High-frequency circuit and communication device

Abstract

The high-frequency circuit (1) includes an antenna connection terminal (101a), switching circuits (30, 40), a duplexer (62), a low-pass filter (70), and a high-pass filter (80). The switching circuit (30) includes a port (31a) connected to the antenna connection terminal (101a) and ports (32-34). The switching circuit (40) includes a single transmission port (41) connected to port (32), a simultaneous transmission port (42) connected to port (33), and port (44). The duplexer (62) is connected to port (44). The low-pass filter (70) is configured on the signal path (92) connecting port (33) and the simultaneous transmission port (42). The high-pass filter (80) is connected to port (34). No filter is configured on the signal path (91) connecting port (32) and the single transmission port (41).

Description

Technical Field

[0001] This invention relates to high-frequency circuits and communication devices. Background Technology

[0002] Previously, high-frequency circuits were known to be used for communication utilizing multiple frequency bands (multi-band) and multiple wireless methods (multi-mode) (hereinafter referred to as multi-band communication).

[0003] For example, Patent Document 1 discloses a high-frequency circuit that includes a multiplexer with multiple filters having different passbands, which separates high-frequency signals according to each frequency band.

[0004] Prior art literature

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2019-205007 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] In the high-frequency circuit disclosed in Patent Document 1, the communication performance may be degraded when multiple frequency bands of high-frequency signals are transmitted simultaneously.

[0009] Therefore, the object of the present invention is to provide a high-frequency circuit and a communication device capable of suppressing the degradation of communication performance of high-frequency signals.

[0010] Technical solutions for solving the problem

[0011] One aspect of the present invention relates to a high-frequency circuit comprising: an antenna connection terminal; a first switching circuit; a second switching circuit; a first filter having a first frequency band as a passband; a second filter having at least a portion of the first frequency band as a passband and having a second frequency band including a second frequency as a stopband, the second frequency being a frequency that is n times the first frequency within the first frequency band (n being a natural number greater than or equal to 2); and a third filter having a third frequency band including the second frequency as a passband. The first switching circuit includes: a first port connected to the antenna connection terminal; and a second port, a third port, and a fourth port, capable of switching between being on and off relative to the first port. The second switching circuit includes: a single transmission port connected to the second port; a simultaneous transmission port connected to the third port; and an input / output port, capable of switching between being on and off relative to the single transmission port and the simultaneous transmission port. The first filter is connected to the input / output port. The second filter is disposed on a first signal path connecting the third port and the simultaneous transmission port. The third filter is connected to the fourth port. No filter is configured on the second signal path that connects the second port and the single transmission port.

[0012] One aspect of the present invention relates to a communication device comprising: an RF signal processing circuit for processing high-frequency signals transmitted and received by an antenna; and the aforementioned high-frequency circuit for transmitting high-frequency signals between the antenna and the RF signal processing circuit.

[0013] Invention Effects

[0014] The high-frequency circuit and communication device according to the present invention can suppress the degradation of communication performance. Attached Figure Description

[0015] Figure 1 This is a diagram showing the structure of the communication device according to Embodiment 1.

[0016] Figure 2 This is a circuit diagram of the high-frequency circuit involved in Implementation Method 1.

[0017] Figure 3 This is a circuit diagram illustrating an example of the signal path of the high-frequency circuit according to Embodiment 1 when it operates in single transmission mode.

[0018] Figure 4 This is a circuit diagram showing an example of the signal path of the high-frequency circuit according to Embodiment 1 when it operates in simultaneous transmission mode.

[0019] Figure 5 This is a circuit diagram of a high-frequency circuit involved in a variation of Implementation 1.

[0020] Figure 6 This is a circuit diagram of the high-frequency circuit involved in Implementation Method 2.

[0021] Figure 7 This is a circuit diagram illustrating an example of the signal path of the high-frequency circuit according to Embodiment 2 when it operates in single transmission mode.

[0022] Figure 8 This is a circuit diagram illustrating an example of the signal path of the high-frequency circuit according to Embodiment 2 when it operates in simultaneous transmission mode.

[0023] Figure 9 This is a circuit diagram of a high-frequency circuit involved in a variation of embodiment 2. Detailed Implementation

[0024] Hereinafter, a high-frequency circuit according to embodiments of the present invention will be described in detail with reference to the accompanying drawings. Furthermore, the embodiments described below are all specific examples of the present invention. Therefore, the values, shapes, materials, constituent elements, arrangements of constituent elements, connection methods, steps, and order of steps shown in the following embodiments are merely examples and are not intended to limit the present invention. Therefore, constituent elements not described in the independent claims in the following embodiments will be described as arbitrary constituent elements.

[0025] Furthermore, these figures are illustrative and may not be strictly accurate. Therefore, for example, the scales may not be consistent across figures. Additionally, substantially identical structures are labeled with the same reference numerals across figures, and redundant descriptions are omitted or simplified.

[0026] Furthermore, in this specification, the term "connection" includes not only direct connections via connection terminals and / or wiring conductors, but also electrical connections via other circuit elements. Additionally, the term "connection between A and B" means a connection between A and B, and between A and B.

[0027] Furthermore, unless otherwise stated, in this specification, ordinal numbers such as "first" and "second" do not imply the quantity or order of constituent elements, but are used for the purpose of avoiding confusion between constituent elements of the same kind and for differentiation.

[0028] (Implementation Method 1)

[0029] [1-1. Structure]

[0030] First, using Figure 1 as well as Figure 2 The structure of the high-frequency circuit and communication device involved in this embodiment will be described. Figure 1 This is a diagram showing the structure of the communication device 5 according to this embodiment. Figure 2 This is a circuit diagram of the high-frequency circuit 1 involved in this embodiment.

[0031] [1-1-1. Communication device]

[0032] First, using Figure 1 The structure of communication device 5 will be described.

[0033] Figure 1 The communication device 5 shown is a device used in a communication system, such as a smartphone or a portable terminal like a tablet computer. Figure 1 As shown, the communication device 5 includes a high-frequency circuit 1, antennas 2a and 2b, an RF signal processing circuit (RFIC) 3, and a baseband signal processing circuit (BBIC) 4.

