high frequency circuit

Abstract

Provided is a high-frequency circuit capable of suppressing an increase in the number of components in a case where attenuation is strictly required outside a band separated from an in-band. The high-frequency circuit includes: a first filter having a passband including a reception band of a first frequency band; a second filter having a passband including a reception band of a second frequency band; a switch circuit including a common terminal connected to an antenna connection terminal, a first selection terminal connected to the first filter, and a second selection terminal connected to the second filter; a first matching circuit connected between the first selection terminal and the first filter; and a second matching circuit connected between the second selection terminal and the second filter, wherein, in a first mode in which a signal of the first frequency band is received and a signal of the second frequency band is not received, the switch circuit is configured to connect the common terminal to the first selection terminal and the second selection terminal.

Description

Technical Field

[0001] This invention relates to a high-frequency circuit. Background Technology

[0002] Patent Document 1 discloses a high-frequency circuit that, in order to reduce resistance loss caused by switching, includes a switching circuit and an impedance circuit (matching circuit) connected between two signal paths and ground.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: International Publication No. 2019 / 049545 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] However, in the aforementioned prior art, when the attenuation requirements for out-of-band signals, which are separate from in-band signals, are stringent, the number of components in the high-frequency circuit can sometimes increase.

[0008] Therefore, the present invention provides a high-frequency circuit that can suppress the increase in the number of components when the attenuation requirements of the out-of-band circuit, which is separate from the in-band circuit, are strict.

[0009] Solution for solving the problem

[0010] One aspect of the present invention relates to a high-frequency circuit comprising: a first filter having a passband including a receiving frequency band of a first frequency band; a second filter having a passband including a receiving frequency band of a second frequency band; a switching circuit including a common terminal connected to an antenna connection terminal, a first selection terminal connected to the first filter, and a second selection terminal connected to the second filter; a first matching circuit connected between the first selection terminal and the first filter; and a second matching circuit connected between the second selection terminal and the second filter, wherein, in a first mode of receiving signals of the first frequency band but not receiving signals of the second frequency band, the switching circuit is configured to connect the common terminal to the first selection terminal and the second selection terminal.

[0011] The effects of the invention

[0012] According to the present invention, it is possible to suppress the increase in the number of components in high-frequency circuits when the attenuation requirements of out-of-band circuits, which are separate from in-band circuits, are strictly controlled. Attached Figure Description

[0013] Figure 1 This is a structural diagram of the communication device involved in the implementation method.

[0014] Figure 2This is a diagram illustrating a first mode of the high-frequency circuit involved in the implementation.

[0015] Figure 3 This is a diagram illustrating a second mode of the high-frequency circuit involved in the implementation.

[0016] Figure 4 This is a diagram illustrating a third mode of the high-frequency circuit involved in the implementation.

[0017] Figure 5 This is a graph showing the throughput characteristics of the high-frequency circuits involved in the embodiments and comparative examples. Detailed Implementation

[0018] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Furthermore, the embodiments described below are general or specific examples. The numerical values, shapes, materials, constituent elements, arrangements of constituent elements, and connection methods shown in the following embodiments are examples and are not intended to limit the present invention.

[0019] Furthermore, the figures are schematic diagrams that have been appropriately emphasized, omitted, or proportionally adjusted for the purpose of illustrating the invention, and are not necessarily strictly illustrative, sometimes differing from the actual shapes, positional relationships, and proportions. In the figures, substantially identical structures are labeled with the same reference numerals, and sometimes repeated descriptions are omitted or simplified.

[0020] In the following description, "connection" includes not only direct connections via connection terminals and / or wiring conductors, but also electrical connections via other circuit elements. "C connected between A and B" means that one end of C is connected to A and the other end of C is connected to B; it means that C is connected in series in the path connecting A and B. "The path connecting A and B" refers to the path formed by conductors that electrically connect A and B.

[0021] The "passband of a filter" is a portion of the spectrum transmitted by the filter, defined as the frequency band between two frequencies that is 3 dB greater than the minimum power insertion loss.

