FILTER, RADIO FREQUENCY DEVICE AND ELECTRONIC DEVICE

Abstract

A filter, a radio frequency device, and an electronic apparatus. The filter comprises a series branch, N parallel branches, and a bridged branch; the series branch comprises M series resonators arranged in series; each of the N parallel branches comprises a parallel resonator; the bridged branch comprises a bridged resonator and a first inductor; each of the parallel branches comprises a first end and a second end opposite each other, the first end of each of the parallel branches being grounded, the second end of each of the parallel branches being connected to the series branch;The bridged branch comprises a third end and a fourth end; the third end is located on a side of the bridged resonator furthest from the first inductor; the fourth end is located on a side of the first inductor furthest from the bridged resonator; the third end is connected to the first end of the i-th parallel branch; the fourth end is connected to the second end of the (i+k)-th parallel branch; both M and N are positive integers greater than or equal to 3; i is a positive integer greater than or equal to 1 and less than or equal to N-2; and k is a positive integer greater than or equal to 2. In this way, the filter can simultaneously reduce insertion loss and improve out-of-band suppression performance.

Description

FIELD OF TECHNOLOGY

[0001] Embodiments of the present disclosure relate to a filter, a radio frequency device, and an electronic apparatus. STATE OF THE ART

[0002] With the rapid development of mobile communication technology, the application of radio frequency devices has increased significantly. As an important component in radio frequency devices, the use of filters will increase significantly, leading to the explosive growth of the filter market. Currently, the filters used in personal mobile devices (such as mobile phones) are piezoelectric acoustic wave filters. Piezoelectric acoustic wave filters are mainly composed of resonators. These resonators can include film bulk acoustic resonators (FBARs), fixed-mount resonators (SMRs), and surface acoustic wave (SAW) resonators. Film bulk acoustic resonators (FBARs) and fixed-mount resonators (SMRs) are collectively referred to as bulk acoustic wave (BAW) resonators.

[0003] The working principle of a surface acoustic wave resonator is to convert the electrical signal into an acoustic wave propagating on a surface of the piezoelectric layer through an interdigital transducer, where the resonance frequency of the surface acoustic wave resonator can be determined by the distance between strip electrodes in the interdigital transducer; the working principle of a bulk acoustic wave resonator is to convert the electrical signal into a bulk acoustic wave propagating along the thickness direction of the piezoelectric layer, where the resonance frequency is determined by the thickness of the piezoelectric layer.The difference between the film bulk acoustic resonator and the fixed resonator is that the film bulk acoustic resonator uses the acoustic impedance of air, which is approximately zero, to achieve total internal reflection of the interface acoustic waves, while the fixed resonator realizes total internal reflection based on Bragg reflection layers consisting of alternating layers of high acoustic impedance and layers of low acoustic impedance. SUMMARY

[0004] Embodiments of the present disclosure provide a filter, a radio frequency device, and an electronic apparatus. By connecting the bridged resonator and the first inductor in series and then bridging the bridged resonator between the first end of the i-th parallel branch and the second end of the (i+2)-th parallel branch, the introduction of the bridged resonator can increase two zero points in the passband, and the value of the first inductor can shift these two zero points to an appropriate position outside the passband to increase the out-of-band rejection while playing a role in optimizing the impedance matching of the input and output terminals so that the insertion loss is reduced. In this way, the filter can simultaneously reduce the insertion loss and improve the out-of-band rejection performance.

[0005] At least one embodiment of the present disclosure provides a filter comprising: a series branch comprising M series resonators arranged in series; N parallel branches, each of the N parallel branches comprising a parallel resonator; and a bridged branch comprising a bridged resonator and a first inductor, each of the parallel branches comprising a first end and a second end opposite each other, the first end of each of the parallel branches being grounded, the second end of each of the parallel branches being connected to the series branch, the bridged branch comprising a third end and a fourth end, the third end being arranged on a side of the bridged resonator remote from the first inductor, the fourth end being located on a side of the first inductor remote from the bridged resonator, the third end being connected to the first end of the i-th parallel branch,the fourth end is connected to the second end of the (i+k)-th parallel branch, both M and N are positive integers greater than or equal to 3, i is a positive integer greater than or equal to 1 and less than or equal to Nk, and k is a positive integer greater than or equal to 2.

[0006] For example, in the filter according to an embodiment of the present disclosure, the value of k is equal to 2.

[0007] For example, in the filter according to an embodiment of the present disclosure, the second end of the first parallel branch is located between the first series resonator and the second series resonator, the second end of the j-th parallel branch is located between the j-th series resonator and the (j+1)-th series resonator, the second end of the N-th parallel branch is located between the N-th series resonator, away from the (N-1)-th series resonator, and j is a positive integer greater than 1 and less than N.

[0008] For example, in the filter according to an embodiment of the present disclosure, the value of i is 1, and the values ​​of M and N are equal.

[0009] For example, in the filter according to an embodiment of the present disclosure, the series branch includes an input end and an output end arranged opposite to each other, the M series resonators are arranged between the input end and the output end, the filter further includes: a second inductor, the second inductor is arranged in parallel with the first series resonator.

[0010] For example, in the filter according to an embodiment of the present disclosure, a value range of an inductance of the second inductor is between 5nH and 9nH.

[0011] For example, the filter provided by an embodiment of the present disclosure further comprises: a third inductor, wherein one end of the third inductor is grounded and the other end of the third inductor is connected to the output end.

[0012] For example, in the filter according to an embodiment of the present disclosure, a value range of an inductance of the third inductor is between 10 nH and 17 nH.

[0013] For example, in the filter according to an embodiment of the present disclosure, a value range of the inductance of the first inductor is between 10 nH and 17 nH.

[0014] For example, in the filter according to an embodiment of the present disclosure, the series branch includes an input end and an output end arranged opposite to each other, the M series resonators are arranged between the input end and the output end, the filter further includes: a fourth inductor, the fourth inductor is arranged in series between the first series resonator and the second end of the first parallel branch.

[0015] For example, in the filter according to an embodiment of the present disclosure, a value range of an inductance of the first inductor is between 11 nH and 18 nH, and a value range of an inductance of the fourth inductor is between 0.3 nH and 0.7 nH.

[0016] For example, in the filter according to an embodiment of the present disclosure, the filter further comprises: a fifth inductor, wherein the fifth inductor is arranged in series between the first end of the Nth parallel branch and the parallel resonator.

[0017] For example, in the filter according to an embodiment of the present disclosure, a value range of an inductance of the first inductor is from 10 nH to 17 nH, and a value range of an inductance of the fifth inductor is 4.5 nH-6.5 nH.

[0018] For example, in the filter according to an embodiment of the present disclosure, at least one of the M series resonators and the parallel resonators in the N parallel branches is a bulk acoustic wave resonator.

[0019] In the filter according to an embodiment of the present disclosure, the bulk acoustic wave resonator includes, for example: a substrate; a piezoelectric film; a first driving electrode; and a second driving electrode.

[0020] In the filter according to an embodiment of the present disclosure, the M series resonators include, for example, a first bulk acoustic wave resonator and a second bulk acoustic wave resonator, wherein the first bulk acoustic wave resonator and the second bulk acoustic wave resonator adopt a bulk acoustic wave resonator structure, the filter further comprising an insulating layer and a first terminal electrode, a second terminal electrode, a third terminal electrode, and a fourth terminal electrode arranged on a side of the insulating layer remote from the substrate, wherein the first terminal electrode is electrically connected to the first drive electrode of the first bulk acoustic wave resonator via a through-hole in the insulating layer and the piezoelectric film,the second terminal electrode is electrically connected to the second drive electrode of the first bulk acoustic wave resonator via a through-hole in the insulating layer, the third terminal electrode is electrically connected to the first drive electrode of the second bulk acoustic wave resonator via a through-hole in the insulating layer and the piezoelectric film, and the fourth terminal electrode is connected to the second drive electrode of the second bulk acoustic wave resonator via a through-hole in the insulating layer, and the third terminal electrode is connected to the second terminal electrode to connect the first bulk acoustic wave resonator and the second bulk acoustic wave resonator in series.

[0021] For example, in the filter according to an embodiment of the present disclosure, the i-th parallel branch includes a first bulk acoustic wave resonator, the bridged resonator includes a second bulk acoustic wave resonator, the first bulk acoustic wave resonator and the second bulk acoustic wave resonator adopt a bulk acoustic wave resonator structure, the filter further includes an insulating layer and a first terminal electrode, a second terminal electrode, a third terminal electrode, and a fourth terminal electrode arranged on a side of the insulating layer remote from the substrate, wherein the first terminal electrode is electrically connected to the first drive electrode of the first bulk acoustic wave resonator via a through-hole in the insulating layer and the piezoelectric film,The second terminal electrode is electrically connected to the second driving electrode of the first bulk acoustic wave resonator via a through-hole in the insulating layer, the third terminal electrode is electrically connected to the first driving electrode of the second bulk acoustic wave resonator via a through-hole in the insulating layer and the piezoelectric film, and the fourth terminal electrode is connected to the second driving electrode of the second bulk acoustic wave resonator via a through-hole in the insulating layer, and the third terminal electrode is connected to the second terminal electrode to connect the first bulk acoustic wave resonator and the second bulk acoustic wave resonator in series.

