Acoustic resonator filter

Abstract

The present disclosure provides an acoustic resonator filter including: a series unit including at least one series acoustic resonator electrically connected in series between a first port and a second port through which a radio frequency (RF) signal passes; a first shunt unit disposed in a first shunt connection path between the at least one series acoustic resonator and a ground, the first shunt unit including a plurality of shunt acoustic resonators connected in series with each other and having different resonance frequencies; and a second shunt unit disposed in a second shunt connection path between the at least one series acoustic resonator and the ground, the second shunt unit including at least one shunt acoustic resonator and having an inductance higher than an inductance of the first shunt unit.

Description

[0001] This application claims the benefit of priority to Korean Patent Application No. 10-2020-0152505, filed with the Korean Intellectual Property Office on November 16, 2020, the entire disclosure of which is incorporated herein by reference for all purposes. Technical Field

[0002] The following description relates to an acoustic resonator filter. Background Technology

[0003] Recently, with the rapid development of mobile communication devices, chemical and biological testing devices, and other electronic devices, the demand for small and lightweight filters, oscillators, resonant elements, and acoustic resonant quality sensors used in these devices has increased.

[0004] Because acoustic resonators are very small and offer excellent performance compared to, for example, dielectric filters, metallic cavity filters, and waveguides, they (such as bulk acoustic wave (BAW) filters) can be configured to implement small and lightweight filters, oscillators, resonant elements, acoustic resonant mass sensors, and other components. Such acoustic resonators are widely used in communication modules of modern mobile devices that require good performance (e.g., wide passband width). Summary of the Invention

[0005] This summary is provided to introduce the selected concept in a simplified form, and the concept is further described below in detail in the specific embodiments. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used to help determine the scope of the claimed subject matter.

[0006] In one general aspect, an acoustic resonator filter includes: a series unit comprising at least one series acoustic resonator connected in series between a first port and a second port through which a radio frequency (RF) signal passes; a first shunt unit disposed in a first shunt connection path between the at least one series acoustic resonator and ground, the first shunt unit comprising a plurality of shunt acoustic resonators connected in series with each other and having different resonant frequencies; and a second shunt unit disposed in a second shunt connection path between the at least one series acoustic resonator and ground, the second shunt unit comprising at least one shunt acoustic resonator and having an inductance higher than that of the first shunt unit.

[0007] The acoustic resonator filter may further include a third branch unit, which is disposed in a third branch connection path between the at least one series acoustic resonator and the ground and includes at least one branch acoustic resonator. The resonant frequency of the at least one branch acoustic resonator included in the third branch unit is lower than a higher resonant frequency among the plurality of resonant frequencies of the plurality of branch acoustic resonators included in the first branch unit, and lower than the resonant frequency of the at least one branch acoustic resonator included in the second branch unit.

[0008] The resonant frequency of the at least one shunt acoustic resonator included in the third shunt unit may be the same as the lower of the plurality of resonant frequencies of the plurality of shunt acoustic resonators included in the first shunt unit.

[0009] The higher of the plurality of resonant frequencies of the plurality of shunt acoustic resonators included in the first shunt unit may be equal to or higher than the resonant frequency of the at least one series acoustic resonator.

[0010] The higher of the plurality of resonant frequencies of the plurality of shunt acoustic resonators of the first shunt unit may be higher than the resonant frequency of at least one shunt acoustic resonator of the second shunt unit.

[0011] The acoustic resonator filter may further include multiple third-splitter units, which are respectively arranged in multiple third-splitter connection paths between the at least one series acoustic resonator and the ground. Each of the multiple third-splitter units may include at least one branch acoustic resonator, and the resonant frequency of the at least one branch acoustic resonator included in the multiple third-splitter unit is lower than the higher resonant frequency among the different resonant frequencies of the multiple branch acoustic resonators included in the first-splitter unit.

[0012] The at least one series acoustic resonator may include a plurality of series acoustic resonators electrically connected among the plurality of third branch units. The first branch unit may be electrically connected between a node between the plurality of series acoustic resonators and the ground.

[0013] The first branch unit may include a plurality of first branch units, which are arranged in multiple first branch connection paths between the at least one series acoustic resonator and the ground. One of the plurality of first branch units may include the plurality of branch acoustic resonators. Another of the plurality of first branch units may include a further plurality of branch acoustic resonators, which are connected in series with each other and have different resonant frequencies.

[0014] The at least one series acoustic resonator may include one or more series acoustic resonators electrically connected between the plurality of first branch units.

[0015] The second shunt unit may further include an inductor, which is electrically connected in series with the at least one shunt acoustic resonator included in the second shunt unit.

[0016] In another general aspect, an acoustic resonator filter includes: at least one series acoustic resonator electrically connected in series between a first port and a second port through which a radio frequency (RF) signal passes; at least one second shunt acoustic resonator electrically connected between the at least one series acoustic resonator and ground; a plurality of first shunt acoustic resonators electrically connected between the at least one series acoustic resonator and ground, wherein the resonant frequencies of the plurality of first shunt acoustic resonators are higher than the resonant frequencies of the at least one second shunt acoustic resonator; and an inductor electrically connected in series with a portion of the plurality of first shunt acoustic resonators. At least one of the remaining portions of the plurality of first shunt acoustic resonators is electrically connected in series with the at least one second shunt acoustic resonator.

[0017] The resonant frequency of at least one of the remaining portions of the plurality of first shunt acoustic resonators may be equal to or higher than the resonant frequency of the at least one series acoustic resonator.

