Electroacoustic RF filter and multiplexer components

Abstract

An improved electroacoustic RF filter (FC) is provided. The RF filter includes an electroacoustic resonator (EAR) connected between an input port and an output port; an impedance element; and a damping and / or dissipating element (DE) in mechanical contact with the impedance element. The damping and / or dissipating element is provided and configured to remove acoustic energy from the impedance element, which has a similar construction to the resonator on the same substrate. With this construction, an acoustically inactive impedance element (AIIE) is achieved.

Description

Technical Field

[0001] The present invention relates to an electroacoustic RF filter and a multiplexer assembly that may include such a filter. The electroacoustic RF filter has improved filter performance and can be implemented with reduced chip space requirements. Background Art

[0002] RF filters can be used in devices for mobile or wireless communication systems. Electroacoustic RF filters incorporate electroacoustic resonators and other circuit components. Electroacoustic resonators use the piezoelectric effect to convert electromagnetic RF signals into acoustic waves. However, the corresponding other circuit components may need to be purely electrical and acoustically inactive.

[0003] Conventional RF filters may include SAW resonators (SAW = surface acoustic wave), BAW resonators (BAW = bulk acoustic wave), or GBAW resonators (GBAW = guided bulk acoustic wave). SAW resonators and GBAW resonators have an interdigitated electrode structure arranged on a piezoelectric material. BAW resonators have a sandwich structure comprising a bottom electrode, a top electrode, and a piezoelectric material between the bottom and top electrodes. When the acoustic effect is neglected, BAW resonators, SAW resonators, and GBAW resonators can be considered as capacitive elements. Therefore, structures similar to acoustically active structures can be used as impedance elements such as capacitive elements.

[0004] Using such a structure as a capacitive element reduces manufacturing effort. However, in conventional RF filters, such a capacitive element, which should be an ideal capacitive element without acoustic activity, appears to exhibit undesirable acoustic activity, thereby causing performance degradation of the corresponding RF filter.

[0005] Conventional RF filters reduce the acoustic activity of such purely capacitive elements by rotating the corresponding interdigitated structures relative to the piezoelectric axis of the piezoelectric material to reduce the electroacoustic coupling factor κ 2. Furthermore, the acoustic resonant frequency of the otherwise acoustically inactive circuit element can shift to a frequency range far from the operating frequency range of the RF filter.

[0006] However, each of these approaches has certain disadvantages. For example, changing the pitch of the IDT structure can lead to increased electrode finger resistance losses and increased manufacturing effort, for example, when smaller tolerances are involved. Summary of the Invention

[0007] Therefore, an object of the present invention is to provide an RF filter with improved filter performance. In particular, an object of the present invention is to reduce the contribution of acoustic activity to circuit elements that should be acoustically inactive. Correspondingly, an object of the present invention is to reduce undesirable acoustic resonances in an RF filter and to provide a corresponding filter assembly, such as a multiplexer assembly, for example, a duplexer assembly, having such an RF filter.

[0008] To this end, an electroacoustic RF filter according to embodiments of the present disclosure is provided, and preferred embodiments are further provided.

[0009] The electroacoustic RF filter includes an input port and an output port. Furthermore, the filter has an electroacoustic resonator electrically connected between the input port and the output port. Furthermore, the electroacoustic RF filter has an acoustically inactive impedance element electrically coupled to the electroacoustic resonator. Additionally, the filter has a damping and / or dissipating element connected to the acoustically inactive impedance element. The damping and / or dissipating element is provided and configured to remove acoustic energy from the inactive impedance element by dissipating acoustic energy, reducing coupling, or suppressing acoustic modes.

[0010] For example, this can be achieved by suppressing or preventing the accumulation of acoustic energy in the inactive impedance element. This can be achieved, for example, by increasing energy dissipation or by reducing electroacoustic excitation (ie, reducing coupling).

[0011] The electroacoustic coupling may even be completely deactivated by one or more damping and / or dissipating elements, resulting in a cut-off of the corresponding acoustic mode for all frequency ranges of interest.

[0012] Thus, an electroacoustic RF filter is provided in which damping and / or dissipative elements are used to remove acoustic energy from an otherwise acoustically inactive impedance element in order to reduce undesirable acoustic effects on the performance of the RF filter.