[0022] "Transmit band" refers to the frequency band used for transmitting in a communication device, while "receive band" refers to the frequency band used for receiving in a communication device. For example, in the FDD (Frequency Division Duplex) band, different frequency bands (uplink and downlink bands) are used as the transmit and receive bands. Conversely, in the TDD (Time Division Duplex) band, the transmit and receive bands use the same frequency band.

[0023] "A combination of frequency bands capable of simultaneous communication" refers to a combination of multiple frequency bands that can transmit, receive, or transmit and receive simultaneously, predefined by standardization organizations such as 3GPP (3rd Generation Partnership Project) and IEEE (Institute of Electrical and Electronics Engineers). Examples of "simultaneous communication" include CA (Carrier Aggregation), EN-DC (E-UTRAN New Radio-Dual Connectivity), NR-DC (New Radio-Dual Connectivity), and NE-DC (New Radio E-UTRAN-Dual Connectivity).

[0024] A "terminal" refers to the point where a conductor within an element ends. Furthermore, when the impedance between conductors between elements is sufficiently low, a terminal can be interpreted not only as a single point, but also as any point on the conductor between elements or the entire conductor.

[0025] "Low-noise amplifier not operating" means that the low-noise amplifier is controlled to be in the off state (that is, the low-noise amplifier cannot amplify high-frequency signals). Specifically, "low-noise amplifier not operating" means that the low-noise amplifier cannot amplify high-frequency signals by not applying a bias voltage and / or power supply voltage. The on / off state of the low-noise amplifier can be controlled by applying / not applying a bias voltage and / or power supply voltage.

[0026] In addition, terms such as "parallel" and "perpendicular" that indicate the relationship between elements, terms such as "rectangle" that indicate the shape of elements, and numerical ranges that do not only indicate strictness but also refer to substantially equivalent ranges, such as including a few percent of error.

[0027] (Implementation Method)

[0028] The implementation method will now be described.

[0029] [1. Structure of Communication Device 5]

[0030] First, refer to Figure 1 The structure of the communication device 5 involved in this embodiment will be explained. Figure 1 This is a structural diagram of the communication device 5 involved in this embodiment.

[0031] also, Figure 1 The illustrated structure shows that the communication device 5 can be installed using any of a variety of circuit mountings and circuit techniques. Therefore, the following description of the communication device 5 should not be interpreted restrictively.

[0032] Communication device 5 can be used to provide wireless connectivity. For example, it can be installed on UE (User Equipment) in cellular networks (also known as mobile networks) such as portable phones, smartphones, tablets, and wearable devices. In another example, by installing communication device 5, wireless connectivity can be provided to IoT (Internet of Things) sensor devices, medical / healthcare equipment, vehicles, unmanned aerial vehicles (UAVs), and automated guided vehicles (AGVs). In yet another example, by installing communication device 5, wireless connectivity can also be provided via a wireless access point or wireless hotspot.

[0033] The communication device 5 includes a high-frequency circuit 1, an antenna 2, an RFIC (Radio Frequency Integrated Circuit) 3, and a BBIC (Baseband Integrated Circuit) 4.

[0034] High-frequency circuit 1 is capable of transmitting high-frequency signals between antenna 2 and RFIC 3. The circuit structure of high-frequency circuit 1 will be described later.

[0035] Antenna 2 is connected to high-frequency circuit 1. Antenna 2 can receive high-frequency signals from outside the communication device 5 and provide them to high-frequency circuit 1. Furthermore, antenna 2 can also receive high-frequency signals from high-frequency circuit 1 and transmit them to outside the communication device 5. Alternatively, antenna 2 may not be included in the communication device 5. Additionally, the communication device 5 may have one or more antennas besides antenna 2.

[0036] RFIC 3 is an example of a signal processing circuit that processes high-frequency signals. Specifically, RFIC 3 can process the transmit signal input from BBIC 4 through up-conversion or the like, and output the high-frequency transmit signal generated by the signal processing to high-frequency circuit 1. Furthermore, RFIC 3 can also process the high-frequency receive signal input from high-frequency circuit 1 through down-conversion or the like, and output the receive signal generated by the signal processing to BBIC 4. Additionally, RFIC 3 may have a control unit for controlling switches and amplifiers in high-frequency circuit 1. Moreover, some or all of the functions of the control unit in RFIC 3 may be included externally to RFIC 3, for example, in BBIC 4 or high-frequency circuit 1.