[0022] For example, in the filter according to an embodiment of the present disclosure, the bulk acoustic wave filter further comprises: an air gap located in the substrate, the first driving electrode is located on a side of the piezoelectric film close to the substrate, the second driving electrode is located on a side of the piezoelectric film remote from the substrate, and the air gap is located on a side of the substrate close to the first driving electrode, or the air gap is located on a side of the substrate remote from the first driving electrode.

[0023] In the filter according to an embodiment of the present disclosure, the M series resonators include, for example, a third bulk acoustic wave resonator and a fourth bulk acoustic wave resonator, wherein the third bulk acoustic wave resonator and the fourth bulk acoustic wave resonator adopt a bulk acoustic wave resonator structure, the first driving electrode of the third bulk acoustic wave resonator is arranged on a side of the piezoelectric film remote from the substrate, the second driving electrode of the third bulk acoustic wave resonator is arranged on a side of the piezoelectric film close to the substrate,the first driving electrode of the fourth bulk acoustic wave resonator is arranged on a side of the piezoelectric film close to the substrate, and the second driving electrode of the fourth bulk acoustic wave resonator is arranged on a side of the piezoelectric film remote from the substrate, and the second driving electrode of the third bulk acoustic wave resonator and the first driving electrode of the fourth bulk acoustic wave resonator are arranged on the same layer and electrically connected to connect the third bulk acoustic wave resonator and the fourth bulk acoustic wave resonator in series.

[0024] For example, in the filter according to an embodiment of the present disclosure, the i-th parallel branch includes a third bulk acoustic wave resonator, the bridged resonator includes a fourth bulk acoustic wave resonator, the third bulk acoustic wave resonator and the fourth bulk acoustic wave resonator adopt a bulk acoustic wave resonator structure, the first driving electrode of the third bulk acoustic wave resonator is located on a side of the piezoelectric film remote from the substrate, the second driving electrode of the third bulk acoustic wave resonator is located on a side of the piezoelectric film close to the substrate,the first driving electrode of the fourth bulk acoustic wave resonator is arranged on a side of the piezoelectric film close to the substrate, and the second driving electrode of the fourth bulk acoustic wave resonator is arranged on a side of the piezoelectric film remote from the substrate, and the second driving electrode of the third bulk acoustic wave resonator and the first driving electrode of the fourth bulk acoustic wave resonator are arranged on the same layer and electrically connected to connect the third bulk acoustic wave resonator and the fourth bulk acoustic wave resonator in series.

[0025] For example, in the filter according to an embodiment of the present disclosure, the bulk acoustic wave filter further comprises: high acoustic impedance layers and low acoustic impedance layers arranged alternately, wherein the high acoustic impedance layers and the low acoustic impedance layers are arranged on a side of the piezoelectric film close to the substrate.

[0026] For example, in the filter according to an embodiment of the present disclosure, the bridged resonator includes a fifth bulk acoustic wave resonator, the (i+k)-th series resonator includes a sixth bulk acoustic wave resonator, the fifth bulk acoustic wave resonator and the sixth bulk acoustic wave resonator adopt a bulk acoustic wave resonator structure, the filter further includes an insulating layer and a fifth terminal electrode, a sixth terminal electrode, a seventh terminal electrode, and an eighth terminal electrode arranged on a side of the insulating layer remote from the substrate, the fifth terminal electrode being electrically connected to the first drive electrode of the fifth bulk acoustic wave resonator via a through-hole in the insulating layer and the piezoelectric film,the sixth terminal electrode is electrically connected to the second drive electrode of the fifth bulk acoustic wave resonator via a through-hole in the insulating layer, the seventh terminal electrode is electrically connected to the first drive electrode of the sixth bulk acoustic wave resonator via a through-hole in the insulating layer and the piezoelectric film, and the eighth terminal electrode is connected to the second drive electrode of the sixth bulk acoustic wave resonator via a through-hole in the insulating layer, wherein the first inductor is arranged on a side of the insulating layer remote from the substrate and is connected to the sixth terminal electrode and the eighth terminal electrode, respectively.

[0027] In the filter according to an embodiment of the present disclosure, the first inductor is, for example, a single-layer inductor or a three-dimensional inductor.

[0028] At least one embodiment of the present disclosure further provides a radio frequency device comprising one of the above-mentioned filters.

[0029] At least one embodiment of the present disclosure further provides an electronic device comprising one of the above-mentioned radio frequency devices. SHORT DESCRIPTION OF THE CHARACTERS

[0030] To clarify the technical solution of the embodiments of the present disclosure, the drawings of the embodiments will be briefly described. It is obvious that the drawings described below relate only to some embodiments of the present disclosure and are therefore not to be construed as limiting the present disclosure. Fig. Figure 1 is a schematic diagram of a bulk acoustic wave filter; Fig. 2 is an S21 curve diagram of the Fig. 1 shown filter in a broadband range; Fig. 3 is an S21 curve diagram of the Fig. 1 shown filter at a center frequency point; Fig. 4 is a schematic diagram of a filter according to an embodiment of the present disclosure; Fig. 5A is a schematic structural diagram of a bulk acoustic wave resonator according to an embodiment of the present disclosure; Fig. 5B is a schematic structural diagram of another bulk acoustic wave resonator according to an embodiment of the present disclosure; Fig. 5C is a schematic structural diagram of another bulk acoustic wave resonator according to an embodiment of the present disclosure; Fig. 5D is a schematic structural diagram of a series-connected bulk acoustic wave resonator according to an embodiment of the present disclosure; Fig. 5E is a schematic structural diagram of another series-connected bulk acoustic wave resonator according to an embodiment of the present disclosure; Fig. 5F is a schematic structural diagram of a connection mode between a bulk acoustic wave resonator and an inductor, according to an embodiment of the present disclosure; Fig. 5G is a schematic structural diagram of a connection mode between a bulk acoustic wave resonator and an inductor, according to an embodiment of the present disclosure; Fig. 5H is a schematic diagram of a resonator in parallel with an inductor, according to an embodiment of the present disclosure; Fig. 6 is a comparison diagram of the transmission coefficients of a filter according to an embodiment of the present disclosure and a conventional bulk acoustic wave filter in a wide frequency range; Fig. 7 is a comparison diagram of the transmission coefficients of a filter according to an embodiment of the present disclosure and a conventional bulk acoustic wave filter in a mid-frequency range; Fig. 8 is a schematic diagram of another filter according to an embodiment of the present disclosure; Fig. 9 is a graph of the transmission coefficient curve of another filter in a wide frequency range, according to an embodiment of the present disclosure; Fig. 10 is a graph of the transmission coefficient curve of another filter in a mid-frequency range, according to an embodiment of the present disclosure; Fig. 11 is a schematic diagram of another filter according to an embodiment of the present disclosure; Fig. 12 is a graph of the transmission coefficient curve of another filter in a wide frequency range according to an embodiment of the present disclosure; Fig. 13 is a graph of the transmission coefficient curve of another filter in a mid-frequency range according to an embodiment of the present disclosure; Fig. 14 is a schematic diagram of another filter according to an embodiment of the present disclosure; Fig. 15 is a graph of the transmission coefficient curve of another filter in a wide frequency range according to an embodiment of the present disclosure; Fig. 16 is a graph of the transmission coefficient curve of another filter in a mid-frequency range according to an embodiment of the present disclosure; Fig. 17 is a schematic diagram of another filter according to an embodiment of the present disclosure; Fig. 18 is a graph of the transmission coefficient curve of another filter in a wide frequency range according to an embodiment of the present disclosure; Fig. 19 is a graph of the transmission coefficient curve of another filter in a mid-frequency range according to an embodiment of the present disclosure; Fig. 20 is a schematic diagram of another filter according to an embodiment of the present disclosure; Fig. 21 is a schematic diagram of another filter according to an embodiment of the present disclosure; Fig. 22 is a schematic diagram of another filter according to an embodiment of the present disclosure; Fig. 23 is a schematic diagram of a radio frequency device according to an embodiment of the present disclosure; and Fig. 24 is a schematic diagram of an electronic device according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF REVELATION

[0031] To further clarify the objectives, technical details, and advantages of the embodiments of the present disclosure, the technical solutions of the embodiments will be described in a clear and fully understandable manner in conjunction with the drawings relating to the embodiments of the present disclosure. Obviously, the described embodiments are only a part, but not all, of the embodiments of the present disclosure. Starting from the embodiments described here, one skilled in the art can obtain other embodiments that fall within the scope of the present disclosure without inventive step.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The terms "first," "second," etc., as used in this disclosure, are not intended to indicate order, quantity, or importance, but rather to distinguish various components. Also, the terms "comprise," "contain," "include," "including," etc., are intended to indicate that the elements or items listed before these terms include the elements or items listed after these terms and their equivalents, but do not exclude the other elements or items. The terms "connect," "connected," etc., are not intended to define a physical or mechanical connection, but may include a direct or indirect electrical connection.

