Filter, radio-frequency device, and electronic apparatus

Abstract

A filter, a radio-frequency device, and an electronic apparatus. The filter comprises a series branch, N parallel branches and a first bridging branch, wherein the series branch comprises M first resonators, which are arranged in series; each parallel branch comprises a second resonator; the first bridging branch comprises a third resonator and a fourth resonator, which are arranged in series; each parallel branch comprises a first end and a second end, the first end is grounded, and the second end is connected to the series branch; and the first bridging branch comprises a third end and a fourth end, the series branch comprises a first node, the first node and the second end of each parallel branch are spaced apart by at least one first resonator, the third end of the first bridging branch is connected to the first node, the fourth end of the first bridging branch is connected to the second end of each parallel branch, and M and N are both positive integers greater than or equal to 2. By means of the introduction of a first bridging branch, impedance matching between an input port and output port of a series branch is improved and zero points are increased, thereby reducing the insertion loss and optimizing the out-of-band rejection.

Description

Filters, RF components and electronic devices Technical Field

[0001] Embodiments of the present disclosure relate to a filter, a radio frequency device, and an electronic apparatus. Background Art

[0002] With the rapid development of mobile communication technology, the application of radio frequency devices has increased significantly. As an important component of radio frequency devices, the use of filters will increase significantly, thereby driving explosive growth in the filter market. Currently, the filters used in personal mobile terminals (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 wave resonators (FBAR), solid-state mounted resonators (SMR), and surface acoustic wave resonators (SAW). Among them, film bulk acoustic wave resonators (FBAR) and solid-state mounted resonators (SMR) can be collectively referred to as BAW (bulk acoustic wave resonators).

[0003] The operating principle of a surface acoustic wave resonator is to convert electrical signals into acoustic waves that propagate along the surface of a piezoelectric layer through an interdigital transducer. The resonant frequency of the resonator is determined by the spacing between the strip electrodes in the interdigital transducer. The operating principle of a bulk acoustic wave resonator is to convert electrical signals into bulk acoustic waves that propagate along the thickness of the piezoelectric layer. The resonant frequency is determined by the thickness of the piezoelectric layer. The difference between a thin film bulk acoustic wave resonator and a solid-state assembly resonator is that the thin film bulk acoustic wave resonator uses the acoustic impedance of air to approximately equal zero to achieve total reflection of the interfacial acoustic waves, while the solid-state assembly resonator achieves total reflection based on a Bragg reflection layer composed of alternating high and low acoustic impedance layers.

[0004] Summary of the Invention

[0005] The embodiments of the present disclosure provide a filter, a radio frequency device, and an electronic apparatus. The introduction of the first jumper branch of the filter improves the impedance matching between the input port and the output port of the series branch and adds a zero point, thereby reducing insertion loss and optimizing out-of-band suppression.

[0006] At least one embodiment of the present disclosure provides a filter, comprising: a series branch, comprising M first resonators arranged in series; N parallel branches, each of the parallel branches comprising a second resonator; and a first jumper branch, comprising a third resonator and a fourth resonator arranged in series, each of the parallel branches comprising a first end and a second end opposite to each other, the first end of each parallel branch being grounded, and the second end of each parallel branch being connected to the series branch, the first jumper branch comprising a third end and a fourth end, the third end being located at an end of the fourth resonator of the first jumper branch away from the third resonator, and the fourth end being located at an end of the third resonator of the first jumper branch away from the fourth resonator, the series branch comprising a first node, at least one first resonator being spaced between the first node and the second end of each parallel branch, the third end of the first jumper branch being connected to the first node, and the fourth end of the first jumper branch being connected to the second end of the parallel branch, and M and N being positive integers greater than or equal to 2.

[0007] For example, the filter provided in one embodiment of the present disclosure also includes: a second jumper branch, including a fifth resonator, the second jumper branch including a fifth end and a sixth end, the fifth end is connected between the third resonator and the fourth resonator of the first jumper branch, the fourth end of the first jumper branch is connected to the second end of the i-th parallel branch, and the sixth end of the second jumper branch is connected to the second end of the j-th parallel branch, i and j are both positive integers greater than or equal to 1 and less than or equal to N, and i is greater than or equal to j.