[0013] The RF filter may include other electroacoustic resonators connected between the input port and the output port. The electroacoustic resonators may be coupled in a ladder-like circuit topology with a series resonator electrically connected in series between the input port and the output port. A parallel resonator in the shunt path electrically connects the signal path to ground potential.

[0014] Furthermore, grid-like circuit topologies comprising one electroacoustic resonator or several electroacoustic resonators are also possible.In addition to single-port resonators, multi-port resonators or DMS (Dual Mode SAW) resonators can also be used.

[0015] The acoustically inactive impedance element can be electrically coupled to one or more of the electroacoustic resonators. However, the acoustically inactive impedance element can also be directly connected to at least one port of an electroacoustic resonator. The acoustically inactive impedance element can be an impedance element of an impedance matching circuit or the like. Capacitive elements are also often used to increase the steepness of the filter skirt by reducing the distance between the resonance and antiresonance of the resonator connected in parallel with the capacitive element.

[0016] The damping and / or dissipating element connected to the acoustically inactive impedance element can be directly and physically connected to the acoustically inactive impedance element, so that good energy transfer from the acoustically inactive impedance element to the damping and / or dissipating element can be achieved. The damping and / or dissipating element can then function as a dissipating element. Correspondingly, the term "inactive" means that the corresponding impedance element should have the lowest possible acoustic activity.

[0017] Thus, the electroacoustic RF filter of the present invention differs from conventional RF filters in that the IDT or sandwich structure is decoupled from its environment as much as possible to avoid energy dissipation. Thus, conventional RF filters include a housing in which the IDT or sandwich structure can be arranged in a cavity beneath a cover or protective layer.

[0018] The acoustically inactive impedance element may be a capacitive element or an inductive element.

[0019] In particular, the acoustically inactive impedance element may be a capacitive element and the electrode structure of the capacitive element may have a similar construction as the electrode structure of the electroacoustic resonator, since similar manufacturing steps for building the resonator and the acoustically inactive capacitive element may then be utilized.

[0020] It should be noted that the damping and / or dissipation elements do not necessarily need to remove as much acoustic energy as possible. In particular, it is sufficient to prevent or reduce the accumulation of acoustic energy in a specific frequency range. This frequency range may in particular be the operating frequency range of the electroacoustic RF filter or the frequency range of any other filter to which the electroacoustic RF filter is connected in a multiplexer environment (in particular for carrier aggregation).

[0021] Correspondingly, the electroacoustic resonator may be a SAW resonator, a BAW resonator or a GBAW resonator.Further, the acoustically inactive impedance element may include an interdigitated electrode structure or two electrodes separated by a dielectric layer between the electrodes.

[0022] Damping and / or dissipating elements can prevent or reduce acoustic energy accumulation by directing the acoustic energy away from the structure. Thus, the damping and / or dissipating elements can conduct the acoustic energy into components within the carrier substrate or housing of the RF filter, where it does not further degrade performance. However, damping and / or dissipating elements can also achieve a reduction in acoustic energy accumulation in other ways. Thus, the damping and / or dissipating elements can prevent acoustic energy accumulation within a specific frequency range by detuning the electrode structure of an acoustically inactive impedance element.

[0023] It is also possible to use damping and / or dissipating elements which operate in such a way that the electroacoustic excitation of the acoustic mode is greatly reduced, ie the coupling is reduced. Furthermore, by utilizing a cut-off condition, the excitation of the mode can be eliminated completely.

[0024] If the acoustically inactive impedance element has an interdigitated structure with interdigitated electrode fingers similar to a SAW resonator, the damping and / or dissipating element may include a material layer disposed below or above the electrode fingers of the IDT structure. The damping and / or dissipating element may include a dielectric element disposed between the corresponding electrode fingers. As its mass loading increases or decreases and / or through its specific mechanical stiffness parameters and corresponding detuning, the accumulation of acoustic energy in a specific frequency range may be reduced by shifting the corresponding acoustic energy to another location in space or another frequency range, or both.

[0025] If the acoustically inactive impedance element has a sandwich-like structure similar to a BAW resonator, the damping and / or dissipating element may comprise material of a layer arranged below the bottom electrode or above the top electrode or material between the bottom electrode and the top electrode.

[0026] Correspondingly, the electroacoustic resonator may have a first layer construction and the acoustically inactive impedance element may have a second layer construction. The first and second layer constructions differ in at least one parameter selected from the group consisting of the number of layers, layer thickness, layer material, and layer viscosity.