[0037] BBIC 4 is a baseband signal processing circuit that performs signal processing using a frequency band lower than the frequency of the high-frequency signal transmitted by high-frequency circuit 1. Signals processed by BBIC 4 include, for example, image signals used for image display and / or sound signals used for communication via a speaker. Furthermore, BBIC 4 may not be included in the communication device 5.

[0038] [2. Circuit structure of high-frequency circuit 1]

[0039] Next, refer to Figure 1 The circuit structure of the high-frequency circuit 1 involved in this embodiment will be explained below. Furthermore, Figure 1 An exemplary circuit structure is shown. The high-frequency circuit 1 can be installed using any of a variety of circuit mounting and circuit techniques. Therefore, the following description of the high-frequency circuit 1 should not be interpreted restrictively.

[0040] The high-frequency circuit 1 includes low-noise amplifiers 21 and 22, filters 31 and 32, switching circuit 41, matching circuits 51, 52, 53 and 54, antenna connection terminal 100, and high-frequency output terminals 121 and 122.

[0041] Antenna connection terminal 100 is an external connection terminal of high-frequency circuit 1. Antenna connection terminal 100 is used to receive high-frequency signals from antenna 2. Antenna connection terminal 100 is connected to antenna 2 externally in high-frequency circuit 1 and to switching circuit 41 internally in high-frequency circuit 1.

[0042] High-frequency output terminals 121 and 122 are external connection terminals of the high-frequency circuit 1, used to provide high-frequency signals to the RFIC 3. High-frequency output terminals 121 and 122 are connected to the RFIC 3 externally in the high-frequency circuit 1, and are connected to low-noise amplifiers 21 and 22 internally in the high-frequency circuit 1, respectively.

[0043] A low-noise amplifier 21 is connected between the filter 31 and the high-frequency output terminal 121. Specifically, the input of the low-noise amplifier 21 is connected to the filter 31 via a matching circuit 53, and the output of the low-noise amplifier 21 is connected to the high-frequency output terminal 121. The low-noise amplifier 21 can, for example, switch between an on and off state based on a digital control signal from the RFIC 3.

[0044] A low-noise amplifier 22 is connected between the filter 32 and the high-frequency output terminal 122. Specifically, the input of the low-noise amplifier 22 is connected to the filter 32 via a matching circuit 54, and the output of the low-noise amplifier 22 is connected to the high-frequency output terminal 122. The low-noise amplifier 22 can, for example, switch between an on and off state based on a digital control signal from the RFIC 3.

[0045] Furthermore, low-noise amplifiers 21 and / or 22 may not be included in the high-frequency circuit 1. In this case, low-noise amplifiers 21 and / or 22 may be connected between the high-frequency circuit 1 and the RFIC 3, or they may be included in the RFIC 3.

[0046] Filter 31 is an example of the first filter, and is a bandpass filter having a passband that includes the receiving band (A-Rx) of frequency band A and the receiving band (C-Rx) of frequency band C. However, filter 31 is not limited to a bandpass filter. Filter 31 can also be a band-stop filter, a high-pass filter, a low-pass filter, or any combination thereof. Furthermore, the passband of filter 31 may not include the receiving band of frequency band C.

[0047] Filter 31 is connected between switching circuit 41 and low-noise amplifier 21. Specifically, one end of filter 31 is connected to switching circuit 41 via matching circuit 51. The other end of filter 31 is connected to the input of low-noise amplifier 21 via matching circuit 53.

[0048] Filter 32 is an example of a second filter, and is a bandpass filter having a passband that includes the receiving frequency band B (B-Rx). Furthermore, filter 32 is not limited to a bandpass filter. Filter 32 can also be a band-stop filter, a high-pass filter, a low-pass filter, or any combination thereof.

[0049] Filter 32 is connected between switching circuit 41 and low-noise amplifier 22. Specifically, one end of filter 32 is connected to switching circuit 41 via matching circuit 52. The other end of filter 32 is connected to the input of low-noise amplifier 22 via matching circuit 54.