[0034] High-frequency circuit 1 transmits high-frequency signals between antennas 2a and 2b and RFIC 3, respectively. The internal structure of high-frequency circuit 1 will be described later.

[0035] Antenna 2a is connected to antenna connection terminal 101a of high-frequency circuit 1, which is an example of a first antenna connection terminal. Antenna 2b is connected to antenna connection terminal 101b of high-frequency circuit 1, which is an example of a second antenna connection terminal. Antennas 2a and 2b respectively transmit high-frequency signals output from high-frequency circuit 1. In addition, antennas 2a and 2b respectively receive high-frequency signals from the outside and output them to high-frequency circuit 1.

[0036] RFIC3 is an example of a signal processing circuit that processes high-frequency signals. Specifically, RFIC3 processes the high-frequency received signal input via the receiving path of high-frequency circuit 1 using down-conversion or the like, and outputs the received signal generated by this signal processing to BBIC4. Furthermore, RFIC3 processes the transmitted signal input from BBIC4 using up-conversion or the like, and outputs the high-frequency transmitted signal generated by this signal processing to the transmitting path of high-frequency circuit 1.

[0037] BBIC4 is a baseband signal processing circuit that performs signal processing using an intermediate frequency band that is lower than the high-frequency signal transmitted by high-frequency circuit 1. The signals processed by BBIC4 can be, for example, image signals for image display and / or audio signals for communication via a speaker.

[0038] Furthermore, in the communication device 5 according to this embodiment, antennas 2a and 2b and BBIC4 are not essential components.

[0039] [1-1-2. Structure of High-Frequency Circuits]

[0040] Next, using Figure 2 The structure of high-frequency circuit 1 will be described.

[0041] Figure 2 The high-frequency circuit 1 shown is capable of simultaneously transmitting high-frequency signals from multiple frequency bands that are different from each other. Simultaneous transmission includes at least one of simultaneous transmission, simultaneous reception, and simultaneous transmission and reception. Simultaneous transmission is sometimes also referred to as carrier aggregation (CA). In this embodiment, the high-frequency circuit 1 has a simultaneous transmission mode and a single transmission mode as its operating modes.

[0042] For example, in simultaneous transmission mode, high-frequency circuit 1 can simultaneously transmit high-frequency signals in the mid-high frequency band (MHB) and high-frequency signals in the ultra-high frequency band (UHB). Furthermore, in single transmission mode, high-frequency circuit 1 transmits only one of the high-frequency signals in the mid-high frequency band and the high-frequency signals in the ultra-high frequency band.

[0043] Mid-high frequency (MHF) and ultra-high frequency (UHF) bands are frequency band groups that comprise multiple communication frequency bands used for signal transmission and reception. Furthermore, the term "communication frequency band" refers to a frequency band predefined for communication systems by standardization organizations (e.g., 3GPP (3rd Generation Partnership Project), IEEE (Institute of Electrical and Electronics Engineers)). The term "communication system" refers to a communication system built using Radio Access Technology (RAT). Examples of communication systems include 5G-NR (5th Generation New Radio), LTE (Long Term Evolution), and WLAN (Wireless Local Area Network), but are not limited to these.

[0044] The mid-to-high frequency band is a group of frequency bands with frequencies below 3 GHz. The mid-to-high frequency band includes communication bands using frequency division duplex (FDD) and time division duplex (TDD) communication methods. Specifically, the mid-to-high frequency bands include 4G-LTE bands B1 (transmit band: 1920-1980MHz, receive band: 2110-2170MHz), B2 (transmit band: 1850-1910MHz, receive band: 1930-1990MHz), B3 (transmit band: 1710-1785MHz, receive band: 1805-1880MHz), B7 (transmit band: 2500-2570MHz, receive band: 2620-2690MHz), B32 (receive band: 1452-1496MHz), and B41 (transmit / receive band: 2496-2690MHz). Bands B1, B2, B3, and B7 are FDD (Frequency Direct Drive) communication bands. Band B41 is a TDD (Turbocharged Direct Drive) communication band.

[0045] The ultra-high frequency (UHF) band is a group of frequency bands with a frequency range of 3 GHz or higher. The UHF band includes communication bands using the TDD (Transmit-Device) method. Specifically, the UHF band includes 5G NR bands n77 (transmit / receive band: 3300-4200 MHz) and n79 (transmit / receive band: 4400-5000 MHz), etc. Bands n77 and n79 are TDD communication bands.

[0046] Furthermore, high-frequency circuit 1 can also simultaneously transmit high-frequency signals belonging to multiple frequency bands in the mid-high frequency band. Similarly, high-frequency circuit 1 can also simultaneously transmit high-frequency signals belonging to multiple frequency bands in the ultra-high frequency band. In this way, the combination of communication frequency bands that can be transmitted simultaneously is not particularly limited, but in the following description, "simultaneous transmission mode" means the simultaneous transmission of high-frequency signals in the mid-high frequency band and high-frequency signals in the ultra-high frequency band. Furthermore, "single transmission mode" means the transmission of high-frequency signals belonging to only one communication frequency band, either the mid-high frequency band or the ultra-high frequency band, but in the following description, unless otherwise stated, it means the transmission of high-frequency signals in the mid-high frequency band.

[0047] like Figure 2 As shown, the high-frequency circuit 1 includes a power amplifier 10, a low-noise amplifier 20, switching circuits 30, 40, and 50, a multiplexer 61, duplexers 62 and 63, a filter 64, a low-pass filter 70, a high-pass filter 80, a filter 81, and a control circuit 100. Furthermore, the high-frequency circuit 1 includes at least one antenna connection terminal. Specifically, the high-frequency circuit 1 includes two antenna connection terminals 101a and 101b. Additionally, although in Figure 2 Although not shown, the high-frequency circuit 1 has multiple output terminals for outputting high-frequency received signals to RFIC3 and multiple input terminals for inputting high-frequency transmitted signals from RFIC3.

[0048] Power amplifier 10 amplifies the high-frequency transmission signal input from RFIC3 via its input terminal. Specifically, power amplifier 10 amplifies the ultra-high frequency transmission signal. The output terminal of power amplifier 10 is connected to port 52 of switching circuit 50.