[0008] For example, in the filter provided in an embodiment of the present disclosure, the difference between the value of i and the value of j is equal to 1.

[0009] For example, in a filter provided by an embodiment of the present disclosure, the first resonator, the third resonator, and the fifth resonator have the same resonant frequency and anti-resonant frequency, and the second resonator and the fourth resonator have the same resonant frequency and anti-resonant frequency.

[0010] For example, in the filter provided in one embodiment of the present disclosure, the series branch includes an input end and an output end that are relatively arranged, the M first resonators are arranged between the input end and the output end, and the third end of the first jumper branch is connected between the input end and the first of the first resonators in the series branch.

[0011] For example, in the filter provided in one embodiment of the present disclosure, the second end of the first parallel branch is connected between the first first resonator and the second first resonator of the series branch, the second end of the kth parallel branch is connected between the kth first resonator and the k+1th first resonator of the series branch, and the second end of the Nth parallel branch is connected to the end of the Nth first resonator of the series branch away from the (N-1)th first resonator, where k is a positive integer greater than or equal to 1 and less than N.

[0012] For example, in the filter provided in an embodiment of the present disclosure, the values ​​of M and N are equal.

[0013] For example, in the filter provided in one embodiment of the present disclosure, the fourth end of the first jumper branch is connected to the second end of the second parallel branch, and the sixth end of the second jumper branch is connected to the second end of the first parallel branch.

[0014] For example, in the filter provided in an embodiment of the present disclosure, the values ​​of M and N are both 3.

[0015] For example, the filter provided in an embodiment of the present disclosure further includes at least one parallel inductor, wherein the parallel inductor is arranged in parallel with the first resonator of the series branch.

[0016] For example, in the filter provided in an embodiment of the present disclosure, the inductance of the parallel inductor ranges from 4nH to 8nH.

[0017] For example, in the filter provided in one embodiment of the present disclosure, the at least one parallel inductor includes a first parallel inductor and a second parallel inductor, the series branch includes an input end and an output end arranged opposite to each other, the M first resonators are arranged between the input end and the output end, the first parallel inductor is arranged in parallel with the first resonator of the series branch adjacent to the output end, and the inductance of the first parallel inductor is in the range of 5nH-9nH, and the second parallel inductor is arranged in parallel with the first resonator of the series branch adjacent to the input end, and the inductance of the second parallel inductor is in the range of 2nH-4nH.

[0018] For example, the filter provided in an embodiment of the present disclosure further includes at least one first series inductor, wherein the first series inductor is arranged in series with the second resonator of the parallel branch.

[0019] For example, in the filter provided in an embodiment of the present disclosure, the inductance of the first series inductor ranges from 6 nH to 10 nH.

[0020] For example, the filter provided in an embodiment of the present disclosure further includes: a second series inductor, which is arranged in series with the third resonator of the first jumper branch.

[0021] For example, in the filter provided in an embodiment of the present disclosure, the inductance of the second series inductor ranges from 6 nH to 10 nH.

[0022] For example, the filter provided in one embodiment of the present disclosure also includes: a parallel inductor, which is arranged in parallel with the first resonator of the series branch; and a first series inductor, which is arranged in series with the second resonator of the parallel branch. The inductance of the parallel inductor is in the range of 7nH-11nH, and the inductance of the first series inductor is in the range of 9nH-14nH.

[0023] For example, the filter provided in one embodiment of the present disclosure also includes: a third jumper branch, including a sixth resonator, the third jumper branch including a seventh end and an eighth end, the seventh end is connected between the third resonator and the fourth resonator of the first jumper branch, and the eighth end of the third jumper branch is connected to the second end of the pth parallel branch, where p is a positive integer greater than or equal to 1 and less than or equal to N.

[0024] For example, in the filter provided by an embodiment of the present disclosure, at least one of the first resonator, the second resonator, the third resonator, and the fourth resonator is a bulk acoustic wave resonator.

[0025] For example, in a filter provided in an embodiment of the present disclosure, the BAW resonator includes: a substrate; a piezoelectric film located on the substrate; and a first driving electrode and a second driving electrode located on the substrate and on both sides of the piezoelectric film. The BAW resonator also includes an air gap located in the substrate.

