this connection structure, the switch 51 can connect at least one of the terminals 512 to 514 to the terminal 511 based on a control signal from the RFIC 3, for example. That is, the switch 51 can switch the connection and non-connection between the antenna connection terminal 100 and each of the filters 61 to 63. The switch 51 is constituted by, for example, a multi-connection type switch circuit and is called an antenna switch.

[0049] The filter 61 (A-Tx) is an example of a first filter and has a passband including a transmission band of the communication band A. One end of the filter 61 is connected to the antenna connection terminal 100 via the switch 51. The other end of the filter 61 is connected to the output terminal 116 of the power amplifier 11.

[0050] The filter 62 (B-Tx) is an example of a second filter and has a passband including a transmission band of the communication band B. One end of the filter 62 is connected to the antenna connection terminal 100 via the switch 51. The other end of the filter 62 is connected to the output terminal 126 of the power amplifier 12.

[0051] The filter 63 (C-Rx) is an example of a third filter and has a passband including a reception band of the communication band C. One end of the filter 63 is connected to the antenna connection terminal 100 via the switch 51. The other end of the filter 63 is connected to the input of the low-noise amplifier 21.

[0052] The transmission band means a band for transmission within the communication band. If the communication band is a band for FDD, the transmission band corresponds to the uplink operating band which is the part designated as the uplink within the communication band. If the communication band is a band for TDD, the transmission band corresponds to the entire communication band.

[0053] The receive band refers to the band for reception within the communication band. If the communication band is a band used for FDD, the receive band is equivalent to the downlink operating band, which is the part within the communication band designated as the downlink. If the communication band is a band used for TDD, the receive band is equivalent to the entire communication band.

[0054] These filters 61 to 63 can also be, for example, any one of an elastic wave filter using SAW (Surface Acoustic Wave), an elastic wave filter using BAW (Bulk Acoustic Wave), an LC resonance filter, and a dielectric filter, and are not limited to these filters.

[0055] In addition, Figure 1 Some of the circuit elements shown may not be included in the high-frequency circuit 1. For example, the high-frequency circuit 1 only needs to have at least the power amplifiers 11 and 12 and the filters 61 to 63, and may not have other circuit elements (such as the switch 51 and the low-noise amplifier 21, etc.).

[0056] [1.1.3 Circuit Structure of Power Amplifier 11]

[0057] Next, with reference to Figure 2 an example of the circuit structure of the power amplifier 11 will be described. Figure 2 is a circuit structure diagram of the power amplifier 11 included in the high-frequency circuit 1 according to the embodiment. Hereinafter, a transformer will be simply referred to as a trans.

[0058] As Figure 2 shown, the power amplifier 11 includes an input terminal 115 and an output terminal 116, amplification elements 11A to 11C, an output transformer 31, a capacitor 32, and an input transformer 33.

[0059] The input terminal 115 is connected to the high-frequency input terminal 111 of the high-frequency circuit 1. The unbalanced signal received from the outside by the high-frequency input terminal 111 is transmitted to the input terminal 115.

[0060] The amplification element 11C corresponds to the input stage of a multi-stage amplifier. The input of the amplification element 11C is connected to the input terminal 115 of the power amplifier 11, and the output of the amplification element 11C is connected to the input transformer 33. In such a connection structure, the amplification element 11C can amplify the unbalanced signal received by the input terminal 115 in a state where the power supply voltage Vcc1 is applied.

[0061] The input transformer 33 is an example of an input converter. The input transformer 33 includes a primary-side coil 33a and a secondary-side coil 33b. The coil 33a is an example of a third coil, one end of which is connected to the output terminal of the amplifying element 11C, and the other end of which is applied with the power supply voltage Vcc1. The coil 33b is an example of a fourth coil, one end of which is connected to the input of the amplifying element 11A, and the other end of which is connected to the input of the amplifying element 11B.

[0062] The input transformer 33 can convert the unbalanced signal amplified by the amplifying element 11C into a balanced signal. That is to say, the input transformer 33 is an unbalanced / balanced converter. Specifically, the input transformer 33 can convert the transmission signal in communication band A amplified by the amplifying element 11C into an inverted signal with phase inversion and a non-inverted signal without phase inversion.