[0027] The acoustically inactive impedance element may also have an orientation that is rotated relative to the orientation of the electroacoustic resonator to further reduce the electroacoustic coupling coefficient κ2.

[0028] The viscosity of the damping and / or dissipating element may be higher than the viscosity of the material in the immediate vicinity of the electroacoustic resonator.

[0029] In this regard, the material in the immediate vicinity of the electroacoustic resonator may be in direct contact with the structure of the electroacoustic resonator, for example, in direct contact with an electrode structure of the resonator.

[0030] The electroacoustic resonator may be arranged in the housing based on a packaging technology selected from the group consisting of: TFAP packaging, CSSP packaging, CSSP+ packaging, DSSP packaging.

[0031] TFAP packages (TFAP = Thin Film Acoustic Package) use a thin film to protect sensitive structures from unwanted environmental influences. This thin film is characterized by the use of thin film material deposition techniques such as PVD (Physical Vapor Deposition), (CVD = Chemical Vapor Deposition), or MBE (Molecular Beam Epitaxy) material deposition techniques. CSSP packages (CSSP = Chip-Scale SAW Package) use a cover to protect the sensitive resonator structure. The CCSSP+ package is an improved version of the CSSP package. The DSSP package (DSSP = Chip-Scale SAW Package) uses the wafer material of the cover to protect the sensitive structure.

[0032] The protective film of the thin film encapsulation may have a thickness between 1 μm and 20 μm. In contrast, the width of the finger structures may range from 100 nm to 1 μm.

[0033] Elements of the housing may create damping and / or dissipating elements.

[0034] Thus, instead of increasing the complexity of the manufacturing process by adding additional layers or additional materials to the corresponding components, existing materials or existing elements can be arranged in direct contact with the acoustically inactive impedance element to prevent the accumulation of acoustic energy in the corresponding frequency range. Thus, the damping and / or dissipating element can be a layer or a segment of a layer of a CSSP package, a CSSP+ package, a DSSP package, or a TFAP package, or another type of package.

[0035] In particular, the membrane of the TFAP can be arranged at a distance above the electroacoustic resonator and directly on the acoustically inactive impedance element.

[0036] Cavities can be provided above and / or below the resonator structure and the packaging and / or additional cavities can be provided above and / or below the acoustically inactive impedance element and its packaging. However, the cavity between the acoustically inactive impedance element and its housing element can be filled with a specific material having favorable acoustic properties (i.e., viscosity), and / or stiffness and density parameters. Thus, the cavity can be filled with a specific atmosphere at a specific pressure, filled with a liquid or filled with a gel. In particular, liquids that are necessary during the manufacturing steps can be used. In particular, the manufacturing steps can also be simplified by omitting a protective device only from the location of the acoustically inactive impedance element, which protective device is applied at the location of the resonator to protect the resonator from the effects of the handling material during the manufacturing steps.

[0037] Acoustically inactive circuit elements may be directly covered by elements of the housing. This can be achieved by omitting the corresponding cavity that would otherwise be required above the resonator structure.

[0038] Correspondingly, one or more of the electro-acoustic filters described above may be utilized in a multiplexer (eg, a duplexer, triplexer, quadplexer, or multiplexer to a higher degree).

[0039] Therefore, there is provided an RF filter and a multiplexer assembly with improved electrical performance. Electrical performance is enhanced by suppressing the acoustic resonance of an impedance element that should be an ideal electrical impedance element. By removing acoustic energy from the impedance element within the corresponding frequency range, the acoustic resonance of such an impedance element is suppressed or reduced. Only when the complexity of the manufacturing process is slightly increased or even when the complexity of the manufacturing process is reduced, the device described above for improving the performance of the filter can be applied. The device does not require additional space and, in an embodiment in which the cavity is omitted, even requires less chip space. Therefore, the electroacoustic filter provided is compatible with the ongoing miniaturization trend. Especially when the number of cavities is reduced or when the cavity is filled with material, the physical stability of the corresponding assembly (especially for the force applied in the vertical direction) is improved.

