High frequency circuit

Abstract

A high frequency circuit (1) comprises a low-noise amplifier (30) including an FET (31) having a gate terminal, a drain terminal, and a source terminal, a filter (11) having a passband that includes at least a portion of a band A, a filter (21) having a passband that includes at least a portion of a band C, an inductor (41) connected between the gate terminal and the filter (11), and an inductor (42) connected between the filter (21) and a path connecting the inductor (41) and the filter (11), wherein the low-noise amplifier (30) further includes an inductor (43) connected between the source terminal and ground, and the inductor (42) and the inductor (43) constitute a transformer.

Description

High-frequency circuit

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

[0002] Patent Document 1 discloses a high-frequency module (high-frequency circuit) including a plurality of filters having passbands corresponding to different bands, a low-noise amplifier capable of amplifying signals of the different bands, a switch and a plurality of impedance adjustment circuits connected between the plurality of filters and the low-noise amplifier. According to the above configuration, by switching the switch, the connection state of the plurality of impedance adjustment circuits changes, so that impedance matching between the selected filter and the low-noise amplifier can be achieved.

[0003] Japanese Patent Application Laid-Open No. 2018-026795

[0004] In the high-frequency circuit disclosed in Patent Document 1, in order to reduce the signal transmission loss of each band, a plurality of impedance adjustment circuits are arranged to achieve impedance matching between the plurality of filters and the low-noise amplifier, resulting in an increase in the size of the high-frequency circuit. In addition, it is difficult to change the input impedance of the low-noise amplifier itself corresponding to the selected filter (band).

[0005] Therefore, the present invention has been made to solve the above problems, and an object thereof is to provide a small-sized high-frequency circuit in which the input impedance of a low-noise amplifier is variable corresponding to the signal transmission of a selected band.

[0006] To achieve the above object, a high-frequency circuit according to an aspect of the present invention includes a low-noise amplifier including an amplification transistor having an input terminal, an output terminal, and a ground terminal, a first filter having a passband including at least a part of a first band, a second filter having a passband including at least a part of a second band, a first inductor connected between the input terminal and the first filter, and a second inductor connected between a path connecting the first inductor and the first filter and the second filter. The low-noise amplifier further includes a third inductor connected between the ground terminal and the ground, and the second inductor and the third inductor constitute a transformer.

[0007] Furthermore, a high-frequency circuit according to one aspect of the present invention includes a low-noise amplifier including an amplifying transistor having an input terminal, an output terminal, and a ground terminal; a first filter having a passband including at least a portion of a first band; a second filter having a passband including at least a portion of a second band; a first inductor connected between the input terminal and the first filter; and a second inductor connected between the path connecting the first inductor and the first filter and the second filter, wherein the low-noise amplifier further includes a third inductor connected between the ground terminal and ground, and the distance between the second inductor and the third inductor is smaller than the distance between the first inductor and the third inductor.

[0008] Furthermore, a high-frequency circuit according to one aspect of the present invention includes a low-noise amplifier including an amplifying transistor having an input terminal, an output terminal, and a ground terminal; a first filter having a passband including at least a portion of a first band; a second filter having a passband including at least a portion of a second band; a first inductor connected between the input terminal and the first filter; and a second inductor connected between the path connecting the first inductor and the first filter and the second filter, wherein the low-noise amplifier further includes a third inductor connected between the ground terminal and ground, and the angle between the winding axis direction of the second inductor and the winding axis direction of the third inductor is smaller than the angle between the winding axis direction of the first inductor and the winding axis direction of the third inductor.

[0009] According to the present invention, it is possible to provide a compact high-frequency circuit in which the input impedance of a low-noise amplifier is variable in response to signal transmission in a selected band.

[0010] Figure 1 is a circuit diagram of a high-frequency circuit and communication device according to an embodiment. Figure 2 is a diagram showing an example of the circuit configuration of a low-noise amplifier according to an embodiment. Figure 3A is a circuit state diagram of the high-frequency circuit and communication device according to an embodiment when receiving a VLB. Figure 3B is a circuit state diagram of the high-frequency circuit and communication device according to an embodiment when receiving an LB. Figure 4A is an equivalent circuit for measuring the reflection characteristics of the third inductor according to an embodiment when receiving a VLB and an LB. Figure 4B is a graph showing the reflection characteristics of the third inductor according to an embodiment when receiving a VLB and an LB. Figure 4C is a Smith chart showing the impedance of the third inductor according to an embodiment when receiving a VLB and an LB. Figure 5 is a plan view and a cross-sectional view of the high-frequency circuit according to an embodiment. Figure 6 is a plan view and a cross-sectional view of the high-frequency circuit according to modification 1 of the embodiment. Figure 7 is a plan view of the high-frequency circuit according to modification 2 of the embodiment. Figure 8 is a circuit diagram of the high-frequency circuit according to modification 3 of the embodiment.

[0011] The embodiments of this disclosure will be described in detail below with reference to the drawings. The embodiments described below are all general or specific examples. The numerical values, shapes, materials, components, arrangement of components, and connection configurations shown in the following embodiments are examples only and are not intended to limit the present invention. Components in the following embodiments that are not described in an independent claim will be described as optional components. Furthermore, the sizes or size ratios of the components shown in the drawings are not necessarily precise.

[0012] The figures are schematic diagrams that have been appropriately emphasized, omitted, or had their proportions adjusted to illustrate the present invention, and are not necessarily strictly accurate representations. Actual shapes, positional relationships, and proportions may differ. In each figure, substantially identical components are denoted by the same reference numerals, and redundant explanations may be omitted or simplified.

[0013] In the circuit configurations of this disclosure, “connected” includes not only direct connection via connection terminals and / or wiring conductors, but also electrical connection via matching elements or switching circuits. “Connected between A and B” means connected to both A and B.

[0014] In this invention, "terminal" means the point where a conductor within an element ends. However, if the impedance of the conductors between elements is sufficiently low, the terminal is interpreted not only as a single point, but as any point (node) on the conductor between elements or as the entire conductor.

[0015] Furthermore, in this disclosure, "signal path" and "path" mean a transmission line consisting of wiring through which a high-frequency transmission signal or high-frequency reception signal propagates, electrodes directly connected to said wiring, and terminals directly connected to said wiring or electrodes.

[0016] Furthermore, in the circuit element arrangement of this disclosure, "circuit element A is arranged in series with path B" means that the signal input terminal and signal output terminal of circuit element A are connected to each of the two wires that constitute at least a part of path B. At least one of the two wires may be an electrode or a terminal.