[0050] As filters 31 and 32, surface acoustic wave (SAW) filters, bulk acoustic wave (BAW) filters, LC filters or dielectric filters, or any combination thereof, may also be used, and are not limited to them.

[0051] Frequency bands A through C are frequency bands used in communication systems built using Radio Access Technology (RAT). Frequency bands A through C are predefined by standardization organizations such as 3GPP and IEEE. Examples of communication systems include 5G NR (5th Generation New Radio), 4G LTE (4th Generation Long Term Evolution), and 2G GSM (2nd Generation Global System for Mobile communications).

[0052] Frequency band A is an example of the first frequency band and can be any of the FDD, TDD, and SDL (Supplementary Downlink) bands. For example, band A can use Band53 for LTE, or n53 or n254 for 5G NR. Furthermore, the receive band of frequency band A can completely or partially encompass the receive band of frequency band C.

[0053] Frequency band B is an example of a second frequency band, and can be any of the FDD, TDD, and SDL bands. For example, frequency band B can be Band1, Band3, Band25, Band34, Band39, Band40, or Band66 for LTE, or n1, n3, n25, n34, n39, n40, or n66 for 5G NR.

[0054] Frequency band C is an example of a third frequency band, which can be any of the FDD, TDD, and SDL bands. The receiving frequency band of frequency band C is closer to the receiving frequency band of frequency band A than the receiving frequency band of frequency band B. That is, the difference in center frequencies between frequency band A and frequency band C is smaller than the difference in center frequencies between frequency band B and frequency band C. Furthermore, signal reception in frequency band C can occur simultaneously with signal reception in frequency band B. In other words, frequency bands B and C are a combination of frequency bands capable of simultaneous communication. For example, frequency band C can use Band41 for LTE or n41 for 5G NR. Moreover, the receiving frequency band of frequency band C can completely encompass the receiving frequency band of frequency band A, or it can partially encompass the receiving frequency band of frequency band A.

[0055] A switching circuit 41 is connected between the antenna connection terminal 100 and filters 31 and 32. Specifically, the switching circuit 41 includes a common terminal 410 and selection terminals 411 and 412. The common terminal 410 is connected to the antenna connection terminal 100. Selection terminal 411 is an example of a first selection terminal, connected to filter 31 via matching circuit 51. Selection terminal 412 is an example of a second selection terminal, connected to filter 32 via matching circuit 52.

[0056] In this configuration, the switching circuit 41 can, for example, connect the common terminal 410 to the selection terminals 411 and 412 based on digital control signals from the RFIC 3. Specifically, the switching circuit 41 is a multi-connection type switching circuit capable of independently controlling the connection between the common terminal 410 and the selection terminal 411, as well as the connection between the common terminal 410 and the selection terminal 412.

[0057] Matching circuit 51, an example of a first matching circuit, is connected between the selection terminal 411 of the switching circuit 41 and the filter 31. Specifically, one end of matching circuit 51 is connected to the selection terminal 411 of the switching circuit 41, and the other end is connected to one end of the filter 31. Matching circuit 51 includes an inductor 511 connected between the path connecting the selection terminal 411 and the filter 31 and ground. With this circuit structure, matching circuit 51 can achieve impedance matching between the switching circuit 41 and the filter 31. Furthermore, the circuit structure of matching circuit 51 is not limited to... Figure 1 The circuit structure shown is shown.

[0058] Matching circuit 52, an example of a second matching circuit, is connected between the selection terminal 412 of switching circuit 41 and filter 32. Specifically, one end of matching circuit 52 is connected to the selection terminal 412 of switching circuit 41. The other end of matching circuit 52 is connected to one end of filter 32. Matching circuit 52 includes capacitor 521 and inductor 522.

[0059] Capacitor 521 is a tunable capacitor connected between select terminal 412 and filter 32. For example, capacitor 521 has an electrostatic capacitance of 1~10pF. Alternatively, capacitor 521 may not be a tunable capacitor, or it may be a capacitor with a fixed electrostatic capacitance.