[0026] For example, in a filter provided in an embodiment of the present disclosure, the bulk acoustic wave resonator includes: a substrate; a piezoelectric film located on the substrate; and a first drive electrode and a second drive electrode located on the substrate and on both sides of the piezoelectric film. The bulk acoustic wave resonator also includes alternating high acoustic impedance layers and low acoustic impedance layers, and the high acoustic impedance layers and the low acoustic impedance layers are located on a side of the piezoelectric film close to the substrate.

[0027] At least one embodiment of the present disclosure provides a radio frequency device, including any of the filters described above.

[0028] At least one embodiment of the present disclosure provides an electronic device including the above-mentioned radio frequency device. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings in the following description only relate to some embodiments of the present disclosure, rather than limiting the present disclosure.

[0030] FIG1 is a schematic diagram of a bulk acoustic wave filter;

[0031] FIG2 is a transmission coefficient curve diagram of the filter shown in FIG1 within a wide frequency band;

[0032] FIG3 is a transmission coefficient curve diagram of the filter shown in FIG1 at the center frequency;

[0033] FIG4 is a schematic diagram of a filter provided in an embodiment of the present disclosure;

[0034] FIG5 is a transmission coefficient curve diagram of the filter shown in FIG4 within a wide frequency band;

[0035] FIG6 is a transmission coefficient curve diagram of the filter shown in FIG4 at the center frequency range;

[0036] FIG7 is a schematic diagram of another filter provided by an embodiment of the present disclosure;

[0037] FIG8 is a transmission coefficient curve diagram of the filter shown in FIG7 within a wide frequency band;

[0038] FIG9 is a transmission coefficient curve diagram of the filter shown in FIG7 at the center frequency;

[0039] FIG10 is a schematic diagram of another filter provided by an embodiment of the present disclosure;

[0040] FIG11 is a transmission coefficient curve diagram of the filter shown in FIG10 within a wide frequency band;

[0041] FIG12 is a transmission coefficient curve diagram of the filter shown in FIG10 at the center frequency;

[0042] FIG13 is a schematic diagram of another filter provided by an embodiment of the present disclosure;

[0043] FIG14 is a transmission coefficient curve diagram of the filter shown in FIG13 within a wide frequency band;

[0044] FIG15 is a graph showing the transmission coefficient of the filter shown in FIG13 at the center frequency;

[0045] FIG16 is a schematic diagram of another filter provided by an embodiment of the present disclosure;

[0046] FIG17 is a transmission coefficient curve diagram of the filter shown in FIG16 within a wide frequency band;

[0047] FIG18 is a graph showing the transmission coefficient of the filter shown in FIG16 at the center frequency;

[0048] FIG19 is a schematic diagram of another filter provided by an embodiment of the present disclosure;

[0049] FIG20 is a schematic diagram of another filter provided by an embodiment of the present disclosure;

[0050] FIG21 is a schematic diagram of another filter provided by an embodiment of the present disclosure;

[0051] FIG22 is a schematic diagram of another filter provided by an embodiment of the present disclosure;

[0052] FIG23 is a schematic structural diagram of a bulk acoustic wave resonator provided by an embodiment of the present disclosure;

[0053] FIG24 is a schematic structural diagram of another bulk acoustic wave resonator provided by an embodiment of the present disclosure;

[0054] FIG25 is a schematic structural diagram of another bulk acoustic wave resonator provided by an embodiment of the present disclosure;

[0055] FIG26 is a schematic diagram of a structure of a bulk acoustic wave resonator connected in series according to an embodiment of the present disclosure;

[0056] FIG27 is a schematic diagram of another structure of a bulk acoustic wave resonator connected in series according to an embodiment of the present disclosure;

[0057] FIG28 is a schematic structural diagram of a connection method between a bulk acoustic wave resonator and an inductor provided in one embodiment of the present disclosure;

[0058] FIG29 is a schematic structural diagram of another connection method between a BAW resonator and an inductor provided in one embodiment of the present disclosure;

[0059] FIG30 is a schematic diagram of a structure in which a resonator and an inductor are connected in parallel according to an embodiment of the present disclosure;

[0060] FIG31 is a schematic structural diagram of a surface acoustic wave resonator provided by an embodiment of the present disclosure;

