Elastic wave device

Abstract

A multiplexer (10) is provided with a filter (100), a resin layer (60), and a conductive layer (70). The passband of the filter (200) is lower than the passband of the filter (100). The filter (100) is in contact with the conductive layer, and the filter (200) is not in contact with the conductive layer. The filter (200) is a ladder-type filter. The thermal resistance of the filter (200) is greater than that of the filter (100), and the passband decreases if the temperature rises. In the piezoelectric substrate of the filter (200), if the filter (100) side is set as a first region and the opposite side is set as a second region from the center of the piezoelectric substrate, and the area of the region in which the elastic wave resonators included in the parallel arm circuit are formed is set as a first area and a second area in the first region and the second region, the second area is greater than the first area.

Description

Technical Field

[0001] This disclosure relates to elastic wave devices including elastic wave elements, and more specifically, to techniques for suppressing the degradation of characteristics associated with temperature rise in multiplexers containing multiple elastic wave elements. Background Technology

[0002] International Patent Publication No. 2013 / 146374 (Patent Document 1) discloses a structure in which multiple elastic wave elements are mounted onto a mounting substrate using a flip-chip mounting method. In the elastic wave device disclosed in International Patent Publication No. 2013 / 146374 (Patent Document 1), the elastic wave elements on the mounting substrate are sealed with resin, and the support substrate forming each elastic wave element is configured to be in direct contact with a high thermal conductivity member. This structure allows heat generated in the elastic wave elements to be rapidly radiated to the outside via the high thermal conductivity member. Therefore, the heat dissipation of the elastic wave device is improved, and the degradation of the device's characteristics can be suppressed.

[0003] Prior art literature

[0004] Patent documents

[0005] Patent Document 1: International Publication No. 2013 / 146374 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] In a structure like that described in International Publication No. 2013 / 146374 (Patent Document 1), the heat generated in one elastic wave element may be transferred to other elastic wave elements via the sealing resin and the high thermal conductivity member.

[0008] On the other hand, the material of the piezoelectric substrate forming the elastic wave element sometimes varies depending on the elastic wave element. In such cases, it is possible to produce a state where the temperature characteristics of each elastic wave element are different. Therefore, if the heat generated in the elastic wave element is transferred to other elastic wave elements through the sealing resin or the high thermal conductivity member for heat dissipation, the characteristics of the other elastic wave elements may deteriorate.

[0009] This disclosure was made to solve such a problem, and its purpose is to suppress the degradation of the characteristics of the elastic wave device due to the effects of heat in an elastic wave device having multiple elastic wave elements.

[0010] Technical solutions for solving the problem

[0011] The first aspect of this disclosure relates to an elastic wave device comprising a mounting substrate, a first filter and a second filter disposed on the mounting substrate, a resin layer sealing the first filter and the second filter, and a conductive layer covering the resin layer. The second filter is disposed adjacent to the first filter in a first direction. The passband of the second filter is higher than that of the first filter. Each of the first and second filters includes a piezoelectric substrate and an elastic wave resonator disposed on the piezoelectric substrate. The first filter is in contact with the conductive layer, while the second filter is not in contact with the conductive layer. The second filter is a trapezoidal elastic wave filter including at least one parallel arm resonator and at least one series arm resonator, or a longitudinally coupled elastic wave filter including at least one longitudinally coupled resonator. The thermal resistance of the piezoelectric substrate of the second filter in the first direction is greater than that of the piezoelectric substrate of the first filter in the first direction. The second filter has the characteristic that the passband decreases if the temperature of the piezoelectric substrate of the second filter increases. In the piezoelectric substrate of the second filter, relative to an imaginary line orthogonal to the first direction and passing through the center of the piezoelectric substrate, the region on the side of the first filter is designated as the first region, and the region on the opposite side of the first filter is designated as the second region. All the parallel arm resonators included in the trapezoidal elastic wave filter are designated as parallel arm circuits, all the series arm resonators included in the trapezoidal elastic wave filter are designated as series arm circuits, and all the longitudinally coupled resonators included in the longitudinally coupled elastic wave filter are designated as longitudinally coupled circuits. In the first region and the second region, the areas of the regions forming the elastic wave resonators included in the parallel arm circuits or longitudinally coupled circuits are designated as the first area and the second area, respectively. At this time, the second area is larger than the first area.

[0012] The second aspect of this disclosure relates to an elastic wave device comprising a mounting substrate, a first filter and a second filter disposed on the mounting substrate, a resin layer sealing the first filter and the second filter, and a conductive layer covering the resin layer. The second filter is disposed adjacent to the first filter in a first direction. The passband of the second filter is higher than that of the first filter. Each of the first and second filters includes a piezoelectric substrate and an elastic wave resonator disposed on the piezoelectric substrate. The first filter is in contact with the conductive layer, while the second filter is not in contact with the conductive layer. The second filter is a trapezoidal elastic wave filter including at least one parallel arm resonator and at least one series arm resonator, or a longitudinally coupled elastic wave filter including at least one longitudinally coupled resonator. The thermal resistance of the piezoelectric substrate of the second filter in the first direction is greater than that of the piezoelectric substrate of the first filter in the first direction. The second filter has the characteristic that the passband increases as the temperature of the piezoelectric substrate of the second filter rises. In the piezoelectric substrate of the second filter, relative to an imaginary line orthogonal to the first direction and passing through the center of the piezoelectric substrate, the region on the side of the first filter is designated as the first region, and the region on the opposite side of the first filter is designated as the second region. All the parallel arm resonators included in the trapezoidal elastic wave filter are designated as parallel arm circuits, all the series arm resonators included in the trapezoidal elastic wave filter are designated as series arm circuits, and all the longitudinally coupled resonators included in the longitudinally coupled elastic wave filter are designated as longitudinally coupled circuits. In the first region and the second region, the area of ​​the region forming the elastic wave resonators included in the parallel arm circuit or the longitudinally coupled circuit is designated as the first area and the second area, respectively. At this time, the first area is larger than the second area.

[0013] The third aspect of this disclosure relates to an elastic wave device comprising a mounting substrate, a first filter and a second filter disposed on the mounting substrate, a resin layer sealing the first filter and the second filter, and a conductive layer covering the resin layer. The second filter is disposed adjacent to the first filter in a first direction. The passband of the second filter is lower than that of the first filter. Each of the first and second filters includes a piezoelectric substrate and an elastic wave resonator disposed on the piezoelectric substrate. The first filter is in contact with the conductive layer, while the second filter is not in contact with the conductive layer. The second filter is a trapezoidal elastic wave filter including at least one parallel arm resonator and at least one series arm resonator, or a longitudinally coupled elastic wave filter including at least one longitudinally coupled resonator. The thermal resistance of the piezoelectric substrate of the second filter in the first direction is greater than that of the piezoelectric substrate of the first filter in the first direction. The second filter has the characteristic that its passband increases as the temperature of the piezoelectric substrate of the second filter rises. In the piezoelectric substrate of the second filter, relative to an imaginary line orthogonal to the first direction and passing through the center of the piezoelectric substrate, the region on the side of the first filter is designated as the first region, and the region on the opposite side of the first filter is designated as the second region. All the parallel arm resonators included in the trapezoidal elastic wave filter are designated as parallel arm circuits, all the series arm resonators included in the trapezoidal elastic wave filter are designated as series arm circuits, and all the longitudinally coupled resonators included in the longitudinally coupled elastic wave filter are designated as longitudinally coupled circuits. In the first region and the second region, the areas of the regions forming the elastic wave resonators included in the series arm circuits or longitudinally coupled circuits are designated as the third area and the fourth area, respectively. At this time, the fourth area is larger than the third area.