[0033] Unless otherwise defined, features such as "parallel," "vertical," and "identical" used in embodiments of the present disclosure include all strictly defined situations such as "parallel," "vertical," and "identical," as well as situations where "substantially parallel," "substantially vertical," and "substantially identical" contain certain errors. The above "substantially" may mean, for example, that the difference between the compared objects is 10% of the average value of the compared objects or within 5%. When the number of a component or element is not specifically stated in the following embodiments of this disclosure, it means that the component or element may be one or more or can be understood as at least one component. "At least one" refers to one or more, and "multiple" or "multiple" refers to at least two.

[0034] For a filter used in a radio frequency device, key performance indicators include insertion loss, out-of-band rejection, and roll-off coefficient. Insertion loss is often represented by the parameter IL (insert loss) because a signal does not arrive in its entirety at an output; instead, energy is lost as the signal passes through the filter. Insertion loss defines the energy loss, which can be expressed as the ratio of the input power Pin to the output power PL, i.e., IL(dB) = 10*lg(Pin / PL) = -S21, where S21 is the transfer coefficient from the input end to the output end, which can be measured using a vector network analyzer. Out-of-band rejection is a measure of attenuation outside the filter's passband, indicating the ability to reject unwanted frequency signals.The roll-off coefficient, also called the square-wave coefficient, describes the steepness of the filter's transition band, and the steeper it is, the better the filter's frequency selection performance; the roll-off coefficient can usually be expressed as the ratio of the 60 dB bandwidth to the 3 dB bandwidth.

[0035] Fig. 1 is a schematic diagram of a bulk acoustic wave filter. As shown in Fig. 1, the bulk acoustic wave filter 10 comprises an input end 11, an output end 12, a series branch 13 connected between the input end 11 and the output end 12, and three parallel branches 14.The series branch 13 comprises three series resonators S1, S2 and S3 arranged in series; the three parallel branches 14 comprise a first parallel branch, a second parallel branch and a third parallel branch; the first parallel branch comprises a parallel resonator P1, one end of the parallel resonator P1 being connected between the series resonator S1 and the series resonator S2 and the other end being grounded; the second parallel branch comprises a parallel resonator P2, one end of the parallel resonator P2 being connected between the series resonator S2 and the series resonator S3 and the other end being grounded; and the third parallel branch comprises a parallel resonator P3, one end of the parallel resonator P3 being connected between the series resonator S3 and the output end 12 and the other end being grounded.

[0036] Fig. 2 is a diagram of the transmission coefficient curve of the Fig. 1 shown filter in a wide frequency range; and Fig. 3 shows a diagram of the transmission coefficient curve of the Fig. 1 shown filter at the center frequency. As in Fig. 2 and Fig. As shown in Figure 3, the minimum insertion loss of the filter is 1.18 dB, and the out-of-band rejection is less than 40 dB. This is because the 3-stage topology filter has a large number of resonant units through which the signal must pass, resulting in increased insertion loss. However, in the out-of-band rejection parameters, the number of orders of the 3-stage topology filter is relatively small, which is not enough to achieve better out-of-band rejection.

[0037] Therefore, to improve the performance of both insertion loss and out-of-band rejection, embodiments of the present disclosure provide a filter, a radio frequency device, and an electronic apparatus. The filter comprises a series branch, N parallel branches, and a bridged branch; the series branch comprises M series resonators arranged in series; each of the N parallel branches comprises a parallel resonator; the bridged branch comprises a bridged resonator and a first inductor; each of the parallel branches comprises a first end and a second end opposite each other, the first end of each of the parallel branches is grounded, the second end of each of the parallel branches is connected to the series branch;the bridged branch has a third end and a fourth end, the third end is located on a side of the bridged resonator remote from the first inductor, the fourth end is located on a side of the first inductor remote from the bridged resonator, the third end is connected to the first end of the i-th parallel branch, the fourth end is connected to the second end of the (i+2)-th parallel branch, both M and N are positive integers greater than or equal to 3, i is a positive integer greater than or equal to 1 and less than or equal to N-2;

[0038] In the filter provided by the embodiment of the present disclosure, the bridged resonator and the first inductor are connected in series and then bridged between the first end of the i-th parallel arm and the second end of the (i+2)-th parallel arm. The introduction of the bridged resonator adds two zero points in the passband; and the value of the first inductor can shift these two zero points to an appropriate position outside the passband to increase the out-of-band rejection; at the same time, the first inductor plays the role of optimizing the impedance matching of the input end and the output end, thus reducing the insertion loss. In this way, the filter can simultaneously reduce the insertion loss and improve the out-of-band rejection performance.

[0039] Hereinafter, the filter, the radio frequency device and the electronic apparatus provided by the embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0040] At least one embodiment of the present disclosure provides a filter. Fig. 4 is a schematic diagram of a filter according to an embodiment of the present disclosure. As in Fig. 4, the filter 100 comprises a series branch 110, N parallel branches 120, and a bridged branch 130; the series branch 110 comprises M series resonators 210 arranged in series; each of the parallel branches 120 comprises a parallel resonator 220; the bridged branch 130 comprises a bridged resonator 230 and a first inductor 241; each of the parallel branches 120 comprises a first end 120A and a second end 120B opposite each other, the first end 120A of each of the parallel branches 120 is grounded, the second end 120B of each of the parallel branches 120 is connected to the series branch 110;the bridged branch 130 includes a third end 130A and a fourth end 130B, the third end 130A is located on a side of the bridged resonator 230 remote from the first inductor 241, the fourth end 130B is located on the side of the first inductor 241 remote from the bridged resonator 230, that is, the bridged resonator 230 and the first inductor 241 are arranged in series between the third end 130A and the fourth end 130B;

[0041] As in Fig. 4, the third end 130A is connected to the first end 120A of the i-th parallel branch 120, the fourth end 130B is connected to the second end 120B of the (i+k)-th parallel branch 120, that is, the third end 130A is connected to the side of the parallel resonator 220 in the i-th parallel branch 120 that is remote from the series branch 110, and the fourth end 130B is connected to the position where the (i+k)-th parallel branch 120 is connected to the series branch 110. Both M and N are positive integers greater than or equal to 3, i is a positive integer greater than or equal to 1 and less than or equal to Nk, and k is a positive integer greater than or equal to 2. Note that the above "connected" refers to electrically connected.

[0042] In the filter provided by the embodiment of the present disclosure, the bridged resonator and the first inductor are connected in series and connected between the first end of the i-th parallel branch and the second end of the (i+k)-th parallel branch. The introduction of the bridged resonator adds two zero points in the passband. The value of the first inductor can shift these two zero points to an appropriate position outside the passband to increase the out-of-band rejection, and the bridged resonator simultaneously plays a role in optimizing the impedance matching of the input and output ends, thereby reducing the insertion loss. In this way, the filter can simultaneously reduce the insertion loss and improve the out-of-band rejection performance.

[0043] In some examples, at least one of the M series resonators 210 and the parallel resonators 220 in the N parallel branches 120 is a bulk acoustic wave resonator. In this way, the filter can have the advantages of lower insertion loss, high Q, steeper roll-off characteristics, and greater power capacity, etc.

[0044] In some examples, the M series resonators 210 and the parallel resonators 220 in the N parallel branches 120 may all use bulk acoustic wave resonators.

[0045] For example, the above-mentioned bulk acoustic wave resonator may be at least a film bulk acoustic resonator (FBAR) or a solid-state resonator (SMR).

[0046] Fig. 5A is a schematic structural diagram of a bulk acoustic wave resonator according to an embodiment of the present disclosure; Fig. 5B is a schematic structural diagram of another bulk acoustic wave resonator according to an embodiment of the present disclosure; and Fig. 5C is a schematic structural diagram of another bulk acoustic wave resonator according to an embodiment of the present disclosure.

[0047] As in Fig. As shown in Figure 5A, the bulk acoustic wave resonator 260 includes a substrate 261, an air gap 262 located in the substrate 261, a piezoelectric film 263, and a first driving electrode 264 and a second driving electrode 265 located on two sides of the piezoelectric film 263; the first driving electrode 264 is located on a side of the piezoelectric film 263 close to the substrate 261; the second driving electrode 265 is located on a side of the piezoelectric film 263 remote from the substrate 261. The air gap 262 is located on a side of the substrate 261 close to the first driving electrode 264, which can be obtained by etching from the side of the substrate 261 close to the first driving electrode 264.In this way, the bulk acoustic wave resonator 260 can convert electrical signals into bulk acoustic waves that propagate along the thickness direction of the piezoelectric film, and utilize the air gap to realize total reflection of the acoustic surface wave.