[0063] The amplifying elements 11A and 11B are examples of a first amplifying element and a second amplifying element respectively, and can independently amplify the balanced signal output from the input transformer 33. The input of the amplifying element 11A is connected to one end of the coil 33b of the input transformer 33, and the output of the amplifying element 11A is connected to one end of the coil 31a of the output transformer 31 and one end of the capacitor 32. The input of the amplifying element 11B is connected to the other end of the coil 33b of the input transformer 33, and the output of the amplifying element 11B is connected to the other end of the coil 31a of the output transformer 31 and the other end of the capacitor 32.

[0064] The output transformer 31 is an example of an output converter. The output transformer 31 includes a primary-side coil 31a and a secondary-side coil 31b. The coil 31a is an example of a first coil, one end of which is connected to the output of the amplifying element 11A, and the other end of which is connected to the output of the amplifying element 11B. In addition, the power supply voltage Vcc2 is applied to the midpoint of the coil 31a. The coil 31b is an example of a second coil, one end of which is connected to the output terminal 116, and the other end of which is connected to the ground. That is to say, the output transformer 31 is connected between the outputs of the amplifying element 11A and the amplifying element 11B and the output terminal 116.

[0065] The output transformer 31 can convert the balanced signal into an unbalanced signal by synthesizing the balanced signals amplified by the amplifying elements 11A and 11B. That is to say, the output transformer 31 is a balanced / unbalanced converter. Specifically, the output transformer 31 can synthesize the inverted signal and the non-inverted signal of the transmission signal in communication band A.

[0066] The capacitor 32 is connected between the outputs of the amplifying elements 11A and 11B. Specifically, one end of the capacitor 32 is connected to the output of the amplifying element 11A and one end of the coil 31a. Further, the other end of the capacitor 32 is connected to the output of the amplifying element 11B and the other end of the coil 31a.

[0067] According to the circuit configuration of the power amplifier 11, the amplifying elements 11A and 11B operate in an inverted phase. At this time, the currents in the fundamental waves of the amplifying elements 11A and 11B flow in an inverted phase, that is, in opposite directions. Therefore, it is difficult for the currents in the fundamental waves to flow into the ground wiring and the power supply wiring that are arranged at substantially equal distances from the amplifying elements 11A and 11B. Accordingly, it is possible to suppress the inflow of useless currents into the ground wiring and the power supply wiring, and thus it is possible to suppress the decrease in the power gain observed in conventional power amplifiers. Further, since the non-inverted signal and the inverted signal amplified by the amplifying elements 11A and 11B, respectively, are combined, it is possible to cancel out the noise components that are similarly superimposed on the two signals, and it is possible to reduce the even-order harmonic components.

[0068] In addition, Figure 2 The circuit configuration of the power amplifier 11 is an example and is not limited thereto. For example, the power amplifier 11 may not include the amplifying element 11C and the capacitor 32. Further, when a balanced signal is input to the power amplifier 11, the power amplifier 11 may not include the input transformer 33.

[0069] In addition, in the present embodiment, transformers are used for the unbalanced / balanced conversion and the balanced / unbalanced conversion, but are not limited thereto. That is, the input converter and the output converter are not limited to the input transformer 33 and the output transformer 31. For example, as the input converter and the output converter, a delay line can also be used.

[0070] [1.2 Flow of signals in the high-frequency circuit 1]

[0071] Next, the simultaneous utilization of the transmission in the communication band A, the transmission in the communication band B, and the reception in the communication band C in the communication device 5 will be described. Figure 3 is a diagram showing the flow of signals in the communication device 5 according to the embodiment. In Figure 3 , the dashed arrows indicate the flow of signals.

[0072] In Figure 3 , the transmission in the communication band A, the transmission in the communication band B, and the reception in the communication band C are simultaneously utilized. That is, in Figure 3 , a state in which the transmission signal in the communication band A, the transmission signal in the communication band B, and the reception signal in the communication band C are simultaneously transmitted is shown.

