Multiplexer

Abstract

This invention provides a multiplexer that can simultaneously transmit signals from two bands with small frequency gaps in a decoupled manner. [Solution] The multiplexer 1 comprises filters 10 and 20 connected to a common terminal 100. Filter 10 comprises series arm resonators s11 to s15 arranged in a first series arm path, and a first variable capacitance circuit connected in parallel to the series arm resonator s11 closest to the common terminal 100. The first variable capacitance circuit has capacitors 31 and switches 41 connected in series with each other. Filter 20 comprises parallel arm resonators p21 and p22 connected between a second series arm path and ground, and a second variable capacitance circuit connected in series to the parallel arm resonator p21 closest to the common terminal 100. The second variable capacitance circuit has capacitors 32 and switches 42 connected in parallel with each other.

Description

Technical Field

[0001] The present invention relates to a multiplexer.

Background Art

[0002] Patent Document 1 discloses a multiplexer including a first filter having a passband of mid-high band (MHB: 1710 - 2370 MHz) and Band 41 (2496 - 2690 MHz) using an elastic wave resonator, and a second filter having a passband of WLAN (Wireless Local Area Network) 2.4 GHz band.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The frequency gap between the WLAN 2.4 GHz band and Band 41 is 14 MHz. For example, the frequency gap between Band 53 (2483.5 - 2495 MHz) having a frequency band between Band 41 and the WiFi 2.4 GHz band and the WiFi 2.4 GHz band is 1.5 MHz. Here, for example, when simultaneously transmitting signals of the WLAN 2.4 GHz band and Band 53, since the frequency gap is small, it is difficult to demultiplex these two signals with the multiplexer disclosed in Patent Document 1. That is, in each of the modes of simultaneously transmitting Band A and Band B, and the mode of simultaneously transmitting Band A and Band C having a frequency gap smaller than the frequency gap between Band A and Band B, it may be difficult to transmit the two signals to be simultaneously transmitted in a demultiplexable manner.

[0005] Therefore, the present invention has been made to solve the above problems, and aims to provide a multiplexer that can simultaneously transmit signals from two bands with small frequency gaps in a decoupled manner. [Means for solving the problem]

[0006] To achieve the above objective, a multiplexer according to one aspect of the present invention comprises a common terminal, a first input / output terminal, a second input / output terminal, a first filter connected between the common terminal and the first input / output terminal, and a second filter connected between the common terminal and the second input / output terminal, wherein the first filter is arranged in a first series arm path connecting the common terminal and the first input / output terminal and comprises one or more series arm resonators including an elastic wave resonator, one or more parallel arm resonators connected between the first series arm path and ground and comprising an elastic wave resonator, and a parallel connection to the first series arm resonator among the one or more series arm resonators of the first filter that is closest to the common terminal. The second filter comprises a connected first variable capacitance circuit, the first variable capacitance circuit having a first capacitor and a first switch connected in series with each other, the second filter is arranged in a second series arm path connecting a common terminal and a second input / output terminal and comprises one or more series arm resonators including an elastic wave resonator, one or more parallel arm resonators including an elastic wave resonator connected between the second series arm path and ground, and a second variable capacitance circuit connected in series with the first parallel arm resonator that is the closest to the common terminal among the one or more parallel arm resonators of the second filter, the second variable capacitance circuit having a second capacitor and a second switch connected in parallel with each other. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a multiplexer that can simultaneously transmit signals from two bands with small frequency gaps in a manner that allows for the desynchronization of signals. [Brief explanation of the drawing]

[0008] [Figure 1] This figure shows an example of the circuit configuration of a multiplexer according to the embodiment. [Figure 2]This is a graph showing the pass-through characteristics of the first filter according to the embodiment. [Figure 3] This is a Smith chart showing the impedance characteristics of the series-arm resonator and the impedance of the first filter according to the embodiment. [Figure 4] This is a graph showing the pass-through characteristics of the second filter according to the embodiment. [Figure 5] This is a Smith chart showing the impedance characteristics of the parallel arm resonator and the impedance of the second filter according to the embodiment. [Figure 6] This is a circuit diagram of a multiplexer according to an embodiment. [Figure 7] This graph shows a schematic representation of the passage characteristics of the multiplexer according to Example 1. [Figure 8] This graph shows a schematic representation of the passage characteristics of the multiplexer according to Example 2. [Figure 9] This graph shows a schematic representation of the passage characteristics of the multiplexer according to Example 3. [Figure 10] This graph shows a schematic representation of the passage characteristics of the multiplexer according to Example 4. [Figure 11] This figure shows an example of a circuit configuration of a multiplexer according to a modified embodiment. [Figure 12] This is a plan view of a multiplexer according to an embodiment. [Figure 13] This is a cross-sectional view of a multiplexer according to an embodiment. [Modes for carrying out the invention]

[0009] 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.

[0010] 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.

[0011] 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.

[0012] 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.

[0013] 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.

[0014] In the following figures, the x-axis and the y-axis are axes orthogonal to each other on a plane parallel to the main surface of the module substrate. Specifically, when the module substrate has a rectangular shape in plan view, the x-axis is parallel to the first side of the module substrate, and the y-axis is parallel to the second side orthogonal to the first side of the module substrate. Also, the z-axis is an axis perpendicular to the main surface of the module substrate, the positive direction thereof indicates the upward direction, and the negative direction thereof indicates the downward direction.

[0015] Also, terms indicating the relationship between elements such as "parallel" and "perpendicular", terms indicating the shape of elements such as "rectangle", and numerical ranges do not represent only a strict meaning, but mean substantially equivalent ranges, for example, including an error of about several percent.

[0016] In the component arrangement of the present invention, "in the plan view of the module substrate" means looking at an object by orthographically projecting it onto the xy plane from the positive z-axis side. "A overlaps B in plan view" means that at least a part of the region of A projected onto the xy plane overlaps at least a part of the region of B projected onto the xy plane. Also, "A is arranged between B and C" means that at least one of a plurality of line segments connecting an arbitrary point in B and an arbitrary point in C passes through A.

[0017] In the component arrangement of the present invention, "a component is arranged on a substrate" includes that the component is arranged on the main surface of the substrate and that the component is arranged inside the substrate. "A component is arranged on the main surface of the substrate" includes that the component is arranged in contact with the main surface of the substrate, and also includes that the component is arranged above the main surface without contacting the main surface (for example, the component is laminated on another component arranged in contact with the main surface). Also, "a component is arranged on the main surface of the substrate" may include that the component is arranged in a recess formed in the main surface. "A component is arranged inside the substrate" includes that the component is encapsulated inside the module substrate, that all of the component is arranged between the two main surfaces of the substrate but a part of the component is not covered by the substrate, and that only a part of the component is arranged inside the substrate.

[0018] Furthermore, in the following embodiment, the passband of a band-pass filter is defined as the frequency band between two frequencies where the insertion loss is 3 dB greater than the minimum value within the passband. In addition, the stopband of a band-stop filter is defined as the frequency band between two frequencies where the insertion loss is 10 dB, and where the insertion loss is continuously 10 dB or greater.

[0019] Furthermore, an elastic wave resonator is defined as any of the following: (1) a resonant circuit consisting of an elastic wave resonator and a circuit (or circuit element) connected in parallel to the elastic wave resonator (a parallel connection circuit between an elastic wave resonator and a circuit (or circuit element)); (2) a resonant circuit consisting of an elastic wave resonator and a circuit (or circuit element) connected to only one of the two input / output terminals of the elastic wave resonator, wherein the connection node connecting the elastic wave resonator and the circuit (or circuit element) is configured such that no other circuits (and other circuit elements) and ground are connected to it (a series connection circuit between an elastic wave resonator and a circuit (or circuit element)); (3) a resonant circuit consisting of multiple elastic wave resonators connected in parallel to each other (a parallel connection circuit of segmented resonators); and (4) a resonant circuit consisting of multiple elastic wave resonators connected in series to each other, wherein the connection node connecting the multiple elastic wave resonators is configured such that no circuits (and circuit elements) other than the multiple elastic wave resonators and ground are connected to it (a series connection circuit of segmented resonators).

[0020] Furthermore, in the embodiments of this disclosure, the resonant bandwidth means the frequency difference between the anti-resonant frequency and the resonant frequency of the elastic wave resonator.

[0021] The resonant and anti-resonant frequencies shown in the above embodiments and modifications can be derived, for example, by contacting the two input and output electrodes of an elastic wave resonator or elastic wave resonator with an RF probe and measuring the reflection characteristics (impedance characteristics) with a network analyzer or the like, while the elastic wave resonator or elastic wave resonator is not connected to any other circuit elements.

[0022] 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 built 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.

[0023] (Embodiment) [1. Specific Circuit Configuration of a Multiplexer] Figure 1 shows an example of the circuit configuration of a multiplexer 1 according to an embodiment. The multiplexer 1 includes filters 10 and 20, a common terminal 100, and input / output terminals 110 (first input / output terminal) and 120 (second input / output terminal). The common terminal 100 is connected to an antenna, for example.

[0024] Filter 10 is an example of a first filter and is connected between the common terminal 100 and the input / output terminal 110. Filter 20 is an example of a second filter and is connected between the common terminal 100 and the input / output terminal 120.

[0025] The filter 10 comprises series arm resonators s11, s12, s13, s14, and s15, parallel arm resonators p11, p12, p13, and p14, a capacitor 31, a switch 41, and an inductor 51.

[0026] Each of the series arm resonators s11 to s15 includes an elastic wave resonator and is positioned in the first series arm path connecting the common terminal 100 and the input / output terminal 110. Each of the parallel arm resonators p11 to p14 includes an elastic wave resonator and is connected between the first series arm path and ground.