[0014] The fourth aspect of this disclosure relates to an elastic wave device comprising a mounting substrate, a first filter and a second filter disposed on the mounting substrate, a resin layer sealing the first filter and the second filter, and a conductive layer covering the resin layer. The second filter is disposed adjacent to the first filter in a first direction. The passband of the second filter is lower than that of the first filter. Each of the first and second filters includes a piezoelectric substrate and an elastic wave resonator disposed on the piezoelectric substrate. The first filter is in contact with the conductive layer, while the second filter is not in contact with the conductive layer. The second filter is a trapezoidal elastic wave filter including at least one parallel arm resonator and at least one series arm resonator, or a longitudinally coupled elastic wave filter including at least one longitudinally coupled resonator. The thermal resistance of the piezoelectric substrate of the second filter in the first direction is greater than that of the piezoelectric substrate of the first filter in the first direction. The second filter has the characteristic that the passband decreases if the temperature of the piezoelectric substrate of the second filter increases. In the piezoelectric substrate of the second filter, relative to an imaginary line orthogonal to the first direction and passing through the center of the piezoelectric substrate, the region on the side of the first filter is designated as the first region, and the region on the opposite side of the first filter is designated as the second region. All the parallel arm resonators included in the trapezoidal elastic wave filter are designated as parallel arm circuits, all the series arm resonators included in the trapezoidal elastic wave filter are designated as series arm circuits, and all the longitudinally coupled resonators included in the longitudinally coupled elastic wave filter are designated as longitudinally coupled circuits. In the first region and the second region, the areas of the regions forming the elastic wave resonators included in the series arm circuits or longitudinally coupled circuits are designated as the third area and the fourth area, respectively. At this time, the third area is larger than the fourth area.

[0015] Invention Effects

[0016] In the elastic wave device according to this disclosure, the elastic wave element (first filter) with relatively low thermal resistance is configured to be in contact with the conductive layer covering the outer periphery of the elastic wave element, while the elastic wave element (second filter) with relatively high thermal resistance is configured not to be in contact with the conductive layer. Furthermore, the configuration of the elastic wave resonator included in the second filter is determined based on the frequency-temperature characteristics of the second filter with relatively high thermal resistance. By adopting such a structure, it is possible to suppress the degradation of the elastic wave device's characteristics due to thermal effects. Attached Figure Description

[0017] Figure 1 This is a diagram illustrating an example of the circuit structure of the elastic wave device according to Embodiment 1.

[0018] Figure 2 yes Figure 1 A cross-sectional view of a multiplexer.

[0019] Figure 3This is a diagram used to illustrate the details of a piezoelectric substrate.

[0020] Figure 4 This is a cross-sectional view of a comparative example multiplexer.

[0021] Figure 5 yes Figure 1 An example of a temperature distribution diagram in a multiplexer.

[0022] Figure 6 This is a diagram used to illustrate the effect of the piezoelectric substrate material and its contact state with the conductive layer on the filter temperature.

[0023] Figure 7 This is a graph used to illustrate the change in loss (parallel setup loss) generated by adjacent filters with temperature rise.

[0024] Figure 8 This is a diagram used to illustrate the losses of parallel setups in scenario 1.

[0025] Figure 9 This is a diagram illustrating the configuration of the parallel arm resonator in case 1.

[0026] Figure 10 This is a diagram used to illustrate the area of ​​the region forming the elastic wave resonator.

[0027] Figure 11 This is a diagram used to illustrate the losses in parallel setups under scenario 2.

[0028] Figure 12 This is a diagram illustrating the configuration of the parallel arm resonator in case 2.

[0029] Figure 13 This is a diagram used to illustrate the losses of parallel setups in scenario 3.

[0030] Figure 14 This is a diagram illustrating the configuration of the series arm resonator in case 3.

[0031] Figure 15 This is a diagram used to illustrate the losses of parallel setups in scenario 4.

[0032] Figure 16 This is a diagram illustrating the configuration of the series arm resonator in case 4.

[0033] Figure 17 This is a diagram illustrating an example of the circuit structure of the multiplexer involved in Embodiment 2. Detailed Implementation

[0034] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Furthermore, the same or equivalent reference numerals in the drawings will not be repeated in their description.

[0035] [Implementation Method 1]

[0036] (Structure of a multiplexer)

[0037] Figure 1 This is a diagram showing the circuit structure of a multiplexer 10, which is an example of an elastic wave device according to Embodiment 1. The multiplexer 10 is, for example, a filter for the transceiver circuit of a communication device.

[0038] Reference Figure 1 The multiplexer 10 includes an antenna terminal T1 and a transmit (TX) filter 100 and a receive (RX) filter that are electrically connected to the antenna ANT at the antenna terminal T1. Figure 1 The example of the multiplexer 10 described is a so-called duplexer that contains two filters.

[0039] Filter 100 is a trapezoidal filter connected between antenna terminal T1 and transmitting terminal T2, filtering the signal received by transmitting terminal T2 and outputting it from antenna ANT. Filter 100 is configured to allow signals in passband BW1 (first passband) to pass through.

[0040] The transmitting filter 100 includes a series arm circuit and a parallel arm circuit. The series arm circuit includes series arm resonators S1 to S5 connected in series between the antenna terminal T1 and the transmitting terminal T2. The parallel arm circuit includes parallel arm resonators P1 to P4 connected between the series arm circuit and the ground potential GND. Each resonator of the series arm resonators S1 to S5 and the parallel arm resonators P1 to P4 is configured to include at least one elastic wave resonator. Figure 1 In the example, each of the series arm resonators S1 and S5 and the parallel arm resonators P1 to P4 contains one elastic wave resonator, and each of the series arm resonators S2 to S4 contains two elastic wave resonators. However, the number of elastic wave resonators in each resonator is not limited to this and can be appropriately selected according to the characteristics of the filter. For example, surface acoustic wave (SAW) resonators or bulk acoustic wave (BAW) resonators can be used as elastic wave resonators.

[0041] One end of the parallel arm resonator P1 is connected to the connection point between the series arm resonators S1 and S2, and the other end is connected to the ground potential GND via inductor L1. One end of the parallel arm resonator P2 is connected to the connection point between the series arm resonators S2 and S3, and the other end is similarly connected to the parallel arm resonator P1 via inductor L1 and to the ground potential GND. One end of the parallel arm resonator P3 is connected to the connection point between the series arm resonators S3 and S4, and the other end is similarly connected to the parallel arm resonators P1 and P2 via inductor L1 and to the ground potential GND. One end of the parallel arm resonator P4 is connected to the connection point between the series arm resonators S4 and S5, and the other end is connected to the ground potential GND via inductor L2.

[0042] The receiving filter 200 is a trapezoidal filter connected between the antenna terminal T1 and the receiving terminal T3. It filters the signal received by the antenna ANT and outputs it from the receiving terminal T3. The filter 200 is configured to allow signals in the passband BW2 (second passband) to pass through. The passband BW2 of the filter 200 is different from the passband BW1 of the filter 100. The filter 200 is connected to the antenna terminal T1 via an impedance matching inductor L11.