[0061] FIG32 is a schematic diagram of a radio frequency device provided in an embodiment of the present disclosure; and

[0062] FIG33 is a schematic diagram of an electronic device provided according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0063] To make the purpose, technical solutions, and advantages of the embodiments of the present disclosure more clear, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0064] Unless otherwise defined, the technical or scientific terms used in this disclosure should have the usual meanings understood by persons of ordinary skill in the field to which this disclosure belongs. The words "first", "second" and similar terms used in this disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "include" or "comprise" mean that the elements or objects preceding the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

[0065] Unless otherwise defined, the features such as "parallel", "perpendicular" and "same" used in the embodiments of the present disclosure include the cases of "parallel", "perpendicular", "same" in a strict sense, as well as the cases of "approximately parallel", "approximately perpendicular", "approximately the same" and the like which contain certain errors. For example, the above-mentioned "approximately" may mean 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 indicated below in the embodiments of the present disclosure, it means that the component or element may be one or more, or may be understood as at least one. "At least one" refers to one or more, and "multiple" refers to at least two. The "same-layer arrangement" in the embodiments of the present disclosure refers to the relationship between multiple film layers formed by the same material after the same step (for example, a one-step patterning process). The "same layer" here does not always mean that the thickness of multiple film layers is the same or the height of multiple film layers in the cross-sectional view is the same.

[0066] For filters used in RF devices, key performance indicators include insertion loss, out-of-band rejection, and roll-off factor. Insertion loss is often represented by the parameter IL (Insert Loss). Because the signal cannot fully reach the output, energy loss will occur when passing through the filter. Insertion loss defines this energy loss and can be expressed as the ratio of input power Pin to output power PL, that is, IL (dB) = 10*lg(Pin / PL) = -S21, where S21 is the transmission coefficient from input to output and can be measured by a vector network analyzer. Out-of-band rejection is the attenuation outside the filter's passband, indicating its ability to suppress unwanted frequency signals. The roll-off factor, also known as the rectangular coefficient, describes the steepness of the filter's transition band. The steeper the slope, the better the filter's frequency selection performance. The roll-off factor is typically expressed as the ratio of 60dB bandwidth to 3dB bandwidth.

[0067] FIG1 is a schematic diagram of a bulk acoustic wave filter. As shown in FIG1 , the bulk acoustic wave filter 10 includes an input terminal 11, an output terminal 12, a series branch 13 connected between the input terminal 11 and the output terminal 12, and three parallel branches 14. The series branch 13 includes three series resonators S1, S2, and S3 arranged in series; the three parallel branches 14 include a first parallel branch, a second parallel branch, and a third parallel branch. The first parallel branch includes a parallel resonator P1, one end of which is connected between the series resonators S1 and S2 and the other end is grounded; the second parallel branch includes a parallel resonator P2, one end of which is connected between the series resonators S2 and S3 and the other end is grounded; and the third parallel branch includes a parallel resonator P3, one end of which is connected between the series resonator S3 and the output terminal 12 and the other end is grounded.

[0068] Figure 2 plots the transmission coefficient of the filter shown in Figure 1 over a wide bandwidth; Figure 3 plots the transmission coefficient of the filter shown in Figure 1 at its center frequency. As shown in Figures 2 and 3, the filter's minimum insertion loss is 1.18dB, and its out-of-band rejection is less than 40dB. This is because the signal must pass through a large number of resonant units in this three-step ladder topology filter, resulting in increased insertion loss. However, the low order of this three-step ladder topology filter is insufficient for achieving optimal out-of-band rejection.

[0069] In this regard, an embodiment of the present disclosure provides a filter, a radio frequency device, and an electronic device. The filter includes a series branch, N parallel branches, and a first jumper branch. The series branch includes M first resonators arranged in series, each parallel branch of the N parallel branches includes a second resonator, and the first jumper branch includes a third resonator and a fourth resonator arranged in series. Each parallel branch includes a first end and a second end opposite to each other, the first end of each parallel branch is grounded, and the second end of each parallel branch is connected to the series branch. The first jumper branch includes a third end and a fourth end, the third end is located at an end of the fourth resonator of the first jumper branch away from the third resonator, and the fourth end is located at an end of the third resonator of the first jumper branch away from the fourth resonator. The series branch includes a first node, at least one first resonator is spaced between the first node and the second end of each parallel branch, the third end of the first jumper branch is connected to the first node, and the fourth end of the first jumper branch is connected to the second end of the parallel branch, and M and N are both positive integers greater than or equal to 2.