[0027] Capacitor 31 is an example of a first capacitor, and switch 41 is an example of a first switch. Capacitor 31 and switch 41 are connected in series with each other to form a first variable capacitance circuit. The first variable capacitance circuit is connected in parallel with the series arm resonator s11. Series arm resonator s11 is an example of a first series arm resonator and is connected closest to the common terminal 100 among the series arm resonators s11 to s15 provided by the filter 10. Series arm resonator s11, capacitor 31, and switch 41 constitute a series arm resonator S10.

[0028] Inductor 51 is connected between each of the parallel arm resonators p11 to p14 and ground.

[0029] The filter 20 comprises series arm resonators s21 and s22, parallel arm resonators p21 and p22, capacitors 32, 33 and 34, a switch 42, and inductors 52 and 53.

[0030] Each of the series arm resonators s21 and s22 includes an elastic wave resonator and is positioned in the second series arm path connecting the common terminal 100 and the input / output terminal 120. Each of the parallel arm resonators p21 and p22 includes an elastic wave resonator and is connected between the second series arm path and ground.

[0031] Capacitor 32 is an example of a second capacitor, and switch 42 is an example of a second switch. Capacitor 32 and switch 42 are connected in parallel to each other to form a second variable capacitance circuit. The second variable capacitance circuit is connected in series to the parallel arm resonator p21. Parallel arm resonator p21 is an example of a first parallel arm resonator and is the one of the parallel arm resonators p21 and p22 provided by the filter 20 that is closest to the common terminal 100. Parallel arm resonator p21, capacitor 32, and switch 42 constitute the parallel arm resonator P20.

[0032] Inductor 52 and capacitor 33 are connected in parallel to each other and arranged in series in the second series arm path between the series arm resonator s22 and the input / output terminal 120. Inductor 53 and capacitor 34 are connected in series to each other and connected between the second series arm path between the series arm resonator s22 and the input / output terminal 120 and ground.

[0033] With the above configuration, filter 10 becomes, for example, a ladder-type bandpass filter including an elastic wave resonator, and filter 20 becomes, for example, a ladder-type bandstop filter including an elastic wave resonator.

[0034] Note that filters 10 and 20 are not limited to the circuit configuration shown in Figure 1. Filter 10 may include a series arm resonator S10, one or more series arm resonators, and one or more parallel arm resonators. Filter 20 may include a parallel arm resonator P20, one or more series arm resonators, and one or more parallel arm resonators.

[0035] Filter 10 may be a band-stop filter, and filter 20 may be a band-pass filter.

[0036] [2. Examples of Multiplexer 1 applications] Conventionally, front-end circuits have been proposed for simultaneously transmitting signals from MHB (1710-2370MHz), WLAN 2.4GHz band (WiFi® 2.4GHz band: e.g., 2400-2482MHz), and Band 41 for LTE (Long Term Evolution) or n41 (2496-2690MHz) for 5GNR (5th Generation New Radio). The frequency gap between MHB and the WLAN 2.4GHz band is 30MHz (relative bandwidth 1.3%), and the frequency gap between the WLAN 2.4GHz band and Band 41 is 14MHz (relative bandwidth 0.6%). To realize a front-end circuit that can simultaneously transmit signals from the above three frequency bands in a deselectable manner, elastic wave resonators with high resonant Q values ​​are used.

[0037] In the following specifications, for simplification, Band A for LTE or nA for 5GNR may simply be referred to as Band A.

[0038] In recent years, Band 53 (2483.5-2495MHz), which has a frequency bandwidth between the WLAN 2.4GHz band and Band 41, has been released. This necessitates a front-end circuit that can simultaneously transmit signals from MHB, the WLAN 2.4GHz band, and Band 41, as well as signals from the WLAN 2.4GHz band and Band 53. However, the frequency gap between the WLAN 2.4GHz band and Band 53 is 1.5MHz (relative bandwidth 0.06%), making it difficult to simultaneously transmit signals from the WLAN 2.4GHz band and Band 53 in a descalable manner using conventional front-end circuits employing elastic wave resonators.

[0039] In contrast, the multiplexer 1 according to this embodiment makes it possible to change the passband (or stopband) of filters 10 and 20 to correspond to (1) simultaneous transmission of a WLAN 2.4GHz band signal and a band 41 signal (hereinafter referred to as Mode A), and (2) simultaneous transmission of a WLAN 2.4GHz band signal and a band 53 signal (hereinafter referred to as Mode B). As a result, a frequency gap can be secured for the two signals to be transmitted simultaneously in both Mode A and Mode B, making it possible to transmit the two signals simultaneously in a way that allows for demultiplexing. The passband characteristics of the multiplexer 1 according to this embodiment will be described in detail below.

[0040] [3. Pass-through characteristics of Multiplexer 1] First, we will explain the basic operating principle of a ladder-type bandpass filter using elastic wave resonators.

[0041] A parallel arm resonator has a resonant frequency frp where the impedance is minimum and an anti-resonant frequency fap (>frp) where the impedance is maximum, while a series arm resonator has a resonant frequency frs where the impedance is minimum and an anti-resonant frequency fas (>frs>frp) where the impedance is maximum. In series and parallel arm resonators having the above resonance characteristics, the anti-resonant frequency fap of the parallel arm resonator and the resonant frequency frs of the series arm resonator are generally brought close together. As a result, the area near the resonant frequency frp, where the impedance of the parallel arm resonator approaches zero, becomes a low-frequency stopband. Furthermore, as the frequency increases beyond this point, the impedance of the parallel arm resonator becomes high near the anti-resonant frequency fap, and the impedance of the series arm resonator approaches zero near the resonant frequency frs. As a result, the area near the anti-resonant frequency fap to the resonant frequency frs becomes a signal passband in the signal path, which is the series arm path. This makes it possible to form a passband that reflects the electrode parameters and electromechanical coupling coefficients of the elastic wave resonator. Furthermore, as the frequency increases and approaches the anti-resonant frequency fas, the impedance of the series arm resonator increases, resulting in a high-frequency stopband.

[0042] Next, we will explain the basic operating principle of a ladder-type bandstop filter using elastic wave resonators.

[0043] A series arm resonator has a resonant frequency frs where the impedance is minimum and an anti-resonant frequency fas (>frs) where the impedance is maximum, while a parallel arm resonator has a resonant frequency frp where the impedance is minimum and an anti-resonant frequency fap (>frp>frs) where the impedance is maximum. In series and parallel arm resonators having the above resonance characteristics, the anti-resonant frequency fas of the series arm resonator and the resonant frequency frp of the parallel arm resonator are generally brought close together. As a result, the area near the resonant frequency frs, where the impedance of the series arm resonator approaches zero, becomes a low-frequency passband. Furthermore, as the frequency increases beyond this point, the impedance of the series arm resonator becomes high near the anti-resonant frequency fas, and the impedance of the parallel arm resonator approaches zero near the resonant frequency frp. As a result, the area near the anti-resonant frequency fas to the resonant frequency frp becomes a signal stopband in the signal path, which is the series arm path. This makes it possible to form a stopband that reflects the electrode parameters and electromechanical coupling coefficients of the elastic wave resonator. Furthermore, as the frequency increases and approaches the anti-resonant frequency fap, the impedance of the parallel arm resonators increases, resulting in a high-frequency passband.

[0044] In both series-arm and parallel-arm resonators, the impedance of the resonator exhibits capacitive properties (C) in the frequency band lower than the resonant frequency, and inductive properties (L) in the frequency band higher than the resonant frequency and lower than the anti-resonant frequency. Furthermore, in the frequency band higher than the anti-resonant frequency, the impedance of the resonator exhibits capacitive properties.

[0045] Figure 2 is a graph showing the pass-through characteristics of the filter 10 according to the embodiment. Figure (a) shows the pass-through characteristics of the filter 10 between the common terminal 100 and the input / output terminal 110 when the switch 41 is in a non-conductive state, and Figure (b) shows the pass-through characteristics of the filter 10 between the common terminal 100 and the input / output terminal 110 when the switch 41 is in a conductive state.

[0046] As shown in Figure 2(a), when switch 41 is in a non-conductive state, filter 10 has a first passband that includes the WLAN 2.4GHz band (2400-2482MHz). In addition, the attenuation band on the higher frequency side of the first passband also includes band 41.

[0047] Furthermore, as shown in Figure 2(b), when switch 41 is in a conductive state, filter 10 has a second passband that includes a portion of the WLAN 2.4GHz band (2400-2450MHz). The attenuation band on the higher frequency side of the second passband includes band 53.

[0048] Figure 3 shows (a) the impedance characteristics of the series arm resonator S10 of the filter 10 according to the embodiment, and (b) a Smith chart showing the impedance of the filter 10.

[0049] As shown in Figure 3(a), when switch 41 is in a non-conductive state, the resonance characteristics of the series arm resonator S10 become the resonance characteristics of the series arm resonator s11. In this case, as shown in Figure 2(a), the filter 10 has a first passband.

[0050] Furthermore, when switch 41 is in the conductive state, the capacitor 31 is connected in parallel to the series arm resonator s11 in the series arm resonator S10, causing the anti-resonant frequency to shift to the lower frequency side, and reducing the resonant bandwidth of the series arm resonator S10. Therefore, when switch 41 is in the conductive state, the filter 10 becomes a second passband where the high-frequency end is located at a lower frequency than the high-frequency end of the first passband, as shown in Figure 2(b), because the resonant bandwidth of the series arm resonator s11, which defines the high-frequency side of the passband, is reduced.

[0051] Furthermore, as shown in Figure 3(a), the impedance in the band between the resonant frequency and the anti-resonant frequency of the series arm resonator S10 becomes more inductive when the switch 41 is in a conductive state. As a result, as shown in Figure 3(b), the impedance seen from the common terminal 100 of the filter 10 rotates clockwise, especially near the high frequency of the passband. Consequently, the frequency band in which the circuit is open shifts to the lower frequency side, and the high frequency side of the first passband changes from a passband to an attenuation band (within the dashed line in Figure 2(b)).