[0018] The resonant frequency of a portion of the plurality of first shunt acoustic resonators may be lower than the resonant frequency of at least one of the remaining portions of the plurality of first shunt acoustic resonators.

[0019] The at least one second-splitter acoustic resonator may include a plurality of second-splitter acoustic resonators. The number of the plurality of second-splitter acoustic resonators may be greater than the number of the plurality of first-splitter acoustic resonators.

[0020] The number of the at least one first shunt acoustic resonator in the remaining portion of the plurality of first shunt acoustic resonators that are connected in series with the at least one second shunt acoustic resonator may be greater than the number of the first shunt acoustic resonators in the portion of the plurality of first shunt acoustic resonators that are connected in series with the inductor.

[0021] The inductance of the branch connection path provided with the inductor can be greater than each of the multiple inductors in the multiple branch connection paths provided with the at least one second branch acoustic resonator.

[0022] Other features and aspects will become apparent from the following detailed description, drawings, and claims. Attached Figure Description

[0023] Figures 1A to 1H This is a diagram illustrating an acoustic resonator filter according to an embodiment.

[0024] Figure 2A This illustrates an embodiment. Figure 1G The graph shows the bandwidth of the acoustic resonator filter.

[0025] Figure 2B This illustrates an embodiment. Figure 1G The graph shows the S-parameters of the acoustic resonator filter.

[0026] Figure 3A This illustrates an embodiment. Figure 1H The graph shows the bandwidth of the acoustic resonator filter.

[0027] Figure 3B This illustrates an embodiment. Figure 1H The graph shows the S-parameters of the acoustic resonator filter.

[0028] Figure 4 This is a side view showing the detailed structure of the acoustic resonator of the acoustic resonator filter according to an embodiment.

[0029] Throughout the accompanying drawings and detailed embodiments, the same reference numerals indicate the same elements. The drawings may not be drawn to scale, and for clarity, illustration, and convenience, the relative sizes, scales, and depictions of the elements in the drawings may be exaggerated. Detailed Implementation

[0030] The following detailed embodiments are provided to aid the reader in gaining a comprehensive understanding of the methods, apparatus, and / or systems described herein. However, various changes, modifications, and equivalents of the methods, apparatus, and / or systems described herein will become apparent upon understanding this disclosure. For example, the order of operations described herein is merely illustrative and is not limited to the order set forth herein; changes may be made that will become apparent upon understanding this disclosure, except for operations that must occur in a specific order. Furthermore, descriptions of features known in the art may be omitted for clarity and brevity.

[0031] The features described herein may be implemented in different forms and are not to be construed as limited to the examples described herein. Rather, the examples provided herein are merely to illustrate some of the many feasible ways in which the methods, apparatus, and / or systems described herein will become apparent upon understanding this disclosure. Embodiments of this disclosure will be described in detail below with reference to the accompanying drawings, and it should be noted that the examples are not limited to the embodiments described.

[0032] Throughout this specification, when an element (such as a layer, region, or substrate) is described as being "on" another element, "connected" to another element, or "bonded" to another element, the element may be directly "on" said other element, directly "connected" to said other element, or directly "bonded" to said other element, or there may be one or more other elements in between. In contrast, when an element is described as being "directly on" another element, directly "connected" to another element, or "bonded" to another element, there are no other elements in between. As used herein, a "part" of an element may include the entire element or less than the entire element.

[0033] As used herein, the term “and / or” includes any one or any combination of two or more of the relevant listed items; similarly, “at least one of…” includes any one or any combination of two or more of the relevant listed items.

[0034] Although terms such as “first,” “second,” and “third” may be used herein to describe various components, assemblies, regions, layers, or parts, these components, assemblies, regions, layers, or parts will not be limited by these terms. Rather, these terms are used only to distinguish one component, assembly, region, layer, or part from another. Therefore, without departing from the teaching of the examples described herein, the first component, first assembly, first region, first layer, or first part mentioned in the examples may also be referred to as a second component, second assembly, second region, second layer, or second part.

[0035] For ease of description, spatial relative terms such as “above,” “above,” “below,” and “under” are used herein to describe the relationship between one element and another as shown in the accompanying drawings. Such spatial relative terms are intended to include not only the orientation depicted in the drawings but also the different orientations of the device during use or operation. For example, if the device in the drawings is flipped, an element described as being “above” or “above” relative to another element will be located “below” or “under” relative to that other element. Therefore, the term “above” includes both “above” and “below” orientations depending on the spatial orientation of the device. The device may also be positioned in other ways (rotated 90 degrees or in other orientations), and the spatial relative terms used herein will be interpreted accordingly.

[0036] The terminology used herein is for the purpose of describing various examples only and is not intended to limit this disclosure. Unless the context clearly indicates otherwise, the singular form is intended to include the plural form as well. The terms “comprising,” “including,” and “having” enumerate the presence of the stated features, quantities, operations, components, elements, and / or combinations thereof, but do not exclude the presence or addition of one or more other features, quantities, operations, components, elements, and / or combinations thereof.

[0037] The features of the examples described herein can be combined in various ways that will become apparent upon understanding this disclosure. Furthermore, although the examples described herein have various configurations, other configurations that will become apparent upon understanding this disclosure are possible.

[0038] Here, the use of the term “may” in relation to an example (e.g., what an example may include or implement) means that there exists at least one example that includes or implements such a feature, but is not limited to all examples that include or implement such a feature.