[0043] The filter 200 includes a series arm circuit and a parallel arm circuit. The series arm circuit includes series arm resonant sections S11 to S14 connected in series between the inductor L11 and the receiving terminal T3. The parallel arm circuit includes parallel arm resonant sections P11 to P14 connected between the series arm circuit and the ground potential GND. Each resonant section of the series arm resonant sections S11 to S14 and the parallel arm resonant sections P11 to P14 is configured to include at least one elastic wave resonator. Similar to the filter 100, the number of elastic wave resonators included in each resonant section is not limited in the filter 200. Figure 1 In such cases, the appropriate filter can be selected based on its characteristics. Furthermore, regarding the elastic wave resonator used, SAW resonators or BAW resonators can also be used.

[0044] One end of the parallel arm resonant section P11 is connected to the connection point between inductor L11 and series arm resonant section S11, and the other end is connected to ground potential GND. One end of the parallel arm resonant section P12 is connected to the connection point between series arm resonant sections S11 and S12, and the other end is connected to ground potential GND. One end of the parallel arm resonant section P13 is connected to the connection point between series arm resonant sections S12 and S13, and the other end is connected to ground potential GND. One end of the parallel arm resonant section P14 is connected to the connection point between series arm resonant sections S13 and S14, and the other end is connected to ground potential GND.

[0045] Furthermore, filter 100 corresponds to "first filter" in this disclosure, and filter 200 corresponds to "second filter" in this disclosure.

[0046] Figure 2 yes Figure 1 A cross-sectional view of the multiplexer 10. (Refer to...) Figure 2 In addition to filters 100 and 200, the multiplexer 10 also includes a mounting substrate 50, a resin layer 60, and a conductive layer 70. Furthermore, in the following description, we will use the case where filters 100 and 200 are elastic wave resonators and SAW resonators are used as examples.

[0047] Filters 100 and 200 have a WLP (Wafer Level Package) structure and are disposed adjacently on the mounting substrate 50. Furthermore, in the following description, the thickness direction of the mounting substrate 50 is defined as the Z-axis direction, and the adjacent direction of filters 100 and 200 in the in-plane direction of the mounting substrate 50 is defined as the X-axis direction. Figure 2 In the example, filter 100 is positioned separately from filter 200 along the positive X-axis. Furthermore, the positive Z-axis direction is sometimes referred to as the upper surface side, and the negative direction as the lower surface side.

[0048] The mounting substrate 50 is, for example, a single-layer or multi-layer substrate formed of a resin such as epoxy or polyimide. Although not shown, the mounting substrate 50 includes connection terminals formed on the upper and lower surfaces and wiring patterns formed in the substrate and / or on the substrate surface.

[0049] The filter 100 includes a piezoelectric substrate 110, a support layer 120, a cover layer 130, a functional element 140, a columnar electrode 150, and a wiring pattern 160.

[0050] like Figure 3 As shown, the piezoelectric substrate 110 includes a base substrate 112, a piezoelectric layer 111 disposed on the lower surface side of the base substrate 112, and an intermediate layer 113 disposed between the piezoelectric layer 111 and the base substrate 112.

[0051] The piezoelectric layer 111 is formed, for example, of a piezoelectric single crystal material such as lithium tantalate (LiTaO3:LT), lithium niobate (LiNbO3:LN), bauxite, silicon (Si), and sapphire, or of a piezoelectric multilayer material containing LiTaO3 or LiNbO3. The substrate 112 is formed, for example, of silicon (Si), lithium tantalate (LT), or lithium niobate (LN).

[0052] The intermediate layer 113 is composed of a low-velocity layer 1131 and a high-velocity layer 1132. The low-velocity layer 1131 and the high-velocity layer 1132 are arranged from the substrate 112 toward the piezoelectric layer 111 in the order of high-velocity layer 1132 and low-velocity layer 1131.

[0053] The low-velocity layer 1131 is formed of a material whose volume wave velocity propagating in the low-velocity layer 1131 is lower than that propagating in the piezoelectric layer 111. The low-velocity layer 1131 is formed, for example, of dielectrics such as silicon dioxide (SiO2), glass, silicon oxynitride, tantalum oxide, or compounds of silicon dioxide with added fluorine, carbon, boron, etc.

[0054] Furthermore, the high-velocity acoustic layer 1132 is formed of a material whose volume wave velocity propagating in the high-velocity acoustic layer 1132 is higher than that of the elastic wave velocity propagating in the piezoelectric layer 111. The high-velocity acoustic layer 1132 is formed of materials such as silicon nitride (SiN), aluminum nitride, alumina (bauxite), silicon oxynitride, silicon carbide, diamond-like carbon (DLC), and diamond.

[0055] By configuring a structure in which a low-velocity acoustic layer 1131 and a high-velocity acoustic layer 1132 are disposed between the piezoelectric layer 111 and the substrate 112, the low-velocity acoustic layer 1131 and the high-velocity acoustic layer 1132 function as reflective layers (mirror layers). That is, surface acoustic waves leaking from the piezoelectric layer 111 toward the substrate 112 are reflected in the high-velocity acoustic layer 1132 due to the difference in propagation sound velocity, and are thus confined within the low-velocity acoustic layer 1131. In this way, the loss of acoustic energy of the propagating surface acoustic waves can be suppressed by the intermediate layer 113, thus enabling efficient propagation of surface acoustic waves.

[0056] In addition, Figure 3 In this example, an example is described where a low-velocity layer 1131 and a high-velocity layer 1132 are each formed as an intermediate layer 113. However, the intermediate layer 113 may also have a structure in which multiple low-velocity layers 1131 and high-velocity layers 1132 are alternately arranged. Furthermore, the intermediate layer 113 is not a necessary structure, and the piezoelectric substrate 110 may also be formed only by the piezoelectric layer 111 and the substrate 112.

[0057] At least one functional element 140 is formed on the lower surface of the piezoelectric layer 111 of the piezoelectric substrate 110. The functional element 140 includes, for example, a pair of comb-shaped IDT (Interdigital Transducer) electrodes, which are formed using electrode materials such as elemental metals containing at least one of aluminum, copper, silver, gold, titanium, tungsten, platinum, chromium, nickel, and molybdenum, or alloys with these as main components. In the filter 100, a surface acoustic wave (SAW) resonator is formed by the piezoelectric substrate 110 and the IDT electrodes.

[0058] A support layer 120 is disposed on the lower surface of the piezoelectric substrate 110, surrounding the functional element 140. The support layer 120 supports the cover layer 130 at a given distance from the piezoelectric substrate 110 in the Z-axis direction. Both the support layer 120 and the cover layer 130 are formed of insulating resins mainly composed of epoxy, polyimide, acrylic acid, urethane, etc. A hollow space 180 is formed by the piezoelectric substrate 110, the support layer 120, and the cover layer 130. The functional element 140 is disposed within this hollow space 180.

[0059] Furthermore, a wiring pattern 160 is formed on the lower surface of the piezoelectric substrate 110 for electrically connecting the functional elements 140 to each other and electrically connecting the functional elements 140 to the columnar electrode 150 (via).

[0060] The columnar electrode 150 protrudes downward (in the negative Z-axis direction) from the lower surface of the piezoelectric substrate 110 and penetrates the support layer 120 and the cover layer 130. The columnar electrode 150 is connected to connection terminals formed on the mounting substrate 50 via conductive connection members such as solder bumps 170. The columnar electrode 150 enables electrical connection between the functional element 140 and other electronic components on the mounting substrate 50. The columnar electrode 150 and the wiring pattern 160 are formed of conductive materials such as aluminum, copper, silver, and gold.