[0052] In this embodiment, the filter 10 has a variable anti-resonant frequency function added to the series arm resonator s11, which is the closest to the common terminal 100 among the series arm resonators s11 to s15. The impedance of the series arm resonator s11, which is closest to the common terminal 100, is the most dominant impedance of the filter 10 as seen from the common terminal 100. Therefore, in the filter 20, which is connected to the common terminal 100 in the same way as the filter 10, the degradation of the passband characteristics of the filter 20 by the passband characteristics of the filter 10 can be most effectively suppressed. Thus, a low-loss multiplexer 1 with a variable passband can be provided.

[0053] Figure 4 is a graph showing the pass-through characteristics of the filter 20 according to the embodiment. Figure (a) shows the pass-through characteristics of the filter 20 between the common terminal 100 and the input / output terminal 120 when the switch 42 is in a non-conductive state, and Figure (b) shows the pass-through characteristics of the filter 20 between the common terminal 100 and the input / output terminal 120 when the switch 42 is in a conductive state.

[0054] As shown in Figure 4(a), when switch 42 is in a non-conductive state, filter 20 has a third stopband that includes the WLAN 2.4GHz band (2400-2482MHz). In addition, the passband on the higher frequency side of the third stopband includes band 41.

[0055] Furthermore, as shown in Figure 4(b), when switch 42 is in a conductive state, filter 20 has a fourth stopband that includes a portion of the WLAN 2.4GHz band (2400-2450MHz). In addition, the passband on the higher frequency side of the fourth stopband includes band 53.

[0056] Figure 5 shows (a) the impedance characteristics of the parallel arm resonator P20 of the filter 20 according to the embodiment, and (b) a Smith chart showing the impedance of the filter 20.

[0057] As shown in Figure 5(a), when switch 42 is in a non-conductive state, the resonance characteristics of the parallel arm resonator P20 become those of the parallel arm resonator p21 with capacitor 32 connected in series. As a result, the resonance frequency of the parallel arm resonator P20 shifts to a higher frequency side compared to the resonance frequency of the parallel arm resonator p21 alone, and the resonance bandwidth of the parallel arm resonator P20 becomes smaller. At this time, as shown in Figure 4(a), filter 20 has a third stopband.

[0058] Furthermore, when switch 42 is in the conductive state, the ends of capacitor 32 are short-circuited, and the resonance characteristics of parallel arm resonator P20 become those of parallel arm resonator p21. In this case, as shown in Figure 4(b), filter 20 has a fourth stopband.

[0059] Furthermore, as shown in Figure 5(a), the impedance in the band between the resonant frequency and the anti-resonant frequency of the parallel arm resonator P20 becomes more inductive when switch 42 is in a conductive state. As a result, as shown in Figure 5(b), the impedance seen from the common terminal 100 of the filter 20 rotates clockwise, especially near the high frequency of the stopband. Consequently, the impedance near the high frequency of the third stopband shifts to the center of the Smith chart, changing it into the passband (within the dashed line in Figure 4(a)).

[0060] In this embodiment, the filter 20 has a variable resonant frequency function added to the parallel arm resonator p21, which is the closest to the common terminal 100 among the parallel arm resonators p21 and p22. The impedance of the parallel arm resonator p21, which is closest to the common terminal 100, is the most dominant impedance of the filter 20 as seen from the common terminal 100. Therefore, in the filter 10, which is connected to the common terminal 100 in the same way as the filter 20, the degradation of the passband characteristics of filter 10 by the passband characteristics of filter 20 can be most effectively suppressed. Thus, a low-loss multiplexer 1 with a variable passband can be provided.

[0061] In the multiplexer 1 according to this embodiment, when switch 41 is in a conductive state, switch 42 becomes conductive, and when switch 41 is in a non-conductive state, switch 42 becomes non-conductive.

[0062] When both switches 41 and 42 are in a non-conductive state, filter 10 has a first passband as shown in Figure 2(a), and filter 20 has a third stopband as shown in Figure 4(a). In other words, the high-frequency end of the third stopband is located on the higher frequency side than the high-frequency end of the first passband. This ensures a frequency gap between the first passband of filter 10 and the high-frequency passband of the third stopband of filter 20. For example, by passing a WLAN 2.4GHz (2400-2482MHz) signal through filter 10 and a band 41 signal through filter 20, it becomes possible to simultaneously transmit WLAN 2.4GHz signals and band 41 signals in a decoupled manner. In other words, the series arm resonator S10 and the parallel arm resonator P20 allow adjustment of the passbands (and stopbands) of the band-pass filter and band-stop filter, providing a multiplexer 1 that transmits signals in a wider frequency band with low loss.

[0063] Furthermore, when both switches 41 and 42 are conducting, filter 10 has a second passband as shown in Figure 2(b), and filter 20 has a fourth stopband as shown in Figure 4(b). In other words, the high-frequency end of the fourth stopband is located on the higher frequency side than the high-frequency end of the second passband. This ensures a frequency gap between the second passband of filter 10 and the high-frequency passband of the fourth stopband of filter 20. For example, by passing a portion of the WLAN 2.4GHz signal (2400-2450MHz) through filter 10 and the signal of band 53 through filter 20, it becomes possible to simultaneously transmit signals in the WLAN 2.4GHz band and band 53 in a decoupled manner.

[0064] [4. Circuit configuration of Multiplexer 1] Figure 6 is a circuit diagram of a multiplexer 1 according to an embodiment. The multiplexer 1 shown in Figure 6 shows only the essential components of the multiplexer according to the present invention, compared to the multiplexer 1 shown in Figure 1. As shown in Figure 6, the multiplexer 1 includes filters 10 and 20, a common terminal 100, and input / output terminals 110 (first input / output terminal) and 120 (second input / output terminal). In the following, the multiplexer 1 shown in Figure 6 will be described, with the same configuration as the multiplexer 1 shown in Figure 1 omitted, and the differences will be the focus of the description.

[0065] The filter 10 comprises a series arm resonator S10, a parallel arm resonator p11, and an elastic wave resonator circuit 5. The elastic wave resonator circuit 5 includes an elastic wave resonator. The elastic wave resonator circuit 5 is optional. The filter 10 allows for variable passband or stopband by switching the conduction and non-conductivity of switch 41.

[0066] The filter 20 comprises a parallel arm resonator P20, a series arm resonator s21, and an elastic wave resonant circuit 6. The elastic wave resonant circuit 6 includes an elastic wave resonator. The elastic wave resonant circuit 6 is optional. The filter 20 allows for variable passband or stopband by switching the conduction and non-conductivity of switch 42.

[0067] [5. Multiplexer relating to Example 1] The multiplexer 1 according to Embodiment 1 has the circuit configuration of the multiplexer 1 shown in Figure 6. Figure 7 is a graph showing a schematic of the passband characteristics of the multiplexer 1 according to Embodiment 1. In the multiplexer 1 according to this embodiment, the filter 10 is a band-pass filter in which a first passband and a second passband are variable, the high-frequency edge of which is located on the lower frequency side than the high-frequency edge of the first passband are located. The filter 10 has a first passband when the switch 41 is in a non-conductive state, and a second passband when the switch 41 is in a conductive state.

[0068] Furthermore, filter 20 is a band-pass filter in which a third passband and a fourth passband are variable, the fourth passband having a low-frequency end located at a lower frequency than the low-frequency end of the third passband. Filter 20 has a third passband when switch 42 is in a non-conductive state, and a fourth passband when switch 42 is in a conductive state.

[0069] The low-frequency end of the third passband is located higher than the high-frequency end of the first passband, and the low-frequency end of the fourth passband is located higher than the high-frequency end of the second passband.

[0070] According to this, when both switches 41 and 42 are in a non-conductive state, a frequency gap can be secured between the first passband and the third passband, making it possible to simultaneously transmit the signal passing through filter 10 and the signal passing through filter 20 in a decoupled manner. Also, when both switches 41 and 42 are in a conductive state, a frequency gap can be secured between the second passband and the fourth passband, making it possible to simultaneously transmit the signal passing through filter 10 and the signal passing through filter 20 in a decoupled manner.

[0071] The first passband includes, for example, the WLAN 2.4GHz band (2400-2482MHz), and the second passband includes, for example, a portion of the WLAN 2.4GHz band (2400-2450MHz). The third passband includes, for example, band 41, and the fourth passband includes, for example, band 53.

[0072] According to this, signals in the WLAN 2.4GHz band and signals in band 41 can be transmitted simultaneously with the ability to separate them, and signals in the WLAN 2.4GHz band and signals in band 53 can also be transmitted simultaneously with the ability to separate them.

[0073] [6. Multiplexer relating to Example 2] The multiplexer 1 according to Embodiment 2 has the circuit configuration of the multiplexer 1 shown in Figure 6. Figure 8 is a graph showing a schematic of the passband characteristics of the multiplexer 1 according to Embodiment 2. In the multiplexer 1 according to this embodiment, the filter 10 is a band-pass filter in which the first passband and the second passband are variable, with the high-frequency edge located on the lower frequency side of the high-frequency edge of the first passband. The filter 10 has the first passband when the switch 41 is in a non-conductive state, and the second passband when the switch 41 is in a conductive state.

[0074] Furthermore, filter 20 is a bandstop filter in which a third stopband and a fourth stopband are variable, the high-frequency end of which is located on the lower frequency side than the high-frequency end of the third stopband are variable. Filter 20 has a third stopband when switch 42 is in a non-conductive state, and a fourth stopband when switch 42 is in a conductive state.

[0075] The frequency at the high-frequency end of the third stopband is greater than or equal to the frequency at the high-frequency end of the first passband, and the frequency at the high-frequency end of the fourth stopband is greater than or equal to the frequency at the high-frequency end of the second passband.