[0039] Figure 1A This is a diagram illustrating an acoustic resonator filter 50a according to an embodiment.

[0040] Reference Figure 1A The acoustic resonator filter 50a may include a series unit 10a, a first branch unit 20g, and a second branch unit 30. Depending on the frequency of the radio frequency (RF) signal, the RF signal can be allowed to pass between the first port P1 and the second port P2, or the RF signal can be blocked between the first port P1 and the second port P2.

[0041] The acoustic resonator filter 50a may include at least one series acoustic resonator 12, a plurality of first shunt acoustic resonators 21 and 31, and at least one second shunt acoustic resonator 22.

[0042] The electrical connection node between at least one series acoustic resonator 12, a plurality of first shunt acoustic resonators 21 and 31, and at least one second shunt acoustic resonator 22 can be implemented using materials with relatively low resistivity (such as gold (Au), gold-tin (Au-Sn) alloys, copper (Cu), copper-tin (Cu-Sn) alloys, aluminum (Al), aluminum alloys, etc.), but is not limited to the examples described above.

[0043] At least one series acoustic resonator 12, multiple first-splitter acoustic resonators 21 and 31, and at least one second-splitter acoustic resonator 22 can each convert the electrical energy of the RF signal into mechanical energy through piezoelectric properties, and can also convert mechanical energy into electrical energy through piezoelectric properties. As the frequency of the RF signal approaches the resonant frequency of the acoustic resonator, the energy transfer rate between the multiple electrodes can be significantly increased. As the frequency of the RF signal approaches the anti-resonant frequency of the acoustic resonator, the energy transfer rate between the multiple electrodes can be significantly decreased. According to piezoelectric properties, the anti-resonant frequency can be higher than the resonant frequency.

[0044] At least one series acoustic resonator 12 may be connected in series between the first port P1 and the second port P2. As the frequency of the RF signal approaches the resonant frequency of the at least one series acoustic resonator 12, the transmittance of the RF signal between the first port P1 and the second port P2 may increase. As the frequency of the RF signal approaches the anti-resonant frequency of the at least one series acoustic resonator 12, the transmittance of the RF signal between the first port P1 and the second port P2 may decrease.

[0045] At least one second shunt acoustic resonator 22 may be electrically connected between at least one series acoustic resonator 12 and ground. The RF signal to ground throughput may increase as the frequency of the RF signal approaches the resonant frequency of at least one second shunt acoustic resonator 22, and may decrease as the frequency of the RF signal approaches the anti-resonant frequency of at least one second shunt acoustic resonator 22.

[0046] The transmittance of the RF signal between the first port P1 and the second port P2 decreases as the transmittance of the RF signal to ground increases. The transmittance of the RF signal between the first port P1 and the second port P2 increases as the transmittance of the RF signal to ground decreases.

[0047] In other words, as the frequency of the RF signal approaches the resonant frequency of at least one second shunt acoustic resonator 22 or the anti-resonant frequency of at least one series acoustic resonator 12, the throughput of the RF signal between the first port P1 and the second port P2 can be reduced.

[0048] Since the anti-resonance frequency is higher than the resonant frequency, the acoustic resonator filter 50a may have a passband with a lowest frequency corresponding to the resonant frequency of at least one second shunt acoustic resonator 22 and a highest frequency corresponding to the anti-resonance frequency of at least one series acoustic resonator 12.

[0049] The passband width can increase as the difference between the resonant frequency of at least one second shunt acoustic resonator 22 and the anti-resonant frequency of at least one series acoustic resonator 12 increases. However, if the difference between the resonant frequency of at least one second shunt acoustic resonator 22 and the anti-resonant frequency of at least one series acoustic resonator 12 is too high, the passband may be split.

[0050] If the resonant frequency of at least one series acoustic resonator 12 is slightly higher than the anti-resonant frequency of at least one second shunt acoustic resonator 22, the bandwidth of the acoustic resonator filter 50a can be wide and not segmented.

[0051] In an acoustic resonator, the difference between the resonant frequency and the anti-resonant frequency can be determined based on the physical characteristic kt of the acoustic resonator. 2 The electromechanical coupling factor is used to determine the frequency, and if the size or shape of the acoustic resonator changes, the resonant frequency and the anti-resonant frequency can change together.

[0052] The series unit 10a may include at least one series acoustic resonator 12 that is electrically connected in series between the first port P1 and the second port P2.

[0053] The first shunt unit 20g may be disposed in a first shunt connection path between at least one series acoustic resonator 12 and ground, and may include a first shunt acoustic resonator 21 and a second shunt acoustic resonator 22, which are connected in series and have different resonant frequencies. The resonant frequency of the first shunt acoustic resonator 21 may be higher than the resonant frequency of the second shunt acoustic resonator 22.

[0054] When the first shunt acoustic resonator 21 and the second shunt acoustic resonator 22 are connected in series, they can function as capacitors for each other, thus increasing their resonant frequencies. Consequently, the resonant frequencies of the first shunt acoustic resonator 21 and the second shunt acoustic resonator 22 can become closer to their respective anti-resonant frequencies.

[0055] Therefore, the transmission zeros and poles can be formed near the resonant frequencies of the first branch acoustic resonator 21 and the second branch acoustic resonator 22, and can be formed near the passband of the acoustic resonator filter 50a, thereby improving the attenuation characteristics of the passband. In other words, the transmission zeros and poles can increase the rate of change of admittance according to the frequency (freq) at the lowest and / or highest frequencies of the passband, and provide a sharp roll-off characteristic for the acoustic resonator filter 50a.