[0060] Inductor 522 is connected between the path connecting capacitor 521 and filter 32 and ground. For example, inductor 522 has an inductance of 1~10nH. With this circuit structure, matching circuit 52 can achieve impedance matching between switching circuit 41 and filter 32.

[0061] Furthermore, the circuit structure of the matching circuit 52 is not limited to Figure 1 The circuit structure shown is illustrated. For example, the matching circuit 52 may also include an inductor connected between the selection terminal 412 and the filter 32, and a capacitor connected between the path connecting the inductor and the filter 32 and ground. That is, the positions of the capacitor 521 and the inductor 522 may be interchanged. Alternatively, for example, the capacitor 521 may also be connected between the inductor 522 and ground.

[0062] Matching circuit 53 is connected between filter 31 and low-noise amplifier 21. Specifically, one end of matching circuit 53 is connected to the other end of filter 31. The other end of matching circuit 53 is connected to the input terminal of low-noise amplifier 21. Matching circuit 53 includes an inductor 531 connected between filter 31 and low-noise amplifier 21. With this circuit structure, matching circuit 53 can achieve impedance matching between filter 31 and low-noise amplifier 21. Furthermore, the circuit structure of matching circuit 53 is not limited to... Figure 1 The circuit structure shown is shown.

[0063] Matching circuit 54 is connected between filter 32 and low-noise amplifier 22. Specifically, one end of matching circuit 54 is connected to the other end of filter 32. The other end of matching circuit 54 is connected to the input terminal of low-noise amplifier 22. Matching circuit 54 includes an inductor 541 connected between filter 32 and low-noise amplifier 22. With this circuit structure, matching circuit 54 can achieve impedance matching between filter 32 and low-noise amplifier 22. Furthermore, the circuit structure of matching circuit 54 is not limited to... Figure 1 The circuit structure shown is shown.

[0064] [3. Communication Mode]

[0065] Next, the communication mode of the high-frequency circuit 1 involved in this embodiment will be described.

[0066] [3.1. First Mode]

[0067] First, refer to Figure 2 To illustrate the first mode included in the communication mode of high-frequency circuit 1. Figure 2 This is a diagram illustrating a first mode of the high-frequency circuit 1 according to this embodiment. Figure 2 In the diagram, the dashed arrow indicates the transmission path of the received signal in frequency band A.

[0068] The first mode is a communication mode that receives signals from frequency band A but does not receive signals from frequency bands B and C. In the first mode, the switching circuit 41 connects the common terminal 410 to the selection terminals 411 and 412. Additionally, the low-noise amplifier 21 operates, while the low-noise amplifier 22 does not operate.

[0069] In this state, the received signal of band A is transmitted from antenna 2 to RFIC 3 via antenna connection terminal 100, switching circuit 41, matching circuit 51, filter 31, matching circuit 53, low noise amplifier 21 and high frequency output terminal 121.

[0070] Furthermore, in the first mode, in the switching circuit 41, the common terminal 410 is connected not only to the selection terminal 411 but also to the selection terminal 412. Thus, an LC series circuit consisting of a capacitor 521 and an inductor 522 is connected between the transmission path of the received signal in frequency band A and ground. Therefore, by appropriately setting the resonant frequency of the LC series circuit consisting of the capacitor 521 and the inductor 522, the matching circuit 52 can increase the attenuation of the frequency band (outside the band) separated from the receiving frequency band (in-band) of frequency band A. Specifically, by setting the resonant frequency of the LC series circuit consisting of the capacitor 521 and the inductor 522 near a frequency band with strict attenuation requirements, the high-frequency circuit 1 can ensure the required attenuation in that frequency band.

[0071] [3.2. Second Mode]

[0072] Next, refer to Figure 3 To illustrate the second mode included in the communication mode of high-frequency circuit 1. Figure 3 This is a diagram illustrating a second mode of the high-frequency circuit 1 according to this embodiment. Figure 3 In the diagram, the dashed arrows indicate the transmission paths of the received signals in frequency bands B and C.