[0076] According to this, when both switches 41 and 42 are in a non-conductive state, a frequency gap can be secured between the first passband and the passband of filter 20 located on the high-frequency side of the third stopband, making it possible to simultaneously transmit signals passing through filter 10 and filters 20 in a decoupled manner. Also, when both switches 41 and 42 are in a conductive state, a frequency gap can be secured between the second passband and the passband of filter 20 located on the high-frequency side of the fourth stopband, making it possible to simultaneously transmit signals passing through filter 10 and filters 20 in a decoupled manner.

[0077] The first passband and the third stopband include, for example, the WLAN 2.4GHz band (2400-2482MHz), and the passband of filter 20 located on the high-frequency side of the third stopband includes, for example, band 41. The second passband includes, for example, a portion of the WLAN 2.4GHz band (2400-2450MHz), and the passband of filter 20 located on the high-frequency side of the fourth stopband includes, for example, band 53.

[0078] According to this, signals in the WLAN 2.4GHz band and signals in band 41 can be transmitted simultaneously with the ability to separate them, and signals in the WLAN 2.4GHz band and signals in band 53 can also be transmitted simultaneously with the ability to separate them.

[0079] [7. Multiplexer relating to Example 3] The multiplexer 1 according to Embodiment 3 has the circuit configuration of the multiplexer 1 shown in Figure 6. Figure 9 is a graph showing a schematic of the pass characteristics of the multiplexer 1 according to Embodiment 3. In the multiplexer 1 according to this embodiment, the filter 10 is a bandstop filter in which the first stopband and the second stopband, whose low-frequency end is located at a lower frequency than the low-frequency end of the first stopband, are variable. The filter 10 has a first stopband when the switch 41 is in a non-conductive state, and a second stopband when the switch 41 is in a conductive state.

[0080] Furthermore, filter 20 is a band-pass filter in which a third passband and a fourth passband are variable, the fourth passband having a low-frequency end located at a lower frequency than the low-frequency end of the third passband. Filter 20 has a third passband when switch 42 is in a non-conductive state, and a fourth passband when switch 42 is in a conductive state.

[0081] The frequency at the low-frequency end of the first stopband is less than or equal to the frequency at the low-frequency end of the third passband, and the frequency at the low-frequency end of the second stopband is less than or equal to the frequency at the low-frequency end of the fourth passband.

[0082] According to this, when both switches 41 and 42 are in a non-conductive state, a frequency gap can be secured between the passband of filter 10 located on the low-frequency side of the first stopband and the third passband, making it possible to simultaneously transmit signals passing through filter 10 and filters 20 in a decoupled manner. Also, when both switches 41 and 42 are in a conductive state, a frequency gap can be secured between the passband of filter 10 located on the low-frequency side of the second stopband and the fourth passband, making it possible to simultaneously transmit signals passing through filter 10 and filters 20 in a decoupled manner.

[0083] The first stopband and the third passband include, for example, band 41, and the passband of filter 10 located on the lower frequency side of the first stopband includes, for example, the WLAN 2.4GHz band (2400-2482MHz). The second stopband and the fourth passband include, for example, band 53, and the passband of filter 10 located on the lower frequency side of the second stopband includes, for example, a portion of the WLAN 2.4GHz band (2400-2450MHz).

[0084] According to this, signals in the WLAN 2.4GHz band and signals in band 41 can be transmitted simultaneously with the ability to separate them, and signals in the WLAN 2.4GHz band and signals in band 53 can also be transmitted simultaneously with the ability to separate them.

[0085] [8. Multiplexer relating to Example 4] The multiplexer 1 according to Embodiment 4 has the circuit configuration of the multiplexer 1 shown in Figure 6. Figure 10 is a graph showing a schematic of the pass characteristics of the multiplexer 1 according to Embodiment 4. In the multiplexer 1 according to this embodiment, the filter 10 is a bandstop filter in which the first stopband and the second stopband, whose low-frequency end is located at a lower frequency than the low-frequency end of the first stopband, are variable. The filter 10 has the first stopband when the switch 41 is in a non-conductive state, and the second stopband when the switch 41 is in a conductive state.

[0086] Furthermore, filter 20 is a bandstop filter in which a third stopband and a fourth stopband are variable, the high-frequency end of which is located on the lower frequency side than the high-frequency end of the third stopband are variable. Filter 20 has a third stopband when switch 42 is in a non-conductive state, and a fourth stopband when switch 42 is in a conductive state.

[0087] The low-frequency end of the first stopband is located at a lower frequency than the high-frequency end of the third stopband, and the low-frequency end of the second stopband is located at a lower frequency than the high-frequency end of the fourth stopband.

[0088] According to this, when both switches 41 and 42 are in a non-conductive state, a frequency gap can be secured between the passband of filter 10 located on the low-frequency side of the first stopband and the passband of filter 20 located on the high-frequency side of the third stopband, making it possible to simultaneously transmit signals passing through filter 10 and filter 20 in a decoupled manner. Furthermore, when both switches 41 and 42 are in a conductive state, a frequency gap can be secured between the passband of filter 10 located on the low-frequency side of the second stopband and the passband of filter 20 located on the high-frequency side of the fourth stopband, making it possible to simultaneously transmit signals passing through filter 10 and filter 20 in a decoupled manner.

[0089] The first stopband includes, for example, band 41, and the passband of filter 10 located on the lower frequency side of the first stopband includes, for example, the WLAN 2.4GHz band (2400-2482MHz). The second stopband includes, for example, band 53, and the passband of filter 10 located on the lower frequency side of the second stopband includes, for example, a portion of the WLAN 2.4GHz band (2400-2450MHz). The third stopband includes, for example, the WLAN 2.4GHz band (2400-2482MHz), and the passband of filter 20 located on the higher frequency side of the third stopband includes, for example, band 41. The fourth stopband includes, for example, a portion of the WLAN 2.4GHz band (2400-2450MHz), and the passband of filter 20 located on the higher frequency side of the fourth stopband includes, for example, band 53.

[0090] According to this, signals in the WLAN 2.4GHz band and signals in band 41 can be transmitted simultaneously with the ability to separate them, and signals in the WLAN 2.4GHz band and signals in band 53 can also be transmitted simultaneously with the ability to separate them.

[0091] [9. Multiplexer 1A with modified form] Figure 11 shows an example of the circuit configuration of a multiplexer 1A according to a modified embodiment. As shown in the figure, the multiplexer 1A includes filters 10A and 20A, a common terminal 100, and input / output terminals 110 (first input / output terminal) and 120 (second input / output terminal). The multiplexer 1A according to this modified embodiment differs from the multiplexer 1 according to the embodiment in that each of the filters 10A and 20A has two variable capacitance circuits. Therefore, in the following description of the multiplexer 1A according to this modified embodiment, the same configuration as the multiplexer 1 according to the embodiment will be omitted, and the description will focus on the variable capacitance circuits, which have a different configuration.

[0092] Filter 10A is an example of a first filter and is connected between the common terminal 100 and the input / output terminal 110. Filter 20A is an example of a second filter and is connected between the common terminal 100 and the input / output terminal 120.

[0093] Filter 10A comprises series arm resonators s11, s12, s13, s14, and s15, parallel arm resonators p11, p12, p13, and p14, capacitors 31 and 35, switches 41 and 43, and an inductor 51. Filter 10A differs from filter 10 according to the embodiment only in the addition of capacitors 35 and switch 43.

[0094] Capacitor 35 is an example of a third capacitor, and switch 43 is an example of a third switch. Capacitor 35 and switch 43 are connected in series to form a third variable capacitance circuit. The third variable capacitance circuit is connected in parallel to the series arm resonator s15. The series arm resonator s15, capacitor 35, and switch 43 constitute a series arm resonator S30. The series arm resonator s15 is an example of a second series arm resonator and is an elastic wave resonator to which the third variable capacitance circuit is connected in parallel. Note that the second series arm resonator to which the third variable capacitance circuit is connected in parallel can be any of the series arm resonators except for the series arm resonator s11.

[0095] Filter 20A comprises series arm resonators s21 and s22, parallel arm resonators p21 and p22, capacitors 32, 33, 34 and 36, switches 42 and 44, and inductors 52 and 53. Filter 20A differs from filter 20 according to the embodiment only in the addition of capacitors 36 and switches 44.

[0096] Capacitor 36 is an example of a fourth capacitor, and switch 44 is an example of a fourth switch. Capacitor 36 and switch 44 are connected in parallel to each other to form a fourth variable capacitance circuit. The fourth variable capacitance circuit is connected in series with the parallel arm resonator p22. The parallel arm resonator p22, capacitor 36, and switch 44 constitute a parallel arm resonator P40. The parallel arm resonator p22 is an example of a second parallel arm resonator and is an elastic wave resonator to which the fourth variable capacitance circuit is connected in series. Note that the second parallel arm resonator to which the fourth variable capacitance circuit is connected in series can be any of the parallel arm resonators except for the parallel arm resonator p21.

[0097] With the above configuration, filter 10A becomes, for example, a ladder-type bandpass filter including an elastic wave resonator, and filter 20A becomes, for example, a ladder-type bandstop filter including an elastic wave resonator.

[0098] In the multiplexer 1A having the above configuration, when switches 41 and 43 are in a non-conductive state, the filter 10A has a first passband that includes, for example, the WLAN 2.4GHz band (2400-2482MHz). The attenuation band on the higher frequency side of the first passband also includes, for example, band 41. When switches 41 and 43 are in a conductive state, the filter 10A has a second passband that includes, for example, a part of the WLAN 2.4GHz band (2400-2450MHz). The attenuation band on the higher frequency side of the second passband also includes, for example, band 53.