[0056] The second shunt unit 30 may be disposed in the second shunt connection path between at least one series acoustic resonator 12 and ground, and may include at least one first shunt acoustic resonator 31. The inductance of the second shunt unit 30 may be higher than that of the first shunt unit 20g. For example, the second shunt unit 30 may also include an inductor 36 connected in series with at least one first shunt acoustic resonator 31.

[0057] The first shunt acoustic resonator 31, as part of a plurality of first shunt acoustic resonators, can be connected in series with the inductor 36, and the first shunt acoustic resonator 21, as another part of a plurality of first shunt acoustic resonators, can be connected in series with the second shunt acoustic resonator 22.

[0058] The additional inductance resulting from the addition of inductor 36 to the second shunt unit 30 contributes to the resonant frequency of the second shunt unit 30, but essentially does not contribute to its anti-resonant frequency. In other words, the characteristics of the second shunt unit 30 with increased inductance are comparable to those with increased kt. 2 The characteristics are similar to those of acoustic resonators.

[0059] When kt 2 When the frequency increases, the difference between the resonant frequency and the anti-resonant frequency of the acoustic resonator increases, so that the difference between the resonant frequency and the anti-resonant frequency of the second shunt unit 30 can be greater than the difference between the resonant frequency and the anti-resonant frequency of the first shunt unit 20g.

[0060] Since the difference between the resonant frequency and anti-resonant frequency of the second branch unit 30 is greater than the difference between the resonant frequency and anti-resonant frequency of the first branch unit 20g, the second branch unit 30 can compensate for the passband cut-off caused by the significant increase in the difference between the resonant frequency of the second branch acoustic resonator 22 of the first branch unit 20g and the anti-resonant frequency of at least one series acoustic resonator 12. Therefore, the passband width of the acoustic resonator filter 50a can be further widened.

[0061] The second splitting unit 30 can further widen the bandwidth formed by the combination of the first splitting unit 20g and the series unit 10a, and the first splitting unit 20g can make the roll-off characteristics of the passband formed by the combination of the second splitting unit 30 and the series unit 10a sharper.

[0062] The acoustic resonator filter 50a achieves a wider passband through the second splitter unit 30 and a sharper roll-off characteristic through the first splitter unit 20g. Furthermore, since the acoustic resonator filter 50a can have a structure in which the first splitter unit 20g and the second splitter unit 30 are complementary to each other, a wide passband and a sharp roll-off characteristic can be effectively obtained, and the balance between passband width and roll-off characteristic can be more effectively matched according to the required standards of the acoustic resonator filter 50a.

[0063] For example, the resonant frequency of the first branch acoustic resonator 31 of the second branch unit 30 may be higher than the resonant frequency of the second branch acoustic resonator 22 of the first branch unit 20g. For example, the resonant frequency of the first branch acoustic resonator 21 of the first branch unit 20g may be higher than the resonant frequency of the first branch acoustic resonator 31 of the second branch unit 30, or the resonant frequency of the first branch acoustic resonator 21 of the first branch unit 20g may be higher than or equal to the resonant frequency of at least one series acoustic resonator 12.

[0064] Therefore, the complementarity between the first branch unit 20g and the second branch unit 30 can be further improved, so that the acoustic resonator filter 50a can more effectively obtain a wide passband and a sharp roll-off characteristic.

[0065] Figures 1B to 1H These are diagrams illustrating acoustic resonator filters 50b to 50h according to embodiments.

[0066] Reference Figure 1B ,and Figure 1A Compared to the at least one series acoustic resonator 12 shown, at least one series acoustic resonator 12 of the series unit 10b of the acoustic resonator filter 50b can be positioned closer to the first port P1. Therefore, the first branch unit 20g and the second branch unit 30 can be connected to each other, while at least one series acoustic resonator 12 is not disposed between the first branch unit 20g and the second branch unit 30. That is, the series unit 10b can be connected between the first port P1 and the first branch unit 20g.

[0067] Reference Figure 1CIn the acoustic resonator filter 50c, the series unit 10c may include a plurality of series acoustic resonators 12 and 16, and the first shunt unit 20g may be electrically connected between the nodes of the plurality of series acoustic resonators 12 and 16 and ground. The number of the plurality of series acoustic resonators 12 and 16 may be appropriately set according to the required standards of the acoustic resonator filter 50c.

[0068] Reference Figure 1D The acoustic resonator filter 50d may include a series unit 10d, which includes multiple series acoustic resonators 12, 13 and 16, and in addition to the first branch unit 20g and the second branch unit 30, the acoustic resonator filter 50d may also include a third branch unit 40d.

[0069] The third branch unit 40d may be disposed in the third branch connection path between the plurality of series acoustic resonators 12, 13 and 16 and ground, and may include the second branch acoustic resonator 42-1. For example, the third branch unit 40d may be connected between the node between the series acoustic resonators 12 and 13 and ground. The resonant frequency of the second branch acoustic resonator 42-1 may be lower than the higher of the plurality of resonant frequencies of the first branch acoustic resonator 21 and the second branch acoustic resonator 22 of the first branch unit 20g, and lower than the resonant frequency of the first branch acoustic resonator 31 of the second branch unit 30.