[0017] Furthermore, in this disclosure, a plan view of the substrate means viewing the substrate and the circuit elements mounted on the substrate by orthogonal projection onto a plane parallel to the main surface of the substrate.

[0018] Furthermore, in the component arrangements of this disclosure, "a component is placed on a substrate" includes the component being placed on the main surface of the substrate, and the component being placed within the substrate. "A component is placed on the main surface of the substrate" includes the component being placed in contact with the main surface of the substrate, as well as the component being placed above the main surface without contact with the main surface (for example, the component being stacked on top of another component that is placed in contact with the main surface). "A component is placed on the main surface of the substrate" may also include the component being placed in a recess formed on the main surface. "A component is placed within the substrate" includes the component being encapsulated within a module substrate, as well as the entire component being placed between the two main surfaces of the substrate but part of the component not being covered by the substrate, and only part of the component being placed within the substrate.

[0019] Furthermore, in the component arrangement of this disclosure, "winding axis directions are aligned" does not only mean that the angle between the two winding axes is 0°, but also includes a range in which the winding axis directions are substantially aligned, meaning, for example, that the angle between the two winding axes (the smaller of the two angles) is within ±30°.

[0020] Furthermore, in the following embodiment, the passband of the filter is the portion of the frequency spectrum transmitted by the filter, and is defined as the frequency band between two frequencies that are 3 dB greater than the minimum power insertion loss.

[0021] Furthermore, in this disclosure, "band" means at least one of the uplink operating band and the downlink operating band of a frequency band predefined by a standardization body (e.g., 3GPP®, IEEE (Institute of Electrical and Electronics Engineers), etc.) for a communication system constructed using Radio Access Technology (RAT). In this embodiment, the communication system can be, but is not limited to, an LTE (Long Term Evolution) system, a 5G (5th Generation)-NR (New Radio) system, and a WLAN (Wireless Local Area Network) system. The uplink operating band of a frequency band means the frequency range designated for uplink use within that frequency band. The downlink operating band of a frequency band means the frequency range designated for downlink use within that frequency band.

[0022] (Embodiment) [1. Circuit Configuration of High-Frequency Circuit 1 and Communication Device 4] The circuit configuration of the high-frequency circuit 1 and communication device 4 according to this embodiment will be described with reference to Figures 1 and 2. Figure 1 is a circuit diagram of the high-frequency circuit 1 and communication device 4 according to this embodiment. Figure 2 is a diagram showing an example of the circuit configuration of the low-noise amplifier 30 according to this embodiment.

[0023] As shown in Figure 1, the communication device 4 comprises a high-frequency circuit 1, an antenna 2, and an RF signal processing circuit (RFIC: Radio Frequency Integrated Circuit) 3.

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

[0025] Antenna 2 is connected to the antenna connection terminal 100 of the high-frequency circuit 1 and receives high-frequency signals from an external source and outputs them to the high-frequency circuit 1. Antenna 2 may also transmit the high-frequency signals output from the high-frequency circuit 1 to an external source.

[0026] RFIC3 is an example of a signal processing circuit that processes high-frequency signals. Specifically, RFIC3 processes the received signal input via the signal path of high-frequency circuit 1 by down-conversion or the like, and outputs the processed received signal to a baseband signal processing circuit (BBIC, not shown). Alternatively, RFIC3 may process the transmitted signal input from BBIC by up-conversion or the like, and output the processed transmitted signal to the transmission path of high-frequency circuit 1.

[0027] Furthermore, RFIC 3 also functions as a control unit that controls the connection switching of switches 50, 51, and 52 of the high-frequency circuit 1, and also controls the power supply voltage Vcc and bias voltage (current) supplied to the low-noise amplifier 30. Note that some or all of the control unit functions of RFIC 3 may be implemented outside of RFIC 3, for example, in the BBIC or the high-frequency circuit 1.

[0028] Note that antenna 2 does not necessarily have to be included in the communication device 4.

[0029] Next, the circuit configuration of the high-frequency circuit 1 will be described. As shown in Figure 1, the high-frequency circuit 1 comprises filters 11, 12, 21, 22, and 23, a low-noise amplifier 30, inductors 41, 42, and 44, switches 50, 51, and 52, a capacitor 61, a power supply voltage terminal 120, an antenna connection terminal 100, and a signal output terminal 110.

[0030] The antenna connection terminal 100 is connected to the antenna 2 and the switch 50. The signal output terminal 110 is connected to the RFIC 3 and the low-noise amplifier 30. The power supply voltage terminal 120 is connected to the low-noise amplifier 30 and the capacitor 61.

[0031] Filter 11 is an example of a first filter and has a passband that includes the downlink operating band of band A (first band). One end of filter 11 is connected to the select terminal 50b of switch 50, and the other end is connected to the select terminal 51b of switch 51.

[0032] The filter 12 has a passband that includes the downlink operating band of band B. One end of the filter 12 is connected to the select terminal 50c of switch 50, and the other end is connected to the select terminal 51c of switch 51.

[0033] Filter 21 is an example of a second filter and has a passband that includes the downlink operating band of band C (second band). One end of filter 21 is connected to the select terminal 50d of switch 50, and the other end is connected to the select terminal 52b of switch 52 via the inductor 44.

[0034] Filter 22 is an example of a third filter and has a passband that includes the downlink operating band of band D (third band). One end of filter 22 is connected to the select terminal 50e of switch 50, and the other end is connected to the select terminal 52c of switch 52.

[0035] The filter 23 has a passband that includes the downlink operating band of band E. One end of the filter 23 is connected to the select terminal 50f of switch 50, and the other end is connected to the select terminal 52d of switch 52.

[0036] Bands A and B belong to the low band group (850 MHz–1 GHz; hereinafter referred to as LB). Bands C, D, and E belong to the very low band group (600 MHz–850 MHz; hereinafter referred to as VLB). LB is located on the higher frequency side than VLB. Band C is located on the lower frequency side than bands D and E. Note that the frequency range of LB is not limited to 850 MHz–1 GHz, but may be, for example, 800 MHz–1 GHz. Also, the frequency range of VLB is not limited to 600 MHz–850 MHz, but may be, for example, 600 MHz–800 MHz.

[0037] Bands A and B are, for example, Band B26, Band B8 for 4G-LTE, Band n26, or Band n8 for 5G-NR, etc. Also, Bands C, D, and E are, for example, Band B71, Band B20 for 4G-LTE, Band n71, or Band n20 for 5G-NR, etc.

[0038] Note that each of Bands A and B may not belong to LB, and each of Bands C, D, and E may not belong to VLB.