[0048] As in Fig. 5B, the bulk acoustic wave resonator 260 includes a substrate 261, an air gap 262 located in the substrate 261, a piezoelectric layer 263, and a first driving electrode 264 and a second driving electrode 265 located on two sides of the piezoelectric layer 263; the first driving electrode 264 is located on a side of the piezoelectric layer 263 close to the substrate 261; the second driving electrode 265 is located on a side of the piezoelectric layer 263 remote from the substrate 261. The air gap 262 is located on a side of the substrate 261 remote from the first driving electrode 264, which can be obtained by etching a side of the substrate 261 remote from the first driving electrode 264.In this way, the bulk acoustic wave resonator 260 can convert electrical signals into bulk acoustic waves propagating along the thickness direction of the piezoelectric film and utilize the air gap to realize the total internal reflection of the interface acoustic wave. As shown in . Fig. 5C, the bulk acoustic wave resonator 270 includes a substrate 271, a plurality of alternately arranged high acoustic impedance layers 272 and low acoustic impedance layers 273 on the substrate 271, a piezoelectric film 274, and a first driving electrode 275 and a second driving electrode 276 disposed on two sides of the piezoelectric film 274; the first driving electrode 275 is located on the side of the piezoelectric film 274 close to the substrate 271; and the second driving electrode 276 is located on a side of the piezoelectric film 274 remote from the substrate 271.In this way, the bulk acoustic wave resonator 270 can convert electrical signals into bulk acoustic waves propagating along the thickness direction of the piezoelectric layer and use a Bragg reflection layer consisting of a high acoustic impedance layer and a low acoustic impedance layer alternately arranged to realize total internal reflection.

[0049] In some examples, at least one of the M-series resonators 210 and the parallel resonators 220 in the N-parallel branches 120 may Fig. 5A shown resonator, which in Fig. 5B or the resonator shown in Fig. 5C. Of course, the embodiments of the present disclosure include, but are not limited to, such resonators, and at least one of the M-series resonators and the N-parallel resonators in the parallel branches may also use other types of resonators.

[0050] Fig. 5D is a schematic structural diagram of a series-connected bulk acoustic wave resonator according to an embodiment of the present disclosure. As in Fig. 5D, the structure includes a first bulk acoustic wave resonator 260A and a second bulk acoustic wave resonator 260B; the first bulk acoustic wave resonator 260A includes a substrate 261, an air gap 262A located in the substrate 261, a piezoelectric film 263, and a first driving electrode 264A and a second driving electrode 265A located on two sides of the piezoelectric film 263; the second bulk acoustic wave resonator 260B includes a substrate 261, an air gap 262B in the substrate 261, a piezoelectric thin film 263, and a first driving electrode 264B and a second driving electrode 265B located on two sides of the piezoelectric layer 263. The first bulk acoustic wave resonator 260A and the second bulk acoustic wave resonator 260B may share the substrate 261 and the piezoelectric thin film 263.

[0051] As in Fig. 5D, the structure may further include an insulating layer 280 and a first terminal electrode 291A, a second terminal electrode 292A, a third terminal electrode 291B, and a fourth terminal electrode 292B disposed on a side of the insulating layer 280 remote from the substrate 261; the first terminal electrode 291A is electrically connected to the first driving electrode 264A in the first bulk acoustic wave resonator 260A via a through-hole passing through the insulating layer 280 and the piezoelectric film 263; the second terminal electrode 292A is electrically connected to the second driving electrode 265A in the first bulk acoustic wave resonator 260A via a through-hole passing through the insulating layer 280;The third terminal electrode 291B is electrically connected to the first drive electrode 264B in the second bulk acoustic wave resonator 260B via a via hole passing through the insulating layer 280 and the piezoelectric film 263. The fourth terminal electrode 292B is electrically connected to the second drive electrode 265B in the second bulk acoustic wave resonator 260B via a via hole passing through the insulating layer 280. In this case, the first bulk acoustic wave resonator 260A and the second bulk acoustic wave resonator 260B can be connected in series by connecting the third terminal electrode 291B and the second terminal electrode 292A. In this way, any two adjacent series resonators in the series branch of the filter provided by the embodiment of the present disclosure can be connected in series in the above-mentioned manner.The parallel resonator in any parallel branch of the filter can also be connected to the series resonator in the series branch in the manner described above; furthermore, the bridged resonators in the bridged branch can also be connected after the parallel resonators of the parallel branch in the manner described above. For example, the second drive electrode of the first series resonator 211 in the series branch 110, the first drive electrode of the second series resonator 212 in the series branch 110, and the first drive electrode of the first parallel resonator 221 in the first parallel branch 121 can be connected in ; Fig. 4 arranged on the same layer and electrically connected to form the Fig. 4 to realize the connection relationship shown.

[0052] Fig. 5E is a schematic structural diagram of another series-connected bulk acoustic wave resonator according to an embodiment of the present disclosure. As in Fig. 5E, the structure includes a third bulk acoustic wave resonator 270A and a fourth bulk acoustic wave resonator 270B; the third bulk acoustic wave resonator 270A includes a substrate 271, a plurality of high acoustic impedance layers 272 and low acoustic impedance layers 273 alternately disposed on the substrate 271, a piezoelectric film 274, and a first drive electrode 275A and a second drive electrode 276A disposed on two sides of the piezoelectric film 274; the fourth bulk acoustic wave resonator 270B comprises a substrate 271, a plurality of high acoustic impedance layers 272 and low acoustic impedance layers 273 alternately disposed on the substrate 271, a piezoelectric film 274, and a first driving electrode 275B and a second driving electrode 276B disposed on two sides of the piezoelectric film 274.It can be seen that the third bulk acoustic wave resonator 270A and the fourth bulk acoustic wave resonator 270B may share the substrate 271, the plurality of high acoustic impedance layers 272 and low acoustic impedance layers 273 arranged alternately, and the piezoelectric layer 274.

[0053] As in Fig. 5E, the first driving electrode 275A of the third bulk acoustic wave resonator 270A is located on a side of the piezoelectric film 274 remote from the substrate 271, the second driving electrode 276A of the third bulk acoustic wave resonator 270A is located on a side of the piezoelectric film 274 near the substrate 271, the first driving electrode 275B of the fourth bulk acoustic wave resonator 270B is located on a side of the piezoelectric layer 274 near the substrate 271, and the second driving electrode 276B of the fourth bulk acoustic wave resonator 270B is located on a side of the piezoelectric layer 274 remote from the substrate 271.In this way, the second driving electrode 276A of the third bulk acoustic wave resonator 270A and the first driving electrode 275B of the fourth bulk acoustic wave resonator 270B can be arranged on the same layer and electrically connected, so that a series connection between the third bulk acoustic wave resonator 270A and the fourth bulk acoustic wave resonator 270A can be realized.In this way, any two adjacent series resonators in the series branch of the filter provided by the embodiment of the present disclosure can be connected in series in the manner mentioned above; the parallel resonator in any parallel branch of the filter can also be connected to the series resonator in the series branch in the manner mentioned above; furthermore, the bridged resonators in the bridged branch can also be connected behind the parallel resonators of the parallel branch in the manner mentioned above. For example, the second driving electrode of the first series resonator 211 in the series branch 110, the first driving electrode of the second series resonator 212 in the series branch 110, and the first driving electrode of the first parallel resonator 221 in the first parallel branch 121 are shown in FIG. Fig. 4 arranged on the same layer and electrically connected to form the Fig. 4 to realize the connection relationship shown.

[0054] As in Fig. 5E, for example, the second driving electrode 276A of the third bulk acoustic wave resonator 270A and the first driving electrode 275B of the fourth bulk acoustic wave resonator 270B may be integrally formed.

[0055] Fig. 5F is a schematic structural diagram of a connection mode between a bulk acoustic wave resonator and an inductor according to an embodiment of the present disclosure. As in Fig. 5F, the structure includes a fifth bulk acoustic wave resonator 260C, a sixth bulk acoustic wave resonator 260D, and an inductor 240; the fifth bulk acoustic wave resonator 260C includes a substrate 261, an air gap 262C disposed in the substrate 261, a piezoelectric film 263, and a first driving electrode 264C and a second driving electrode 265C disposed on two sides of the piezoelectric film 263; the sixth bulk acoustic wave resonator 260D includes a substrate 261, an air gap 262D in the substrate 261, a piezoelectric thin film 263, and a first driving electrode 264D and a second driving electrode 265D on two sides of the piezoelectric thin film 263. The fifth bulk acoustic wave resonator 260C and the sixth bulk acoustic wave resonator 260D may share the substrate 261 and the piezoelectric thin film 263.