[0070] Therefore, the second branch acoustic resonator 42-1 of the third branch unit 40d can form a pole near the lowest frequency of the bandwidth of the acoustic resonator filter 50d, and the roll-off characteristic near the lowest frequency of the bandwidth of the acoustic resonator filter 50d can be sharper. For example, the resonant frequency of the second branch acoustic resonator 42-1 of the third branch unit 40d can be the same as a lower resonant frequency among the multiple resonant frequencies of the first branch acoustic resonator 21 and the second branch acoustic resonator 22 of the first branch unit 20g.

[0071] As the number of multiple series acoustic resonators 12, 13 and 16 in the series unit 10d increases, the roll-off characteristics near the highest frequency of the bandwidth of the acoustic resonator filter 50d can become sharper.

[0072] The inductance of the second branch unit 30 may be greater than the inductance of each of the first branch unit 20g and the third branch unit 40d.

[0073] Reference Figure 1EThe third branch unit 40e of the acoustic resonator filter 50e according to the exemplary embodiments of the present disclosure may include a plurality of third branch units 40-1 and 40-4, each of which is disposed in one of a plurality of third branch connection paths between a plurality of series acoustic resonators 11, 12, 13 and 16 and ground.

[0074] Multiple third branch units 40-1 and 40-4 may each include second branch acoustic resonators 42-1 and 42-4, the resonant frequencies of which are lower than the higher of the multiple resonant frequencies of the first branch acoustic resonator 21 and the second branch acoustic resonator 22 of the first branch unit 20g.

[0075] The series unit 10e may include series acoustic resonators 11 and 12 electrically connected between a plurality of third branch units 40-1 and 40-4, and the first branch unit 20g may be electrically connected between the node between the series acoustic resonators 11 and 12 and ground.

[0076] Therefore, the first branch unit 20g can be configured to be farther from the first port P1 than the third branch unit 40-1 and farther from the second port P2 than the third branch unit 40-4, and can be relatively less affected by external noise or heat generated by the power of the RF signal. Thus, the transmission zeros and poles formed by the first branch unit 20g can be formed more stably (e.g., more resistant to temperature changes), and the acoustic resonator filter 50e can have a more stable roll-off characteristic.

[0077] Reference Figure 1F The third branch unit 40f of the acoustic resonator filter 50f may include multiple third branch units 40-2, 40-3, and 40-4, each of which includes second branch acoustic resonators 42-2, 42-3, and 42-4. The series unit 10f may include multiple series acoustic resonators 11, 12, 14, 15, and 16. The multiple third branch units 40-2, 40-3, and 40-4 may be electrically connected to ground in corresponding connection paths between nodes of the multiple series acoustic resonators 11, 12, 14, 15, and 16. For example, third branch unit 40-2 may be connected at the node between series acoustic resonators 14 and 15, third branch unit 40-3 may be connected at the node between series acoustic resonators 15 and 16, and third branch unit 40-4 may be connected at the node between series acoustic resonators 11 and 14.

[0078] The number of second-branch acoustic resonators 22, 42-2, 42-3, and 42-4 can be greater than the number of first-branch acoustic resonators 21 and 31.

[0079] Therefore, the second branch acoustic resonators 22, 42-2, 42-3, and 42-4 can form the main bandwidth of the acoustic resonator filter 50f, and the first branch acoustic resonators 21 and 31 can widen the main bandwidth of the acoustic resonator filter 50f or make the roll-off characteristic of the main bandwidth sharper.

[0080] Reference Figure 1G The third branch unit 40g of the acoustic resonator filter 50g may include multiple third branch units 40-1, 40-2, 40-3, and 40-4, and the multiple third branch units 40-1, 40-2, 40-3, and 40-4 respectively include second branch acoustic resonators 42-1, 42-2, 42-3, and 42-4. The series unit 10g of the acoustic resonator filter 50g may include multiple series acoustic resonators 11, 12, 13, 14, 15, and 16.

[0081] Reference Figure 1H The third branch unit 40h of the acoustic resonator filter 50h may include multiple third branch units 40-1, 40-2, and 40-3, and the multiple third branch units 40-1, 40-2, and 40-3 respectively include second branch acoustic resonators 42-1, 42-2, and 42-3. The first branch unit 20h of the acoustic resonator filter 50h may include multiple first branch units 20-1 and 20-2, and the multiple first branch units 20-1 and 20-2 are arranged in multiple first branch connection paths between the multiple series acoustic resonators 11, 12, 13, 14, 15, and 16 and ground.

[0082] Multiple first branch units 20-1 and 20-2 may each include first branch acoustic resonators 21-1 and 21-2, and may each include second branch acoustic resonators 22-1 and 22-2.

[0083] One of the series acoustic resonators 11 of the series unit 10h, 11, 12, 13, 14, 15 and 16, can be electrically connected between the multiple first branch units 20-1 and 20-2.

[0084] The number of first shunt acoustic resonators 21-1 and 21-2, which are connected in series with the second shunt acoustic resonators 22-1 and 22-2 respectively, can be greater than the number of first shunt acoustic resonators 31 connected in series with the inductor 36. Therefore, the roll-off characteristic of the acoustic resonator filter 50h can be sharper.

[0085] Figure 2A It is shown Figure 1G The graph shows the bandwidth of the 50g acoustic resonator filter. Figure 2B It is shown Figure 1GThe graph shows the S-parameters of the 50g acoustic resonator filter. Figure 3A It is shown Figure 1H The graph shows the bandwidth of the acoustic resonator filter 50h. Figure 3B It is shown Figure 1H The graph shows the S-parameters of the acoustic resonator filter 50h.