[0049] The low-noise amplifier 20 amplifies the high-frequency received signal from antenna 2a or 2b. Specifically, the low-noise amplifier 20 amplifies the high-frequency received signal in the ultra-high frequency band. The input terminal of the low-noise amplifier 20 is connected to port 53 of the switching circuit 50.

[0050] The power amplifier 10 and the low-noise amplifier 20 can also be, for example, multi-stage amplifiers and / or differential amplifiers, etc. Additionally, although in Figure 2 Not shown, but the high-frequency circuit 1 includes one or more power amplifiers and one or more low-noise amplifiers for amplifying high-frequency signals in the mid-to-high frequency range. These power amplifiers and low-noise amplifiers have the same structure as power amplifier 10 and low-noise amplifier 20.

[0051] Additionally, the power amplifier 10 that amplifies high-frequency signals in the ultra-high frequency band corresponds to power level 2 (maximum output power: 26dBm). On the other hand, the power amplifier (not shown) that amplifies high-frequency signals in the mid-high frequency band corresponds to power level 2 or 3 (maximum output power: 23dBm).

[0052] Additionally, the term "power level" refers to a classification of the terminal's output power, defined by factors such as maximum output power. A smaller power level value indicates a higher output power. Maximum output power is defined by the output power at the terminal's antenna.

[0053] Switching circuit 30 is an example of the first switching circuit, including ports 31a and 31b and three ports 32 to 34. Switching circuit 30 is capable of switching ports 31a and 31b and ports 32 to 34 to be on and off respectively.

[0054] Port 31a is an example of the first port and is connected to antenna connection terminal 101a. In this embodiment, no multiplexer is configured on the signal path 90a connecting port 31a and antenna connection terminal 101a. Specifically, port 31a and antenna connection terminal 101a are directly connected.

[0055] Port 31b is an example of the first port and is connected to antenna connection terminal 101b. In this embodiment, no multiplexer is configured on the signal path 90b that connects port 31b and antenna connection terminal 101b. Specifically, port 31b and antenna connection terminal 101b are directly connected.

[0056] Port 32 is an example of a second port, connected to the single-transmission port 41 of the switching circuit 40. In this embodiment, no filter is configured on the signal path 91 connecting port 32 and single-transmission port 41. Specifically, port 32 and single-transmission port 41 are directly connected. Furthermore, signal path 91 is an example of a second signal path, utilized for the transmission of high-frequency signals in the mid-to-high frequency band under single-transmission mode.

[0057] Port 33 is an example of a third port, connected to the simultaneous transmission port 42 of the switching circuit 40. In this embodiment, a low-pass filter 70 is configured on the signal path 92 connecting port 33 and the simultaneous transmission port 42. Furthermore, signal path 92 is an example of a first signal path, used for transmitting high-frequency signals in the mid-to-high frequency band during simultaneous transmission.

[0058] Port 34 is an example of a fourth port, connected to port 51 of the switching circuit 50. In this embodiment, a high-pass filter 80 is configured on the signal path 93 connecting port 34 and port 51. Furthermore, signal path 93 is an example of a third signal path, utilized for the transmission of high-frequency signals in the ultra-high frequency band regardless of the operating mode.

[0059] Switching circuit 30 is a combination circuit of SPDT (Single Pole Double Throw) and SPST (Single Pole Single Throw) type switches. The SPDT type switch includes ports 31a, 32, and 33. Switching circuit 30 switches between three states: (a) ports 31a and 32 are on (but not on relative to port 33), (b) ports 31a and 33 are on (but not on relative to port 32), and (c) ports 31a, 32, and 33 are all off. Ports 31a or 31b are not simultaneously connected relative to ports 32 and 33 (both are on). The SPST type switch includes ports 31b and 34. Switching circuit 30 switches between on and off states between ports 31b and 34.

[0060] Alternatively, ports 31a and 34 can form an SPST type switch, and ports 31b, 32, and 33 can form an SPDT type switch. Ports 31a and 31b can also switch between forming an SPST type switch and an SPDT type switch. Furthermore, port 31a or 31b can be simultaneously connected (simultaneously powered) to either port 32 or 33 and port 34.

[0061] Switching circuit 40 is an example of a second switching circuit, including a single transmission port 41, a simultaneous transmission port 42, and multiple ports 43 to 46. Switching circuit 40 is capable of switching each of the multiple ports 43 to 46 and one of the single transmission port 41 and the simultaneous transmission port 42 on or off.

[0062] The single transmission port 41 is the port used when the high-frequency circuit 1 operates in single transmission mode.

[0063] Simultaneous transmission port 42 is a port used when the high-frequency circuit 1 operates in simultaneous transmission mode.

[0064] Ports 43-46 are examples of input / output ports that can switch between being active and inactive relative to the single-transmission port 41 and the simultaneous-transmission port 42. Port 43 is connected to multiplexer 61. Port 44 is connected to duplexer 62. Port 45 is connected to duplexer 63. Port 46 is connected to filter 64.

[0065] Switching circuit 40 is a multi-connection type switching circuit. Specifically, switching circuit 40 switches the conduction and non-conduction of single transmission port 41 and ports 43-46 respectively. Furthermore, switching circuit 40 switches the conduction and non-conduction of simultaneous transmission port 42 and ports 43-46 respectively. Switching circuit 40 does not connect (conduct) any of ports 43-46 that is connected to one of the single transmission port 41 and the simultaneous transmission port 42 to the other of the single transmission port 41 and the simultaneous transmission port 42. That is, ports 43-46 are each exclusively connected to only one of the single transmission port 41 and the simultaneous transmission port 42.

[0066] Furthermore, the switching circuit 40 only needs to include at least one of a single transmission port 41, a simultaneous transmission port 42, and ports 43 to 46. That is, the number of ports exclusively connected to the single transmission port 41 and the simultaneous transmission port 42 can be only one, or it can be two, three, or more than five.

[0067] Switching circuit 50 is an example of a third switching circuit, comprising port 51 and two ports 52 and 53. Switching circuit 50 is capable of switching ports 51 and 52 and 53 to be on or off respectively.