[0099] When switch 43 is in the conductive state, the capacitor 35 is connected in parallel to the series arm resonator s15 in the series arm resonator S30, causing the anti-resonant frequency to shift to the lower frequency side, and reducing the resonant bandwidth of the series arm resonator S30. Therefore, when switch 43 is in the conductive state, the filter 10A has a second passband in which the high-frequency end is located at a lower frequency than the high-frequency end of the first passband, because the resonant bandwidth of the series arm resonator s15, which defines the high-frequency side of the passband, is reduced.

[0100] According to the above configuration of filter 10A, the function of varying the anti-resonant frequency is added not only to the series arm resonator s11 but also to the series arm resonator s15. Therefore, it is possible to increase the attenuation amount in the attenuation band close to the high-frequency side of the second passband.

[0101] Furthermore, it is desirable that the anti-resonance frequency of the series arm resonator s15 (second series arm resonator), to which the third variable capacitance circuit is connected in parallel, is closest to the anti-resonance frequency of the series arm resonator s11 among the series arm resonators s12 to s15, excluding the series arm resonator s11 (first series arm resonator).

[0102] According to this, it becomes possible to secure a large amount of attenuation near the anti-resonant frequency of the series arm resonators s11 and s15 in the attenuation band adjacent to the high-frequency side of the second passband.

[0103] Furthermore, it is desirable that the anti-resonance frequency of the series arm resonator s15 (second series arm resonator), to which the third variable capacitance circuit is connected in parallel, is not on the lowest frequency side among the anti-resonance frequencies of the series arm resonators s11 to s15.

[0104] Since the switch 43 is connected in parallel to the series arm resonator s15, the resonant Q value of the series arm resonator S30 may deteriorate when the switch 43 is in a non-conductive state. To counteract this, by setting the anti-resonant frequency of the series arm resonator s15 away from the high-frequency end of the first passband, the increase in insertion loss on the high-frequency side of the first passband can be suppressed. Furthermore, by using multiple series arm resonators S10 and S30 with different anti-resonant frequencies, high attenuation can be ensured over a wide bandwidth.

[0105] Furthermore, in the multiplexer 1A having the above configuration, when switches 42 and 44 are in a non-conductive state, the filter 20A has a third stopband, for example, including the WLAN 2.4GHz band (2400-2482MHz). The passband on the higher frequency side of the third stopband includes, for example, band 41. Furthermore, when switches 42 and 44 are in a conductive state, the filter 20A has a fourth stopband, for example, including a part of the WLAN 2.4GHz band (2400-2450MHz). The passband on the higher frequency side of the fourth stopband includes, for example, band 53.

[0106] When switch 44 is in the conductive state, the ends of capacitor 36 are short-circuited, causing the resonance characteristics of parallel arm resonator P40 to become those of parallel arm resonator p22. In this case, filter 20A has a fourth stopband where the high-frequency end is located on the lower frequency side than the high-frequency end of the third stopband.

[0107] According to the above configuration of filter 20A, the resonant frequency variable function is added not only to the parallel arm resonator p21 but also to the parallel arm resonator p22. Therefore, it is possible to reduce the insertion loss in the passband located on the high-frequency side of the fourth stopband.

[0108] Furthermore, it is desirable that the resonant frequency of the parallel arm resonator p22 (second parallel arm resonator), to which the fourth variable capacitance circuit is connected in parallel, be lower in frequency than the resonant frequency of the parallel arm resonator p21 (first parallel arm resonator) and be closest to that resonant frequency.

[0109] In filter 20A, the high-frequency band of the third stopband is switched to the high-frequency passband of the fourth stopband by making switches 42 and 44 conduct. For this reason, it is desirable that the resonant frequencies of the parallel arm resonators p21 and p22 that form the attenuation poles are located at lower frequencies from the passband. By positioning the resonant frequency of the parallel arm resonator p22 (second parallel arm resonator) at a lower frequency than the resonant frequency of the parallel arm resonator p21 (first parallel arm resonator), it is possible to reduce the insertion loss in the high-frequency passband of the fourth stopband.

[0110] In the multiplexer 1A according to this modified example, when switches 41 and 43 are in a conductive state, switches 42 and 44 are in a conductive state, and when switches 41 and 43 are in a non-conductive state, switches 42 and 44 are in a non-conductive state.

[0111] Note that in filter 20A, capacitor 36 and switch 44 are optional. In this case, if switches 41 and 43 are conducting, switch 42 will be conducting, and if switches 41 and 43 are not conducting, switch 42 will be not conducting.

[0112] Filters 10A and 20A are not limited to the circuit configuration shown in Figure 1. Filter 10A may include series arm resonators S10 and S30 and one or more parallel arm resonators. Filter 20A may include a parallel arm resonator P20 and one or more series arm resonators.

[0113] Furthermore, filter 10A may be a band-stop filter, and filter 20A may be a band-pass filter.

[0114] [10. Multiplexer 1 Placement Configuration] Next, the component arrangement of the multiplexer 1 according to this embodiment will be described.

[0115] Figure 12 is a plan view of the multiplexer 1 according to an embodiment. Figure 13 is a cross-sectional view of the multiplexer 1 according to an embodiment. Figure 12(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. Figure 12(b) shows the arrangement of circuit components when the main surface 90b of the mounting substrate 90 is viewed through from the positive z-axis direction. Figure 13 shows a cross-sectional view along the line XIII-XIII in Figure 12. Note that in Figures 12 and 13, some of the wiring connecting the mounting substrate 90 and each circuit component is omitted.

[0116] The multiplexer 1 shown in Figures 12 and 13 further includes a mounting substrate 90 in addition to the multiplexer 1 shown in Figure 1.

[0117] The mounting substrate 90 has two opposing main surfaces 90a (first main surface) and 90b (second main surface). In Figure 12, the mounting substrate 90 has a rectangular shape in plan view, but the shape of the mounting substrate 90 is not limited to this.

[0118] Examples of the mounting substrate 90 include, but are not limited to, low-temperature co-fired ceramics (LTCC) substrates or high-temperature co-fired ceramics (HTCC) substrates having a laminated structure of multiple dielectric layers, component-embedded substrates, substrates having a redistribution layer (RDL), or printed circuit boards.

[0119] Integrated components 61 are arranged on the main surface 90a of the mounting substrate 90. Integrated components 62 are arranged on the main surface 90b of the mounting substrate 90. As a result, since integrated components 61 and 62 are distributed and arranged on the main surfaces 90a and 90b of the mounting substrate 90, the multiplexer 1 can be miniaturized. In addition, resin members and shield electrode layers may be formed on the main surfaces 90a and 90b.

[0120] The integrated component 61 is an example of a first integrated component and includes series arm resonators s11-s15, parallel arm resonators p11-p14, series arm resonators s21-s22, and parallel arm resonators p21-p22. The integrated component 61 is integrated into a single chip, for example, on a piezoelectric substrate and package.

[0121] The integrated component 62 includes switches 41 and 42. The integrated component 62 is constructed using, for example, CMOS (Complementary Metal Oxide Semiconductor), and is specifically manufactured by an SOI (Silicon on Insulator) process. However, the integrated component 62 is not limited to CMOS.

[0122] Capacitors 31 and 32 are formed on the mounting substrate 90, as shown in Figure 13, and consist of planar electrodes and dielectric layers of the mounting substrate 90. One electrode of capacitor 31 is connected to the integrated component 61, and the other electrode is connected to the integrated component 62. One electrode of capacitor 32 is connected to the integrated components 61 and 62, and the other electrode is connected to the ground electrode 95 of the integrated component 62 and the mounting substrate 90.

[0123] Although capacitors 33 and 34, and inductors 51 to 53 are not shown in Figures 12 and 13, they are located on either the main surface 90a, 90b, or inside the mounting board 90.

[0124] Here, when the main surfaces 90a and 90b are viewed from above, the integrated component 61 and the integrated component 62 overlap at least partially.

[0125] According to this, the wiring connecting the series arm resonator s11 and the switch 41, and the wiring connecting the parallel arm resonator p21 and the switch 42 can be shortened, thereby reducing the parasitic capacitance of these wires. Consequently, the insertion loss of filters 10 and 20 can be reduced.

[0126] Furthermore, it is desirable that capacitor 31 overlaps with integrated components 61 and 62 in at least a portion of the above plan view. Similarly, it is desirable that capacitor 32 overlaps with integrated components 61 and 62 in at least a portion of the above plan view.

[0127] According to this, the wiring connecting the series arm resonator s11 and switch 41 to the capacitor 31, and the wiring connecting the parallel arm resonator p21 and switch 42 to the capacitor 32 can be shortened, thereby reducing the parasitic capacitance of these wires. Therefore, the insertion loss of filters 10 and 20 can be reduced.

[0128] [11. Effects, etc.] As described above, the multiplexer 1 according to this embodiment comprises a common terminal 100, input / output terminals 110 and 120, a filter 10 connected between the common terminal 100 and the input / output terminal 110, and a filter 20 connected between the common terminal 100 and the input / output terminal 120. The filter 10 is arranged in a first series arm path connecting the common terminal 100 and the input / output terminal 110 and comprises one or more series arm resonators s11 to s15 including elastic wave resonators, one or more parallel arm resonators p11 to p14 connected between the first series arm path and ground and including elastic wave resonators, and the series arm resonator s11 among the series arm resonators s11 to s15 that is closest to the common terminal 100 and connected in parallel. The filter 20 comprises a first variable capacitance circuit, the first variable capacitance circuit having capacitors 31 and switches 41 connected in series with each other, and the filter 20 is arranged in a second series arm path connecting a common terminal 100 and an input / output terminal 120 and comprises one or more series arm resonators s21 and s22 including elastic wave resonators, one or more parallel arm resonators p21 and p22 connected between the second series arm path and ground and including elastic wave resonators, and a second variable capacitance circuit connected in series with the parallel arm resonator p21 that is closest to the common terminal 100 among the parallel arm resonators p21 and p22, the second variable capacitance circuit having capacitors 32 and switches 42 connected in parallel with each other.