[0039] Also, each of Bands A to E is not limited to a band for frequency division duplexing (FDD: Frequency Division Duplex), and may be a band for time division duplexing (TDD: Time Division Duplex). That is, the filter 11 only needs to have a passband including at least a part of Band A. Also, the filter 12 only needs to have a passband including at least a part of Band B. Also, the filter 21 only needs to have a passband including at least a part of Band C. Also, the filter 22 only needs to have a passband including at least a part of Band D. Also, the filter 23 only needs to have a passband including at least a part of Band E.

[0040] Next, the low-noise amplifier 30 will be described using FIG. 2. As shown in FIG. 2, the low-noise amplifier 30 has, for example, an FET 31, inductors 43 and 45, and capacitors 62 and 63.

[0041] The FET 31 is an example of an amplification transistor and is a field effect transistor (FET: Field Effect Transistor) having a gate terminal (input terminal), a drain terminal (output terminal), and a source terminal (ground terminal). The gate terminal is connected to the inductor 41 via the capacitor 62, the drain terminal is connected to the signal output terminal 110 via the capacitor 63, and is also connected to the power supply voltage terminal 120 via the inductor 45, and the source terminal is connected to the ground via the inductor 43.

[0042] Inductor 43 is an example of a third inductor and is connected between the source terminal and the ground. Inductor 43 is an inductive element for directly grounding the source terminal and is an impedance matching element that contributes to the input impedance of low-noise amplifier 30.

[0043] Capacitors 62 and 63 are capacitive elements for cutting DC components. Inductor 45 is an inductive element for suppressing leakage of high-frequency signals.

[0044] Note that low-noise amplifier 30 may have a plurality of amplification transistors. Also, capacitors 62 and 63, and inductor 45 may not be included in low-noise amplifier 30. Further, FET 31 may be a bipolar transistor having a base terminal (input terminal), a collector terminal (output terminal), and an emitter terminal (ground terminal).

[0045] Returning to FIG. 1, the circuit configuration of high-frequency circuit 1 will be described.

[0046] Switch 51 has a common terminal 51a, selection terminals 51b and 51c, and switches the connection between the common terminal 51a and the selection terminal 51b, and the connection between the common terminal 51a and the selection terminal 51c. The common terminal 51a is connected to inductor 41, the selection terminal 51b is connected to the other end of filter 11, and the selection terminal 51c is connected to the other end of filter 12. Switch 51 is, for example, a SPDT (Single Pole Double Throw) type switch.

[0047] Switch 52 is an example of a first switch and has a common terminal 52a, and select terminals 52b, 52c, and 52d, and switches between connecting common terminal 52a to select terminal 52b, connecting common terminal 52a to select terminal 52c, connecting common terminal 52a to select terminal 52d, and disconnecting common terminal 52a from select terminals 52b, 52c, and 52d. Common terminal 52a is connected to inductor 42, select terminal 52b is connected to the other end of filter 21 via inductor 44, select terminal 52c is connected to the other end of filter 22, and select terminal 52d is connected to the other end of filter 23. Switch 52 is, for example, an SP3T (Single Pole 3 Throw) type switch.

[0048] Switch 50 has a common terminal 50a and select terminals 50b, 50c, 50d, 50e, and 50f, and switches the connection and disconnection of common terminal 50a to select terminal 50b, common terminal 50a to select terminal 50c, common terminal 50a to select terminal 50d, common terminal 50a to select terminal 50e, and common terminal 50a to select terminal 50f. Switch 50 is, for example, a switch circuit including five SPST (Single Pole Single Throw) type switches.

[0049] Inductor 41 is an example of a first inductor and is connected between the gate terminal of FET 31 and filters 11 and 12. More specifically, one end of inductor 41 is connected to the gate terminal of FET 31, and the other end of inductor 41 is connected to filters 11 and 12 via switch 51. In other words, inductor 41 is arranged in series in the path connecting the gate terminal of FET 31 and the common terminal 51a.

[0050] Inductor 42 is an example of a second inductor and is connected between a node on the path connecting inductor 41 and filter 11 and filters 21, 22, and 23. More specifically, one end of inductor 42 is connected to a node on the path connecting inductor 41 and filter 11, and the other end of inductor 42 is connected to filters 21 to 23 via switch 52. In other words, inductor 42 is arranged in series with the path connecting the node on the path connecting inductor 41 and filter 11 and the common terminal 52a.

[0051] Inductor 44 is an example of a fourth inductor and is connected between the filter 21 and the switch 52. The arrangement of inductor 44 makes it possible to optimize the impedance matching between the filter 21, which includes at least a portion of the lowest frequency band C among bands C, D, and E, and the low-noise amplifier 30, in the same way as the impedance matching between the filter 22 or 23 and the low-noise amplifier 30.

[0052] Here, inductors 42 and 43 constitute a transformer.

[0053] Furthermore, when we say that two inductors constitute a transformer, it means that the two inductors are magnetically coupled, and the magnetic flux generated by the current flowing through one inductor is transmitted to the other inductor, and the two inductors are arranged in such a way that an induced electromotive force can be generated in the other inductor.

[0054] Filters 11 and 21, the low-noise amplifier 30, and the inductors 41 and 42 are essential components of the high-frequency circuit 1, while filters 12, 22 and 23, switches 50 to 52, and the capacitor 61 do not necessarily need to be included in the high-frequency circuit 1.

[0055] According to the above circuit configuration, the high-frequency circuit 1 can selectively perform a mode of transmitting a signal from either band A or band B (LB reception), and a mode of transmitting a signal from any of bands C to E (VLB reception).

[0056] Next, the cases in which the high-frequency circuit 1 and communication device 4 receive signals in band C (VLB receiving mode) and (2) signals in band B (LB receiving mode) will be explained using Figures 3A and 3B, respectively.

[0057] Figure 3A is a circuit state diagram of the high-frequency circuit 1 and communication device 4 according to the embodiment when receiving a VLB. Figure 3B is a circuit state diagram of the high-frequency circuit 1 and communication device 4 according to the embodiment when receiving an LB.

[0058] First, as shown in Figure 3A, (1) in VLB reception mode (during VLB reception), the common terminal 52a and the selection terminal 52b are connected, and the common terminal 50a and the selection terminal 50d are connected. In this circuit state, the signal of band C passes through antenna 2, antenna connection terminal 100, switch 50, filter 21, switch 52, inductor 42, inductor 41, and low-noise amplifier 30 and is output from signal output terminal 110. In VLB reception mode, inductors 41 and 42 are connected in series, and a large inductance value is added in series to the signal path. At this time, current (signal) flows through inductor 42 from the switch 52 side to the inductor 41 side. Also, since the low-noise amplifier 30 performs signal amplification, current flows through inductor 43 from the source terminal side of FET 31 to the ground side.