[0068] Port 51 is an example of the 5th port, which is connected to port 34 of the switching circuit 30 via a high-pass filter 80.

[0069] Port 52 is an example of port 6, which is connected to the output terminal of power amplifier 10.

[0070] Port 53 is an example of port 7, which is connected to the input terminal of low-noise amplifier 20 via filter 81.

[0071] Switching circuit 50 is an SPDT type switch. Specifically, switching circuit 50 exclusively connects port 51 to either port 52 or 53.

[0072] Switching circuits 30, 40, and 50 can be constructed from independent components or integrated within a semiconductor integrated circuit. A semiconductor integrated circuit is an electronic circuit formed on and inside a semiconductor chip (also called a bare die), also known as a semiconductor component. Semiconductor integrated circuits are constructed, for example, using CMOS (Complementary Metal Oxide Semiconductor), specifically, using SOI (Silicon on Insulator) technology. This allows for the inexpensive manufacture of semiconductor integrated circuits. Alternatively, semiconductor integrated circuits can also be constructed from at least one of GaAs, SiGe, and GaN. This enables the realization of high-quality semiconductor integrated circuits.

[0073] Multiplexer 61, duplexers 62 and 63, and filter 64 each include an example of a first filter having a first frequency band as its passband. The first filter has a frequency band other than the first frequency band as its stopband. The first frequency band is the transmit, receive, or transceiver band of a communication frequency band included in the mid-to-high frequency band. The first filter is a bandpass filter having the transmit, receive, or transceiver band of a communication frequency band included in the mid-to-high frequency band as its passband. A high-frequency transmit signal, amplified by a power amplifier (not shown), is input to the first filter and output to the corresponding port. Alternatively, a high-frequency receive signal is input to the first filter from the corresponding port and output to a low-noise amplifier (not shown).

[0074] Furthermore, the passband is the frequency band that allows high-frequency signals to pass through, and it is a frequency band with a gain greater than a given value (e.g., -3dB). The stopband is the frequency band that suppresses the passage of high-frequency signals, and it is a frequency band with a gain less than the aforementioned given value.

[0075] Multiplexer 61 includes multiple first filters for FDD-style frequency band demultiplexing and / or multiplexing. For example, multiplexer 61 includes five filters: a transmit filter and a receive filter for frequency band B1, a transmit filter and a receive filter for frequency band B3, and a receive filter for frequency band B32. Furthermore, the transmit filter is a filter whose passband includes the transmit band (uplink operating band) of the corresponding communication frequency band. The receive filter is a filter whose passband includes the receive band (downlink operating band) of the corresponding communication frequency band.

[0076] Duplexers 62 and 63 each contain two first filters for FDD-style frequency band demultiplexing and / or multiplexing. For example, duplexer 62 includes a transmit filter and a receive filter for frequency band B2. Duplexer 63 includes, for example, a transmit filter and a receive filter for frequency band B7.

[0077] Filter 64 is the first filter for the communication band in TDD mode. For example, filter 64 includes the transmit and receive bands of band B41 as the passband.

[0078] Furthermore, the passband of each filter is merely an example and can be appropriately changed. For instance, the combination of filters included in multiplexer 61 is not limited to the example described above. Additionally, high-frequency circuit 1 may not include at least one of multiplexer 61, duplexer 62 and 63, and filter 64.

[0079] Low-pass filter 70 is an example of a second filter, which has at least a portion of a first frequency band, which is the passband of the first filter, as its passband, and a second frequency band, which does not overlap with the first frequency band, as its stopband. The second frequency band is a band containing a second frequency, which is an n-fold multiple of the first frequency within the first frequency band. Furthermore, n is a natural number greater than or equal to 2. In other words, low-pass filter 70 suppresses the passage of the nth harmonic of the high-frequency signal that passes through the first filter.

[0080] The low-pass filter 70 has a stopband that is at a higher frequency than the passband. Specifically, the low-pass filter 70 has a mid-to-high frequency band as the passband and an ultra-high frequency band as the stopband. For example, the cutoff frequency of the low-pass filter 70 is contained in the range below 3 GHz. The low-pass filter 70 is configured on the signal path 92 used for simultaneous transmission.

[0081] High-pass filter 80 is an example of a third filter having a third frequency band encompassing the second frequency as a passband. The third frequency band is a band that at least partially overlaps with the ultra-high frequency band. High-pass filter 80 has a stopband with frequencies lower than the passband. For example, high-pass filter 80 has an ultra-high frequency band as a passband and a mid-high frequency band as a stopband. For example, the cutoff frequency of high-pass filter 80 is contained in the range below 3 GHz.

[0082] Filter 81 is an example of a fourth filter, configured between port 53 of the switching circuit 50 and the low-noise amplifier 20. Filter 81 is, for example, a bandpass filter with a transmit / receive band of frequency band n77 in the ultra-high frequency range as its passband.

[0083] The first filter, filter 64, low-pass filter 70, high-pass filter 80, and filter 81 included in multiplexers 61, 62, and 63 may be, for example, a surface acoustic wave (SAW) filter, an elastic wave filter using BAW (Bulk Acoustic Wave), an LC resonant filter, and a dielectric filter, and are not limited to these.

[0084] The control circuit 100 can be implemented, for example, using an LSI (Large Scale Integration) as an integrated circuit (IC). The control circuit 100 controls the switching circuits 30, 40, and 50. Specifically, the control circuit 100 controls the switching between the on and off states of the ports of each switching circuit. Specific control examples will be described later.

[0085] Alternatively, the high-frequency circuit 1 may not have a control circuit 100. The functions performed by the control circuit 100 may also be performed by the RFIC 3 or other circuits. The high-frequency circuit 1 may also have an input terminal that receives control signals from the RFIC 3, etc., which are used to switch the switching circuits 30, 40 and 50.

[0086] In this embodiment, multiple circuit components constituting the high-frequency circuit 1 are arranged on the same substrate. For example, switching circuits 30 and 40 and low-pass filter 70 are arranged on the same substrate. Furthermore, at least one of the following components may be arranged on the same substrate: high-pass filter 80, switching circuit 50, multiplexer 61, duplexers 62 and 63, filters 64 and 81, power amplifier 10, low-noise amplifier 20, and control circuit 100. The high-frequency circuit 1 may also be modularized by arranging all its components on the same substrate.