[0073] Here, all of the terminals 512 to 514 of the switch 51 are connected to the terminal 511. Thus, the transmission signal of communication band A is transmitted from the RFIC 3 to the antenna 2 via the high-frequency input terminal 111, the power amplifier 11, the filter 61, the switch 51, and the antenna connection terminal 100 in sequence. In addition, the transmission signal of communication band B is transmitted from the RFIC 3 to the antenna 2 via the high-frequency input terminal 112, the power amplifier 12, the filter 62, the switch 51, and the antenna connection terminal 100 in sequence. In addition, the received signal of communication band C is transmitted from the antenna 2 to the RFIC 3 via the antenna connection terminal 100, the switch 51, the filter 63, the low-noise amplifier 21, and the high-frequency output terminal 121 in sequence.

[0074] At this time, in the switch 51 and / or the filters 61 to 63, etc., IMD is generated between the second harmonic of the transmission signal of communication band A and the fundamental wave of the transmission signal of communication band B. The frequency fIMD of IMD is expressed as follows using the frequency fA of the fundamental wave of the transmission signal of communication band A and the frequency fB of the fundamental wave of the transmission signal of communication band B.

[0075] fIMD = 2fA - fB

[0076] In addition, as the frequency fA, any frequency within the transmission band of communication band A can be used. Similarly, as the frequency fB, any frequency within the transmission band of communication band B can be used. Therefore, the frequency fIMD of IMD also varies within the frequency range determined by the transmission bands of communication bands A and B.

[0077] If the frequency fIMD of this IMD is included in the reception band of communication band C, the unwanted wave of IMD will interfere with the received signal of communication band C, resulting in a decrease in reception sensitivity. For such a situation, the high-frequency circuit 1 according to the present embodiment includes a differential amplification type amplifier as the power amplifier 11 for amplifying the transmission signal of communication band A. Thus, the generation of the second harmonic of the transmission signal of communication band A can be suppressed, and the unwanted wave of IMD can be reduced.

[0078] [1.3 Specific Examples of Communication Bands A, B, and C]

[0079] Here, specific examples of communication bands A, B, and C are described. In the present embodiment, communication bands A to C satisfy the following conditions (1) and (2). Condition (1): Transmission of communication band A, transmission of communication band B, and reception of communication band C can be utilized simultaneously. Condition (2): At least a part of the frequency range of IMD generated between the second harmonic of the transmission signal of communication band A and the fundamental wave of the transmission signal of communication band B overlaps with at least a part of the reception band of communication band C.

[0080] As a specific example of the communication frequency bands A to C that satisfy the conditions (1) and (2) above, the combinations in Table 1 can be considered.

[0081] [Table 1]

[0082] Communication Band A (Transmission Band) Communication Band B (Transmission Band) Communication Band C (Receiving Band) Band1 Band3 Band1 Band3 Band1 Band32 Band40 Band1 Band41 Band40 Band1 Band7 Band1 Band7 Band32 Band1 Band40 Band7 Band1 Band40 Band41

[0083] In addition, the combinations of the communication frequency bands in Table 1 are merely examples, and the communication frequency bands A to C are not limited thereto.

[0084] [1.4 Effects, etc.]

[0085] As described above, the high-frequency circuit 1 according to the present embodiment includes: a filter 61 having a passband including a transmission band of the communication frequency band A; a filter 62 having a passband including a transmission band of a communication frequency band B different from the communication frequency band A; a filter 63 having a passband including a reception band of the communication frequency band C; a power amplifier 11 connected to the filter 61; and a power amplifier 12 connected to the filter 62, wherein transmission in the communication frequency band A, transmission in the communication frequency band B, and reception in the communication frequency band C can be utilized simultaneously, at least a part of the frequency range of the intermodulation distortion overlaps with at least a part of the reception band of the communication frequency band C, and the intermodulation distortion is generated between the second harmonic of the transmission signal in the communication frequency band A and the fundamental wave of the transmission signal in the communication frequency band B. The power amplifier 11 includes: amplification elements 11A and 11B; and an output transformer having coils 31a and 31b, one end of the coil 31a is connected to the output of the amplification element 11A, the other end of the coil 31a is connected to the output of the amplification element 11B, and one end of the coil 31b is connected to the output terminal 116 of the power amplifier 11.