[0059] Next, as shown in Figure 3B, in (2) LB reception mode (when LB is being received), the common terminal 51a and the selection terminal 51c are connected, and the common terminal 50a and the selection terminal 50c are connected. In this circuit state, the signal of band B passes through antenna 2, antenna connection terminal 100, switch 50, filter 12, switch 51, inductor 41, and low-noise amplifier 30 and is output from the signal output terminal 110, while a weak signal component flows from a node on the path connecting switch 51 and inductor 41 to ground via inductor 42 and the off capacitance of switch 52. In LB reception mode, inductor 42 is configured to be shunt-connected to inductor 41, and a smaller inductance value is added in series to the signal path compared to VLB reception mode. At this time, a weak current flows through inductor 42 from the node side to the switch 52 side. Also, since the low-noise amplifier 30 performs signal amplification, current flows through inductor 43 from the source terminal side of FET 31 to the ground side.

[0060] Here, the change in the inductance value of the inductor 43 in VLB reception mode and LB reception mode will be explained using Figures 4A to 4C. Figure 4A is an equivalent circuit for measuring the reflection characteristics of the inductor 43 during VLB reception and LB reception according to the embodiment.

[0061] In VLB reception mode, the direction of the signal flowing through inductor 42 and the direction of the signal flowing through inductor 43 are opposite, so inductor 43 is not affected by the magnetic interference of inductor 42. In other words, the inductance value of inductor 43 when a VLB (band C to band E) signal is flowing is equal to the inductance value of inductor 43 when no signal is flowing through inductor 43. For this reason, in VLB reception mode, the reflection characteristics of inductor 43 are equivalent to the reflection characteristics of inductor 43 alone.

[0062] On the other hand, in LB reception mode, the direction of the signal flowing through inductor 42 and the direction of the signal flowing through inductor 43 are the same, so inductor 43 is subjected to magnetic interference from inductor 42. For this reason, in LB reception mode, the reflection characteristics of inductor 43 are measured by an equivalent circuit in which inductor 43 and inductor 42 are magnetically coupled.

[0063] Figure 4B is a graph showing the reflection characteristics of the inductor 43 according to the embodiment when receiving a VLB and LB signal. Figure 4C is a Smith chart showing the impedance of the inductor 43 according to the embodiment when receiving a VLB and LB signal. Figure 4B shows the reflection characteristics of the inductor 43 at node n1 in the equivalent circuit shown in Figure 4A. Figure 4C shows the impedance seen from node n1 to the inductor 43 in the equivalent circuit shown in Figure 4A.

[0064] As shown in Figure 4C, the inductive reactance is greater in the VLB receiving mode than in the LB receiving mode. Also, as shown in Figure 4B, the reflection loss is greater in the LB receiving mode than in the VLB receiving mode. From these, it can be seen that the impedance (jωL) of inductor 43 in the LB receiving mode is smaller than the impedance (jωL) of inductor 43 in the VLB receiving mode. In other words, the inductance value (L) of inductor 43 in the LB receiving mode is smaller than the inductance value (L) of inductor 43 in the VLB receiving mode.

[0065] In other words, the direction of the signal flowing through the inductor 42 is reversed between the LB receiving mode and the VLB receiving mode. As a result, the inductance value of the inductor 43 in the LB receiving mode is smaller compared to the VLB receiving mode, making it possible to change the input impedance of the low-noise amplifier 30. This allows for optimization of the matching between the input impedance of the low-noise amplifier 30 and the impedance seen from the inductor 41 to the filters 11 and 12. Therefore, since the input impedance of the low-noise amplifier 30 can be changed without using circuit elements such as switches, signals of multiple bands can be transmitted with low loss using a single low-noise amplifier 30. Thus, a miniaturized and low-loss high-frequency circuit 1 can be provided.

[0066] In LB reception mode, inductor 42 is configured to be shunt-connected to the flow of the LB signal. However, due to the off capacitance of switch 52, it is grounded at high frequency by switch 52, resulting in an equivalent circuit configuration where a weak signal current flows through inductor 42. Therefore, in order to effectively reduce the inductance value of inductor 43 in LB reception mode, it is effective to make the inductance value of inductor 42 larger than that of inductor 43. Furthermore, it is even more desirable to make the inductance value of inductor 42 10 times or more than that of inductor 43.

[0067] Furthermore, in this embodiment, LB is located on the higher frequency side than VLB, and the inductance value of inductor 43 is smaller when transmitting the LB signal compared to when transmitting the VLB signal. However, in the high-frequency circuit according to the present invention, it is sufficient if inductors 42 and 43 are configured as transformers such that the inductance value of inductor 43 differs when transmitting signals in different frequency bands.

[0068] [2. Component Arrangement Configuration of High-Frequency Circuit 1] The component arrangement configuration of the high-frequency circuit 1 according to this embodiment will be described with reference to Figure 5. Figure 5 is a plan view and a cross-sectional view of the high-frequency circuit 1 according to this embodiment. Figure 5(a) shows the arrangement of circuit components when the main surface 90a of the mounting substrate 90 is viewed from the positive z-axis direction. Note that in Figure 5(a), circuit components arranged on the main surface 90b of the mounting substrate 90 are shown with dashed lines. Also, Figure 5(b) shows a cross-sectional view along the VB-VB line in Figure 5(a). Note that in Figure 5, the illustration of the wiring connecting the mounting substrate 90 and each circuit component is partially omitted. Also, in Figure 5, marks indicating the function of the filters are added so that the arrangement relationship of the filters can be easily understood, but these marks are not added to the actual filters.

[0069] The high-frequency circuit 1 shown in Figure 5 further comprises a mounting substrate 90, resin members 91 and 92, and a shield electrode layer 95, compared to the high-frequency circuit 1 shown in Figure 1.

[0070] The mounting substrate 90 has two opposing main surfaces 90a (first main surface) and 90b (second main surface), and is a substrate for mounting circuit components that constitute the high-frequency circuit 1. Examples of mounting substrates 90 include low-temperature co-fired ceramics (LTCC) substrates having a laminated structure of multiple dielectric layers, high-temperature co-fired ceramics (HTCC) substrates, component-embedded substrates, substrates having a redistribution layer (RDL), or printed circuit boards.

[0071] The resin member 91 is arranged to cover the main surface 90a, the filters 11, 12, 21-23, and the inductors 41-43. The resin member 92 is arranged to cover the main surface 90b and the semiconductor IC 70. The shield electrode layer 95 is formed to cover the surface of the resin member 91, the side surface of the resin member 92, and the side surface of the mounting substrate 90, and is set to ground potential. At least one of the resin members 91, 92, and the shield electrode layer 95 may be omitted.