[0061] Filter 200 has a structure substantially the same as filter 100, including a piezoelectric substrate 210, a support layer 220, a cover layer 230, functional elements 240, pillar electrodes 250, and wiring patterns 260. Functional elements 240 are formed within a hollow space 280 formed by the piezoelectric substrate 210, support layer 220, and cover layer 230. Filter 200 is connected to mounting substrate 50 via conductive connecting members such as solder bumps 270. Furthermore, the piezoelectric substrate 210 of filter 200 includes a piezoelectric layer 211, a base substrate 212, and an intermediate layer 213. Since the elements of filter 200 are the same as their corresponding elements in filter 100, detailed descriptions will not be repeated.

[0062] The filters 100 and 200 disposed on the mounting substrate 50 are sealed by the resin layer 60. The resin layer 60 is formed, for example, of a material incorporating inorganic fillers such as metals into a material such as a silicon compound, epoxy resin, silicone resin, fluorine resin, or acrylic resin. A conductive layer 70 is disposed such that it covers the resin layer 60.

[0063] The conductive layer 70 is formed of a metallic material, such as aluminum, copper, silver, or gold, which has electrical conductivity and high thermal conductivity. The conductive layer 70 is connected to the ground potential on the mounting substrate 50. The conductive layer 70 functions as a shield to prevent electromagnetic noise generated inside the multiplexer 10 from leaking out of the device and to prevent electromagnetic noise from entering the multiplexer 10 from the outside of the device.

[0064] In the multiplexer 10 of embodiment 1, like in Figure 1 As explained, filter 100 is used as a transmitting filter, and filter 200 is used as a receiving filter. Generally, for the transmitting signal, a power amplifier is used to transmit it with higher power than the receiving signal, so as to radiate the radio waves as far as possible. Therefore, filter 100 consumes more power than filter 200 and is more prone to overheating.

[0065] Therefore, in the multiplexer 10, the structure is configured such that the upper surface of the piezoelectric substrate 110 in the filter 100 is exposed from the resin layer 60 and directly contacted with the conductive layer 70. As described above, the conductive layer 70 is formed of a metallic material with high thermal conductivity. Therefore, the conductive layer 70 functions as a heat sink for the filter 100, through which heat generated in the filter 100 is diffused and radiated.

[0066] On the other hand, in the multiplexer 10 of Embodiment 1, the piezoelectric substrate 210 of the filter 200 is formed thinner than the piezoelectric substrate 110 of the filter 100 and is not in contact with the conductive layer 70. As described above, the conductive layer 70 functions as a heat sink for the filter 100, but because it has high thermal conductivity, if like Figure 4 In the comparative example, where the piezoelectric substrate 210# of filter 200# is configured to be in contact with the conductive layer 70, as in the multi-function adapter 10#, heat from filter 100 is transferred to filter 200# via the conductive layer 70. If this is the case, the temperature of filter 200# will rise due to the heat from filter 100, potentially leading to a decrease in the filter characteristics of filter 200#.

[0067] For example, depending on the material forming the piezoelectric substrate, the passband of a filter can sometimes shift due to an increase in substrate temperature. When the Temperature Characteristics of Frequency (TCF) is positive (TCF > 0), an increase in temperature will shift the frequency band towards higher frequencies. Conversely, when the TCF is negative (TCF < 0), an increase in temperature will shift the frequency band towards lower frequencies.

[0068] In a structure like a multiplexer where filters with different passbands are arranged adjacently, if the passband of one filter shifts to approach the passband of another filter when the two passbands are close together, the impedance between the filters decreases, and the isolation may deteriorate. This can lead to a decrease in the insertion loss of the filters. In this disclosure, such an increase in loss between adjacent filters is referred to as "parallel setup loss".

[0069] In the multiplexer 10 of Embodiment 1, for the filter 100 on the transmitting side, which generates relatively more heat, the thickness (dimension in the Z-axis direction) of the piezoelectric substrate 110 is increased so that it is in direct contact with the conductive layer 70, thereby improving heat dissipation and reducing heat transfer via the resin layer 60. Furthermore, for the filter 200 on the receiving side, which generates relatively less heat, the piezoelectric substrate 210 is thinned so that it is not in contact with the conductive layer 70, thereby suppressing heat transfer via the conductive layer 70. Therefore, by adopting such a structure, heat transfer from the filter 100 to the filter 200 can be reduced, thus reducing the parallel arrangement loss caused by placing the filters 100 and 200 adjacent to each other.

[0070] Figure 5 It shows that Figure 1 A diagram showing an example of the temperature distribution under the condition of multiplexer 10 in operation. Figure 5 In the diagram, a multiplexer 10 is mounted on the motherboard 300, and the temperature distribution is shown using isotherms. Figure 5 In the middle, the temperature of the part of filter 100 is the highest, and the temperature gradually decreases in the direction of arrow AR0.

[0071] like Figure 5 As shown, due to the conductive layer 70, the temperature on the upper surface of the resin layer 60 on the filter 200 side becomes higher than the temperature near the filter 200. It can be seen that by thinning the thickness of the piezoelectric substrate 210 of the filter 200, the heat transferred to the piezoelectric substrate 210 via the conductive layer 70 is reduced.

[0072] Figure 6 This diagram illustrates the effect of different materials of the piezoelectric substrates 110 and 210 and their contact states with the conductive layer 70 on the temperature of the filter 200. Figure 6In the diagram, solid line LN1 indicates the following situation: piezoelectric substrate 110 is made of silicon (Si), piezoelectric substrate 210 is made of lithium niobate (LN), and piezoelectric substrate 210 is not in contact with conductive layer 70. Dashed line LN2 indicates the following situation: both piezoelectric substrates 110 and 210 are made of silicon, and piezoelectric substrate 210 is not in contact with conductive layer 70. Single-dotted line LN3 indicates the following situation: both piezoelectric substrates are made of silicon, and piezoelectric substrate 210 is in contact with conductive layer 70 (i.e., ...). Figure 4 (Comparative example). The double-dotted line LN4 shows the following situation: both piezoelectric substrates 110 and 210 are made of silicon, and piezoelectric substrate 210 is not in contact with conductive layer 70.

[0073] In addition, Figure 6 In the figure, the horizontal axis shows the distance from the outer end of filter 200 towards the X-axis. Figure 2 The coordinate axis α in the figure shows the relative temperature difference with the dashed line LN3 as the reference.

[0074] Reference Figure 6 In Embodiment 1 (lines LN1, LN2, LN4), where the piezoelectric substrate 210 does not contact the conductive layer 70, the temperature of the piezoelectric substrate 210 decreases compared to the comparative example (line LN3). Furthermore, it is known that when lithium niobate is used as the material for the piezoelectric substrate 210, the temperature gradient in the X-axis direction is larger compared to when silicon is used. Therefore, when a material with high thermal resistance, such as lithium niobate, is used as the material for the piezoelectric substrate 210, and when the thickness of the piezoelectric substrate 210 is thin, performance degradation may occur depending on the location of the elastic wave resonator within the piezoelectric substrate 210.