[0040] Especially when the corresponding RF filter is implemented in a multiplexer such as a higher-order duplexer or multiplexer, and especially when the corresponding multiplexer is to be used in a carrier aggregation operating mode, not only the passband of the RF filter but also the performance in the adjacent frequency range is important. Damping and / or dissipation elements can improve the frequency characteristics not only within the passband or stopband, but also in the frequency ranges above and below the passband, in order to improve the cooperation of the corresponding RF filter with other corresponding RF filters in the multiplexer. For example, Figure 9 The improvement shown allows the use of corresponding RF filters in a multiplexer provided for the combination of frequency bands 41 and 7.

[0041] The position, arrangement, orientation and corresponding material parameters of the damping and / or dissipative elements, such as elastic tensor and density, can be selected so that resonances within a specific frequency range can be eliminated or shifted so that multiple corresponding frequency bands can be utilized within a single multiplexer or with a reduced number of filters in the multiplexer. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The main aspects of the electro-acoustic RF filters are shown in the accompanying schematic diagrams together with details of their operating principles and preferred embodiments.

[0043] In the accompanying drawings,

[0044] Figure 1 shows the technical details of the basic construction of the filter assembly FC;

[0045] Figure 2 A filter component based on a BAW structure is shown;

[0046] Figure 3 shows the use of thin film encapsulation;

[0047] Figure 4 shows a cross section of a film used as a damping and / or dissipating element;

[0048] Figure 5 Compatibility with traditional packaging technologies is shown;

[0049] Figure 6 shows a comparison of the transfer functions of a conventional filter and an RF filter as described above;

[0050] Figure 7 Different transfer functions within a specific frequency range are shown;

[0051] Figure 8 shows a comparison of the input reflection coefficients of a conventional filter and the filter as described above within a specific frequency range; and

[0052] Figure 9 A comparison between the output reflection coefficients of a conventional RF filter and the RF filter as described above is shown. DETAILED DESCRIPTION

[0053] Figure 1 The technical details of a filter assembly FC are shown, wherein a damping and / or dissipating element DE prevents or reduces the accumulation of acoustic energy at the location of an acoustically inactive impedance element AIIE, at least within a specific frequency range. The assembly comprises a carrier substrate CS on which an electroacoustic resonator EAR structure is arranged. Figure 1 The structure shown in the embodiment is an interdigitated structure (IDTS) of a SAW resonator (SAWR). This structure includes interdigitated electrodes arranged on a piezoelectric material. The piezoelectric effect is used to convert acoustic waves into electromagnetic RF signals. To function properly, an electroacoustic resonator (EAR) requires acoustic isolation of the vibrating structure.

[0054] In contrast, the structure of the acoustically inactive impedance element AIIE is in mechanical contact with the material of the damping and / or dissipating element DE, such that acoustic resonances are prevented or strongly reduced. Figure 1 The filter component FC shown utilizes electrode structures provided as interdigitated structures IDTS to create capacitive elements as acoustically inactive inductive elements AIIE.

[0055] The stiffness and viscosity parameters of the material of the damping and / or dissipating element DE, as well as its density, are selected so as to prevent or significantly reduce the accumulation of acoustic energy in a corresponding critical frequency range. The critical frequency range may be a range around the center frequency of a filter's passband or stopband, or in the carrier aggregation band in the case of a multiplexer.

[0056] Although Figure 1 The diagram shows a resonator structure with interdigitated electrode fingers and an impedance structure, but Figure 2 The following diagram illustrates a resonator structure and an inductor element structure based on a BAW architecture. An acoustically active resonator (EAR) is arranged on a carrier substrate (CS). The resonator (EAR) is provided as a BAW resonator (BAWR). The resonator has a bottom electrode (BE) and a top electrode (TE). A piezoelectric material (PM) is arranged between the bottom and top electrodes (BE and TE).

[0057] The resonator EAR is electrically coupled to an acoustically inactive impedance element AIIE. The impedance element is provided in the form of a sandwich construction SAC comprising a bottom electrode BE and a top electrode TE. A dielectric material is arranged between the bottom electrode BE and the top electrode TE. The dielectric material or at least a portion of the dielectric material is implemented by a damping and / or dissipating element DE. The provision of the damping and / or dissipating element DE results in a reduction in the accumulation of acoustic energy at the location of the impedance element AIIE within a specific frequency range. The construction of the impedance element is similar to that of the resonator. Accordingly, at least some of the manufacturing steps used to manufacture the resonator can be used to create the impedance element. By changing the thickness of the dielectric material between the bottom electrode BE and the top electrode TE, the accumulation of acoustic energy within the corresponding frequency range can be prevented or reduced.