[0087] [1-2. Actions]

[0088] Next, the operation of the high-frequency circuit 1 configured as described above will be explained. As mentioned above, in this embodiment, the high-frequency circuit 1 has a single transmission mode and a simultaneous transmission mode as its operating modes.

[0089] [1-2-1. Single Transmission Mode]

[0090] First, using Figure 3 The single transmission mode is explained. Figure 3 This is a circuit diagram showing an example of the signal path of the high-frequency circuit 1 according to this embodiment when it operates in single transmission mode.

[0091] Single transmission mode is an operating mode for transmitting a high-frequency signal within a communication frequency band encompassing the mid-to-high frequency band. Figure 3 As an example, the transmission of a high-frequency signal in band B2 is shown (specifically, the case using the signal path via duplexer 62).

[0092] In addition, Figure 3 In the diagram, thick lines represent signal paths used in transmission, along with terminals and filters along those paths; dashed lines represent unused signal paths, terminals, filters, and switching circuits, etc., as described later. Figure 4 , Figure 7 as well as Figure 8 The same diagrammatic method is also used in the text.

[0093] In single-transmission mode, the switching circuit 40 turns on the single transmission port 41 and any one of the multiple ports 43-46. For example, as Figure 3 As shown, switching circuit 40 turns on single transmission port 41 and port 44 connected to duplexer 62. At this time, switching circuit 40 does not connect simultaneous transmission ports 42 and 43-46, thus preventing them from conducting. Furthermore, switching circuit 30 turns on ports 31a and 32. At this time, switching circuit 30 does not connect ports 31b and 32-34, thus preventing them from conducting.

[0094] Thus, antenna 2a (antenna connection terminal 101a) and duplexer 62 are connected via signal path 91. High-frequency signals are transmitted in signal path 91 without filters, thereby reducing insertion loss caused by filters.

[0095] [1-2-2. Simultaneous Transmission Mode]

[0096] Next, using Figure 4 The simultaneous transmission mode is explained. Figure 4 This is a circuit diagram showing an example of the signal path of the high-frequency circuit 1 according to this embodiment when it operates in the simultaneous transmission mode.

[0097] Simultaneous transmission mode is an operation mode that simultaneously transmits a high-frequency signal from a communication frequency band included in the mid-high frequency band and a high-frequency signal from a communication frequency band included in the ultra-high frequency band. Figure 4 As an example, the simultaneous transmission (e.g., simultaneous sending) of high-frequency signals in bands B2 and n77 is shown.

[0098] In simultaneous transmission mode, the switching circuit 40 turns on the simultaneous transmission port 42 and any one of the multiple ports 43-46. For example, as Figure 4As shown, the switching circuit 40 enables simultaneous transmission port 42 and port 44 connected to the duplexer 62 to conduct. At this time, the switching circuit 40 does not connect single transmission port 41 and ports 43-46, thus deactivating them.

[0099] Furthermore, switch circuit 30 turns on ports 31a and 33, and turns on ports 31b and 34. Subsequently, switch circuit 50 turns on ports 51 and 52.

[0100] Therefore, antenna 2a (antenna connection terminal 101a) and duplexer 62 are connected via signal path 92. Furthermore, antenna 2b (antenna connection terminal 101b) is connected to power amplifier 10. Thus, it is possible to simultaneously transmit high-frequency signals in band B2 from antenna 2a and high-frequency signals in band n77 from antenna 2b. Additionally, when receiving high-frequency signals in band n77, switching circuit 50 only needs to turn on ports 51 and 53. Therefore, simultaneous reception or simultaneous transmission and reception of high-frequency signals in bands B2 and n77 can be achieved.

[0101] A low-pass filter 70 is provided on signal path 92, thus suppressing the passage of harmonics of the high-frequency signal in band B2 passing through duplexer 62. Therefore, it is possible to suppress these harmonics from entering the UHF signal path via switching circuit 30 and / or antennas 2a and 2b. Furthermore, a high-pass filter 80 is provided on signal path 93, thus suppressing noise components and other noise components contained in the high-frequency signal transmitted in signal path 93 from entering the mid-to-high frequency signal path via switching circuit 30 and / or antennas 2a and 2b.

[0102] [1-3. Effects, etc.]

[0103] As described above, the high-frequency circuit 1 according to this embodiment includes: an antenna connection terminal; a switching circuit 30; a switching circuit 40; a first filter having a first frequency band as a passband; a second filter having at least a portion of the first frequency band as a passband and a second frequency band including a second frequency as a stopband, the second frequency being a frequency that is n times the first frequency within the first frequency band (n is a natural number greater than or equal to 2); and a third filter having a third frequency band including the second frequency as a passband. The switching circuit 30 includes: a port 31a connected to the antenna connection terminal; and ports 32 to 34 capable of switching between being on and off relative to port 31a. The switching circuit 40 includes: a single transmission port 41 connected to port 32; a simultaneous transmission port 42 connected to port 33; and ports 43 to 46 capable of switching between being on and off relative to the single transmission port 41 and the simultaneous transmission port 42. The first filter is connected to one of ports 43 to 46. The second filter is configured on signal path 92, which connects port 33 and simultaneous transmission port 42. The third filter is connected to port 34. No filter is configured on signal path 91, which connects port 32 and single transmission port 41. Furthermore, the second filter may be, for example, a low-pass filter 70.

[0104] Therefore, when using the simultaneous transmission port 42, the passage of the nth harmonic can be suppressed by the low-pass filter 70, and the harmonics can be prevented from winding into other signal paths. Furthermore, since no filter is provided in the signal path 91, the insertion loss caused by the filter can be reduced when using the single transmission port 41. Thus, according to the high-frequency circuit 1, even when using either the simultaneous transmission port 42 or the single transmission port 41, the degradation of communication performance can be suppressed.

[0105] Furthermore, for example, the high-frequency circuit 1 has multiple antenna connection terminals. The switching circuit 30 includes two ports 31a and 31b. The multiple antenna connection terminals include an antenna connection terminal 101a connected to port 31a and an antenna connection terminal 101b connected to port 31b.