[0086] Accordingly, the power amplifier 11 can independently amplify the balanced signal with the amplification elements 11A and 11B, and can synthesize the amplified balanced signals with the output transformer 31 to generate an unbalanced signal. Therefore, the component of the second harmonic included in the unbalanced signal can be reduced, and thus the intermodulation distortion generated between the second harmonic of the transmission signal in the communication frequency band A and the fundamental wave of the transmission signal in the communication frequency band B can also be reduced. As a result, the useless wave of the intermodulation distortion can be suppressed from interfering with the reception signal in the communication frequency band C, and the decrease in the reception sensitivity due to the intermodulation distortion can be suppressed. In addition, the output transformer 31 can perform impedance transformation in addition to the balance / unbalance transformation, and can achieve impedance matching between the output impedance of the power amplifier 11 and the input impedance of the filter 61.

[0087] Further, for example, in the high-frequency circuit 1 according to the present embodiment, it may also be that the power amplifier 11 corresponds to a high power level, the power amplifier 12 corresponds to a non-high power level, and the maximum output power of the high power level may also be larger than the maximum output power of the non-high power level.

[0088] Accordingly, it is possible to suppress the generation of second harmonics in the power amplifier 11 that requires a larger output power. Therefore, it is possible to effectively reduce the second harmonics of the transmission signal in the communication band A, and it is also possible to more effectively reduce the intermodulation distortion generated between the second harmonics of the transmission signal in the communication band A and the fundamental wave of the transmission signal in the communication band B.

[0089] Further, for example, in the high-frequency circuit 1 according to the present embodiment, the amplification elements 11A and 11B can independently amplify the balanced signal that is the transmission signal in the communication band A, and the output transformer 31 can convert the balanced signal into an unbalanced signal by synthesizing the balanced signals amplified by the amplification elements 11A and 11B.

[0090] Accordingly, it is possible to independently amplify the balanced signal and synthesize the amplified balanced signals to generate an unbalanced signal.

[0091] Further, for example, in the high-frequency circuit 1 according to the present embodiment, the power amplifier 12 can amplify the transmission signal in the communication band B while maintaining it in an unbalanced signal state.

[0092] Accordingly, it is possible to use a so-called non-differential amplification type amplifier as the power amplifier 12. In a non-differential amplification type amplifier, it is possible to reduce the number of amplification elements and omit elements for balance / unbalance conversion, etc. Therefore, the power amplifier 12 can be miniaturized compared to a differential amplification type amplifier, which can contribute to the miniaturization of the high-frequency circuit 1. In addition, in the present embodiment, the influence of the second harmonics generated by the power amplifier 12 on the intermodulation distortion included in the reception band of the communication band C is small. Therefore, although a differential amplification type amplifier is not used for the power amplifier 12, it is possible to suppress the decrease in reception sensitivity due to intermodulation distortion by using a differential amplification type amplifier for the power amplifier 11.

[0093] Further, for example, in the high-frequency circuit 1 according to the present embodiment, the power amplifier 11 further includes an input converter that is connected to the amplification elements 11A and 11B and can convert the transmission signal in the first communication band from an unbalanced signal into a balanced signal.

[0094] Accordingly, the power amplifier 11 can convert an unbalanced signal into a balanced signal, and thus can receive the transmission signal of communication band A from the RFIC 3 as an unbalanced signal. Therefore, the conventional high-frequency circuit can be replaced with the high-frequency circuit 1 according to the present embodiment.

[0095] In addition, for example, in the high-frequency circuit 1 according to the present embodiment, the input converter may be an input transformer 33 including a coil 33a and a coil 33b, or one end of the coil 31a may be connected to the input terminal 115 of the power amplifier 11, one end of the coil 33b may be connected to the input of the amplifying element 11A, and the other end of the coil 33b may be connected to the input of the amplifying element 11B.