[0056] As in Fig. 5F, the structure may further include an insulating layer 280 and a fifth terminal electrode 291C, a sixth terminal electrode 292C, a seventh terminal electrode 291D, and an eighth terminal electrode 292D disposed on a side of the insulating layer 280 remote from the substrate 261; the fifth terminal electrode 291C is electrically connected to the first driving electrode 264C in the fifth bulk acoustic wave resonator 260C via a through-hole passing through the insulating layer 280 and the piezoelectric film 263; the sixth terminal electrode 292C is electrically connected to the second driving electrode 265C in the fifth bulk acoustic wave resonator 260C via a through-hole passing through the insulating layer 280; the seventh terminal electrode 291D is electrically connected to the first driving electrode 264D in the sixth bulk acoustic wave resonator 260D via a through-hole,that passes through the insulating layer 280 and the piezoelectric film 263, and the eighth terminal electrode 292D is electrically connected to the second drive electrode 265D in the sixth bulk acoustic wave resonator 260D via a through-hole that passes through the insulating layer 280. In this case, the inductor 240 may be a single-layer inductor located on a side of the insulating layer 281 remote from the substrate 261 and connected to the sixth terminal electrode 292C and the eighth terminal electrode 292D, respectively, and the insulating layer 281 is arranged between each of the terminal electrodes and the inductor 240. In this way, the resonator and the inductor in the filter provided by the embodiment of the present disclosure canbe connected in the manner described above. For example, the bridged resonators of the bridged branch and the first inductor can be connected to the series resonators of the series branch in the manner described above.

[0057] Fig. 5G is a schematic structural diagram of a connection mode between a bulk acoustic wave resonator and an inductor according to an embodiment of the present disclosure. As shown in Fig. 5G, the inductor 240, unlike the inductors shown in Fig. 5F, the connection method may be a three-dimensional inductor and include a subconductive portion 240A and a subconductive portion 240B arranged in a plurality of film layers. The subconductive portion 240A is located on a side of the insulating layer 281 remote from the substrate 261, and the subconductive portion 240B is located on a side of the insulating layer 282 remote from the subconductive portion 240A.

[0058] In some examples, the aforementioned piezoelectric layer may include piezoelectric crystals or piezoelectric ceramics. Of course, the embodiments of the present disclosure include, but are not limited to, such materials, and the piezoelectric material layer may also be made of other types of piezoelectric materials.

[0059] In some examples, the above-mentioned piezoelectric layer may be composed of one or more of aluminum nitride (AIN), doped aluminum nitride (doped ALN), zinc oxide (ZnO), lead zirconate titanate (PZT), lithium niobate (LiNbO3), quartz (Quartz), potassium niobate (KNbO3), and lithium tantalate (LiTaO3). Of course, the embodiments of the present disclosure include, but are not limited to, such materials. The piezoelectric material layer may also be a composite piezoelectric thin film structure, such as a composite lithium tantalate film / silicon dioxide / silicon substrate piezoelectric structure.

[0060] In some examples, such as Fig. 4, the second end 120B of the first parallel branch 120 is located between the first series resonator 210 and the second series resonator 210, the second end 120B of the j-th parallel branch 120 is located between the j-th series resonator 210 and the (j+1)-th series resonator 210, and the second end 120B of the N-th parallel branch 120 is located between the N-th series resonator 210 and the (N-1)-th series resonator 210, where j is a positive integer greater than 1 and less than N. Note that the order of the above-mentioned parallel branches can be arranged along the direction from the input end to the output end of the filter.

[0061] In some examples, such as Fig. As shown in Figure 4, the value of i is 1, and the values ​​of M and N are equal. Thus, the filter has better filtering performance.

[0062] In some examples, such as Fig. 4, the filter 100 comprises a series branch 110, three parallel branches 120, and a bridged branch 130. The filter 100 comprises an input end 100A and an output end 100B. The series branch 110 is arranged between the input end 100A and the output end 100B, wherein the input end 100A and the output end 100B can also be considered as two ends of the series branch 110. The series branch 110 comprises three series resonators 210 arranged in series, including a first series resonator 211, a second series resonator 212, and a third series resonator 213.

[0063] As in Fig. 4, each of the three parallel branches 120 comprises a first parallel branch 121, a second parallel branch 122, and a third parallel branch 123; each of the parallel branches 120 comprises a parallel resonator 220; in this case, the first parallel branch 121 comprises a first parallel resonator 221, the second parallel branch 122 comprises a second parallel resonator 222, and the third parallel branch 123 comprises a third parallel resonator 223.Each of the parallel branches 120 includes a first end 120A and a second end 120B opposite each other; the first end 120A of the first parallel branch 121 is grounded, the second end 120B of the first parallel branch 121 is connected between the first series resonator 211 and the second series resonator 212; the first end 120A of the second parallel branch 122 is grounded, the second end 120B of the second parallel branch 122 is connected between the second series resonator 212 and the third series resonator 213; the first end 120A of the third parallel branch 123 is grounded, and the second end 120B of the third parallel branch 123 is connected between the third series resonator 213 and the output end 100B.

[0064] As in Fig. 4, the bridged branch 130 includes a bridged resonator 230 and a first inductor 241; the bridged branch 130 includes a third end 130A and a fourth end 130B, the third end 130A is connected to the first end 120A of the first parallel branch 121, and the fourth end 130B is connected to the second end 120B of the third parallel branch 123.

[0065] In some examples, the inductance of the first inductor 241 is between 10 nH and 17 nH.

[0066] In some examples, such as Fig. As shown in Figure 4, the series branch 110 comprises an input end 100A and an output end 100B arranged opposite each other. M series resonators 210 are arranged between the input end 100A and the output end 100B. The filter 100 further comprises a second inductor 242 arranged in parallel with the first series resonator 210. In this way, the second inductor and the capacitance of the first series resonator can form a new LC resonance peak in parallel, which can add an additional zero point outside the passband of the filter, thus further improving the out-of-band rejection.

[0067] In some examples, the inductance of the second inductor 242 is between 5 nH and 9 nH. Of course, the embodiments of the present disclosure include, but are not limited to, such.

[0068] In some examples, when the inductance of the second inductor 242 is between 5 nH and 9 nH, the inductance of the first inductor 241 is between 10 nH and 17 nH. Of course, embodiments of the present disclosure include, but are not limited to, such.

[0069] Fig. 5H is a schematic diagram of a resonator in parallel with an inductor, according to an embodiment of the present disclosure. As in Fig. 5H, the structure includes a seventh bulk acoustic wave resonator 260E and an inductor 240; the seventh bulk acoustic wave resonator 260E includes a substrate 261, an air gap 262C located in the substrate 261, a piezoelectric film 263, and a first drive electrode 264E and a second drive electrode 265E located on two sides of the piezoelectric film 263; the inductor 240 may be a three-dimensional inductor and may include subconductive parts located in multiple film layers (for a specific description, refer to the corresponding description in Fig. 5G). The structure may further include a ninth terminal electrode 291E and a tenth terminal electrode 292E; the ninth terminal electrode 291E is connected to the first driving electrode 264E, the tenth terminal electrode 292E is connected to the second driving electrode 265E; one end of the inductor 240 is connected to the ninth terminal electrode 291D, and the other end is connected to the tenth terminal electrode 292D, thus realizing a parallel connection of the inductor 240 and the seventh bulk acoustic wave resonator 260E.

[0070] For example, the second inductor 242 and the first series resonator 210 may be arranged in the Fig. 4 are arranged in parallel in the manner described above.

[0071] In some examples, such as Fig. 4, the value of i in the filter is 1 and the value of k is 2.

[0072] Fig. 6 is a comparison diagram of the transmission coefficients of a filter according to an embodiment of the present disclosure and a conventional bulk acoustic wave filter in a wide frequency range; and Fig. 7 is a comparison diagram of the transmission coefficients of a filter according to an embodiment of the present disclosure and a conventional bulk acoustic wave filter in a mid-frequency range. As in Fig. 6 and Fig. As shown in Figure 7, the insertion loss of this filter is about 0.83 dB better than that of the conventional bulk acoustic wave filter; and from 1.9 GHz to 1.98 GHz and from 1.98 GHz to 2.5 GHz, the out-of-band rejection of this filter is significantly improved.

[0073] Of course, the embodiments of the present invention include, but are not limited to, such, and the filter may also be arranged without the above-mentioned second inductor.

[0074] Fig. 8 is a schematic diagram of another filter according to an embodiment of the present disclosure. As in Fig. 8, the filter 100 comprises the above-mentioned series branch 110, the parallel branch 120 and the bridged branch 130.