[0106] Therefore, when transmitting high-frequency signals in multiple communication bands simultaneously, two antennas 2a and 2b can be used, thus improving the isolation between high-frequency signals in different communication bands.

[0107] Furthermore, for example, when the switching circuit 40 turns on at least one of the single transmission ports 41 and 43-46, the switching circuit 30 turns on ports 31a and 32, and turns off ports 33 and 34 relative to either port 31a or 31b. When the switching circuit 40 turns on at least one of the simultaneous transmission ports 42 and 43-46, the switching circuit 30 turns on ports 31a and 33, turns on ports 31b and 34, and turns off port 32 relative to either port 31a or 31b.

[0108] Therefore, in simultaneous transmission mode, using simultaneous transmission port 42 allows for the suppression of harmonic interference by the low-pass filter 70. Furthermore, in single transmission mode, using single transmission port 41 allows high-frequency signals to be transmitted through the unfiltered signal path 91, reducing insertion loss caused by the filter.

[0109] Furthermore, for example, the high-frequency circuit 1 also includes a switching circuit 50, which includes: port 51 connected to port 34; and ports 52 and 53 capable of switching between being on and off relative to port 51. A third filter is configured on the signal path 93 connecting port 34 and port 51. Furthermore, for example, the third filter is a high-pass filter 80.

[0110] Therefore, a high-pass filter 80 is provided on the signal path 93, so that noise components contained in the high-frequency signal transmitted on the signal path 93 can be suppressed from entering other signal paths via the switching circuit 30 and the like.

[0111] Furthermore, for example, no multiplexer is configured on signal paths 90a and 90b that connect the antenna connection terminals and ports 31a and 31b.

[0112] This allows for the suppression of insertion loss caused by the multiplexer.

[0113] Furthermore, for example, the first frequency band is at least a portion of a first communication frequency band used for frequency division duplex (FDD). The third frequency band is a second communication frequency band used for time division duplex (TDD). Furthermore, for example, the first frequency band is contained in the range below 3 GHz. The second and third frequency bands are contained in the range above 3 GHz. Furthermore, for example, the switching circuits 30 and 40 and the low-pass filter 70 are configured on the same substrate.

[0114] Therefore, it is possible to transmit high-frequency signals in both the ultra-high frequency band and the mid-to-high frequency band simultaneously.

[0115] Furthermore, for example, the communication device 5 according to this embodiment includes: RFIC3, which processes high-frequency signals transmitted and received by antennas 2a and 2b; and high-frequency circuit 1, which transmits high-frequency signals between antennas 2a and 2b and RFIC3.

[0116] This allows us to suppress the degradation of communication performance.

[0117] [1-4. Variations]

[0118] Next, using Figure 5 A variation of Implementation 1 will be described.

[0119] Figure 5 This is the circuit diagram of the high-frequency circuit 1A involved in this variation example. For example... Figure 5 As shown, high-frequency circuit 1A and Figure 2 Compared to the high-frequency circuit 1 shown, the difference is that it does not have a high-pass filter 80 and a filter 81. The high-frequency circuit 1A has a band-pass filter 82.

[0120] Bandpass filter 82 is an example of a third filter, configured between port 34 of switching circuit 30 and port 51 of switching circuit 50. Bandpass filter 82 is, for example, a bandpass filter with a transmit / receive band of frequency band n77 in the ultra-high frequency range as its passband. Bandpass filter 82 is a TDD-type filter used in both transmission and reception.

[0121] Even in this case, similar to the high-frequency circuit 1 according to Embodiment 1, it is possible to suppress the intrusion of high-frequency signals, and thus suppress the degradation of communication performance.

[0122] (Implementation Method 2)

[0123] Next, implementation method 2 will be described.

[0124] The high-frequency circuit involved in Embodiment 2 differs from that in Embodiment 1 in that it has only one antenna connection terminal. The following description focuses on the differences from Embodiment 1, omitting or simplifying the description of the commonalities.

[0125] [2-1. Structure]

[0126] First, using Figure 6 The circuit structure of the high-frequency circuit involved in this embodiment will be described. Figure 6 This is a circuit diagram of the high-frequency circuit 201 involved in this embodiment.

[0127] like Figure 6 As shown, high-frequency circuit 201 and Figure 2Compared to the high-frequency circuit 1 shown, the switching circuit 230 is provided instead of the switching circuit 30. In addition, the high-frequency circuit 201 has a single (i.e., only one) antenna connection terminal 101.

[0128] Antenna connection terminal 101 is connected to an antenna 2.

[0129] Switching circuit 230 is an example of a first switch, including port 31 and three ports 32-34. Port 31 is an example of a first port, and ports 32-34 are the same as in embodiment 1. No multiplexer is configured on the signal path 90 connecting port 31 and antenna connection terminal 101. Specifically, port 31 and antenna connection terminal 101 are directly connected.

[0130] Switching circuit 230 is a multi-connection type switching circuit. Specifically, switching circuit 230 can switch the conduction and non-conduction of ports 31 and 32-34 respectively. More specifically, switching circuit 230 switches between three states: (a) ports 31 and 32 are on (non-conducting relative to ports 33 and 34), (b) ports 31, 33, and 34 are on (non-conducting relative to port 32), and (c) ports 31 and 34 are on (non-conducting relative to ports 32 and 33). Port 31 is not simultaneously connected (conducting simultaneously) relative to ports 32 and 33. Furthermore, when ports 34 and 31 are connected, port 31 is not connected to port 32.

[0131] The switching between the ports of the switching circuit 230, including both on and off states, is based on control by the control circuit 100.

[0132] [2-2. Action]

[0133] Next, the operation of the high-frequency circuit 201 configured as described above will be explained. In this embodiment, the high-frequency circuit 201 also has a single transmission mode and a simultaneous transmission mode as operating modes.

[0134] [2-2-1. Single Transmission Mode]

[0135] First, using Figure 7 The single transmission mode is explained.

[0136] Figure 7 This is a circuit diagram illustrating an example of the signal path of the high-frequency circuit 201 according to this embodiment when operating in single transmission mode. Figure 7 In, with Figure 3 Similarly, as an example, the transmission of high-frequency signals in band B2 is shown (specifically, the case using the signal path via duplexer 62).