[0096] Accordingly, a transformer can be used as the input converter. Therefore, the input converter can perform impedance conversion in addition to unbalanced / balanced conversion.

[0097] In addition, for example, in the high-frequency circuit 1 according to the present embodiment, both communication band A and communication band C may be Band1 for LTE or 5GNR, and communication band B may be Band3 for LTE or 5GNR. In addition, for example, in the high-frequency circuit 1 according to the present embodiment, communication band A may be Band3 for LTE or 5GNR, communication band B may be Band1 for LTE or 5GNR, and communication band C may be Band32 for LTE or 5GNR. In addition, for example, in the high-frequency circuit 1 according to the present embodiment, communication band A may be Band40 for LTE or 5GNR, communication band B may be Band1 for LTE or 5GNR, and communication band C may be Band41 for LTE or 5GNR. In addition, for example, in the high-frequency circuit 1 according to the present embodiment, communication band A may be Band40 for LTE or 5GNR, communication band B may be Band1 for LTE or 5GNR, and communication band C may be Band7 for LTE or 5GNR. In addition, for example, in the high-frequency circuit 1 according to the present embodiment, communication band A may be Band1 for LTE or 5GNR, communication band B may be Band7 for LTE or 5GNR, and communication band C may be Band32 for LTE or 5GNR.

[0098] By using these communication bands for communication bands A to C, it is possible to effectively suppress the decrease in reception sensitivity caused by intermodulation distortion.

[0099] In addition, the communication device 5 according to the present embodiment 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.

[0100] Accordingly, in the communication device 5, the same effects as those of the high-frequency circuit 1 can be achieved.

[0101] (Other Embodiments)

[0102] As described above, the high-frequency circuit and the communication device according to the present invention have been described based on the embodiments. However, the high-frequency circuit and the communication device according to the present invention are not limited to the above-described embodiments. Modification examples obtained by making various modifications that occur to those skilled in the art to the above-described embodiments within the scope not departing from the gist of the present invention, and various devices incorporating the above-described high-frequency circuit and communication device are also included in the present invention.

[0103] For example, it may also be that, in the circuit configurations of the high-frequency circuit and the communication device according to the above-described embodiment, other circuit elements and wirings are inserted between the paths connecting the respective circuit elements and signal paths disclosed in the drawings. For example, it may also be that an impedance matching circuit is inserted between the switch 51 and each of the filters 61 to 63. In this case, the impedance matching circuit can be constituted by, for example, an inductor and / or a capacitor.

[0104] In addition, for example, it may also be that, in the circuit configurations of the high-frequency circuit and the communication device according to the above-described embodiment, the amplifiers in the power amplifiers 11 and 12 and the low-noise amplifier 21 are shared among a plurality of communication bands. For example, it may also be that the power amplifier 11 is connected to a plurality of filters via a switch.

[0105] In addition, for example, when the communication bands A and C are the same communication band, in the circuit configuration of the high-frequency circuit according to the above-described embodiment, the filters 61 and 63 may also be configured as a duplexer.

[0106] In addition, for example, the communication device according to the above-described embodiment may also include a plurality of antennas. In this case, the filters 61 to 63 may also be independently connected to different filters. Alternatively, it may be that two of the filters 61 to 63 are connected to one antenna, and the remaining one of the filters 61 to 63 is connected to another antenna.

[0107] Industrial Applicability

[0108] The present invention, as a high-frequency circuit configured in a front end portion, can be widely used in communication devices such as mobile phones.

[0109] Explanation of Reference Numerals

[0110] 1: High-frequency circuit; 2: Antenna; 3: RFIC; 4: BBIC; 5: Communication device; 11, 12: Power amplifiers; 11A, 11B, 11C, 12A, 12B: Amplifying elements; 21: Low-noise amplifier; 31: Output transformer; 31a, 31b, 33a, 33b: Coils; 32: Capacitor; 33: Input transformer; 51: Switch; 61, 62, 63: Filters; 100: Antenna connection terminal; 111, 112: High-frequency input terminals; 115, 125: Input terminals; 116, 126: Output terminals; 121: High-frequency output terminal; 511, 512, 513, 514: Terminals.