[0075] As in Fig. 8, the series branch 110 comprises three series resonators 210 arranged in series, including a first series resonator 211, a second series resonator 212, and a third series resonator 213. Each of the three parallel branches 120 comprises a first parallel branch 121, a second parallel branch 122, and a third parallel branch 123; each of the parallel branches 120 comprises a parallel resonator 220; in this case, the first parallel branch 121 comprises a first parallel resonator 221, the second parallel branch 122 comprises a second parallel resonator 222, and the third parallel branch 123 comprises a third parallel resonator 223.Each parallel branch 120 includes a first end 120A and a second end 120B opposite each other; the first end 120A of the first parallel branch 121 is grounded, the second end 120B of the first parallel branch 121 is connected between the first series resonator 211 and the second series resonator 212; the first end 120A of the second parallel branch 122 is grounded, the second end 120B of the second parallel branch 122 is connected between the second series resonator 212 and the third series resonator 213; the first end 120A of the third parallel branch 123 is grounded, and the second end 120B of the third parallel branch 123 is connected between the third series resonator 213 and the output end 100B.

[0076] As in Fig. 8, the third end 130A of the bridged branch 130 is connected to the first end 120A of the first parallel branch 121, and the fourth end 130B of the bridged branch 130 is connected to the second end 120B of the third parallel branch 123.

[0077] Fig. 9 is a graph of the transmission coefficient curve of another filter in a wide frequency range according to an embodiment of the present disclosure; and Fig. 10 is a graph of the transmission coefficient curve in a mid-frequency range of another filter according to an embodiment of the present disclosure. As in Fig. 9 and Fig. As illustrated in Figure 10, the introduction of the bridged resonator adds two zero points in the passband. Since the bridged resonator and the first inductor are connected in series and then bridged between the first end of the first parallel branch and the second end of the third parallel branch, the value of the first inductor can shift the two zero points to a suitable position outside the passband to increase the out-of-band rejection. At the same time, the bridged resonator plays a role in optimizing the impedance matching of the input end and the output end, so that the insertion loss is reduced. In this way, the filter can simultaneously reduce the insertion loss and improve the out-of-band rejection performance.

[0078] Fig. 11 is a schematic diagram of another filter according to an embodiment of the present disclosure. As in Fig. As shown in Figure 11, the filter 100 includes a series branch 110, a parallel branch 120, a bridged branch 130, and a second inductor 242, mentioned above. The series branch 110 includes three series-arranged series resonators 210, including a first series resonator 211, a second series resonator 212, and a third series resonator 213. Three of the parallel branches 120 include a first parallel branch 121, a second parallel branch 122, and a third parallel branch 123; each of the parallel branches 120 includes a parallel resonator 220; in this case, the first parallel branch 121 includes a first parallel resonator 221, the second parallel branch 122 includes a second parallel resonator 222, and the third parallel branch 123 includes a third parallel resonator 223.Each of the parallel branches 120 includes a first end 120A and a second end 120B opposite each other; the first end 120A of the first parallel branch 121 is grounded, the second end 120B of the first parallel branch 121 is connected between the first series resonator 211 and the second series resonator 212; the first end 120A of the second parallel branch 122 is grounded, the second end 120B of the second parallel branch 122 is connected between the second series resonator 212 and the third series resonator 213; and the first end 120A of the third parallel branch 123 is grounded, the second end 120B of the third parallel branch 123 is connected between the third series resonator 213 and the output end 100B.

[0079] As in Fig. As shown in Figure 11, the third end 130A of the bridged branch 130 is connected to the first end 120A of the first parallel branch 121, the fourth end 130B of the bridged branch 130 is connected to the second end 120B of the third parallel branch 123; the second inductor 242 is arranged in parallel with the first series resonator 211. Furthermore, the filter 100 also includes a third inductor 243; one end of the third inductor 243 is grounded, and the other end of the third inductor 243 is connected to the output end 100B. In this way, the introduction of the grounded third inductor 243 can improve the impedance matching in the passband.

[0080] Fig. 12 is a graph of the transmission coefficients of another filter in a wide frequency range according to an embodiment of the present disclosure; and Fig. 13 is a graph of the transmission coefficients in a mid-frequency range of another filter according to an embodiment of the present disclosure. As in Fig. 12 and Fig. As shown in Figure 13, the filter achieves a 60 dB out-of-band rejection from 1.64 GHz to 1.81 GHz and from 2.06 GHz to 2.2 GHz.

[0081] In some examples, the inductance of the above-mentioned third inductor is between 10 nH and 17 nH. Of course, the present embodiments include, but are not limited to, such.

[0082] Fig. 14 is a schematic diagram of another filter according to an embodiment of the present disclosure. As in Fig. 14, the filter 100 comprises a series branch 110, a parallel branch 120, and a bridged branch 130, mentioned above. The series branch 110 comprises three series-arranged series resonators 210, including a first series resonator 211, a second series resonator 212, and a third series resonator 213. Three of the parallel branches 120 comprise a first parallel branch 121, a second parallel branch 122, and a third parallel branch 123; each of the parallel branches 120 comprises a parallel resonator 220; in this case, the first parallel branch 121 comprises a first parallel resonator 221, the second parallel branch 122 comprises a second parallel resonator 222, and the third parallel branch 123 comprises a third parallel resonator 223.Each of the parallel branches 120 includes a first end 120A and a second end 120B opposite each other; the first end 120A of the first parallel branch 121 is grounded, the second end 120B of the first parallel branch 121 is connected between the first series resonator 211 and the second series resonator 212; the first end 120A of the second parallel branch 122 is grounded, the second end 120B of the second parallel branch 122 is connected between the second series resonator 212 and the third series resonator 213; the first end 120A of the third parallel branch 123 is grounded, and the second end 120B of the third parallel branch 123 is connected between the third series resonator 213 and the output end 100B.

[0083] As in Fig. As shown in Figure 14, the third end 130A of the bridged branch 130 is connected to the first end 120A of the first parallel branch 121, and the fourth end 130B of the bridged branch 130 is connected to the second end 120B of the third parallel branch 123. Furthermore, the filter 100 also includes a fourth inductor 244; the fourth inductor 244 is arranged in series between the first series resonator 211 and the second end 120B of the first parallel branch 121. In this way, by connecting the fourth inductor 244 in series between the first series resonator 211 and the second end 120B of the first parallel branch 121, the impedance matching in the passband can be improved, so that the in-band fluctuation of the filter is smoother.

[0084] Fig. 15 is a graph of the transmission coefficient curve of another filter in a wide frequency range according to an embodiment of the present disclosure; and Fig. 16 is a graph of the transmission coefficient curve of another filter according to an embodiment of the present disclosure in a mid-frequency range. As in Fig. 15 and Fig. 16, the in-band fluctuation of the filter is smoother.

[0085] In some examples, the above-mentioned fourth inductor has an inductance in the range of 0.3 nH to 0.7 nH. Of course, the present embodiments include, but are not limited to, such inductances.

[0086] In some examples, in the case where the above-mentioned fourth inductor has an inductance value of 0.3 nH to 0.7 nH, the range of the inductance value of the first inductor may be from 11 nH to 18 nH. Of course, the embodiments of the present disclosure include, but are not limited to, such.

[0087] Fig. 17 is a schematic diagram of another filter according to an embodiment of the present disclosure. As in Fig. As shown in Figure 17, the filter 100 comprises a series branch 110, a parallel branch 120, and a bridged branch 130, mentioned above. The series branch 110 comprises three series-arranged series resonators 210, including a first series resonator 211, a second series resonator 212, and a third series resonator 213. Three of the parallel branches 120 comprise a first parallel branch 121, a second parallel branch 122, and a third parallel branch 123; each of the parallel branches 120 comprises a parallel resonator 220; in this case, the first parallel branch 121 comprises a first parallel resonator 221, the second parallel branch 122 comprises a second parallel resonator 222, and the third parallel branch 123 comprises a third parallel resonator 223.Each of the parallel branches 120 includes a first end 120A and a second end 120B opposite each other; the first end 120A of the first parallel branch 121 is grounded, the second end 120B of the first parallel branch 121 is connected between the first series resonator 211 and the second series resonator 212; the first end 120A of the second parallel branch 122 is grounded, the second end 120B of the second parallel branch 122 is connected between the second series resonator 212 and the third series resonator 213; and the first end 120A of the third parallel branch 123 is grounded, and the second end 120B of the third parallel branch 123 is connected between the third series resonator 213 and the output end 100B.