[0072] As shown in Figure 5, filters 11, 12, 21-23 and inductors 41-43 are arranged on the main surface 90a. The semiconductor IC 70 and signal output terminal 110 are arranged on the main surface 90b.

[0073] The semiconductor IC 70 is an example of a semiconductor integrated component and includes a low-noise amplifier 30 and switches 50-52. The semiconductor IC 70 is constructed using, for example, CMOS (Complementary Metal Oxide Semiconductor), and may specifically be manufactured by an SOI (Silicon on Insulator) process. The semiconductor IC 70 may also be composed of at least one of GaAs, SiGe, and GaN. However, the semiconductor material of the semiconductor IC 70 is not limited to the materials described above.

[0074] Although the capacitor 61, antenna connection terminal 100, and power supply voltage terminal 120 are not shown in Figure 5, they may be placed on the mounting board 90.

[0075] According to this, the circuit components constituting the high-frequency circuit 1 are distributed and arranged on both sides of the mounting board 90, so the high-frequency circuit 1 can be miniaturized.

[0076] Each of the inductors 41 to 43 is a surface-mount type chip inductor. At least one of the inductors 41 to 43 may be a coil conductor formed on the mounting substrate 90. Inductor 43 may also be formed within the semiconductor IC 70.

[0077] As shown in Figure 5(a), the distance D between inductor 42 and inductor 43 ３２ The distance D between inductor 41 and inductor 43 is the distance between inductor 41 and inductor 43. ３１ It is smaller than that.

[0078] According to this, the degree of magnetic field coupling between inductor 43 and inductor 42 can be made higher than the degree of magnetic field coupling between inductor 43 and inductor 41. Due to this magnetic field coupling between inductor 43 and inductor 42, and the fact that the direction of the signal flowing through inductor 42 is reversed between LB reception mode and VLB reception mode, it becomes possible to change the inductance value of inductor 43 between LB reception mode and VLB reception mode. This makes it possible to individually optimize (1) the matching of the input impedance of the low-noise amplifier 30 with the impedance seen from inductor 41 to the filters 11 and 12 in LB reception mode, and (2) the matching of the input impedance of the low-noise amplifier 30 with the impedance seen from inductor 41 to the filters 21-23 in VLB reception mode. Therefore, since the input impedance of the low-noise amplifier 30 can be changed without using circuit elements such as switches, signals of multiple bands can be transmitted with low loss using one low-noise amplifier 30. Thus, a miniaturized and low-loss high-frequency circuit 1 can be provided.

[0079] Figure 6 is a plan view and a cross-sectional view of the high-frequency circuit 1A according to the first modified example of the embodiment. The high-frequency circuit 1A according to this modified example differs from the high-frequency circuit 1 according to the embodiment only in the mounting configuration of the inductor 43. Therefore, in the following description of the high-frequency circuit 1A according to this modified example, the same configuration as the high-frequency circuit 1 according to the embodiment will be omitted, and the focus will be on the mounting configuration of the inductor 43.

[0080] As shown in Figure 6, filters 11, 12, 21-23, and inductors 41 and 42 are arranged on the main surface 90a. A semiconductor IC 70 and a signal output terminal 110 are arranged on the main surface 90b. The inductor 43 is made up of a coil conductor formed on the mounting substrate 90.

[0081] The semiconductor IC 70 is an example of a semiconductor integrated component and includes a low-noise amplifier 30 and switches 50-52.

[0082] According to this, the circuit components constituting the high-frequency circuit 1A are distributed and arranged on both sides and inside the mounting board 90, so the high-frequency circuit 1A can be miniaturized.

[0083] Each of the inductors 41 and 42 is a surface-mount type chip inductor. At least one of the inductors 41 and 42 may be a coil conductor formed on the mounting substrate 90.

[0084] As shown in Figure 6(a), the distance D between inductor 42 and inductor 43 ３２ The distance D between inductor 41 and inductor 43 is the distance between inductor 41 and inductor 43. ３１ It is smaller than that.

[0085] According to this, similar to the high-frequency circuit 1 in the embodiment, the input impedance of the low-noise amplifier 30 can be changed without using circuit elements such as switches, so that signals of multiple bands can be transmitted with low loss using a single low-noise amplifier 30. Therefore, a miniaturized and low-loss high-frequency circuit 1A can be provided.

[0086] [3. Component Arrangement Configuration of High-Frequency Circuit 1B According to Modification 2] The component arrangement configuration of the high-frequency circuit 1B according to Modification 2 will be explained with reference to Figure 7. Figure 7 is a plan view of the high-frequency circuit 1B according to Modification 2 of the embodiment. Figure 7 shows the arrangement of circuit components when the main surface 90a of the mounting substrate 90 is viewed from the positive z-axis direction. In Figure 7, circuit components arranged on the main surface 90b of the mounting substrate 90 are shown with dashed lines. In Figure 7, the illustration of the wiring connecting the mounting substrate 90 and each circuit component is partially omitted. Also, in Figure 7, marks indicating the function of the filters are added so that the arrangement relationship of the filters can be easily understood, but these marks are not added to the actual filters.

[0087] The high-frequency circuit 1B shown in Figure 7 further includes a mounting substrate 90 compared to the high-frequency circuit 1 shown in Figure 1. The high-frequency circuit 1B according to this modified example has a different arrangement configuration of inductors 41 to 43 compared to the high-frequency circuit 1 according to the embodiment. Therefore, in the following description of the high-frequency circuit 1B according to this modified example, the same configuration as the high-frequency circuit 1 according to the embodiment will be omitted, and the focus will be on the arrangement configuration of inductors 41 to 43.

[0088] As shown in Figure 7, filters 11, 12, 21-23 and inductors 41-43 are arranged on the main surface 90a. The semiconductor IC 70 and signal output terminal 110 are arranged on the main surface 90b.

[0089] According to this, the circuit components constituting the high-frequency circuit 1B are distributed and arranged on both sides of the mounting board 90, so the high-frequency circuit 1B can be miniaturized.

[0090] Each of the inductors 41 to 43 is a surface-mount type chip inductor. At least one of the inductors 41 to 43 may be a coil conductor formed on the mounting substrate 90. Inductor 43 may also be formed within the semiconductor IC 70.

[0091] As shown in Figure 7, the winding axis direction of inductor 42 and the winding axis direction of inductor 43 are aligned, while the winding axis direction of inductor 41 and the winding axis direction of inductor 43 are perpendicular.