[0058] Figure 3 The diagram illustrates the possibility of using a thin film TF to protect the sensitive structures of an electroacoustic resonator (EAR). The same film can also be used to protect the structure of an acoustically inactive impedance element (AIIE). The material of the damping and / or dissipating element DE can be arranged below the electrode structure of the impedance element. The material of the damping and / or dissipating element DE can be embedded in the carrier substrate below the electrode structure of the impedance element. However, the material of the dielectric element DE can also be arranged on the top surface of the carrier substrate, and the electrode structure of the impedance element can also be arranged on the material of the damping and / or dissipating element above the top surface of the carrier substrate CS.

[0059] Figure 4The diagram shows details of an embodiment in which the material of the thin film TF serves as the damping and / or dissipative element DE. This material is in direct contact with the electrode structure of the acoustically inactive impedance element (AIIE). This direct contact improves the efficiency of conducting acoustic energy out of the impedance element. Alternatively, the DE can also reduce electroacoustic excitation. In addition to improving performance, the size of the AIIE can be reduced because a safety margin between the thin film platform and the IDT structure is no longer required.

[0060] However, the application of damping and / or dissipating elements DE is also compatible with other housing technologies. Figure 5 The technical details of the filter circuit are shown, in which a conventional cover C is used to protect the sensitive electrode structure of the electroacoustic resonator EAR. In the same cavity, the structure of the impedance element AIIE and the material of the damping and / or dissipation element DE can be arranged.

[0061] Figure 6 The transfer function S of a traditional electroacoustic bandpass filter is shown in the figure. 21 A comparison of the transfer function of an electroacoustic RF filter comprising damping and / or dissipative elements in direct contact with the impedance element is shown. It can be clearly seen that the transfer function remains unchanged within the passband around 1800 MHz. However, the resonance that creates distortion in the transfer function of the conventional filter around 2600 MHz is significantly reduced. The filter assembly (shown in FIG. 1 ) Figure 6 The improved transfer function in ) is based on a filter component with a TFAP package, where the thin film material is in direct contact with the structure of the impedance element, such as Figure 4 shown.

[0062] Figure 7 The corresponding critical frequency range around 2600 MHz is shown in an enlarged view. The solid line shows the transfer function of the conventional filter assembly. The dashed line shows the improved transfer function according to the improved RF filter.

[0063] For the same critical frequency range, Figure 8 The input reflection coefficient S of the conventional filter (solid line) and the improved filter (dashed line) are shown. 11 Conventional filters have two frequencies where the reflection coefficient is significantly reduced. One of the two significant reductions in the reflection coefficient is eliminated in the improved electro-acoustic RF filter.

[0064] Correspondingly, Figure 9 The output reflection coefficient is shown in the critical frequency range. The solid line shows a significant reduction in the reflection coefficient between 2600 MHz and 2650 MHz. The improved RF filter (dashed line) has a significantly improved reflection coefficient in this frequency range, making it suitable for carrier aggregation.

[0065] The electroacoustic RF filters and multiplexers are not limited to the technical details described above or shown in the accompanying drawings. The RF filters may include other circuit elements and other resonators. Several electroacoustic RF filters as described above can be used together or with conventional RF filters to create improved multiplexer circuits and multiplexer assemblies.

[0066] Reference Signs List

[0067] FC: Filter Component

[0068] CS: Carrier Substrate

[0069] EAR: Electroacoustic Resonator

[0070] SAWR: SAW resonator

[0071] IDTS: Interdigitated Electrode Structure

[0072] DE: Damping and / or dissipative element

[0073] AIIE: Acoustically Inactive Impedance Element

[0074] BE: bottom electrode

[0075] TE: Top Electrode

[0076] PM: Piezoelectric Materials

[0077] SAC: Sandwich construction

[0078] BAWR: BAW resonator

[0079] TF: Thin film layer of thin film encapsulation

[0080] C: Capacitor

[0081] S 21 : transfer function

[0082] S 11 : Reflection factor (at the input port)

[0083] S 22 : Reflection factor (at the output port)

[0084] In the following, further embodiments are described to facilitate understanding of the present invention:

[0085] 1. An electroacoustic RF filter comprising

[0086] - input ports and output ports,

[0087] - an electroacoustic resonator electrically connected between the input port and the output port,

[0088] - an acoustically inactive impedance element electrically coupled to the electroacoustic resonator, and

[0089] - a damping and / or dissipating element connected to said acoustically inactive impedance element,

[0090] in

[0091] - the damping and / or dissipating element is provided and configured to remove acoustic energy from the passive impedance element by dissipation of the acoustic energy, or by reducing coupling, or by suppressing acoustic modes.