[0070] In the filter provided in the embodiment of the present disclosure, the first jumper branch includes a third resonator and a fourth resonator arranged in series, the third end of the first jumper branch is connected to the series branch, and the fourth end of the first jumper branch is connected to the second end of the parallel branch. The introduction of the first jumper branch improves the impedance matching between the input port and the output port of the series branch, thereby reducing the insertion loss. At the same time, the introduction of the first jumper branch also increases the zero point and optimizes the out-of-band suppression.

[0071] The filter, radio frequency device, and electronic device provided by the embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

[0072] An embodiment of the present disclosure provides a filter. FIG4 is a schematic diagram of a filter provided by an embodiment of the present disclosure. As shown in FIG4 , the filter 100 includes a series branch 110, N parallel branches 120, and a first jumper branch 130. The series branch 110 includes M first resonators 210 arranged in series, each parallel branch 120 of the N parallel branches 120 includes a second resonator 220, and the first jumper branch 130 includes a third resonator 231 and a fourth resonator 232 arranged in series. Each parallel branch 120 includes a first end 120A and a second end 120B opposite to each other, the first end 120A of each parallel branch 120 being grounded, and the second end 120B of each parallel branch 120 being connected to the series branch 110. The first jumper branch 130 includes a third end 130A and a fourth end 130B. The third end 130A is located at the end of the first jumper branch 130 away from the third resonator 231 and the fourth end 130B is located at the end of the first jumper branch 130 away from the third resonator 231 and the fourth resonator 232. The series branch 110 includes a first node 110P. At least one first resonator 210 is located between the first node 110P and the second end 120B of each parallel branch 120. The third end 130A of the first jumper branch 130 is connected to the first node 110P, and the fourth end 130B of the first jumper branch 130 is connected to the second end 120B of the parallel branch 120. Both M and N are positive integers greater than or equal to 2.

[0073] In the filter 100 provided in the embodiment of the present disclosure, the first jumper branch 130 includes a third resonator 231 and a fourth resonator 232 arranged in series, and the third end 130A of the first jumper branch 130 is connected to the series branch 110. The introduction of the first jumper branch 130 improves the impedance matching between the input end 100A and the output end 100B of the series branch 110, thereby reducing the insertion loss. At the same time, the introduction of the first jumper branch 130 also increases the zero point and optimizes the out-of-band suppression.

[0074] In some examples, as shown in FIG4 , the first node 110P is located between the input terminal 100A of the series branch 110 and the first first resonator 210. Of course, the embodiment of the present disclosure does not limit the location of the first node 110P, and the first node 110P may also be a node between any two first resonators 210 on the series branch 110.

[0075] In some examples, as shown in FIG. 4 , the fourth end 130B of the first jumper branch 130 may be connected to the second end 120B of any one of the N parallel branches 120 , which is not limited in the present disclosure.

[0076] In some examples, as shown in FIG4 , the filter 100 further includes a second jumper branch 140, and the second jumper branch 140 includes a fifth resonator 240. The second jumper branch 140 includes a fifth end 140A and a sixth end 140B, wherein the fifth end 140A is connected between the third resonator 231 and the fourth resonator 232 of the first jumper branch 130, the fourth end 130B of the first jumper branch 130 is connected to the second end 120B of the i-th parallel branch 120, and the sixth end 140B of the second jumper branch 140 is connected to the second end 120B of the j-th parallel branch 120, where i and j are both positive integers greater than or equal to 1 and less than or equal to N, and i is greater than or equal to j.

[0077] In this example, the filter 100 further introduces a second jumper branch 140 on the basis of the first jumper branch 130. The fifth end 140A of the second jumper branch 140 is connected between the third resonator 231 and the fourth resonator 232 of the first jumper branch 130. The fifth resonator 240 of the second jumper branch 140 and the fourth resonator 232 of the first jumper branch 130 form a parallel relationship. By adjusting the parameters of each resonator, the impedance matching between the input end 100A and the output end 100B of the series branch 110 can be further improved, thereby further reducing the insertion loss. At the same time, the introduction of the first jumper branch 130 and the second jumper branch 140 increases the zero point, further optimizing the out-of-band suppression.