Claims

1. A high-frequency circuit, comprising: A first filter having a passband including a transmission band of a first communication band; A second filter having a passband including a transmission band of a second communication band different from the first communication band; A third filter having a passband including a reception band of a third communication band; A first power amplifier connected to the first filter; And A second power amplifier connected to the second filter, Wherein, transmission in the first communication band, transmission in the second communication band, and reception in the third communication band can be utilized simultaneously, At least a part of the frequency range of intermodulation distortion overlaps at least a part of the reception band of the third communication band, and the intermodulation distortion is generated between the second harmonic of the transmission signal in the first communication band and the fundamental wave of the transmission signal in the second communication band, The first power amplifier includes: A first amplifying element and a second amplifying element; and An output converter which is a first transformer having a first coil and a second coil, One end of the first coil is connected to the output of the first amplifying element, The other end of the first coil is connected to the output of the second amplifying element, One end of the second coil is connected to the output terminal of the first power amplifier.

2. The high-frequency circuit according to claim 1, wherein, The first power amplifier corresponds to a first power level, The second power amplifier corresponds to a second power level, The maximum output power of the first power level is greater than the maximum output power of the second power level.

3. The high-frequency circuit according to claim 1 or 2, wherein, The first amplifying element and the second amplifying element can independently amplify a balanced signal as the transmission signal in the first communication band, The output converter can synthesize the balanced signals amplified by the first amplifying element and the second amplifying element to convert the balanced signal into an unbalanced signal.

4. The high-frequency circuit according to claim 3, wherein, The second power amplifier can amplify the transmission signal in the second communication band while maintaining it in an unbalanced signal state.

5. The high-frequency circuit according to claim 3, wherein, The first power amplifier further includes an input converter connected to the first amplifying element and the second amplifying element, and capable of converting the transmission signal in the first communication band from an unbalanced signal into the balanced signal.

6. The high-frequency circuit according to claim 5, wherein, The input converter is a second transformer having a third coil and a fourth coil, One end of the third coil is connected to the input terminal of the first power amplifier, One end of the fourth coil is connected to the input of the first amplifying element, The other end of the fourth coil is connected to the input of the second amplifying element.

7. The high-frequency circuit according to claim 1 or 2, wherein, Both the first communication band and the third communication band are Band1 for LTE (Long Term Evolution) or 5G NR (5G New Radio), The second communication frequency band is Band 3 for LTE or 5G NR.

8. The high-frequency circuit according to claim 1 or 2, wherein the first communication frequency band is Band 3 for LTE, i.e., Long-Term Evolution, or 5G NR, i.e., 5G New Radio, the second communication frequency band is Band 1 for LTE or 5G NR, the third communication frequency band is Band 32 for LTE or 5G NR.

9. The high-frequency circuit according to claim 1 or 2, wherein the first communication frequency band is Band 40 for LTE, i.e., Long-Term Evolution, or 5G NR, i.e., 5G New Radio, the second communication frequency band is Band 1 for LTE or 5G NR, the third communication frequency band is Band 41 for LTE or 5G NR.

10. The high-frequency circuit according to claim 1 or 2, wherein the first communication frequency band is Band 40 for LTE, i.e., Long-Term Evolution, or 5G NR, i.e., 5G New Radio, the second communication frequency band is Band 1 for LTE or 5G NR, the third communication frequency band is Band 7 for LTE or 5G NR.

11. The high-frequency circuit according to claim 1 or 2, wherein the first communication frequency band is Band 1 for LTE, i.e., Long-Term Evolution, or 5G NR, i.e., 5G New Radio, the second communication frequency band is Band 7 for LTE or 5G NR, the third communication frequency band is Band 32 for LTE or 5G NR.

12. A communication device comprising: a signal processing circuit that processes high-frequency signals; and the high-frequency circuit according to any one of claims 1 to 11, which transmits the high-frequency signals between the signal processing circuit and an antenna.

Images