[0137] In single-transmission mode, switch circuit 230 turns on ports 31 and 32. At this time, switch circuit 230 turns off ports 31, 33, and 34.

[0138] Thus, antenna 2 (antenna connection terminal 101) and duplexer 62 are connected via signal path 91. High-frequency signals are transmitted in signal path 91 without filters, thereby reducing insertion loss caused by filters.

[0139] [2-2-2. Simultaneous Transmission Mode]

[0140] Next, using Figure 8 The simultaneous transmission mode is explained.

[0141] Figure 8 This is a circuit diagram illustrating an example of the signal path of the high-frequency circuit 201 according to this embodiment when operating in simultaneous transmission mode. Figure 8 In, with Figure 4 Similarly, as an example, the simultaneous transmission (e.g., simultaneous sending) of high-frequency signals in bands B2 and n77 is shown.

[0142] In simultaneous transmission mode, switching circuit 230 turns on ports 31 and 33, and also turns on ports 31 and 34. Ports 31 and 32 are not turned on. Subsequently, switching circuit 50 turns on ports 51 and 52.

[0143] Thus, antenna 2 (antenna connection terminal 101) and duplexer 62 are connected via signal path 92. Furthermore, antenna 2 (antenna connection terminal 101) is connected to power amplifier 10. Therefore, it is possible to simultaneously transmit high-frequency signals in frequency band B2 and high-frequency signals in frequency band n77 from antenna 2.

[0144] A low-pass filter 70 is provided on signal path 92, so harmonics of the high-frequency signal in frequency band B2 passing through duplexer 62 are suppressed by the low-pass filter 70. Therefore, it is possible to suppress the harmonics from entering the ultra-high frequency band signal path via the switching circuit 230. In addition, a high-pass filter 80 is provided on signal path 93, so it is possible to suppress noise components and other noise components contained in the high-frequency signal transmitted in signal path 93 from entering the mid-high frequency band signal path via the switching circuit 230.

[0145] [2-3. Effects, etc.]

[0146] As described above, the high-frequency circuit 201 in this embodiment has only one antenna connection terminal.

[0147] Therefore, when using the simultaneous transmission port 42, antenna 2 is shared, that is, ports 33 and 34 are connected via port 31 within the switching circuit 230. Consequently, high-frequency signals can easily be introduced via the switching circuit 230, making it more effective to suppress the passage of the nth harmonic using the low-pass filter 70. Furthermore, since no filter is provided in the signal path 91, insertion loss due to the filter can be reduced when using the single transmission port 41. Thus, according to the high-frequency circuit 201, degradation of communication performance can be suppressed even when using either the simultaneous transmission port 42 or the single transmission port 41.

[0148] Furthermore, for example, when the switching circuit 40 turns on at least one of the single transmission ports 41 and 43-46, the switching circuit 230 turns on ports 31 and 32, and turns off ports 33 and 34 relative to port 31. When the switching circuit 40 turns on at least one of the simultaneous transmission ports 42 and 43-46, the switching circuit 230 turns on ports 31, 33, and 34, and turns off port 32 relative to port 31.

[0149] Therefore, in simultaneous transmission mode, using simultaneous transmission port 42 allows for the suppression of harmonic interference by the low-pass filter 70. Furthermore, in single transmission mode, using single transmission port 41 allows high-frequency signals to be transmitted through the unfiltered signal path 91, reducing insertion loss caused by the filter.

[0150] Furthermore, for example, in the high-frequency circuit 201, the third filter is configured on the signal path 93 that connects port 34 and port 51.

[0151] Therefore, a high-pass filter 80 is provided on the signal path 93, so that noise components contained in the high-frequency signal transmitted in the signal path 93 can be suppressed from entering other signal paths via the switching circuit 230 and the like.

[0152] Furthermore, for example, port 52 is connected to power amplifier 10. Port 53 is connected to low-noise amplifier 20. High-frequency circuit 201 also includes a filter 81 configured between port 53 and low-noise amplifier 20.

[0153] Therefore, the noise components contained in the received signal can be removed by using a bandpass filter.

[0154] [2-4. Variations]

[0155] Next, using Figure 9 A variation of Implementation Method 2 will be described.

[0156] Figure 9This is the circuit diagram of the high-frequency circuit 201A involved in this variation. (See diagram below.) Figure 9 As shown, high-frequency circuit 201A and Figure 6 Compared to the high-frequency circuit 201 shown, the difference lies in that the low-pass filter 70 and the high-pass filter 80 are disposed on the same substrate. In other words, the low-pass filter 70 and the high-pass filter 80 are composed of a single-chip component with two inputs and two outputs.

[0157] This enables the miniaturization of the high-frequency circuit 201A.

[0158] (other)

[0159] The high-frequency circuit and communication device of the present invention have been described above based on the above embodiments, but the present invention is not limited to the above embodiments.

[0160] For example, the low-pass filter 70 may not include the entire ultra-high frequency band as a stopband, as long as it can suppress the passage of harmonics of high-frequency signals in the mid-to-high frequency communication band transmitted in simultaneous transmission mode. Therefore, for example, high-frequency circuits 1, 1A, 201, or 201A can replace the low-pass filter 70 to provide a band-stop filter. The band-stop filter has a stopband that includes a frequency that is n times the frequency contained in the mid-to-high frequency communication band transmitted in simultaneous transmission mode.

[0161] Alternatively, millimeter-wave bands above 7 GHz can be used instead of ultra-high frequency bands. For example, low-pass filter 70 may have a millimeter-wave band as a stopband, and high-pass filter 80 or band-pass filter 82 may have a millimeter-wave band as a passband.

[0162] Alternatively, for example, a filter can be configured between port 52 and power amplifier 10 in high-frequency circuits 1, 201, or 201A. This filter is, for example, a bandpass filter having the same passband and stopband as filter 81. This removes noise components generated in power amplifier 10, thus suppressing degradation of communication performance.

[0163] Furthermore, for example, high-frequency circuits 1, 1A, 201, or 201A can also transmit high-frequency signals in multiple communication bands of the UHF band. For example, a switch for switching communication bands, a bandpass filter for band n77, and a bandpass filter for band n79 can also be configured in signal path 93.