[0092] According to this, the degree of magnetic field coupling between inductor 43 and inductor 42 can be made higher than the degree of magnetic field coupling between inductor 43 and inductor 41. Due to the magnetic field coupling between inductor 43 and inductor 42, and the fact that the direction of the signal flowing through inductor 42 is reversed between LB reception mode and VLB reception mode, it becomes possible to change the inductance value of inductor 43 between LB reception mode and VLB reception mode. This makes it possible to individually optimize (1) the matching of the input impedance of the low-noise amplifier 30 with the impedance seen from inductor 41 to the filters 11 and 12 in LB reception mode, and (2) the matching of the input impedance of the low-noise amplifier 30 with the impedance seen from inductor 41 to the filters 21-23 in VLB reception mode. Therefore, since the input impedance of the low-noise amplifier 30 can be changed without using circuit elements such as switches, signals of multiple bands can be transmitted with low loss using one low-noise amplifier 30. Thus, a miniaturized and low-loss high-frequency circuit 1B can be provided.

[0093] Furthermore, if the inductor is a surface-mount chip component, its winding axis is the winding axis of the coil formed inside the chip component. Also, if the inductor is composed of a planar coil formed on the mounting substrate 90, its winding axis is an axis perpendicular to the plane containing the planar coil and intersecting the region enclosed by the planar coil.

[0094] In this modified example, the winding axis direction of inductor 42 is aligned with the winding axis direction of inductor 43, and the winding axis direction of inductor 41 is perpendicular to the winding axis direction of inductor 43. However, the relationship between the winding axis directions of inductors 41, 42, and 43 is not limited to this. The angle between the winding axis direction of inductor 42 and the winding axis direction of inductor 43 may be smaller than the angle between the winding axis direction of inductor 41 and the winding axis direction of inductor 43.

[0095] According to this, the degree of magnetic field coupling between inductor 43 and inductor 42 can be made higher than the degree of magnetic field coupling between inductor 43 and inductor 41. Due to the magnetic field coupling between inductor 43 and inductor 42, and the fact that the direction of the signal flowing through inductor 42 is reversed between LB receiving mode and VLB receiving mode, it becomes possible to change the inductance value of inductor 43 between LB receiving mode and VLB receiving mode. Therefore, the input impedance of the low-noise amplifier 30 can be changed without using circuit elements such as switches, so that signals of multiple bands can be transmitted with low loss using one low-noise amplifier 30. Thus, a miniaturized and low-loss high-frequency circuit can be provided.

[0096] Furthermore, a ground metal plate may be placed between inductor 41 and inductor 43, but it is not necessary to place a ground metal plate between inductor 42 and inductor 43.

[0097] According to this, the degree of magnetic field coupling between inductor 43 and inductor 42 can be made higher than the degree of magnetic field coupling between inductor 43 and inductor 41. Therefore, a miniaturized and low-loss high-frequency circuit can be provided.

[0098] Furthermore, in the high-frequency circuit 1 according to the embodiment, the high-frequency circuit 1A according to modification 1, and the high-frequency circuit 1B according to modification 2, when the mounting substrate 90 is viewed from above, at least one of the inductors 41 to 43 and the semiconductor IC 70 may overlap by at least a portion. This allows the wiring connecting the low-noise amplifier 30 and the inductors 41 to 43, and the wiring connecting the inductors 41 to 43 and the switches 51 and 52 to be shortened, thereby reducing the losses of the high-frequency circuits 1, 1A, and 1B.

[0099] [4 Configuration of the High-Frequency Circuit 1C According to Modification 3] Figure 8 is a circuit diagram of the high-frequency circuit 1C according to Modification 3 of the embodiment. As shown in the figure, the high-frequency circuit 1C comprises filters 11, 12, 21, 22, and 23, a low-noise amplifier 30, inductors 41, 42, and 44, switches 50, 51, 52, and 53, a capacitor 61, a power supply voltage terminal 120, an antenna connection terminal 100, and a signal output terminal 110. The high-frequency circuit 1C according to this modification differs from the high-frequency circuit 1 according to the embodiment only in that a switch 53 is added. Therefore, in the following, the same configuration as the high-frequency circuit 1 according to the embodiment will be omitted from the explanation of the high-frequency circuit 1C according to this modification, and the connection configuration and switching operation of the switch 53 will be explained in detail.

[0100] Switch 53 is an example of a second switch, connected between inductor 42 and switch 52, and switches the connection and disconnection between inductor 42 and switch 52. Switch 53 is, for example, a single SPST type switch.

[0101] In the high-frequency circuit 1C according to this modified example, when switch 52 has made the common terminal 52a and the selection terminals 52b, 52c, and 52d non-conductive (unconnected), switch 53 has made the inductor 42 unconnected to the common terminal 52a.

[0102] When switch 52 has non-conductive (unconnected) connections between the common terminal 52a and the selection terminals 52b, 52c, and 52d, the off capacitance of switch 52 increases with the number of selection terminals, resulting in increased transmission loss in LB reception mode. In contrast, by connecting switch 53 in series with switch 52, the off capacitance connected to inductor 42 in LB reception mode can be reduced. Therefore, transmission loss in LB reception mode can be reduced.

[0103] [5 Effects, etc.] As described above, the high-frequency circuit 1 according to the embodiment, the high-frequency circuit 1A according to modification 1, the high-frequency circuit 1B according to modification 2, and the high-frequency circuit 1C according to modification 3 each include a low-noise amplifier 30 including an FET 31 having a gate terminal, a drain terminal, and a source terminal, a filter 11 having a passband that includes at least a part of band A, a filter 21 having a passband that includes at least a part of band C, an inductor 41 connected between the gate terminal and the filter 11, and an inductor 42 connected between the path connecting the inductor 41 and the filter 11 and the filter 21. The low-noise amplifier 30 further includes an inductor 43 connected between the source terminal and ground, and the inductor 42 and the inductor 43 constitute a transformer.

[0104] According to this, the direction of the signal flowing through the inductor 42 is reversed between the mode for receiving signals from band A (hereinafter referred to as the LB receiving mode) and the mode for receiving signals from band C (hereinafter referred to as the VLB receiving mode), making it possible to change the inductance value of the inductor 43 between the LB receiving mode and the VLB receiving mode. This makes it possible to individually optimize (1) the matching of the input impedance of the low-noise amplifier 30 with the impedance seen from the inductor 41 to the filter 11 in the LB receiving mode, and (2) the matching of the input impedance of the low-noise amplifier 30 with the impedance seen from the inductor 41 to the filter 21 side in the VLB receiving mode. Therefore, since the input impedance of the low-noise amplifier 30 can be changed without using circuit elements such as switches, signals from multiple bands can be transmitted with low loss using a single low-noise amplifier 30. Thus, miniaturized and low-loss high-frequency circuits 1 (1A, 1B, and 1C) can be provided.