[0075] (The effect of heat on filter characteristics)

[0076] Next, use Figure 7 The reason why the loss generated by adjacent filters (parallel setup loss) changes with increasing temperature is explained. Furthermore, in Figure 6 In this example, we will take the case where the passband BW1 of the filter 100 on the transmitting (TX) side is lower than the passband BW2 of the filter 200 on the receiving (RX) side (BW1 < BW2) as an example.

[0077] Figure 7 The upper section is a graph comparing the insertion loss (dashed lines LN11, LN21) of filters 100 and 200 as individual units with the insertion loss (solid lines LN10, LN20) of filters 100 and 200 assembled as multiplexer 10. Figure 7As shown in the upper paragraph, if filters 100 and 200 are connected to a common terminal to function as a multiplexer, the insertion loss (parallel setup loss) of both filters increases (arrow AR1). When viewed from the common terminal, since the impedance of the filter on the other side cannot be completely infinite, a portion of the transmitted signal leaks to the receiving filter 200, or a portion of the received signal leaks to the transmitting filter 100, thus generating this parallel setup loss.

[0078] In this state, if the temperature of filter 200 rises, the passband BW2 of filter 200 may change according to its temperature characteristics. For example, if the passband BW2 of filter 200 decreases with rising temperature (TCF < 0) (dotted line LN22), the passband of filter 200 becomes closer to the passband BW1 of filter 100. If this happens, the isolation between filter 100 and filter 200 decreases, and therefore the insertion loss on the high-frequency side of filter 100 increases as shown by arrow AR2 (dotted line LN12). That is, the parallel loss increases due to the rising temperature of filter 200.

[0079] On the other hand, when the passband BW2 of filter 200 increases with rising temperature (TCF > 0) (dotted line LN23), the passband BW2 of filter 200 becomes further away from the passband BW1 of filter 100. In this case, the isolation between filter 100 and filter 200 increases, and therefore the insertion loss on the high-frequency side of filter 100 decreases as shown by arrow AR3 (dashed line LN13). That is, when TCF > 0, the parallel-mounted loss decreases with rising temperature.

[0080] Conversely, when the passband BW1 of filter 100 is higher than the passband BW2 of filter 200 (BW1 > BW2), the parallel setup loss decreases with increasing temperature when TCF < 0, and the parallel setup loss increases with increasing temperature when TCF > 0.

[0081] The following section details the changes in parallel set losses associated with temperature rise and the corresponding configurations of elastic wave resonators for four scenarios, based on the relationship between the passband sizes of filters 100 and 200 and the relationship of TCF.

[0082] (Scenario 1)

[0083] Figure 8This is a diagram illustrating the losses in parallel setups under Case 1. Case 1 is the case where the passband BW1 of filter 100 is lower than the passband BW2 of filter 200 (BW1 < BW2), and the passband BW2 of filter 200 decreases with increasing temperature (TCF < 0).

[0084] In this case, such as Figure 8 As shown in the upper section, the passband BW2 of filter 200 shifts towards the lower frequency side from the solid line LN40 to the dashed line LN41 (arrow AR20). Consequently, the insertion loss on the high-frequency side of filter 100 increases from the solid line LN30 to the dashed line LN31 (arrow AR10).

[0085] like Figure 1 As shown, filter 200 is a trapezoidal filter; therefore, generally, the attenuation electrode on the low-frequency side is formed by the parallel arm resonators P1 to P4. Therefore, in case 1, in order to suppress the increase in parallel connection loss associated with temperature rise, it is preferable to minimize the temperature rise of the parallel arm resonators, thereby causing the attenuation electrode on the low-frequency side of the passband BW2 to move further towards the high-frequency side. Therefore, in case 1, as... Figure 9 As shown, in the filter 200, the parallel arm resonators P1 to P4 are positioned away from the filter 100 to suppress the temperature rise of the parallel arm resonators P1 to P4.

[0086] picture Figure 9 Thus, in filter 200, with respect to an imaginary line CL1 orthogonal to the arrangement direction of filters 100 and 200 (i.e., the X-axis direction (first direction)) and passing through the center of the piezoelectric substrate 210 of filter 200, the region on the side of filter 100 is designated as region RG1, and the region on the opposite side of filter 100 is designated as region RG2. At this time, the parallel arm resonators P1 to P4 are configured such that the sum of the areas in region RG2 of the areas forming the elastic wave resonators included in the parallel arm resonators P1 to P4 is greater than the sum of the areas in region RG1 (SM1 < SM2).

[0087] By configuring the parallel arm resonators P1 to P4 in this way, thus... Figure 8 As shown in the lower section, the low-frequency side of the passband BW2 of filter 200 is shifted towards the high-frequency side, as shown by the dashed line LN42 (arrow AR21). This improves the isolation between filter 100 and filter 200, and, as shown by the dashed line LN32, reduces the insertion loss on the high-frequency side of the passband BW1 of filter 100 (arrow AR11).

[0088] In the above and subsequent descriptions, the term "area of ​​the region forming the elastic wave resonator" refers to, for example... Figure 10As shown in (A), this refers to the area SQ1 of the intersection region of the electrode fingers in the IDT electrodes included in the elastic wave resonator. Here, the intersection region is the area where multiple electrode fingers of the IDT electrodes overlap when viewed from the direction of elastic wave propagation. For example, in... Figure 10 In case (A), if, when viewed from the direction of propagation of the elastic wave, for the region where multiple electrode fingers overlap, the length in the direction in which the electrode fingers extend is set as L1, and the distance between the outermost electrode fingers in the IDT electrode is set as L2, then the area of ​​the intersection region can be represented by the product of L1 and L2.

[0089] Furthermore, in the case of longitudinally coupled resonators, it refers to Figure 10 The area of ​​the cross region SQ2 in (B). In this case, the cross region is the overlapping area of ​​the multiple electrode fingers of the IDT electrodes IDT1 to IDT3 constituting the longitudinally coupled resonator. For example, in Figure 10 In case (B), if, when viewed from the direction of propagation of the elastic wave, for the region where multiple electrode fingers overlap, the length in the direction in which the electrode fingers extend is set as L3, and the distance between the outermost electrode fingers in the IDT electrodes constituting the longitudinally coupled resonator is set as L4, then the area of ​​the intersection region can be represented by the product of L3 and L4.

[0090] (Scenario 2)

[0091] Figure 11 This diagram illustrates the losses in parallel setups under scenario 2. Scenario 2 is characterized by the following: the passband BW1 of filter 100 is lower than the passband BW2 of filter 200 (BW1 < BW2), and the passband BW2 of filter 200 increases with increasing temperature (TCF > 0). In other words, in scenario 2, if the temperature of filter 200 increases, the gap between the passbands of filter 100 and filter 200 widens, thus improving isolation.

[0092] In this case, such as Figure 11 As shown in the upper section, the passband BW2 of filter 200 shifts towards the higher frequency side from the solid line LN60 to the dashed line LN61 (arrow AR40). As a result, the insertion loss on the high frequency side of filter 100 is reduced from the solid line LN50 to the dashed line LN51 (arrow AR30).

[0093] As explained in Case 1, in the trapezoidal filter 200, the attenuation electrode on the low-frequency side is formed by the parallel arm resonators P1 to P4. In Case 2, if the temperature of the filter 200 increases, the parallel arrangement loss decreases; therefore, it is preferable to increase the temperature of the parallel arm resonators as much as possible, thereby further shifting the attenuation electrode on the low-frequency side of the passband BW2 towards the high-frequency side. Therefore, in Case 2, as... Figure 12 As shown, in filter 200, the parallel arm resonant parts P1 to P4 are positioned close to filter 100, thereby promoting the temperature rise of the parallel arm resonant parts P1 to P4.