[0129] According to this, filter 10 varies its passband (stopband) by switching switch 41 between conduction and non-conductivity, and filter 20 varies its passband (stopband) by switching switch 42 between conduction and non-conductivity. This makes it possible to simultaneously transmit signals from two bands with narrow frequency gaps, by changing the passband (or stopband) of filters 10 and 20 in conjunction with the combination of bands being transmitted simultaneously. Furthermore, in filter 10, a variable anti-resonance frequency function is added to the first series arm resonator connected closest to the common terminal 100, so that the impedance of the passband of filter 10 can be most effectively opened in filter 20. Similarly, in filter 20, a variable resonance frequency function is added to the first parallel arm resonator connected closest to the common terminal 100, so that the impedance of the passband of filter 20 can be most effectively opened in filter 10. Thus, it becomes possible to simultaneously transmit signals from two bands with narrow frequency gaps with low loss and demultiplexing capabilities.

[0130] For example, in multiplexer 1, if switch 41 is in a conductive state, switch 42 becomes conductive, and if switch 41 is in a non-conductive state, switch 42 becomes non-conductive.

[0131] This makes it possible to synchronize and shift the passband (stopband) ends of filter 10 and filter 20, which are adjacent to each other, in the same direction. Therefore, it becomes possible to simultaneously transmit signals from two bands with narrow frequency gaps in a way that allows for demultiplexing.

[0132] For example, in the multiplexer according to Embodiment 1, filter 10 is a band-pass filter that varies a first passband and a second passband whose high-frequency edge is located at a lower frequency than the high-frequency edge of the first passband, and filter 20 is a band-pass filter that varies a third passband and a fourth passband whose low-frequency edge is located at a lower frequency than the low-frequency edge of the third passband, the low-frequency edge of the third passband being located at a higher frequency than the high-frequency edge of the first passband, and the low-frequency edge of the fourth passband being located at a higher frequency than the high-frequency edge of the second passband.

[0133] According to this, when both switches 41 and 42 are in a non-conductive state, a frequency gap can be secured between the first passband and the third passband, making it possible to simultaneously transmit the signal passing through filter 10 and the signal passing through filter 20 in a decoupled manner. Also, when both switches 41 and 42 are in a conductive state, a frequency gap can be secured between the second passband and the fourth passband, making it possible to simultaneously transmit the signal passing through filter 10 and the signal passing through filter 20 in a decoupled manner.

[0134] For example, in the multiplexer according to Embodiment 2, filter 10 is a band-pass filter that varies a first passband and a second passband whose high-frequency edge is located at a lower frequency than the high-frequency edge of the first passband, and filter 20 is a band-stop filter that varies a third stopband and a fourth stopband whose high-frequency edge is located at a lower frequency than the high-frequency edge of the third stopband, wherein the frequency of the high-frequency edge of the third stopband is greater than or equal to the frequency of the high-frequency edge of the first passband, and the frequency of the high-frequency edge of the fourth stopband is greater than or equal to the frequency of the high-frequency edge of the second passband.

[0135] According to this, when both switches 41 and 42 are in a non-conductive state, a frequency gap can be secured between the first passband and the passband of filter 20 located on the high-frequency side of the third stopband, making it possible to simultaneously transmit signals passing through filter 10 and filters 20 in a decoupled manner. Also, when both switches 41 and 42 are in a conductive state, a frequency gap can be secured between the second passband and the passband of filter 20 located on the high-frequency side of the fourth stopband, making it possible to simultaneously transmit signals passing through filter 10 and filters 20 in a decoupled manner.

[0136] For example, in the multiplexer according to Embodiment 3, filter 10 is a band-stop filter that varies a first stopband and a second stopband whose low-frequency edge is located at a lower frequency than the low-frequency edge of the first stopband, and filter 20 is a band-pass filter that varies a third passband and a fourth passband whose low-frequency edge is located at a lower frequency than the low-frequency edge of the third passband, the frequency of the low-frequency edge of the first stopband being less than or equal to the frequency of the low-frequency edge of the third passband, and the frequency of the low-frequency edge of the second stopband being less than or equal to the frequency of the low-frequency edge of the fourth passband.

[0137] According to this, when both switches 41 and 42 are in a non-conductive state, a frequency gap can be secured between the passband of filter 10 located on the low-frequency side of the first stopband and the third passband, making it possible to simultaneously transmit signals passing through filter 10 and filters 20 in a decoupled manner. Also, when both switches 41 and 42 are in a conductive state, a frequency gap can be secured between the passband of filter 10 located on the low-frequency side of the second stopband and the fourth passband, making it possible to simultaneously transmit signals passing through filter 10 and filters 20 in a decoupled manner.

[0138] For example, in the multiplexer according to Embodiment 4, filter 10 is a band-stop filter that varies a first stopband and a second stopband whose low-frequency end is located at a lower frequency than the low-frequency end of the first stopband, and filter 20 is a band-stop filter that varies a third stopband and a fourth stopband whose high-frequency end is located at a lower frequency than the high-frequency end of the third stopband, with the low-frequency end of the first stopband being located at a lower frequency than the high-frequency end of the third stopband, and the low-frequency end of the second stopband being located at a lower frequency than the low-frequency end of the fourth stopband.

[0139] According to this, when both switches 41 and 42 are in a non-conductive state, a frequency gap can be secured between the passband of filter 10 located on the low-frequency side of the first stopband and the passband of filter 20 located on the high-frequency side of the third stopband, making it possible to simultaneously transmit signals passing through filter 10 and filter 20 in a decoupled manner. Furthermore, when both switches 41 and 42 are in a conductive state, a frequency gap can be secured between the passband of filter 10 located on the low-frequency side of the second stopband and the passband of filter 20 located on the high-frequency side of the fourth stopband, making it possible to simultaneously transmit signals passing through filter 10 and filter 20 in a decoupled manner.

[0140] Furthermore, for example, in a modified multiplexer 1A, the filter 10A comprises a plurality of series arm resonators including a series arm resonator s11, one or more parallel arm resonators, a first variable capacitance circuit connected in parallel to the series arm resonator s11, and a third variable capacitance circuit connected in parallel to the second series arm resonators of the plurality of series arm resonators provided by the filter 10A, excluding the series arm resonator s11, and the third variable capacitance circuit has a capacitor 35 and a switch 43 connected in series with each other.

[0141] According to this, the variable anti-resonant frequency function is added not only to the series arm resonator s11 but also to the second series arm resonator. Therefore, it becomes possible to increase the attenuation amount in the attenuation band close to the high-frequency side of the second passband.

[0142] Furthermore, for example, in the modified multiplexer 1A, when switch 41 is in a conductive state, switches 42 and 43 are also in a conductive state, and when switch 41 is not in a conductive state, switches 42 and 43 are also not in a conductive state.

[0143] This makes it possible to synchronize and shift the passband (stopband) ends of filter 10A and filter 20A, which are adjacent to each other, in the same direction. Therefore, it becomes possible to simultaneously transmit signals from two bands with narrow frequency gaps in a decoupled manner.

[0144] For example, in the modified multiplexer 1A, the filter 10A includes three or more series arm resonators, including a series arm resonator s11 and a second series arm resonator, and the anti-resonance frequency of the second series arm resonator is closest to the anti-resonance frequency of the series arm resonator s11 among the three or more series arm resonators excluding the series arm resonator s11.

[0145] According to this, it becomes possible to secure a large amount of attenuation in the attenuation band close to the high-frequency side of the second passband, specifically near the anti-resonance frequency of the series arm resonator s11 and the second series arm resonator.

[0146] Furthermore, for example, in the modified multiplexer 1A, the filter 20A comprises a plurality of parallel arm resonators including a parallel arm resonator p21, one or more series arm resonators, a second variable capacitance circuit connected in series with the parallel arm resonator p21, and a fourth variable capacitance circuit connected in series with the second parallel arm resonators of the plurality of parallel arm resonators provided by the filter 20A, excluding the parallel arm resonator p21, and the fourth variable capacitance circuit has capacitors 36 and switches 44 connected in parallel with each other.

[0147] According to this, the variable resonant frequency function is added not only to the parallel arm resonator p21 but also to the second parallel arm resonator. Therefore, it becomes possible to reduce the insertion loss in the passband located on the high-frequency side of the fourth stopband.

[0148] For example, in the modified multiplexer 1A, when switch 41 is in a conductive state, switches 42, 43, and 44 are in a conductive state, and when switch 41 is in a non-conductive state, switches 42, 43, and 44 are in a non-conductive state.

[0149] This makes it possible to synchronize and shift the passband (stopband) ends of filter 10A and filter 20A, which are adjacent to each other, in the same direction. Therefore, it becomes possible to simultaneously transmit signals from two bands with narrow frequency gaps in a decoupled manner.

[0150] For example, in the modified multiplexer 1A, the filter 20A includes three or more parallel arm resonators, including a parallel arm resonator p21 and a second parallel arm resonator, and the resonant frequency of the second parallel arm resonator is closest to the resonant frequency of the parallel arm resonator p21 among the three or more parallel arm resonators excluding the parallel arm resonator p21.

[0151] This makes it possible to ensure a large amount of attenuation at the high-frequency end of the fourth stopband.

[0152] For example, the multiplexer 1 further includes a mounting substrate 90 having two opposing main surfaces 90a and 90b, where one or more series arm resonators of the filter 10, one or more parallel arm resonators of the filter 10, one or more series arm resonators of the filter 20, and one or more parallel arm resonators of the filter 20 are arranged on the main surface 90a, and the switches 41 and 42 are arranged on the main surface 90b.