[0073] The second mode is a communication mode that simultaneously receives signals from frequency bands B and C but does not receive signals from frequency band A. In the second mode, the switching circuit 41 connects the common terminal 410 to the selection terminals 411 and 412. Additionally, the low-noise amplifiers 21 and 22 operate.

[0074] In this state, the received signal of band B is transmitted from antenna 2 to RFIC 3 via antenna connection terminal 100, switching circuit 41, matching circuit 52, filter 32, matching circuit 54, low noise amplifier 22, and high frequency output terminal 122. Similarly, the received signal of band C is transmitted from antenna 2 to RFIC 3 via antenna connection terminal 100, switching circuit 41, matching circuit 51, filter 31, matching circuit 53, low noise amplifier 21, and high frequency output terminal 121.

[0075] Furthermore, in the second mode, the matching circuit 52 is able to achieve impedance matching between the switching circuit 41 and the filter 32 within the receiving frequency band of frequency band B.

[0076] [3.3. Third Mode]

[0077] Next, refer to Figure 4 To illustrate the third mode included in the communication mode of high-frequency circuit 1. Figure 4 This diagram illustrates a third mode of the high-frequency circuit 1 according to this embodiment. Figure 4 In the diagram, the dashed arrow indicates the transmission path of the received signal in frequency band C.

[0078] The third mode is a communication mode that receives signals from frequency band C but does not receive signals from frequency bands A and B. In the third mode, the switching circuit 41 connects the common terminal 410 to the selection terminal 411 but not to the selection terminal 412. Additionally, the low-noise amplifier 21 operates, while the low-noise amplifier 22 does not operate.

[0079] In this state, the received signal of band C is transmitted from antenna 2 to RFIC 3 via antenna connection terminal 100, switching circuit 41, matching circuit 51, filter 31, matching circuit 53, low noise amplifier 21 and high frequency output terminal 121.

[0080] Furthermore, the communication mode of the high-frequency circuit 1 is not limited to the first mode, the second mode, and the third mode. For example, the communication mode of the high-frequency circuit 1 may also include a mode that receives signals from frequency band B alone.

[0081] [4. Throughput characteristics of high-frequency circuit 1]

[0082] Next, refer to Figure 5 This will be used to illustrate the throughput characteristics of high-frequency circuit 1. Figure 5 This is a graph showing the throughput characteristics of the high-frequency circuit involved in this embodiment and comparative examples.

[0083] The circuit structure of the high-frequency circuit involved in the comparative example is the same as that of the high-frequency circuit 1 involved in this embodiment. However, the difference between the comparative example and this embodiment is that, in the first mode, the common terminal 410 is not connected to the selection terminal 412.

[0084] In this embodiment, the common terminal 410 is connected to the selection terminal 412, thereby connecting an LC series circuit consisting of a capacitor 521 and an inductor 522 between the transmission path of the received signal in frequency band A and ground. As a result, as... Figure 5 As shown, an attenuation pole is formed near 1300MHz, which increases the attenuation in the out-of-band (1610MHz~1626.5MHz) zone, separate from the receiving band (in-band) (2483.5MHz~2495MHz or 2483.5MHz~2500MHz) of frequency band A. Furthermore, the high-frequency circuit 1 can also further increase the out-of-band attenuation by adjusting the electrostatic capacitance of capacitor 521 to bring the attenuation pole closer to the frequency zone with strict attenuation requirements.

[0085] [5. Summary]

[0086] As described above, the high-frequency circuit 1 according to this embodiment includes: a filter 31 having a passband that includes the receiving frequency band of frequency band A; a filter 32 having a passband that includes the receiving frequency band of frequency band B; a switching circuit 41 including a common terminal 410 connected to the antenna connection terminal 100, a selection terminal 411 connected to the filter 31, and a selection terminal 412 connected to the filter 32; a matching circuit 51 connected between the selection terminal 411 and the filter 31; and a matching circuit 52 connected between the selection terminal 412 and the filter 32. In a first mode where the signal of frequency band A is received but the signal of frequency band B is not received, the switching circuit 41 is configured to connect the common terminal 410 to the selection terminal 411 and the selection terminal 412.