[0164] Alternatively, for example, in the circuit structure of high-frequency circuits 1, 1A, 201 or 201A, other circuit elements and wiring may be inserted between the circuit elements and signal paths shown in the figures.

[0165] In addition, the present invention also includes various modifications that can be conceived by those skilled in the art to the various embodiments, and the implementation by arbitrarily combining the constituent elements and functions of the various embodiments without departing from the spirit of the present invention.

[0166] Industrial availability

[0167] The present invention, for example as a high-frequency circuit configured in the front end, can be widely used in communication devices such as portable telephones.

[0168] Explanation of reference numerals in the attached figures

[0169] 1, 1A, 201, 201A: High-frequency circuits;

[0170] 2, 2a, 2b: Antenna;

[0171] 3: RFIC;

[0172] 4: BBIC;

[0173] 5: Communication device;

[0174] 10: Power amplifier;

[0175] 20: Low-noise amplifier;

[0176] 30, 40, 50, 230: Switching circuits;

[0177] 31, 31a, 31b, 32, 33, 34, 43, 44, 45, 46, 51, 52, 53: Ports;

[0178] 41: Single transmission port;

[0179] 42: Simultaneous transmission port;

[0180] 61: Multiplexer;

[0181] 62, 63: Duplexer;

[0182] 64, 81: Filters;

[0183] 70: Low-pass filter;

[0184] 80: High-pass filter;

[0185] 82: Bandpass filter;

[0186] 90, 90a, 90b, 91, 92, 93: Signal paths;

[0187] 100: Control circuit;

[0188] 101, 101a, 101b: Antenna connection terminals.

Claims

1. A high-frequency circuit, comprising: Antenna connection terminals; First switching circuit; Second switching circuit; The first filter has the first frequency band as its passband; The second filter has at least a portion of the first frequency band as a passband and a second frequency band including a second frequency as a stopband, wherein the second frequency is n times the first frequency within the first frequency band. n is a natural number greater than 2; and The third filter has a third frequency band that includes the second frequency as its passband. The first switching circuit includes: Port 1 is connected to the antenna connection terminal; and Ports 2, 3, and 4 can be switched between being on and off relative to port 1. The second switching circuit includes: A single transmission port is connected to the second port; Simultaneously, the transmission port is connected to the third port; and The input / output ports can be switched between being active and inactive relative to the single transmission port and the simultaneous transmission port. The first filter is connected to the input / output port. The second filter is configured on the first signal path that connects the third port and the simultaneous transmission port. The third filter is connected to the fourth port. No filter is configured on the second signal path that connects the second port and the single transmission port.

2. The high-frequency circuit according to claim 1, wherein, The second filter is a low-pass filter or a band-stop filter.

3. The high-frequency circuit according to claim 1 or 2, wherein, Equipped with multiple antenna connection terminals, The first switching circuit includes two of the first ports. The plurality of antenna connection terminals include: The first antenna connection terminal is connected to one of the two first ports; and The second antenna connection terminal is connected to the other of the two first ports.

4. The high-frequency circuit according to claim 3, wherein, When the second switching circuit turns on the single transmission port and the input / output port, the first switching circuit turns on one of the two first ports and the second port, and turns off the third port and the fourth port relative to either of the two first ports. When the second switching circuit turns on the simultaneous transmission port and the input / output port, the first switching circuit turns on one of the two first ports and the third port, turns on the other of the two first ports and the fourth port, and turns off the second port relative to either of the two first ports.

5. The high-frequency circuit according to claim 3 or 4, wherein, The third filter is a bandpass filter.

6. The high-frequency circuit according to claim 5, wherein, It also has a third switching circuit. The third switching circuit includes: Port 5 is connected to port 4; and Ports 6 and 7 can be switched between being active and deactive relative to port 5. The third filter is configured on the third signal path that connects the fourth port and the fifth port.

7. The high-frequency circuit according to claim 1 or 2, wherein, It has only one of the aforementioned antenna connection terminals.

8. The high-frequency circuit according to claim 7, wherein, When the second switching circuit turns on the single transmission port and the input / output port, the first switching circuit turns on the first port and the second port, and turns off the third port and the fourth port relative to the first port. When the second switching circuit turns on the simultaneous transmission port and the input / output port, the first switching circuit turns on the first port, the third port, and the fourth port, and turns off the second port relative to the first port.

9. The high-frequency circuit according to any one of claims 1 to 4, 7 and 8, wherein, The third filter is a high-pass filter.

10. The high-frequency circuit according to claim 9, wherein, It also has a third switching circuit. The third switching circuit includes: Port 5 is connected to port 4; and Ports 6 and 7 can be switched between being active and deactive relative to port 5. The third filter is configured on the third signal path that connects the fourth port and the fifth port.

11. The high-frequency circuit according to claim 10, wherein, The sixth port is connected to the power amplifier. The 7th port is connected to a low-noise amplifier. The high-frequency circuit also features: The fourth filter is configured between the seventh port and the low-noise amplifier.

12. The high-frequency circuit according to any one of claims 9 to 11, wherein, The second filter and the third filter are disposed on the same substrate.

13. The high-frequency circuit according to any one of claims 1 to 12, wherein, No multiplexer is configured on the signal path connecting the antenna connection terminal and the first port.

14. The high-frequency circuit according to any one of claims 1 to 13, wherein, The first frequency band is at least a portion of the first communication frequency band used for Frequency Division Duplex (FDD). The third frequency band is the second communication frequency band used for Time Division Duplex (TDD).

15. The high-frequency circuit according to any one of claims 1 to 14, wherein, The first frequency band includes the range below 3 GHz. The second and third frequency bands are both within the range of 3 GHz and above.

16. The high-frequency circuit according to any one of claims 1 to 15, wherein, The first switching circuit, the second switching circuit, and the second filter are configured on the same substrate.

17. A communication device comprising: RF signal processing circuitry processes high-frequency signals transmitted and received by the antenna; and The high-frequency circuit according to any one of claims 1 to 16 transmits the high-frequency signal between the antenna and the RF signal processing circuit.

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