[0153] According to this, the elastic wave resonator of the multiplexer 1 and the switches 41 and 42 are distributed and arranged on the main surfaces 90a and 90b of the mounting substrate 90, so the multiplexer 1 can be miniaturized.

[0154] For example, in the multiplexer 1, capacitors 31 and 32 include planar electrodes and dielectric layers of the mounting substrate 90.

[0155] According to this, since capacitors 31 and 32 are formed inside the mounting substrate 90, the multiplexer 1 can be miniaturized.

[0156] For example, in the multiplexer 1, the one or more series arm resonators of filter 10, the one or more parallel arm resonators of filter 10, the one or more series arm resonators of filter 20, and the one or more parallel arm resonators of filter 20 are included in the integrated component 61, the switches 41 and 42 are included in the integrated component 62, and when the main surfaces 90a and 90b are viewed from above, the integrated component 61 and the integrated component 62 overlap in at least part.

[0157] According to this, the wiring connecting the series arm resonator s11 and the switch 41, and the wiring connecting the parallel arm resonator p21 and the switch 42 can be shortened, thereby reducing the parasitic capacitance of these wires. Consequently, the insertion loss of filters 10 and 20 can be reduced.

[0158] For example, in the multiplexer according to Example 1, the first passband includes at least a portion of the WiFi 2.4GHz band (2400-2482MHz), the third passband includes band 41, and the fourth passband includes band 53.

[0159] Furthermore, for example, in the multiplexer according to Example 2, the first passband and the third stopband include at least a portion of the WLAN 2.4GHz band (2400-2482MHz).

[0160] For example, in the multiplexer according to Example 3, the first stopband and the third passband include band 41, and the fourth passband includes band 53.

[0161] For example, in the multiplexer according to Example 4, the first stopband includes band 41, the second stopband includes band 53, and the third stopband includes at least a portion of the WLAN 2.4GHz band (2400-2482MHz).

[0162] According to these, it is possible to simultaneously transmit signals in the WLAN 2.4GHz band and signals in band 41 in a manner that allows for demultiplexing, and also to simultaneously transmit signals in the WLAN 2.4GHz band and signals in band 53 in a manner that allows for demultiplexing.

[0163] (Other embodiments) Although the multiplexer according to the present invention has been described above with reference to embodiments, examples, and modifications, the present invention is not limited to the above embodiments, examples, and modifications. Modifications obtained by applying various modifications to the above embodiments, examples, and modifications that can be conceived by those skilled in the art without departing from the spirit of the present invention, as well as various devices incorporating the multiplexer according to the present invention, are also included in the present invention.

[0164] Furthermore, in the multiplexer according to the above embodiments, examples, and modifications, matching elements such as inductors and capacitors, as well as switch circuits, may be connected between each component.

[0165] Furthermore, for example, in the multiplexer according to the above embodiments, examples, and modifications, the elastic wave resonator includes (1) a surface acoustic wave resonator, (2) a bulk elastic wave resonator, and (3) a laterally excited film bulk acoustic resonator (XBAR).

[0166] Surface acoustic wave resonators include (a) resonators having an IDT (InterDigital Transducer) electrode formed on a piezoelectric substrate having a laminated structure of a support substrate, an intermediate layer (such as a low sound velocity layer), and a piezoelectric layer, and (b) resonators having an IDT electrode formed on a single-crystal piezoelectric substrate.

[0167] Bulk acoustic wave resonators include (a) resonators having a structure in which a laminate of piezoelectric layers sandwiched between two planar electrodes is supported by a support substrate, and (b) resonators having a structure in which a laminate of piezoelectric layers sandwiched between two planar electrodes is arranged on an acoustic multilayer film (SMR: Solidly Mounted Resonator).

[0168] Lateral excitation film bulk acoustic resonators include (a) a resonator having a structure in which a piezoelectric layer on which an IDT electrode is formed is supported by a support substrate with an air gap, and (b) a resonator having a structure in which a piezoelectric layer on which an IDT electrode is formed is arranged on an acoustic multilayer film.

[0169] The features of the multiplexer described below are shown based on the above embodiments, examples, and modifications.

[0170] <1> Common terminal and First input / output terminal and, Second input / output terminal, A first filter connected between the common terminal and the first input / output terminal, A second filter connected between the common terminal and the second input / output terminal is provided, The first filter is, Arranged in the first series arm path connecting the common terminal and the first input / output terminal, one or more series arm resonators including an elastic wave resonator, Connected between the preceding first series arm path and ground, and comprising one or more parallel arm resonators including elastic wave resonators, The first filter comprises a first variable capacitance circuit connected in parallel to the first series arm resonator, which is the closest to the common terminal among the one or more series arm resonators provided by the first filter, The first variable capacitance circuit has a first capacitor and a first switch connected in series with each other. The second filter is, Arranged in a second series arm path connecting the common terminal and the second input / output terminal, one or more series arm resonators including an elastic wave resonator, Connected between the preceding second series arm path and ground, and comprising one or more parallel arm resonators including elastic wave resonators, The second filter comprises a first parallel arm resonator, which is the closest to the common terminal among the one or more parallel arm resonators, and a second variable capacitance circuit connected in series with the first parallel arm resonator, The second variable capacitance circuit is a multiplexer having a second capacitor and a second switch connected in parallel with each other.

[0171] <2> When the first switch is in a conductive state, the second switch becomes conductive. When the first switch is in a non-conductive state, the second switch becomes non-conductive. <1> The multiplexer described above.

[0172] <3> The first filter is a band-pass filter that varies a first passband and a second passband in which the high-frequency edge is located on a lower frequency side than the high-frequency edge of the first passband. The second filter is a band-pass filter that varies a third passband and a fourth passband whose low-frequency edge is located at a lower frequency than the low-frequency edge of the third passband. The low-frequency end of the third passband is located on the higher frequency side than the high-frequency end of the first passband. The low-frequency end of the fourth passband is located on the higher frequency side than the high-frequency end of the second passband. <1> or <2> The multiplexer described above.

[0173] <4> The first filter is a band-pass filter that varies a first passband and a second passband in which the high-frequency edge is located on a lower frequency side than the high-frequency edge of the first passband. The second filter is a band-stop filter that varies a third stopband and a fourth stopband whose high-frequency edge is located at a lower frequency than the high-frequency edge of the third stopband. The frequency of the high-frequency edge of the third stopband is greater than or equal to the frequency of the high-frequency edge of the first passband. The frequency at the high-frequency end of the fourth stopband is greater than or equal to the frequency at the high-frequency end of the second passband. <1> or <2> The multiplexer described above.

[0174] <5> The first filter is a band-stop filter that varies a first stopband and a second stopband whose low-frequency end is located at a lower frequency than the low-frequency end of the first stopband. The second filter is a band-pass filter that varies a third passband and a fourth passband whose low-frequency edge is located at a lower frequency than the low-frequency edge of the third passband. The frequency at the low-frequency end of the first stopband is less than or equal to the frequency at the low-frequency end of the third passband. The frequency at the low-frequency end of the second stopband is less than or equal to the frequency at the low-frequency end of the fourth passband. <1> or <2> The multiplexer described above.

[0175] <6> The first filter is a band-stop filter that varies a first stopband and a second stopband whose low-frequency end is located at a lower frequency than the low-frequency end of the first stopband. The second filter is a band-stop filter that varies a third stopband and a fourth stopband whose high-frequency edge is located at a lower frequency than the high-frequency edge of the third stopband. The low-frequency end of the first stopband is located at a lower frequency than the high-frequency end of the third stopband. The low-frequency end of the second stopband is located at a lower frequency than the low-frequency end of the fourth stopband. <1> or <2> The multiplexer described above.

[0176] <7> The first filter is, A plurality of series arm resonators including the first series arm resonator, The aforementioned one or more parallel arm resonators, A first variable capacitance circuit connected in parallel to the first series arm resonator, The first filter comprises a third variable capacitance circuit connected in parallel to the second series arm resonator, excluding the first series arm resonator, among the plurality of series arm resonators provided by the first filter, The third variable capacitance circuit has a third capacitor and a third switch connected in series with each other. <1> ~ <6> A multiplexer as described in any of the following.

[0177] <8> When the first switch is in a conductive state, the second switch and the third switch also become conductive. When the first switch is in a non-conductive state, the second switch and the third switch also become non-conductive. <7> The multiplexer described above.

[0178] <9> The first filter is, The system comprises three or more series arm resonators, including the first series arm resonator and the second series arm resonator. The anti-resonance frequency of the second series arm resonator is the one that is closest to the anti-resonance frequency of the first series arm resonator among the three or more series arm resonators excluding the first series arm resonator. <7> or <8> The multiplexer described above.

[0179] <10> The second filter is, A plurality of parallel arm resonators including the first parallel arm resonator, The aforementioned one or more series arm resonators, A second variable capacitance circuit connected in series with the first parallel arm resonator, The second filter comprises a fourth variable capacitance circuit connected in series with the second parallel arm resonators, excluding the first parallel arm resonator, among the plurality of parallel arm resonators provided by the second filter, The fourth variable capacitance circuit has a fourth capacitor and a fourth switch connected in parallel to each other. <7> ~ <9> A multiplexer as described in any of the following.

[0180] <11> When the first switch is in a conductive state, the second switch, the third switch and the fourth switch also become conductive. When the first switch is in a non-conductive state, the second switch, the third switch, and the fourth switch also become non-conductive. <10> The multiplexer described above.

[0181] <12> The second filter is, The system comprises three or more parallel arm resonators, including the first parallel arm resonator and the second parallel arm resonator, The resonant frequency of the second parallel arm resonator is the one that is closest to the resonant frequency of the first parallel arm resonator among the three or more parallel arm resonators excluding the first parallel arm resonator. <10> or <11> The multiplexer described above.