[0086] Reference Figure 2A and Figure 3A The ripple characteristics (passband ripple) in the bandwidth of the acoustic resonator filter corresponding to the variability of the S-parameters FSg and FSh between the first and second ports can be more stable, and the insertion loss in the bandwidth corresponding to the total value of the S-parameters FSg and FSh can be low.

[0087] Reference Figure 2B The S-parameter FSg between the first port and the second port may have a transmission zero pole FL2 formed near the lowest frequency of the bandwidth and a transmission zero pole FH2 formed near the highest frequency of the bandwidth, and the S-parameter RSg between the first port and the second port may have poles RL3 and RH3 according to the second branch unit and poles RL2, RH2, RL2s and RH2s according to the first branch unit and / or the third branch unit.

[0088] The transmission zeros and poles FL2 and FH2 can be formed due to the resonant frequency difference between the first and second branch acoustic resonators of the first branch unit. Due to the transmission zeros and poles FL2, the slope of the S-parameter FSg in the frequency range of 3.58 GHz to 3.60 GHz may be steeper, and due to the transmission zeros and poles FH2, the slope of the S-parameter FSg in the frequency range of 3.80 GHz to 3.82 GHz may be even steeper.

[0089] The poles RL3 and RH3 of the second shunt unit can be formed by the series connection between the first shunt acoustic resonator and the inductor, which can be located relatively closer to the center frequency of the bandwidth (e.g., 3.70 GHz) and can reduce the insertion loss of the S-parameter FSg that may occur as the bandwidth increases.

[0090] Reference Figure 3B The S-parameter FSh between the first port and the second port may have a transmission zero pole FL2h formed near the lowest frequency of the bandwidth and a transmission zero pole FH2h formed near the highest frequency of the bandwidth, and the S-parameter RSh between the first port and the second port may have poles RL3h and RH3h according to the second branch unit and poles RL2-1, RH2-1, RL2sh, RH2sh, RL2-2 and RH2-2 according to the first branch unit and / or the third branch unit.

[0091] RL2-2 and RH2-2, which are poles RL2-1, RH2-1, RL2sh, RH2sh, RL2-2 and RH2-2 of the first and / or third branch units, can be formed by replacing one of the third branch units with the first branch unit, and the slope of the S-parameter FSg can be made steeper in the frequency range of 3.58 GHz to 3.60 GHz and the frequency range of 3.80 GHz to 3.82 GHz.

[0092] Figure 4 This is a side view showing the detailed structure of the acoustic resonator 10 of the acoustic resonator filter according to an embodiment.

[0093] Reference Figure 4 The acoustic resonator 10 can be a bulk acoustic resonator, a thin-film bulk acoustic resonator (FBAR), or a solid-state assembled resonator (SMR). For convenience, the acoustic resonator 10 will be referred to as a bulk acoustic resonator in the following text.

[0094] The bulk acoustic resonator 10 may include a stacked structure and a cover 200 attached to the stacked structure, the stacked structure including a substrate 110, an insulating layer 120, an air cavity 112 and a resonant portion 135.

[0095] The substrate 110 may include a conventional silicon substrate, and the insulating layer 120 may be disposed on the upper surface of the substrate 110 to electrically isolate the resonant portion 135 from the substrate 110. The insulating layer 120 may be formed on the substrate 110 using either silicon dioxide (SiO2) or aluminum oxide (Al2O3) by chemical vapor deposition, RF magnetron sputtering, or evaporation.

[0096] A gas cavity 112 may be disposed on the insulating layer 120. The gas cavity 112 may be located below the resonant portion 135, so that the resonant portion 135 can vibrate in a predetermined direction. The gas cavity 112 may be formed by the following process: forming a sacrificial layer on the insulating layer 120, forming a film 130 on the sacrificial layer, and etching the sacrificial layer to remove the sacrificial layer. The film 130 may be used as an oxide protective layer or as a protective layer for the substrate 110.

[0097] An etch stop layer 125 may be formed between the insulating layer 120 and the air cavity 112. The etch stop layer 125 protects the substrate 110 and the insulating layer 120 from the etching process and can be used as a substrate for depositing other layers on the etch stop layer 125.

[0098] A seed layer for improving the crystal orientation of the piezoelectric layer 150 may be provided below the first electrode 140. The seed layer may be formed using any one of aluminum nitride (AlN), zinc oxide (ZnO), and lead zirconate titanate (PZT; PbZrTiO) with the same crystallinity as the piezoelectric layer 150.

[0099] The resonant section 135 may include an effective region and an ineffective region. The effective region of the resonant section 135 is the area where the first electrode 140, the piezoelectric layer 150, and the second electrode 160 are vertically stacked above the air cavity 112. The effective region vibrates in a predetermined direction due to the piezoelectric phenomenon that occurs in the piezoelectric layer 150 when electrical energy (such as a radio frequency signal) is applied to the first electrode 140 and the second electrode 160. The ineffective region of the resonant section 135 is the area that does not resonate due to the piezoelectric phenomenon even when electrical energy is applied to the first electrode 140 and the second electrode 160, and is located outside the effective region.

[0100] The resonant section 135 utilizes the piezoelectric phenomenon to output a radio frequency signal with a specific frequency. For example, the resonant section 135 can output a radio frequency signal with a resonant frequency corresponding to the vibration caused by the piezoelectric phenomenon of the piezoelectric layer 150.