[0087] Therefore, in the first mode where signals from frequency band A are received but signals from frequency band B are not received, the common terminal 410 is connected to the selection terminal 412, thereby connecting the matching circuit 52 to the transmission path of the received signal from frequency band A. Thus, even when there is a strict attenuation requirement for the out-of-band frequency band (separate from the in-band reception band of frequency band A), the matching circuit 52 can be used to increase the attenuation of the out-of-band frequency band (separate from the in-band). Therefore, for example, the attenuation of filter 31 can be enhanced without using a longitudinally coupled SAW resonator, and the increase in loss within the passband of filter 31 can be suppressed. Furthermore, without adding inductors and / or capacitors to filter 31 or matching circuit 51, the increase in the number of components in high-frequency circuit 1 can be suppressed.

[0088] Alternatively, for example, in the high-frequency circuit 1 of this embodiment, the matching circuit 52 may include a capacitor 521 connected between the selection terminal 412 and the filter 32, and an inductor 522 connected between the path connecting the capacitor 521 and the filter 32 and ground.

[0089] Therefore, when the common terminal 410 is connected to the selection terminals 411 and 412, the capacitor 521 and the inductor 522 are connected in series between the transmission path of the received signal in frequency band A and ground. Thus, the matching circuit 52 can function as a notch filter circuit, increasing the attenuation of the frequency band (outside the band) that is separated from the received frequency band (in-band) of frequency band A.

[0090] Alternatively, for example, in the high-frequency circuit 1 according to this embodiment, the capacitor 521 may be a tunable capacitor.

[0091] Therefore, the electrostatic capacitance of capacitor 521 can be adjusted to be suitable for the impedance matching circuit in frequency band B and for the notch filter circuit in frequency band A, thereby improving the characteristics of high-frequency circuit 1.

[0092] Alternatively, for example, in the high-frequency circuit 1 involved in this embodiment, the passband of the filter 31 may also include the receiving band of frequency band C, and frequency bands B and C are a combination of frequency bands that can communicate simultaneously.

[0093] Therefore, filter 31 can be shared in both frequency bands, thereby reducing the number of filters. Furthermore, since frequency bands B and C are a combination of frequency bands capable of simultaneous communication, there is a high degree of necessity to connect filter 31 for frequency bands A and C and filter 32 for frequency band B to the same switching circuit 41. In other words, the matching circuit 52 for frequency band B can easily be used as a notch filter circuit for frequency band A.

[0094] Additionally, for example, in the high-frequency circuit 1 of this embodiment, in the second mode where signals of frequency band B and frequency band C are received simultaneously but signals of frequency band A are not received, the switching circuit 41 may be configured to connect the common terminal 410 to the selection terminal 411 and the selection terminal 412. In the third mode where signals of frequency band C are received but signals of frequency band A and frequency band B are not received, the switching circuit 41 may be configured to connect the common terminal 410 to the selection terminal 411 but not to the selection terminal 412.

[0095] Therefore, in the second mode, it is possible to receive signals from both frequency bands B and C simultaneously, and in the third mode, it is possible to receive signals from frequency band C separately.

[0096] Additionally, for example, the high-frequency circuit 1 according to this embodiment may also include a low-noise amplifier 22 connected to the filter 32. In the first mode, the low-noise amplifier 22 may also be configured not to operate.

[0097] Therefore, when the matching circuit 52 is used as a notch filter circuit for frequency band A, the impedance in the receiving band of frequency band A when viewed from the common terminal 410 of the filter 32 and the low noise amplifier 22 can be made closer to an open circuit state, thereby suppressing the leakage of the received signal of frequency band A to the low noise amplifier 22.

[0098] Furthermore, for example, in the high-frequency circuit 1 of this embodiment, frequency band A may be Band 53 for LTE, or n53 or n254 for 5G NR; frequency band B may be Band 1, Band 3, Band 25, Band 34, Band 39, Band 40 or Band 66 for LTE, or n1, n3, n25, n34, n39, n40 or n66 for 5G NR; and frequency band C may be Band 41 for LTE, or n41 for 5G NR.