[0105] Furthermore, the high-frequency circuit 1 according to the embodiment, the high-frequency circuit 1A according to modification 1, and the high-frequency circuit 1C according to modification 3 each include a low-noise amplifier 30 including an FET 31 having a gate terminal, a drain terminal, and a source terminal, a filter 11 having a passband including at least a portion of band A, a filter 21 having a passband including at least a portion of band C, an inductor 41 connected between the gate terminal and the filter 11, and an inductor 42 connected between the path connecting the inductor 41 and the filter 11 and the filter 21, wherein the low-noise amplifier 30 further includes an inductor 43 connected between the source terminal and ground, and the distance D between the inductor 42 and the inductor 43 ３２ The distance D between inductor 41 and inductor 43 is the distance between inductor 41 and inductor 43. ３１ It is smaller than that.

[0106] According to this, the degree of magnetic field coupling between inductor 43 and inductor 42 can be made higher than the degree of magnetic field coupling between inductor 43 and inductor 41. Due to the magnetic field coupling between inductor 43 and inductor 42, and the fact that the direction of the signal flowing through inductor 42 is reversed between LB receiving mode and VLB receiving mode, it becomes possible to change the inductance value of inductor 43 between LB receiving mode and VLB receiving mode. This makes it possible to individually optimize (1) impedance matching between the low-noise amplifier 30 and filter 11 in LB receiving mode, and (2) impedance matching between the low-noise amplifier 30 and filter 21 in VLB receiving mode. Thus, a miniaturized and low-loss high-frequency circuit 1 (1A, 1C) can be provided.

[0107] Furthermore, the high-frequency circuit 1 according to the embodiment, the high-frequency circuit 1B according to modification 2, and the high-frequency circuit 1C according to modification 3 each include a low-noise amplifier 30 including an FET 31 having a gate terminal, a drain terminal, and a source terminal; a filter 11 having a passband that includes at least a portion of band A; a filter 21 having a passband that includes at least a portion of band C; an inductor 41 connected between the gate terminal and the filter 11; and an inductor 42 connected between the path connecting the inductor 41 and the filter 11 and the filter 21. The low-noise amplifier 30 further includes an inductor 43 connected between the source terminal and ground, and the angle between the winding axis direction of the inductor 42 and the winding axis direction of the inductor 43 is smaller than the angle between the winding axis direction of the inductor 41 and the winding axis direction of the inductor 43.

[0108] According to this, the degree of magnetic field coupling between inductor 43 and inductor 42 can be made higher than the degree of magnetic field coupling between inductor 43 and inductor 41. Due to the magnetic field coupling between inductor 43 and inductor 42, and the fact that the direction of the signal flowing through inductor 42 is reversed between the LB receiving mode and the VLB receiving mode, it becomes possible to change the inductance value of inductor 43 between the LB receiving mode and the VLB receiving mode. This makes it possible to individually optimize (1) impedance matching between the low-noise amplifier 30 and filter 11 in the LB receiving mode, and (2) impedance matching between the low-noise amplifier 30 and filter 21 in the VLB receiving mode. Thus, a miniaturized and low-loss high-frequency circuit 1 (1B, 1C) can be provided.

[0109] For example, in high-frequency circuits 1, 1A, 1B, and 1C, band A is located on the higher frequency side than band C, and the inductance value of inductor 43 when a signal in band A is flowing is smaller than the inductance value of inductor 43 when no signal is flowing through inductor 43.

[0110] For example, in high-frequency circuits 1, 1A, 1B, and 1C, the inductance value of inductor 43 when a signal of band C is flowing through it is equal to the inductance value of inductor 43 when no signal is flowing through it.

[0111] According to these findings, the inductance value of inductor 43 in LB reception mode is smaller than that in VLB reception mode, which optimizes the matching between the input impedance of the low-noise amplifier 30 and the impedance seen from inductor 41 to the filter 11 side.

[0112] Furthermore, for example, in high-frequency circuits 1, 1A, 1B, and 1C, the inductance value of inductor 42 is greater than the inductance value of inductor 43.

[0113] According to this, in LB receiving mode, inductor 42 is configured in a shunt connection, making it difficult for current to flow. However, the large inductance value of inductor 42 makes it possible to significantly change the inductance value of inductor 43.

[0114] For example, the high-frequency circuit 1C further includes a filter 22 having a passband that includes at least a portion of band D, a switch 52 connected between the inductor 42 and filters 21 and 22 that switches between (1) the connection between the inductor 42 and filter 21, (2) the connection between the inductor 42 and filter 22, and (3) the disconnection between the inductor 42 and filters 21 and 22, and a switch 53 connected between the inductor 42 and switch 52 that switches between the connection and disconnection of the inductor 42 and switch 52.

[0115] For example, in the high-frequency circuit 1C, if switch 52 disconnects inductor 42 from filters 21 and 22, switch 53 disconnects inductor 42 from switch 52.

[0116] When switch 52 has non-conductive (unconnected) connections between the common terminal 52a and the selection terminals 52b, 52c, and 52d, the off capacitance of switch 52 increases with the number of selection terminals, resulting in increased transmission loss in LB reception mode. In contrast, by connecting switch 53 in series with switch 52, the off capacitance connected to inductor 42 in LB reception mode can be reduced. Therefore, transmission loss in LB reception mode can be reduced.

[0117] For example, the high-frequency circuits 1, 1A, 1B, and 1C further include a filter 22 having a passband that includes at least a portion of band D, a switch 52 connected between an inductor 42 and filters 21 and 22 to switch between the connection between the inductor 42 and filter 21 and the connection between the inductor 42 and filter 22, and an inductor 44 connected between the filter 21 and switch 52, wherein band C is located at a lower frequency than bands A and D.

[0118] According to this, by arranging the inductor 44, it becomes possible to optimize the impedance matching between the filter 21, which includes at least a portion of the lower frequency band C in its passband, and the low-noise amplifier 30, in the same way as the impedance matching between the filter 22 or 23 and the low-noise amplifier 30.

[0119] For example, the high-frequency circuits 1, 1A, 1B, and 1C further include a mounting substrate 90 having two opposing main surfaces 90a and 90b, and the inductor 42 is a surface-mount component and is positioned on the main surface 90a.