[0101] To improve the coupling efficiency with the piezoelectric layer 150, the first electrode 140 and the second electrode 160 may be formed using conductive materials (such as molybdenum (Mo) or alloys thereof), but are not limited thereto. That is, the first electrode 140 and the second electrode 160 may be formed using conductive materials (such as ruthenium (Ru), tungsten (W), iridium (Ir), platinum (Pt), copper (Cu), titanium (Ti), tantalum (Ta), nickel (Ni), chromium (Cr), or alloys thereof).

[0102] The piezoelectric layer 150 may include a piezoelectric material for generating a piezoelectric effect that converts electrical energy into mechanical energy in the form of elastic waves. For example, the piezoelectric material may include any one of aluminum nitride (AlN), zinc oxide (ZnO), and lead zirconate titanate (PZT; PbZrTiO), and may also include any one or two of rare earth metals and transition metals, and may include magnesium (Mg) as a divalent metal. For example, rare earth metals may include any one or any combination of two or more of scandium (Sc), erbium (Er), yttrium (Y), and lanthanum (La), and transition metals may include any one or any combination of two or more of titanium (Ti), zirconium (Zr), hafnium (Hf), tantalum (Ta), and niobium (Nb).

[0103] A protective layer 170 can be provided on the second electrode 160 of the resonant section 135 to prevent the second electrode 160 from being exposed to the outside. The protective layer 170 can be formed using any one of silicon oxide-based insulating materials, silicon nitride-based insulating materials, and aluminum nitride-based insulating materials. Figure 4 The diagram shows a stacked structure housed within a cover 200, but multiple stacked structures can be housed within the cover 200, and these multiple stacked structures can be interconnected according to design. In the multiple stacked structures, wiring electrodes can be disposed on the external exposed portions of the first electrode 140 and the second electrode 160, and can be interconnected.

[0104] The cover 200 can be integrated into the stacked structure to protect the resonant portion 135 from external environmental influences. The cover 200 can be formed in the shape of a cover having an internal space to accommodate the resonant portion 135. For example, the cover 200 may have a receiving portion formed at its center to accommodate the resonant portion 135, and may be integrated into the stacked structure at its edges. Figure 4 The diagram shows a cover 200 bonded to a protective layer 170 stacked on a substrate 110. Alternatively, the cover 200 may be bonded to any one or any combination of two or more of the following: a film 130, an etch stop layer 125, an insulating layer 120, and the substrate 110.

[0105] The cap 200 can be bonded to the substrate 110 via eutectic bonding. In this case, after depositing a binder 250 capable of eutectic bonding with the substrate 110 onto the stacked structure, the substrate wafer and the cap wafer can be pressed and heated to achieve bonding. The binder 250 may include a copper (Cu)-tin (Sn) eutectic material and may also include solder balls.

[0106] At least one via 113 penetrating the substrate 110 in the thickness direction may be formed on the lower surface of the substrate 110. The via 113 may penetrate a portion of the insulating layer 120, the etch stop layer 125, and the film 130, as well as the substrate 110, in the thickness direction. A connection pattern 114 may be formed inside the via 113, and the connection pattern 114 may be formed on the inner surface of the via 113, that is, the connection pattern 114 may be formed on the entire inner wall of the via 113. The via 113 may be omitted according to the design, and a wiring bonding structure may be used instead of the structure of the connection pattern 114.

[0107] The connection pattern 114 can be manufactured by forming a conductive layer on the inner surface of the via 113. For example, the connection pattern 114 can be formed by depositing, coating, or filling a conductive metal (such as gold or copper) along the inner wall of the via 113. For example, the connection pattern 114 can be formed using a titanium (Ti)-copper (Cu) alloy.

[0108] The connection pattern 114 can be connected to either or both of the first electrode 140 and the second electrode 160. For example, the connection pattern 114 can be electrically connected to the first electrode 140 through the substrate 110, the insulating layer 120, the etch stop layer 125, and the film 130, and can be electrically connected to the second electrode 160 through the substrate 110, the insulating layer 120, the etch stop layer 125, the film 130, and the piezoelectric layer 150. The connection pattern 114 formed on the inner surface of the via hole 113 can extend toward the lower surface of the substrate 110 and can be connected to the connection pad 115 for the substrate disposed on the lower surface of the substrate 110. Therefore, the connection pattern 114 can electrically connect the first electrode 140 and the second electrode 160 to the connection pad 115 for the substrate.

[0109] The connecting pad 115 can be electrically connected to an external substrate via bumps, and the external substrate can be disposed below the bulk acoustic wave resonator 10. The bulk acoustic wave resonator 10 can perform RF signal filtering operations by applying signals to the first electrode 140 and the second electrode 160 via the connecting pad 115.

[0110] As explained above, acoustic resonator filters can achieve both a wider passband and a sharper roll-off characteristic.

[0111] In the acoustic resonator filter according to the embodiments disclosed herein, the structure for obtaining a wider passband width and the structure for obtaining a sharper roll-off characteristic complement each other, thereby effectively obtaining a wide passband width and a sharp roll-off characteristic, and the balance between the passband width and the roll-off characteristic can be adjusted more effectively according to the criteria required for the acoustic resonator filter.