[0094] That is, like Figure 12 In this way, in the filter 200, the parallel arm resonators P1 to P4 are configured such that the sum of the areas in region RG1 of the regions forming the elastic wave resonators contained in the parallel arm resonators P1 to P4 is greater than the sum of the areas in region RG2 (SM1 > SM2).

[0095] By configuring the parallel arm resonators P1 to P4 in this way, thus... Figure 11 As shown in the lower section, the low-frequency side of the passband BW2 of filter 200 is further shifted towards the high-frequency side, as shown by the dashed line LN62 (arrow AR41). If this is done, the isolation between filter 100 and filter 200 is further improved, as shown by the dashed line LN52, which can further improve the insertion loss on the high-frequency side of the passband BW1 of filter 100 (arrow AR31).

[0096] (Scenario 3)

[0097] Figure 13 This diagram illustrates the losses in parallel setups under scenario 3. Scenario 3 is characterized by the following: the passband BW1 of filter 100 is higher than the passband BW2 of filter 200 (BW1 > BW2), and the passband BW2 of filter 200 increases with increasing temperature (TCF > 0). In other words, in scenario 3, if the temperature of filter 200 increases, the gap between the passbands of filter 100 and filter 200 narrows, resulting in decreased isolation.

[0098] In this case, such as Figure 13 As shown in the upper section, the passband BW2 of filter 200 shifts towards the higher frequency side from the solid line LN80 to the dashed line LN81 (arrow AR60). Consequently, the insertion loss on the low-frequency side of filter 100 increases from the solid line LN70 to the dashed line LN71 (arrow AR50).

[0099] In the trapezoidal filter 200, generally, the attenuation electrode on the high-frequency side is formed by the series arm resonators S1 to S5. In case 3, if the temperature of the filter 200 rises, the parallel connection loss increases; therefore, it is preferable to suppress the temperature rise of the series arm resonators as much as possible, thereby shifting the attenuation electrode on the high-frequency side of the passband BW2 towards the low-frequency side. Therefore, in case 3, as... Figure 14 As shown, in the filter 200, the series arm resonant parts S1 to S5 are arranged at a position away from the filter 100, thereby suppressing the temperature rise of the series arm resonant parts S1 to S5.

[0100] That is, like Figure 14 Therefore, in the filter 200, the series arm resonant sections S1 to S5 are configured such that the sum of the areas in region RG2 of the regions forming the elastic wave resonators contained in the series arm resonant sections S1 to S5, SM4, is greater than the sum of the areas in region RG1, SM3 (SM3 < SM4).

[0101] By configuring the series arm resonant sections S1 to S5 in this way, thus... Figure 13 As shown in the lower paragraph, the high-frequency side of the passband BW2 of filter 200 shifts towards the low-frequency side, as shown by the dashed line LN82 (arrow AR61). If this is done, the isolation between filter 100 and filter 200 is improved, as shown by the dashed line LN72, which can improve the insertion loss on the low-frequency side of the passband BW1 of filter 100 (arrow AR51).

[0102] (Scenario 4)

[0103] Figure 15 This diagram illustrates the losses in parallel setups under scenario 4. Scenario 4 is characterized by the following: the passband BW1 of filter 100 is higher than the passband BW2 of filter 200 (BW1 > BW2), and the passband BW2 of filter 200 decreases with increasing temperature (TCF < 0). In other words, in scenario 4, if the temperature of filter 200 increases, the gap between the passbands of filter 100 and filter 200 widens, thus improving isolation.

[0104] In this case, such as Figure 15 As shown in the upper section, the passband BW2 of filter 200 shifts towards the lower frequency side from the solid line LN100 to the dashed line LN101 (arrow AR80). As a result, the insertion loss on the low-frequency side of filter 100 decreases from the solid line LN90 to the dashed line LN91 (arrow AR70).

[0105] As explained in Case 3, in the trapezoidal filter 200, the attenuation electrode on the high-frequency side is formed by the series arm resonators S1 to S5. In Case 4, if the temperature of the filter 200 increases, the parallel arrangement loss decreases; therefore, it is preferable to increase the temperature of the series arm resonators as much as possible, thereby further shifting the attenuation electrode on the high-frequency side of the passband BW2 towards the low-frequency side. Therefore, in Case 4, as... Figure 16 As shown, in the filter 200, the series arm resonant parts S1 to S5 are positioned close to the filter 100, thereby promoting the temperature rise of the series arm resonant parts S1 to S5.

[0106] That is, like Figure 16In this way, in the filter 200, the series arm resonant sections S1 to S5 are configured such that the sum of the areas in region RG1 of the regions forming the elastic wave resonators contained in the series arm resonant sections S1 to S5, SM3, is greater than the sum of the areas in region RG2, SM4 (SM3 > SM4).

[0107] By configuring the series arm resonant sections S1 to S5 in this way, thus... Figure 15 As shown in the lower section, the high-frequency side of the passband BW2 of filter 200 is further shifted towards the low-frequency side, as shown by the dashed line LN102 (arrow AR81). If this is done, the isolation between filter 100 and filter 200 is further improved, as shown by the dashed line LN92, which can further improve the insertion loss on the high-frequency side of the passband BW1 of filter 100 (arrow AR71).

[0108] As described above, in the multiplexer of Embodiment 1, by making the filter with relatively small thermal resistance (the first filter) of two adjacent filters in contact with the conductive layer, and making the filter with relatively large thermal resistance (the second filter) not in contact with the conductive layer, heat transfer between adjacent filters can be suppressed. Furthermore, for the second filter, by configuring the elastic wave resonator close to the passband of the first filter based on the frequency-temperature characteristic (TCF), the attenuation electrode of the second filter is moved away from the passband of the first filter, thereby utilizing the temperature gradient generated in the piezoelectric substrate due to thermal resistance to suppress the parallel placement loss generated in the first filter. Therefore, the degradation of the characteristics of the multiplexer (elastic wave device) due to the influence of heat can be suppressed.

[0109] Furthermore, in Embodiment 1, an example was described in which the transmitting filter, which generates relatively more heat, comes into contact with the conductive layer. However, if the thermal resistance of the transmitting filter is greater than that of the receiving filter, the receiving filter may come into contact with the conductive layer while the transmitting filter does not come into contact with the conductive layer.

[0110] Furthermore, the piezoelectric substrates in the two filters can be made of different materials or the same material (e.g., silicon). In this case, the thermal resistance is adjusted by making the thicknesses of the piezoelectric substrates different from each other.

[0111] Furthermore, the two filters do not necessarily have to be a combination of a transmitting filter and a receiving filter; they can be two filters with different passbands. This means that both filters can be transmitting filters or receiving filters. For example, a combination of transmitting and receiving filters can be used in multiplexers with passbands such as transmit (1710–1785 MHz) / receive (1805–1880 MHz) or transmit (2500–2570 MHz) / receive (2620–2690 MHz). Additionally, as a case where both filters are transmitting filters, a multiplexer can be used with passbands such as transmit (1710–1785 MHz) / transmit (1850–1915 MHz).