[0092] 2. The electro-acoustic RF filter according to the preceding embodiment, wherein the acoustically inactive impedance element is a capacitive element or an inductive element.

[0093] 3. The electroacoustic RF filter according to one of the preceding embodiments, wherein

[0094] - the electroacoustic resonator is a SAW resonator, a BAW resonator or a GBAW resonator, and

[0095] - the acoustically inactive impedance element comprises an interdigitated electrode structure or two electrodes separated by a dielectric layer between the electrodes.

[0096] 4. The electroacoustic RF filter according to one of the preceding embodiments, wherein

[0097] - the electroacoustic resonator has a first layer construction and the acoustically inactive impedance element has a second layer construction, and the first layer construction and the second layer construction differ in at least one parameter selected from the group consisting of: number of layers, thickness of layers, material of layers and viscosity of layers.

[0098] 5. The electro-acoustic RF filter according to one of the preceding embodiments, wherein the acoustically inactive impedance element has an orientation that is rotated relative to the orientation of the electro-acoustic resonator.

[0099] 6. Electroacoustic RF filter according to one of the preceding embodiments, wherein the damping and / or dissipating element has a higher viscosity than the directly adjacent material of the electroacoustic resonator.

[0100] 7. The electro-acoustic RF filter according to one of the preceding embodiments, wherein the electro-acoustic resonator is arranged in a housing based on a packaging technology selected from the group consisting of: TFAP packaging, CSSP packaging, CSSP+ packaging, DSSP packaging.

[0101] 8. The electro-acoustic RF filter according to the preceding embodiment, wherein elements of the housing establish the damping and / or dissipating elements.

[0102] 9. The electro-acoustic RF filter according to one of the preceding embodiments, wherein the acoustically inactive circuit element is directly covered by an element of the housing.

[0103] 10. A multiplexer assembly comprising the electroacoustic filter of one of the preceding embodiments.

Claims

1. An electroacoustic RF filter comprising - input ports and output ports, - an electroacoustic resonator electrically connected between the input port and the output port, - an acoustically inactive impedance element electrically coupled to the electroacoustic resonator, and - a damping and / or dissipating element, in mechanical contact with said acoustically inactive impedance element, wherein - the damping and / or dissipating element is provided and configured to remove acoustic energy from the inactive impedance element by dissipation of the acoustic energy or by reducing coupling, wherein the damping and / or dissipating element has a higher viscosity than the material in the immediate vicinity of the electroacoustic resonator. 2 . The electroacoustic RF filter according to claim 1 , wherein the acoustically inactive impedance element is a capacitive element or an inductive element.

3. The electroacoustic RF filter according to claim 1 or 2, wherein - the electroacoustic resonator is a SAW resonator, a BAW resonator or a GBAW resonator, and - the acoustically inactive impedance element comprises an interdigitated electrode structure or two electrodes separated by a dielectric layer between the electrodes.

4. The electroacoustic RF filter according to claim 1 or 2, wherein - the electroacoustic resonator has a first layer construction and the acoustically inactive impedance element has a second layer construction, and the first layer construction and the second layer construction differ in at least one parameter selected from the group consisting of: number of layers, thickness of layers, material of layers and viscosity of layers.

5. The electro-acoustic RF filter according to claim 1 or 2, wherein the acoustically inactive impedance element has an orientation that is rotated relative to the orientation of the electro-acoustic resonator. The electro-acoustic RF filter according to claim 1 , wherein the electro-acoustic resonator is arranged in a housing based on a packaging technology selected from the group consisting of: TFAP packaging, CSSP packaging, CSSP+ packaging, and DSSP packaging.

7. An electro-acoustic RF filter according to claim 6, wherein elements of the housing establish the damping and / or dissipating elements.

8. The electro-acoustic RF filter of claim 6, wherein the acoustically inactive circuit element is directly covered by an element of the housing.

9. A multiplexer assembly comprising the electroacoustic filter according to any one of claims 1 to 8.

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