[0120] For example, in the high-frequency circuits 1, 1A, 1B, and 1C, the low-noise amplifier 30 is included in the semiconductor IC 70 located on the main surface 90b.

[0121] According to this, the circuit components constituting the high-frequency circuit 1 (1A, 1B, and 1C) are distributed and arranged on both sides of the mounting board 90, so the high-frequency circuit 1 (1A, 1B, and 1C) can be miniaturized.

[0122] For example, in high-frequency circuits 1, 1A, 1B, and 1C, the inductor 43 is included in the semiconductor IC 70.

[0123] According to this, the high-frequency circuit 1 (1A, 1B, and 1C) can be miniaturized.

[0124] For example, in the high-frequency circuits 1, 1A, 1B, and 1C, the inductor 43 is a surface-mount component and is positioned on the main surface 90a.

[0125] According to this, since both inductors 42 and 43 are surface-mount components and are arranged on the same main surface 90a, inductors 42 and 43 can easily form a transformer.

[0126] For example, in the high-frequency circuit 1A, the inductor 43 includes a coil conductor formed on the mounting substrate 90.

[0127] According to this, the inductor 43 is formed within the mounting substrate 90, so the high-frequency circuit 1A can be miniaturized.

[0128] (Other Embodiments, etc.) Although embodiments and modifications of the high-frequency circuit and communication device according to the embodiments of the present invention have been described above, the high-frequency circuit and communication device according to the present invention are not limited to the above embodiments and modifications. The present invention also includes other embodiments realized by combining any components in the above embodiments and modifications, modifications obtained by applying various modifications to the above embodiments and modifications that a person skilled in the art can conceive of without departing from the spirit of the present invention, and various devices incorporating the above high-frequency circuit.

[0129] For example, in the high-frequency circuit and communication device according to the above embodiment and its modified form, other circuit elements and wiring may be inserted between the paths connecting each circuit element and signal path disclosed in the drawings.

[0130] This invention can be widely used in communication devices such as mobile phones as a high-frequency circuit placed in the front end.

[0131] 1, 1A, 1B, 1C High-frequency circuits 2 Antenna 3 RF signal processing circuit (RFIC) 4 Communication device 11, 12, 21, 22, 23 Filters 30 Low-noise amplifier 31 FET 41, 42, 43, 44, 45 Inductors 50, 51, 52, 53 Switches 50a, 51a, 52a Common terminals 50b, 50c, 50d, 50e, 50f, 51b, 51c, 52b, 52c, 52d Select terminals 61, 62, 63 Capacitors 70 Semiconductor ICs 90 Mounting boards 90a, 90b Main surface 91, 92 Resin components 95 Shield electrode layer 100 Antenna connection terminal 110 Signal output terminal 120 Power supply voltage terminal

Claims

1. A high-frequency circuit comprising: a low-noise amplifier including an amplifying transistor having an input terminal, an output terminal and a ground terminal; a first filter having a passband including at least a portion of a first band; a second filter having a passband including at least a portion of a second band; a first inductor connected between the input terminal and the first filter; and a second inductor connected between the path connecting the first inductor and the first filter and the second filter, wherein the low-noise amplifier further includes a third inductor connected between the ground terminal and ground, and the second inductor and the third inductor constitute a transformer.

2. A high-frequency circuit comprising: a low-noise amplifier including an amplifying transistor having an input terminal, an output terminal and a ground terminal; a first filter having a passband including at least a portion of a first band; a second filter having a passband including at least a portion of a second band; a first inductor connected between the input terminal and the first filter; and a second inductor connected between a path connecting the first inductor and the first filter and the second filter, wherein the low-noise amplifier further includes a third inductor connected between the ground terminal and ground, and the distance between the second inductor and the third inductor is smaller than the distance between the first inductor and the third inductor.

3. A high-frequency circuit comprising: a low-noise amplifier including an amplifying transistor having an input terminal, an output terminal and a ground terminal; a first filter having a passband including at least a portion of a first band; a second filter having a passband including at least a portion of a second band; a first inductor connected between the input terminal and the first filter; and a second inductor connected between a path connecting the first inductor and the first filter and the second filter, wherein the low-noise amplifier further includes a third inductor connected between the ground terminal and ground, and the angle between the winding axis direction of the second inductor and the winding axis direction of the third inductor is smaller than the angle between the winding axis direction of the first inductor and the winding axis direction of the third inductor.

4. The high-frequency circuit according to any one of claims 1 to 3, wherein the first band is located on the higher frequency side than the second band, and the inductance value of the third inductor when a signal is flowing through the first band is smaller than the inductance value of the third inductor when no signal is flowing through the third inductor.

5. The high-frequency circuit according to claim 4, wherein the inductance value of the third inductor when a signal of the second band is flowing through it is equal to the inductance value of the third inductor when no signal is flowing through it.

6. The high-frequency circuit according to any one of claims 1 to 5, wherein the inductance value of the second inductor is greater than the inductance value of the third inductor.

7. The high-frequency circuit according to any one of claims 1 to 6, further comprising: a third filter having a passband that includes at least a portion of the third band; a first switch connected between the second inductor and the second filter and the third filter for switching between (1) the connection between the second inductor and the second filter, (2) the connection between the second inductor and the third filter, and (3) the disconnection between the second inductor and the second filter and the third filter; and a second switch connected between the second inductor and the first switch for switching between the connection and disconnection between the second inductor and the first switch.

8. The high-frequency circuit according to claim 7, wherein when the first switch disconnects the second inductor from the second filter and the third filter, the second switch disconnects the second inductor from the first switch.

9. The high-frequency circuit according to any one of claims 1 to 6, further comprising: a third filter having a passband that includes at least a portion of the third band; a first switch connected between the second inductor and the second filter and the third filter for switching the connection between the second inductor and the second filter and the connection between the second inductor and the third filter; and a fourth inductor connected between the second filter and the first switch, wherein the second band is located at a lower frequency than the first band and the third band.

10. The high-frequency circuit according to any one of claims 1 to 9, further comprising a mounting substrate having a first main surface and a second main surface facing each other, wherein the second inductor is a surface-mount component and is disposed on the first main surface.

11. The high-frequency circuit according to claim 10, wherein the low-noise amplifier is included in a semiconductor integrated component arranged on the second main surface.

12. The high-frequency circuit according to claim 11, wherein the third inductor is included in the semiconductor integrated component.

13. The high-frequency circuit according to claim 10 or 11, wherein the third inductor is a surface-mount component and is arranged on the first main surface.

14. The high-frequency circuit according to claim 10 or 11, wherein the third inductor includes a coil conductor formed on the mounting substrate.

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