[0088] As in Fig. 17, the third end 130A of the bridged branch 130 is connected to the first end 120A of the first parallel branch 121, the fourth end 130B of the bridged branch 130 is connected to the second end 120B of the third parallel branch 123. In addition, the filter 100 also includes a fifth inductor 245; the fifth inductor 245 is arranged in series between the first end 120A of the third parallel branch 123 and the third parallel resonator 223. In this way, based on the idea of ​​reducing the complexity of the circuit, in this filter, compared to the one in Fig. 13, the inductor in series next to the first series resonator is removed and a fifth inductor is introduced in series between the first end of the third parallel arm and the third parallel resonator. Since the parallel arm resonator is capacitive outside the pass frequency of the filter and can form a new LC resonance with the fifth inductor, a new out-of-band zero point can be formed by adjusting the value of the inductance of the fifth inductor. A new zero point can be substantially the same as the zero point introduced by the bypassed resonator. In this case, the out-of-band suppression effect is optimal and an out-of-band suppression level of 40 dB can be achieved.

[0089] Fig. 18 is a graph of the transmission coefficient curve of another filter in a wide frequency range according to an embodiment of the present disclosure; and Fig. 19 is a graph of the transmission coefficient curve in a mid-frequency range of another filter according to an embodiment of the present disclosure. As in Fig. 18 and Fig. As shown in Figure 19, the filter allows the new zero point to be essentially the same as the zero point introduced via the resonator. In this case, the out-of-band rejection effect is optimal, and an out-of-band rejection level of 40 dB can be achieved.

[0090] In some examples, the inductance range of the above-mentioned fifth inductor is between 4.5 nH and 6.5 nH. Of course, the embodiments of the present disclosure also include, but are not limited to, such.

[0091] In some examples, in the case where the above-mentioned fifth inductor has an inductance value of 4.5 nH to 6.5 nH, the value range of the inductance of the first inductor may be from 10 nH to 17 nH. Of course, the embodiments of the present disclosure include, but are not limited to, such.

[0092] Fig. 20 is a schematic diagram of another filter according to an embodiment of the present disclosure. As in Fig. 20, the filter 100 comprises a series branch 110, four parallel branches 120, a bridged branch 130 and a second inductor 242.

[0093] The series branch 110 comprises four series resonators 210 arranged in series, including a first series resonator 211, a second series resonator 212, a third series resonator 213, and a fourth series resonator 214. Four of the parallel branches 120 comprise a first parallel branch 121, a second parallel branch 122, a third parallel branch 123, and a fourth parallel branch 124; each of the parallel branches 120 comprises a parallel resonator 220; in this case, the first parallel branch 121 comprises a first parallel resonator 221, the second parallel branch 122 comprises a second parallel resonator 222, the third parallel branch 123 comprises a third parallel resonator 223, and the fourth parallel branch 124 comprises a fourth parallel resonator 224.Each of the parallel branches 120 includes a first end 120A and a second end 120B opposite each other; the first end 120A of the first parallel branch 121 is grounded, the second end 120B of the first parallel branch 121 is connected between the first series resonator 211 and the second series resonator 212; the first end 120A of the second parallel branch 122 is grounded, the second end 120B of the second parallel branch 122 is connected between the second series resonator 212 and the third series resonator 213; the first end 120A of the third parallel branch 123 is grounded, the second end 120B of the third parallel branch 123 is connected between the third series resonator 213 and the fourth series resonator 214; the second end 120B of the fourth parallel branch 124 is connected between the fourth series resonator 214 and the output end 100B.

[0094] As in Fig. 20, the third end 130A of the bridged branch 130 is connected to the first end 120A of the first parallel branch 121, and the fourth end 130B of the bridged branch 130 is connected to the second end 120B of the third parallel branch 123. The second inductor 242 is arranged in parallel with the first series resonator 211. In this way, the static capacitance of the second inductor and the first series resonator, which are arranged in parallel, can form a new LC resonance peak, which adds an additional zero point outside the passband of the filter, thus improving the out-of-band suppression. Furthermore, the filter has Fig. 4, the filter shown uses a 4-stage topology structure to achieve better out-of-band rejection.

[0095] It is worth noting that the filters provided by the embodiments of the present disclosure include, but are not limited to, the above-mentioned 3-stage topology structure and the 4-stage topology structure, which may also include a higher-stage topology structure. The newly added series resonator and the parallel branch can be related to the arrangement of the fourth series resonator and the fourth parallel branch.

[0096] Fig. 21 is a schematic diagram of another filter according to an embodiment of the present disclosure. As in Fig. 21, the filter 100 comprises a series branch 110, four parallel branches 120, a bridged branch 130 and a second inductor 242. In contrast to the Fig. 20, the filter further comprises a sixth inductor 246 and a seventh inductor 247. The sixth inductor 246 is arranged in series between the first end 120A of the third parallel branch 123 and the third parallel resonator 223; and the seventh inductor 257 is arranged in series between the first end 120A of the fourth parallel branch 124 and the fourth parallel resonator 224.Since the parallel-arm resonator is capacitive outside the pass frequency of the filter, the third parallel resonator can form a new LC resonance with the sixth inductor, and the fourth parallel resonator forms a new LC resonance with the seventh inductor, so that a new out-of-band zero point can be formed; and by adjusting the inductance values ​​of the sixth inductor and the seventh inductor, a new zero point can be substantially the same as the zero point introduced by the bridged resonator, in this case, the out-of-band suppression effect is optimal, and an out-of-band suppression level of 40 dB can be achieved.

[0097] Fig. 22 is a schematic diagram of another filter according to an embodiment of the present disclosure. As in Fig. 22, the filter 100 comprises a series branch 110, four parallel branches 120, a bridged branch 130 and a second inductor 242. The difference to the Fig. The filter shown in Figure 20 is that the third end 130A of the bridged branch 130 is connected to the first end 120A of the first parallel branch 121, the fourth end 130B of the bridged branch 130 is connected to the second end 120B of the fourth parallel branch 124; that is, the third end 130A of the bridged branch 130 is connected to the side of the parallel resonator 220 in the first parallel branch 121 remote from the series branch 110, and the fourth end 130B of the bridged branch 130 is connected to the position where the fourth parallel branch 124 is connected to the series branch 110. In this way, the bridged branch can bridge three parallel branches. Of course, the embodiments of the present disclosure include, but are not limited to, such branches, and the bridged branch can also be bridged with more parallel branches.

[0098] In the example filter, the bridged resonator and the first inductor are connected in series and then bridged between the first end of the first parallel branch and the second end of the fourth parallel branch. The introduction of the bridged resonator adds two zero points in the passband. The value of the first inductor can shift the two zero points to an appropriate position outside the passband to increase out-of-band rejection. At the same time, the bridged resonator plays a role in optimizing the impedance matching of the input and output ends, thus reducing insertion loss. In this way, the filter can simultaneously reduce insertion loss and improve out-of-band rejection performance.

[0099] At least one embodiment of the present disclosure further provides a radio frequency device. Fig. 23 is a schematic diagram of a radio frequency device according to an embodiment of the present disclosure. As in Fig. As shown in Figure 23, the radio frequency device 300 includes one of the above-mentioned filters. Since the filter can simultaneously reduce insertion loss and improve out-of-band rejection performance, the radio frequency device including the filter has better performance.

[0100] In some examples, the aforementioned radio frequency device includes, but is not limited to, a radio frequency front-end module.

[0101] At least one embodiment of the present disclosure also provides an electronic device. Fig. 24 is a schematic diagram of an electronic device according to an embodiment of the present disclosure. As in Fig.24, the electronic device 500 includes the above-mentioned radio frequency device 300. The electronic device also has higher performance and lower cost.

[0102] In some examples, the aforementioned electronic devices may be end products such as smartphones, WIFI and drones.

[0103] The following points must be explained: (1) The drawings of the embodiments of the present disclosure refer only to the structures related to the embodiments of the present disclosure, and other structures may relate to the general design. (2) The embodiments of the present disclosure and the features in the embodiments can be combined with each other without conflict.

[0104] The above illustration is only the specific embodiment of this disclosure, but the scope of the present disclosure is not limited thereto. Anyone familiar with the technical field can easily imagine modifications or substitutions within the technical field disclosed in the present disclosure, and these should be included within the scope of the present disclosure. Therefore, the scope of the present disclosure should be governed by the scope of the claims.