[0112] Although this disclosure includes specific examples, it will be apparent upon understanding the disclosure of this application that various changes in form and detail may be made to these examples without departing from the spirit and scope of the claims and their equivalents. The examples described herein are to be considered merely for descriptive purposes and not for limiting purposes. The description of features or aspects in each example is to be considered applicable to similar features or aspects in other examples. Suitable results may be obtained if the described techniques are performed in a different order, and / or if components in the described system, architecture, apparatus, or circuit are combined in a different manner and / or if components in the described system, architecture, apparatus, or circuit are replaced or supplemented with other components or their equivalents. Therefore, the scope of this disclosure is not limited by the specific embodiments but by the claims and their equivalents, and all variations within the scope of the claims and their equivalents shall be construed as included in this disclosure.

Claims

1. An acoustic resonator filter, comprising: A series unit includes at least one series acoustic resonator, which is connected in series between a first port through which the radio frequency signal passes and a second port. The first branch unit is disposed in the first branch connection path between the at least one series acoustic resonator and ground. The first branch unit includes a plurality of branch acoustic resonators, which are connected in series with each other and have different resonant frequencies. as well as A second branch unit is disposed in a second branch connection path between the at least one series acoustic resonator and the ground. The second branch unit includes at least one branch acoustic resonator and an inductor and has an inductance higher than that of the first branch unit. The inductor is connected in series with the at least one branch acoustic resonator included in the second branch unit.

2. The acoustic resonator filter according to claim 1, further comprising: A third branch unit is disposed in a third branch connection path between the at least one series acoustic resonator and the ground, and includes at least one branch acoustic resonator. The resonant frequency of the at least one branch acoustic resonator in the third branch unit is lower than a higher resonant frequency among the plurality of resonant frequencies of the plurality of branch acoustic resonators in the first branch unit, and lower than the resonant frequency of the at least one branch acoustic resonator in the second branch unit.

3. The acoustic resonator filter according to claim 2, wherein, The resonant frequency of the at least one shunt acoustic resonator included in the third shunt unit is the same as the lower of the plurality of resonant frequencies of the plurality of shunt acoustic resonators included in the first shunt unit.

4. The acoustic resonator filter according to claim 2, wherein, The higher of the plurality of resonant frequencies of the plurality of shunt acoustic resonators included in the first shunt unit is equal to or higher than the resonant frequency of the at least one series acoustic resonator.

5. The acoustic resonator filter according to claim 2, wherein, The higher of the plurality of resonant frequencies of the plurality of branch acoustic resonators of the first branch unit is higher than the resonant frequency of at least one branch acoustic resonator of the second branch unit.

6. The acoustic resonator filter according to claim 1, further comprising: Multiple third-branch units are respectively arranged in multiple third-branch connection paths between the at least one series acoustic resonator and the ground. Each of the plurality of third branch units includes at least one branch acoustic resonator, and the resonant frequency of the at least one branch acoustic resonator included in the plurality of third branch units is lower than the higher resonant frequency among the different resonant frequencies of the plurality of branch acoustic resonators included in the first branch unit.

7. The acoustic resonator filter according to claim 6, wherein, The at least one series acoustic resonator includes multiple series acoustic resonators electrically connected between the plurality of third branch units, and The first branch unit is electrically connected between the node between the plurality of series acoustic resonators and the ground.

8. The acoustic resonator filter according to claim 1, wherein, The first branching unit includes multiple first branching units, which are arranged in multiple first branching connection paths between the at least one series acoustic resonator and the ground. Wherein, one of the plurality of first branching units includes the plurality of branched acoustic resonators, and Among them, another first branch unit in the plurality of first branch units includes a plurality of additional branch acoustic resonators, which are connected in series with each other and have different resonant frequencies.

9. The acoustic resonator filter according to claim 8, wherein, The at least one series acoustic resonator includes one or more series acoustic resonators electrically connected between the plurality of first branch units.

10. An acoustic resonator filter, comprising: At least one series acoustic resonator is connected in series between the first port and the second port through which the radio frequency signal passes; At least one second shunt acoustic resonator, the shunt being electrically connected between the at least one series acoustic resonator and ground; Multiple first-branch acoustic resonators are electrically connected between the at least one series acoustic resonator and the ground, and the resonant frequency of the multiple first-branch acoustic resonators is higher than the resonant frequency of the at least one second-branch acoustic resonator. as well as An inductor is connected in series with a portion of the plurality of first shunt acoustic resonators. Wherein, at least one of the remaining portions of the plurality of first shunt acoustic resonators is connected in series with the at least one second shunt acoustic resonator, and Wherein, the inductance of the branch connection path provided with the inductor is greater than each of the multiple inductors in the multiple branch connection paths respectively provided with the at least one second branch acoustic resonator.

11. The acoustic resonator filter according to claim 10, wherein, The resonant frequency of at least one of the remaining portions of the plurality of first shunt acoustic resonators is equal to or higher than the resonant frequency of the at least one series acoustic resonator.

12. The acoustic resonator filter according to claim 10, wherein, The resonant frequency of a portion of the plurality of first shunt acoustic resonators is lower than the resonant frequency of at least one of the remaining portions of the plurality of first shunt acoustic resonators.

13. The acoustic resonator filter according to claim 10, wherein, The at least one second-splitter acoustic resonator includes a plurality of second-splitter acoustic resonators, and The number of the plurality of second-branch acoustic resonators is greater than the number of the plurality of first-branch acoustic resonators.

14. The acoustic resonator filter according to claim 13, wherein, The number of at least one first shunt acoustic resonator in the remaining portion of the plurality of first shunt acoustic resonators that are connected in series with the at least one second shunt acoustic resonator is greater than the number of first shunt acoustic resonators in the portion of the plurality of first shunt acoustic resonators that are connected in series with the inductor.

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