[0182] <13> moreover, The mounting substrate comprises a first main surface and a second main surface facing each other, The one or more series arm resonators of the first filter, the one or more parallel arm resonators of the first filter, the one or more series arm resonators of the second filter, and the one or more parallel arm resonators of the second filter are arranged on the first main surface. The first switch and the second switch are arranged on the second main surface. <1> ~ <12> A multiplexer as described in any of the following.

[0183] <14> The first capacitor and the second capacitor include the planar electrodes and dielectric layer of the mounting substrate. <13> The multiplexer described above.

[0184] <15> The one or more series arm resonators, the one or more parallel arm resonators, the one or more series arm resonators, and the one or more parallel arm resonators of the second filter are included in the first integrated component. The first switch and the second switch are included in the second integrated component. When the first main surface and the second main surface are viewed from above, the first integrated component and the second integrated component overlap in at least a portion of each other. <13> or <14> The multiplexer described above.

[0185] <16> The aforementioned first passband includes at least a portion of the WLAN 2.4GHz band. The third passband includes Band 41 for LTE or n41 for 5G NR. The fourth passband includes Band 53 for LTE or n53 for 5G NR. <3> The multiplexer described above.

[0186] <17> The first passband and the third stopband include at least a portion of the WLAN 2.4GHz band. <4> The multiplexer described above.

[0187] <18> The first stopband and the third passband include Band 41 for LTE or n41 for 5GNR. The fourth passband includes Band 53 for LTE or n53 for 5G NR. <5> The multiplexer described above.

[0188] <19> The first stopband includes Band 41 for LTE or n41 for 5GNR, The second stopband includes Band 53 for LTE or n53 for 5GNR. The third stopband includes at least a portion of the WLAN 2.4GHz band. <6> The multiplexer described above. [Industrial applicability]

[0189] This invention, as a multiplexer applicable to multiband frequency standards, can be widely used in communication devices such as mobile phones. [Explanation of symbols]

[0190] 1. 1A Multiplexer 5, 6 Elastic wave resonant circuits 10, 10A, 20, 20A filters 31, 32, 33, 34, 35, 36 Electrode 41, 42, 43, 44 switches 51, 52, 53 Inductors 61, 62 Integrated components 90 Mounting board 90a, 90b main surface 95 Ground electrode 100 Common terminals 110, 120 input / output terminals p11, p12, p13, p14, p21, p22 Parallel Arm Resonators P20, P40 Parallel Arm Resonators s11, s12, s13, s14, s15, s21, s22 Series arm resonators S10, S30 Series Arm Resonator

Claims

1. Common terminal and First input / output terminal and, Second input / output terminal and, A first filter connected between the common terminal and the first input / output terminal, A second filter connected between the common terminal and the second input / output terminal is provided, The first filter is, Arranged in the first series arm path connecting the common terminal and the first input / output terminal, one or more series arm resonators including an elastic wave resonator, Connected between the first series arm path and ground, and comprising one or more parallel arm resonators including an elastic wave resonator, The first filter comprises a first variable capacitance circuit connected in parallel to the first series arm resonator, which is the closest to the common terminal among the one or more series arm resonators provided by the first filter, The first variable capacitance circuit has a first capacitor and a first switch connected in series with each other. The second filter described above is Arranged in a second series arm path connecting the common terminal and the second input / output terminal, one or more series arm resonators including an elastic wave resonator, Connected between the preceding second series arm path and ground, and comprising one or more parallel arm resonators including an elastic wave resonator, The second filter comprises a first parallel arm resonator, which is the closest to the common terminal among the one or more parallel arm resonators, and a second variable capacitance circuit connected in series with the second filter, The second variable capacitance circuit has a second capacitor and a second switch connected in parallel to each other. Multiplexer.

2. When the first switch is in a conductive state, the second switch becomes conductive. When the first switch is in a non-conductive state, the second switch becomes non-conductive. The multiplexer according to claim 1.

3. The first filter is a band-pass filter that varies a first passband and a second passband in which the high-frequency edge is located on the lower frequency side than the high-frequency edge of the first passband. The second filter is a band-pass filter that varies a third passband and a fourth passband whose low-frequency edge is located at a lower frequency than the low-frequency edge of the third passband. The low-frequency end of the third passband is located on the higher frequency side than the high-frequency end of the first passband. The low-frequency end of the fourth passband is located on the higher frequency side than the high-frequency end of the second passband. The multiplexer according to claim 1 or 2.

4. The first filter is a band-pass filter that varies a first passband and a second passband in which the high-frequency edge is located on the lower frequency side than the high-frequency edge of the first passband. The second filter is a band-stop filter that varies a third stopband and a fourth stopband whose high-frequency edge is located on a lower frequency side than the high-frequency edge of the third stopband. The frequency at the high-frequency end of the third stopband is greater than or equal to the frequency at the high-frequency end of the first passband. The frequency at the high-frequency end of the fourth stopband is greater than or equal to the frequency at the high-frequency end of the second passband. The multiplexer according to claim 1 or 2.

5. The first filter is a band-stop filter that varies a first stopband and a second stopband whose low-frequency end is located at a lower frequency than the low-frequency end of the first stopband. The second filter is a band-pass filter that varies a third passband and a fourth passband whose low-frequency edge is located at a lower frequency than the low-frequency edge of the third passband. The frequency at the low-frequency end of the first stopband is less than or equal to the frequency at the low-frequency end of the third passband. The frequency at the low-frequency end of the second stopband is less than or equal to the frequency at the low-frequency end of the fourth passband. The multiplexer according to claim 1 or 2.

6. The first filter is a band-stop filter that varies a first stopband and a second stopband whose low-frequency end is located at a lower frequency than the low-frequency end of the first stopband. The second filter is a band-stop filter that varies a third stopband and a fourth stopband whose high-frequency edge is located on a lower frequency side than the high-frequency edge of the third stopband. The low-frequency end of the first stopband is located at a lower frequency than the high-frequency end of the third stopband. The low-frequency end of the second stopband is located at a lower frequency than the low-frequency end of the fourth stopband. The multiplexer according to claim 1 or 2.

7. The first filter is, A plurality of series arm resonators including the first series arm resonator, The one or more parallel arm resonators described above, A first variable capacitance circuit connected in parallel to the first series arm resonator, The first filter comprises a third variable capacitance circuit connected in parallel to the second series arm resonator, excluding the first series arm resonator, among the plurality of series arm resonators provided by the first filter, The third variable capacitance circuit has a third capacitor and a third switch connected in series with each other. The multiplexer according to claim 1 or 2.

8. When the first switch is in a conductive state, the second switch and the third switch also become conductive. When the first switch is in a non-conductive state, the second switch and the third switch also become non-conductive. The multiplexer according to claim 7.

9. The first filter is, The system comprises three or more series arm resonators, including the first series arm resonator and the second series arm resonator. The anti-resonance frequency of the second series arm resonator is the one that is closest to the anti-resonance frequency of the first series arm resonator among the three or more series arm resonators excluding the first series arm resonator. The multiplexer according to claim 7.

10. The second filter described above is A plurality of parallel arm resonators including the first parallel arm resonator, The above-mentioned one or more series-arm resonators, A second variable capacitance circuit connected in series with the first parallel arm resonator, The second filter comprises a fourth variable capacitance circuit connected in series with the second parallel arm resonators, excluding the first parallel arm resonator, among the plurality of parallel arm resonators provided by the second filter, The fourth variable capacitance circuit has a fourth capacitor and a fourth switch connected in parallel to each other. The multiplexer according to claim 7.

11. When the first switch is in a conductive state, the second switch, the third switch, and the fourth switch become conductive. When the first switch is in a non-conductive state, the second switch, the third switch, and the fourth switch also become non-conductive. The multiplexer according to claim 10.

12. The second filter described above is The system comprises three or more parallel arm resonators, including the first parallel arm resonator and the second parallel arm resonator. The resonant frequency of the second parallel arm resonator is the one that is closest to the resonant frequency of the first parallel arm resonator among the three or more parallel arm resonators excluding the first parallel arm resonator. The multiplexer according to claim 10.

13. moreover, The mounting substrate comprises a first main surface and a second main surface facing each other, The one or more series arm resonators of the first filter, the one or more parallel arm resonators of the first filter, the one or more series arm resonators of the second filter, and the one or more parallel arm resonators of the second filter are arranged on the first main surface. The first switch and the second switch are arranged on the second main surface. The multiplexer according to claim 1 or 2.

14. The first capacitor and the second capacitor include the planar electrodes and dielectric layer of the mounting substrate. The multiplexer according to claim 13.

15. The one or more series arm resonators, the one or more parallel arm resonators, the one or more series arm resonators, and the one or more parallel arm resonators of the second filter are included in the first integrated component. The first switch and the second switch are included in the second integrated component. When the first main surface and the second main surface are viewed from above, the first integrated component and the second integrated component overlap in at least a portion of each other. The multiplexer according to claim 13.

16. The first passband includes at least a portion of the WLAN 2.4GHz band, The third passband includes Band 41 for LTE (Long Term Evolution) or n41 for 5GNR (5th Generation New Radio), The fourth passband includes Band 53 for LTE or n53 for 5GNR. The multiplexer according to claim 3.

17. The first passband and the third stopband include at least a portion of the WLAN 2.4GHz band. The multiplexer according to claim 4.

18. The first stopband and the third passband include Band 41 for LTE or n41 for 5GNR. The fourth passband includes Band 53 for LTE or n53 for 5GNR. The multiplexer according to claim 5.

19. The first stopband includes Band 41 for LTE or n41 for 5GNR. The second stopband includes Band 53 for LTE or n 53 for 5GNR. The third stopband includes at least a portion of the WLAN 2.4GHz band. The multiplexer according to claim 6.

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