[0099] Therefore, high-frequency circuit 1 can be used in LTE or 5G NR systems. In particular, in Band 53 for LTE, or n53 or n254 for 5G NR, the attenuation requirements of the frequency band (1610MHz~1626.5MHz) separated from the receiving frequency band (2483.5MHz~2495MHz or 2483.5MHz~2500MHz) are strict, so using matching circuit 52 as a notch filter circuit is very effective.

[0100] (Other implementation methods)

[0101] The high-frequency circuit of the present invention has been described above based on the embodiments, but the high-frequency circuit of the present invention is not limited to the above embodiments. Other embodiments implemented by combining any of the constituent elements in the above embodiments, variations of the above embodiments that can be conceived by those skilled in the art by implementing various modifications to the above embodiments without departing from the spirit of the present invention, and various devices that incorporate the above high-frequency circuit are also included in the present invention.

[0102] For example, in the circuit structure of the high-frequency circuit according to the above embodiments, other circuit elements and wiring may be inserted between the paths connecting the circuit elements and signal paths disclosed in the drawings. For example, a coupler may be connected between the switching circuit 41 and the antenna connection terminal 100.

[0103] Industrial availability

[0104] As a high-frequency circuit configured in the front end, this invention can be widely used in communication devices such as portable telephones.

[0105] Explanation of reference numerals in the attached figures

[0106] 1: High-frequency circuit; 2: Antenna; 3: RFIC; 4: BBIC; 5: Communication device; 21, 22: Low-noise amplifier; 31, 32: Filter; 41: Switching circuit; 51, 52, 53, 54: Matching circuit; 100: Antenna connection terminal; 121, 122: High-frequency output terminal; 410: Common terminal; 411, 412: Selection terminal; 511, 522, 531, 541: Inductor; 521: Capacitor; A, B, C: Frequency band.

Claims

1. A high-frequency circuit, comprising: A first filter having a passband that includes the receiving frequency band of a first frequency band; The second filter has a passband that includes the receiving frequency band of the second frequency band; A switching circuit includes a common terminal connected to an antenna connection terminal, a first selection terminal connected to the first filter, and a second selection terminal connected to the second filter; A first matching circuit is connected between the first selection terminal and the first filter; as well as A second matching circuit is connected between the second selection terminal and the second filter. In a first mode where the signal of the first frequency band is received but the signal of the second frequency band is not received, the switching circuit is configured to connect the common terminal to the first selection terminal and the second selection terminal.

2. The high-frequency circuit according to claim 1, wherein, The second matching circuit includes: A capacitor connected between the second selection terminal and the second filter; and An inductor is connected between the path connecting the capacitor and the second filter and ground.

3. The high-frequency circuit according to claim 2, wherein, The capacitor is a tunable capacitor.

4. The high-frequency circuit according to any one of claims 1 to 3, wherein, The passband of the first filter also includes the receiving frequency band of the third frequency band. The second frequency band and the third frequency band are a combination of frequency bands that can communicate simultaneously.

5. The high-frequency circuit according to claim 4, wherein, In a second mode where signals from both the second and third frequency bands are received simultaneously, but signals from the first frequency band are not received, the switching circuit is configured to connect the common terminal to both the first and second selection terminals. In a third mode where the signal of the third frequency band is received but the signals of the first frequency band and the second frequency band are not received, the switching circuit is configured to connect the common terminal to the first selection terminal and not to the second selection terminal.

6. The high-frequency circuit according to any one of claims 1 to 5, wherein, The high-frequency circuit also includes a low-noise amplifier connected to the second filter. In the first mode, the low-noise amplifier is configured not to operate.

7. The high-frequency circuit according to any one of claims 1 to 6, wherein, The first frequency band is Band53 for LTE, or n53 or n254 for 5G NR.

8. The high-frequency circuit according to claim 4 or 5, wherein, The first frequency band is Band53 for LTE, or n53 or n254 for 5G NR. The second frequency band is Band1, Band3, Band25, Band34, Band39, Band40, or Band66 for LTE, or n1, n3, n25, n34, n39, n40, or n66 for 5G NR. The third frequency band is Band41 for LTE or n41 for 5G NR.

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