[0112] [Implementation Method 2]

[0113] In Embodiment 1, the case where both filters included in the multiplexer are trapezoidal elastic wave filters was described. In Embodiment 2, the case where the receiving filter is a longitudinally coupled elastic wave filter including a longitudinally coupled resonator was described.

[0114] Figure 17 This is a diagram showing the circuit structure of a multiplexer 10A, which is an example of an elastic wave device according to Embodiment 2. (Refer to...) Figure 17 The multiplexer 10A includes an antenna terminal T1 and a transmitting filter 100A and a receiving filter 200A that are electrically connected to the antenna ANT at the antenna terminal T1.

[0115] The transmitting filter 100A is a trapezoidal elastic wave filter equipped with a series arm circuit and a parallel arm circuit. The series arm circuit includes series arm resonators S21 to S25 connected in series between the antenna terminal T1 and the transmitting terminal T2. The parallel arm circuit includes parallel arm resonators P21 to P24 connected between the series arm circuit and the ground potential GND. Each resonator of the series arm resonators S21 to S25 and the parallel arm resonators P21 to P24 is configured to include at least one elastic wave resonator. Figure 17 In the example, each of the series arm resonators S21 and S25 and the parallel arm resonators P21 to P24 includes one elastic wave resonator, while each of the series arm resonators S22 to S24 includes two elastic wave resonators. Furthermore, the number of elastic wave resonators included in each resonator is not limited to this and can be appropriately selected according to the characteristics of the filter. SAW resonators or BAW resonators can be used as elastic wave resonators.

[0116] One end of the parallel arm resonator P21 is connected to the connection point between the series arm resonators S21 and S22, and the other end is connected to the ground potential GND. One end of the parallel arm resonator P22 is connected to the connection point between the series arm resonators S22 and S23, and the other end is connected to the ground potential GND. One end of the parallel arm resonator P23 is connected to the connection point between the series arm resonators S23 and S24, and the other end is connected to the ground potential GND. One end of the parallel arm resonator P24 is connected to the connection point between the series arm resonators S24 and S25, and the other end is connected to the ground potential GND.

[0117] The receiving filter 200A includes series arm resonators S30 and S31 and an inductor L31. The series arm resonators S30 and S31 are connected in series between the antenna terminal T1 and the receiving terminal T3.

[0118] The series arm resonator S30 includes, for example, an elastic wave resonator. The series arm resonator S31 is a longitudinal coupling circuit containing at least one so-called longitudinally coupled resonator type elastic wave resonator, including three IDT electrodes IDT1 to IDT3 and two reflectors REF.

[0119] One end of the series arm resonator S30 is connected to the antenna terminal T1, which is the common terminal of the filter 100A. The IDT electrode IDT2 of the series arm resonator S31 is connected between the other end of the series arm resonator S30 and the ground potential GND.

[0120] An IDT electrode IDT1 is disposed opposite to one end of the IDT electrode IDT2 in the excitation direction, and an IDT electrode IDT3 is disposed opposite to the other end in the excitation direction. IDT electrodes IDT1 and IDT3 are connected in parallel between the receiving terminal T3 and the ground potential GND. In each of the IDT electrodes IDT1 and IDT3, a reflector REF is disposed opposite to the IDT electrode IDT2 in the excitation direction.

[0121] Inductor L31 is connected between antenna terminal T1 and ground potential GND. Inductor L31 functions as an impedance matching inductor. The inductance of inductor L31 is adjusted so that the impedance of filter 200A becomes an open circuit when viewed from antenna terminal T1 for high-frequency signals in the passband of filter 100A. This suppresses high-frequency signals in the passband of filter 100A from passing through to the receiving terminal T3.

[0122] Furthermore, the cross-sectional view of the multiplexer 10A in Embodiment 2 is basically the same as... Figure 2 Same, by Figure 2The functional element 240 in the middle forms a longitudinally coupled resonator.

[0123] In the multiplexer 10A, the filter 100A on the transmitting side, which generates relatively more heat, is made to have its piezoelectric substrate thickened so that it is in direct contact with the conductive layer, thereby improving heat dissipation and reducing heat transfer via the resin layer. Furthermore, the filter 200A on the receiving side, which generates relatively less heat, is made to have its piezoelectric substrate thinned so that it is not in contact with the conductive layer, thereby suppressing heat transfer via the conductive layer. Therefore, by adopting this structure, heat transfer from filter 100A to filter 200A can be reduced, thus reducing the parallel arrangement losses caused by placing filters 100A and 200A adjacent to each other.

[0124] Here, in filter 200A, either the attenuation electrode on the high-frequency side of the passband or the attenuation electrode on the low-frequency side is determined by the longitudinally coupled resonator. Therefore, the reduction of parallel arrangement loss in cases 1 and 3 of embodiment 1, and the further improvement of insertion loss in cases 2 and 4, can be achieved by configuring the elastic wave resonator included in the longitudinally coupled circuit as shown in each case.

[0125] Specifically, if the area of ​​the region containing the elastic wave resonator included in the longitudinal coupling circuit forming filter 200A is... Figure 9 Let the sum of the areas within region RG1 be SM5, and the sum of the areas within region RG2 be SM6. Then, in cases 1 and 3, each longitudinally coupled resonator is configured such that the sum of the areas within region RG2, SM6, is greater than the sum of the areas within region RG1, SM5 (SM5 < SM6). Furthermore, in cases 2 and 4, each longitudinally coupled resonator is configured such that the sum of the areas within region RG1, SM5, is greater than the sum of the areas within region RG2, SM6 (SM5 > SM6).

[0126] It should be understood that the embodiments disclosed herein are illustrative in all respects and are not restrictive. The scope of this disclosure is not shown by the description of the above embodiments, but by the claims, and is intended to include all modifications equivalent to and within the scope of the claims.

[0127] Explanation of reference numerals in the attached figures

[0128] 10, 10A: Multiplexer; 50: Mounting substrate; 60: Resin layer; 70: Conductive layer; 100, 100A, 200, 200A: Filter; 110, 210: Piezoelectric substrate; 111, 211: Piezoelectric layer; 112, 212: Substrate; 113, 213: Intermediate layer; 120, 220: Support layer; 130, 230: Cover layer; 140, 240: Functional element; 150, 250: Columnar electrode; 160, 260: Wiring pattern; 170, 270: Solder bump; 180, 2 80: Hollow space; 300: Motherboard; 1131: Low-velocity layer; 1132: High-velocity layer; ANT: Antenna; GND: Ground potential; IDT, IDT1~IDT3: IDT electrodes; L1, L2, L11, L31: Inductors; P1~P4, P11~P14, P21~P24: Parallel arm resonator; REF: Reflector; S1~S5, S11~S14, S21~S25, S30, S31: Series arm resonator; T1: Antenna terminal; T2: Transmitter terminal; T3: Receiver terminal.