Claims

[1] Filters, including: a series branch comprising M series resonators arranged in series; N parallel branches, each of the N parallel branches comprising a parallel resonator; and a bridged branch comprising a bridged resonator and a first inductor, wherein each of the parallel branches comprises a first end and a second end which are opposite to each other, the first end of each of the parallel branches is grounded, the second end of each of the parallel branches is connected to the series branch, the bridged branch comprises a third end and a fourth end, the third end is arranged on a side of the bridged resonator remote from the first inductor, the fourth end is arranged on a side of the first inductor remote from the bridged resonator, the third end is connected to the first end of the i-th parallel branch, the fourth end is connected to the second end of the (i+k)-th parallel branch, both M and N are positive integers greater than or equal to 3, i is a positive integer greater than or equal to 1 and less than or equal to Nk, and k is a positive integer greater than or equal to 2. [2] The filter of claim 1, wherein the value of k is 2. [3] The filter of claim 1, wherein the second end of the first parallel branch is arranged between the first series resonator and the second series resonator, the second end of the j-th parallel branch is arranged between the j-th series resonator and the (j+1)-th series resonator, the second end of the N-th parallel branch is arranged between the N-th series resonator and the (N-1)-th series resonator, and j is a positive integer greater than 1 and less than N. [4] A filter according to claim 1, wherein the value of i is 1 and the values ​​of M and N are equal. [5] Filter according to one of claims 1 to 4, wherein the series branch comprises an input end and an output end arranged opposite each other, the M series resonators are arranged between the input end and the output end, the filter further comprising: a second inductor, wherein the second inductor is arranged in parallel with the first series resonator. [6] The filter according to claim 5, wherein a value range of an inductance of the second inductor is from 5nH to 9nH. [7] The filter of claim 5, further comprising: a third inductor, one end of the third inductor being grounded and the other end of the third inductor being connected to the output end. [8] The filter of claim 7, wherein a value range of an inductance of the third inductor is from 10nH to 17nH. [9] Filter according to one of claims 5 to 8, wherein a value range of the inductance of the first inductor is between 10nH and 17nH. [10] A filter according to any one of claims 1 to 4, wherein the series branch comprises an input end and an output end arranged opposite each other, the M-series resonators are arranged between the input end and the output end, the filter further comprises a fourth inductor, the fourth inductor being arranged in series between the first series resonator and the second end of the first parallel branch. [11] The filter of claim 10, wherein a value range of an inductance of the first inductor is between 11nH and 18nH and a value range of an inductance of the fourth inductor is between 0.3nH and 0.7nH. [12] The filter according to any one of claims 1 to 4, wherein the filter further comprises: a fifth inductor, the fifth inductor being arranged in series between the first end of the Nth parallel branch and the parallel resonator. [13] The filter of claim 12, wherein a value range of an inductance of the first inductor is from 10nH to 17nH and a value range of an inductance of the fifth inductor is 4.5nH-6.5nH. [14] A filter according to any one of claims 1 to 13, wherein at least one of the M series resonators and the parallel resonators in the N parallel branches is a bulk acoustic wave resonator. [15] The filter of claim 14, wherein the bulk acoustic wave resonator comprises: a substrate; a piezoelectric film; a first driver electrode; and a second driver electrode. [16] The filter of claim 15, wherein the M series resonators comprise a first bulk acoustic wave resonator and a second bulk acoustic wave resonator, wherein the first bulk acoustic wave resonator and the second bulk acoustic wave resonator adopt a structure of the bulk acoustic wave resonator, the filter further comprises an insulating layer and a first terminal electrode, a second terminal electrode, a third terminal electrode, and a fourth terminal electrode located on a side of the insulating layer remote from the substrate, wherein the first terminal electrode is electrically connected to the first driving electrode of the first bulk acoustic wave resonator via a through-hole in the insulating layer and the piezoelectric film, the second terminal electrode is electrically connected to the second driving electrode of the first bulk acoustic wave resonator via a through-hole in the insulating layer, the third terminal electrode is electrically connected to the first driving electrode of the second bulk acoustic wave resonator via a through-hole in the insulating layer and the piezoelectric film,and the fourth terminal electrode is connected to the second drive electrode of the second bulk acoustic wave resonator via a through hole in the insulating layer, and, the third terminal electrode is connected to the second terminal electrode to connect the first bulk acoustic wave resonator and the second bulk acoustic wave resonator in series. [17] The filter of claim 15, wherein the i-th parallel branch comprises a first bulk acoustic wave resonator, the bridged resonator comprises a second bulk acoustic wave resonator, the first bulk acoustic wave resonator and the second bulk acoustic wave resonator adopt a bulk acoustic wave resonator structure, the filter further comprises an insulating layer and a first terminal electrode, a second terminal electrode, a third terminal electrode, and a fourth terminal electrode located on a side of the insulating layer remote from the substrate, wherein the first terminal electrode is electrically connected to the first driving electrode of the first bulk acoustic wave resonator via a through-hole in the insulating layer and the piezoelectric film, the second terminal electrode is electrically connected to the second driving electrode of the first bulk acoustic wave resonator via a through-hole in the insulating layer, the third terminal electrode is electrically connected to the first driving electrode of the second bulk acoustic wave resonator via a through-hole in the insulating layer and the piezoelectric film,and the fourth terminal electrode is connected to the second drive electrode of the second bulk acoustic wave resonator via a through hole in the insulating layer, and, the third terminal electrode is connected to the second terminal electrode to connect the first bulk acoustic wave resonator and the second bulk acoustic wave resonator in series. [18] A filter according to claim 16 or 17, wherein the bulk acoustic wave filter further comprises: an air gap located in the substrate, wherein the first driving electrode is arranged on a side of the piezoelectric film close to the substrate, the second driving electrode is arranged on a side of the piezoelectric film remote from the substrate, and the air gap is arranged on a side of the substrate close to the first driving electrode, or the air gap is arranged on a side of the substrate remote from the first driving electrode. [19] The filter of claim 15, wherein the M series resonators comprise a third bulk acoustic wave resonator and a fourth bulk acoustic wave resonator, the third bulk acoustic wave resonator and the fourth bulk acoustic wave resonator adopting a bulk acoustic wave resonator structure, the first driving electrode of the third bulk acoustic wave resonator is arranged on a side of the piezoelectric film remote from the substrate, the second driving electrode of the third bulk acoustic wave resonator is arranged on a side of the piezoelectric film close to the substrate, the first driving electrode of the fourth bulk acoustic wave resonator is arranged on a side of the piezoelectric film close to the substrate, and the second driving electrode of the fourth bulk acoustic wave resonator is arranged on a side of the piezoelectric film remote from the substrate, and the second driving electrode of the third bulk acoustic wave resonator and the first driving electrode of the fourth bulk acoustic wave resonator are arranged on the same layer and electrically connected to connect the third bulk acoustic wave resonator and the fourth bulk acoustic wave resonator in series. [20] The filter of claim 15, wherein the i-th parallel branch comprises a third bulk acoustic wave resonator, the bridged resonator comprises a fourth bulk acoustic wave resonator, the third bulk acoustic wave resonator and the fourth bulk acoustic wave resonator adopt a bulk acoustic wave resonator structure, the first driving electrode of the third bulk acoustic wave resonator is arranged on a side of the piezoelectric film remote from the substrate, the second driving electrode of the third bulk acoustic wave resonator is arranged on a side of the piezoelectric film close to the substrate, the first driving electrode of the fourth bulk acoustic wave resonator is arranged on a side of the piezoelectric film close to the substrate, and the second driving electrode of the fourth bulk acoustic wave resonator is arranged on a side of the piezoelectric film remote from the substrate, and the second driving electrode of the third bulk acoustic wave resonator and the first driving electrode of the fourth bulk acoustic wave resonator are arranged on the same layer and electrically connected to connect the third bulk acoustic wave resonator and the fourth bulk acoustic wave resonator in series. [21] Filter according to claims 19 and 20, wherein the bulk acoustic wave filter further comprises: Layers with high acoustic impedance and layers with low acoustic impedance arranged alternately, wherein the high acoustic impedance layers and the low acoustic impedance layers are arranged on a side of the piezoelectric film close to the substrate. [22] The filter according to claim 15, wherein the bridged resonator comprises a fifth bulk acoustic wave resonator, the (i+k)-th series resonator comprises a sixth bulk acoustic wave resonator, the fifth bulk acoustic wave resonator and the sixth bulk acoustic wave resonator adopt a bulk acoustic wave resonator structure, the filter further comprises an insulating layer and a fifth terminal electrode, a sixth terminal electrode, a seventh terminal electrode, and an eighth terminal electrode located on a side of the insulating layer remote from the substrate, wherein the fifth terminal electrode is electrically connected to the first driving electrode of the fifth bulk acoustic wave resonator via a through-hole in the insulating layer and the piezoelectric film, the sixth terminal electrode is electrically connected to the second driving electrode of the fifth bulk acoustic wave resonator via a through-hole in the insulating layer, the seventh terminal electrode is electrically connected to the first driving electrode of the sixth bulk acoustic wave resonator via a through-hole in the insulating layer and the piezoelectric film,and the eighth terminal electrode is connected to the second drive electrode of the sixth bulk acoustic wave resonator via a through hole in the insulating layer, the first inductor is arranged on a side of the insulating layer remote from the substrate and is connected to the sixth terminal electrode or the eighth terminal electrode. [23] The filter of claim 22, wherein the first inductor is a single-layer inductor or a three-dimensional inductor. [24] A radio frequency device comprising the filter according to any one of claims 1 to 23. [25] An electronic device comprising a radio frequency device according to claim 24.

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