Claims

1. An elastic wave device, comprising: Mounting substrate; A first filter, disposed on the mounting substrate, has a first passband; The second filter, disposed adjacent to the first filter in a first direction on the mounting substrate, has a second passband that is higher than the first passband; A resin layer is used to seal the first filter and the second filter on the mounting substrate; and A conductive layer covers the resin layer. The first filter and the second filter each comprise: piezoelectric substrates; and An elastic wave resonator is disposed on the piezoelectric substrate. The first filter is connected to the conductive layer. The second filter is not connected to the conductive layer. The second filter is either a trapezoidal elastic wave filter containing at least one parallel arm resonator and at least one series arm resonator, or a longitudinally coupled elastic wave filter containing at least one longitudinally coupled resonator. The thermal resistance of the piezoelectric substrate of the second filter in the first direction is greater than the thermal resistance of the piezoelectric substrate of the first filter in the first direction. The second filter has the characteristic that its passband decreases if the temperature of the piezoelectric substrate of the second filter increases. In the piezoelectric substrate of the second filter, a region on the side of the first filter is designated as the first region, relative to an imaginary line orthogonal to the first direction and passing through the center of the piezoelectric substrate, and a region on the opposite side of the first filter is designated as the second region. All the parallel arm resonators included in the trapezoidal elastic wave filter are configured as parallel arm circuits, all the series arm resonators included in the trapezoidal elastic wave filter are configured as series arm circuits, and all the longitudinally coupled resonators included in the longitudinally coupled elastic wave filter are configured as longitudinally coupled circuits. In the first region and the second region, the areas of the regions forming the elastic wave resonators included in the parallel arm circuit or the longitudinal coupling circuit are respectively designated as the first area and the second area. The second area is larger than the first area.

2. An elastic wave device, comprising: Mounting substrate; A first filter, disposed on the mounting substrate, has a first passband; The second filter, disposed adjacent to the first filter in a first direction on the mounting substrate, has a second passband that is higher than the first passband; A resin layer is used to seal the first filter and the second filter on the mounting substrate; and A conductive layer covers the resin layer. The first filter and the second filter each comprise: piezoelectric substrates; and An elastic wave resonator is disposed on the piezoelectric substrate. The first filter is connected to the conductive layer. The second filter is not connected to the conductive layer. The second filter is either a trapezoidal elastic wave filter containing at least one parallel arm resonator and at least one series arm resonator, or a longitudinally coupled elastic wave filter containing at least one longitudinally coupled resonator. The thermal resistance of the piezoelectric substrate of the second filter in the first direction is greater than the thermal resistance of the piezoelectric substrate of the first filter in the first direction. The second filter has the characteristic that its passband increases as the temperature of its piezoelectric substrate rises. In the piezoelectric substrate of the second filter, a region on the side of the first filter is designated as the first region, relative to an imaginary line orthogonal to the first direction and passing through the center of the piezoelectric substrate, and a region on the opposite side of the first filter is designated as the second region. All the parallel arm resonators included in the trapezoidal elastic wave filter are configured as parallel arm circuits, all the series arm resonators included in the trapezoidal elastic wave filter are configured as series arm circuits, and all the longitudinally coupled resonators included in the longitudinally coupled elastic wave filter are configured as longitudinally coupled circuits. In the first region and the second region, the areas of the regions forming the elastic wave resonators included in the parallel arm circuit or the longitudinal coupling circuit are respectively designated as the first area and the second area. The first area is larger than the second area.

3. An elastic wave device, comprising: Mounting substrate; A first filter, disposed on the mounting substrate, has a first passband; The second filter, disposed adjacent to the first filter in a first direction on the mounting substrate, has a second passband that is lower than the first passband; A resin layer is used to seal the first filter and the second filter on the mounting substrate; and A conductive layer covers the resin layer. The first filter and the second filter each comprise: piezoelectric substrates; and An elastic wave resonator is disposed on the piezoelectric substrate. The first filter is connected to the conductive layer. The second filter is not connected to the conductive layer. The second filter is either a trapezoidal elastic wave filter containing at least one parallel arm resonator and at least one series arm resonator, or a longitudinally coupled elastic wave filter containing at least one longitudinally coupled resonator. The thermal resistance of the piezoelectric substrate of the second filter in the first direction is greater than the thermal resistance of the piezoelectric substrate of the first filter in the first direction. The second filter has the characteristic that its passband increases as the temperature of its piezoelectric substrate rises. In the piezoelectric substrate of the second filter, a region on the side of the first filter is designated as the first region, relative to an imaginary line orthogonal to the first direction and passing through the center of the piezoelectric substrate, and a region on the opposite side of the first filter is designated as the second region. All the parallel arm resonators included in the trapezoidal elastic wave filter are configured as parallel arm circuits, all the series arm resonators included in the trapezoidal elastic wave filter are configured as series arm circuits, and all the longitudinally coupled resonators included in the longitudinally coupled elastic wave filter are configured as longitudinally coupled circuits. In the first region and the second region, the areas of the regions forming the elastic wave resonators included in the series arm circuit or the longitudinal coupling circuit are respectively designated as the third area and the fourth area. The fourth area is larger than the third area.

4. An elastic wave device, comprising: Mounting substrate; A first filter, disposed on the mounting substrate, has a first passband; The second filter, disposed adjacent to the first filter in a first direction on the mounting substrate, has a second passband that is lower than the first passband; A resin layer is used to seal the first filter and the second filter on the mounting substrate; and A conductive layer covers the resin layer. The first filter and the second filter each comprise: piezoelectric substrates; and An elastic wave resonator is disposed on the piezoelectric substrate. The first filter is connected to the conductive layer. The second filter is not connected to the conductive layer. The second filter is either a trapezoidal elastic wave filter containing at least one parallel arm resonator and at least one series arm resonator, or a longitudinally coupled elastic wave filter containing at least one longitudinally coupled resonator. The thermal resistance of the piezoelectric substrate of the second filter in the first direction is greater than the thermal resistance of the piezoelectric substrate of the first filter in the first direction. The second filter has the characteristic that its passband decreases if the temperature of the piezoelectric substrate of the second filter increases. In the piezoelectric substrate of the second filter, a region on the side of the first filter is designated as the first region, relative to an imaginary line orthogonal to the first direction and passing through the center of the piezoelectric substrate, and a region on the opposite side of the first filter is designated as the second region. All the parallel arm resonators included in the trapezoidal elastic wave filter are configured as parallel arm circuits, all the series arm resonators included in the trapezoidal elastic wave filter are configured as series arm circuits, and all the longitudinally coupled resonators included in the longitudinally coupled elastic wave filter are configured as longitudinally coupled circuits. In the first region and the second region, the areas of the regions forming the elastic wave resonators included in the series arm circuit or the longitudinal coupling circuit are respectively designated as the third area and the fourth area. The third area is larger than the fourth area.

5. The elastic wave device according to any one of claims 1 to 4, wherein, The piezoelectric substrate of the first filter is silicon.

6. The elastic wave device according to any one of claims 1 to 5, wherein, The second filter includes an elastic wave resonator containing IDT electrodes, i.e., interdigital transducer electrodes.

7. The elastic wave device according to any one of claims 1 to 6, wherein, The elastic wave device is a multiplexer that connects the first filter and the second filter to a common terminal. The first filter functions as a transmission filter for transmitting signals through the common terminal. The second filter functions as a receiving filter for receiving signals received from the common terminal.

8. The elastic wave device according to any one of claims 1 to 7, wherein, The conductive layer is formed of a metallic material.

9. The elastic wave device according to claim 8, wherein, The conductive layer has a ground potential.

10. The elastic wave device according to any one of claims 1 to 9, wherein, The second filter includes a cover layer disposed between the piezoelectric substrate and the mounting substrate, wherein a hollow space is formed between the piezoelectric substrate and the cover layer. The elastic wave resonator included in the second filter is disposed on the piezoelectric substrate of the second filter in the hollow space.

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