[0078] For example, compared with other situations in the related art where the resonator is connected between the ground end of the parallel branch and the series branch, or where the resonator is connected between two parallel branches, this example connects the third resonator 231 and the fourth resonator 232 in series, connects one end to the first node of the series branch 110, and connects the other end to the non-grounded end of the parallel branch 120, and further introduces a second jumper branch 140, so that the fifth resonator 240 of the second jumper branch 140 forms a parallel relationship with the fourth resonator 232 of the first jumper branch 130, thereby better improving out-of-band suppression and in-band insertion loss.

[0079] In some examples, as shown in FIG4 , the difference between the value of i and the value of j is equal to 1. For example, the fourth end 130B of the first jumper branch 130 is connected to the second end 120B of the i-th parallel branch 120, and the sixth end 140B of the second jumper branch 140 is connected to the second end 120B of the (i-1)-th parallel branch 120. In this case, i is greater than or equal to 2. Of course, the embodiments of the present disclosure do not limit the parallel branches 120 to which the first jumper branch 130 and the second jumper branch 140 are respectively connected.

[0080] In some examples, the first resonator 210, the third resonator 231, and the fifth resonator 240 have the same resonant frequency and anti-resonant frequency. For example, the second resonator 220 and the fourth resonator 232 have the same resonant frequency and anti-resonant frequency. For example, the first resonator 210, the third resonator 231, and the fifth resonator 240 can be series resonators. For example, the second resonator 220 and the fourth resonator 232 can be parallel resonators.

[0081] In some examples, as shown in FIG4 , the series branch 110 includes an input end 100A and an output end 100B that are oppositely disposed, M first resonators 210 are disposed between the input end 100A and the output end 100B, and the third end 130A of the first jumper branch 130 is connected between the input end 100A and the first first resonator 210 of the series branch 110.

[0082] In some examples, as shown in FIG4 , the second end 120B of the first parallel branch 120 is connected between the first first resonator 210 and the second first resonator 210 of the series branch 110 , the second end 120B of the kth parallel branch 120 is connected between the kth first resonator 210 and the k+1th first resonator 210 of the series branch 110 , and the second end 120B of the Nth parallel branch 120 is connected to the end of the Nth first resonator 210 of the series branch 110 away from the (N-1)th first resonator 210 , where k is a positive integer greater than or equal to 1 and less than N. It should be noted that the order of the aforementioned parallel branches 120 can be arranged along the direction from the input end 100A to the output end 100B of the filter 100 .

[0083] In some examples, as shown in FIG4 , the values ​​of M and N are equal. Therefore, the filter 100 has good filtering performance.

[0084] In some examples, as shown in FIG4 , the filter 100 includes a series branch 110, three parallel branches 120, a first jumper branch 130, and a second jumper branch 140. The filter 100 includes an input terminal 100A and an output terminal 100B. The series branch 110 is disposed between the input terminal 100A and the output terminal 100B. In this case, the input terminal 100A and the output terminal 100B can also be regarded as the two ends of the series branch 110. The series branch 110 includes three first resonators 210 disposed in series, namely, a first first resonator 210a, a second first resonator 210b, and a third first resonator 210c.

[0085] As shown in Figure 4, the three parallel branches 120 include a first parallel branch 121, a second parallel branch 122 and a third parallel branch 123; each parallel branch 120 includes a second resonator 220. At this time, the first parallel branch 121 includes a first second resonator 220a, the second parallel branch 122 includes a second second resonator 220b, and the third parallel branch 123 includes a third second resonator 220c. Each parallel branch 120 includes a first end 120A and a second end 120B opposite to each other; the first end 120A of the first parallel branch 121 is grounded, and the second end 120B of the first parallel branch 121 is connected between the first first resonator 210a and the second first resonator 210b; the first end 120A of the second parallel branch 122 is grounded, and the second end 120B of the second parallel branch 122 is connected between the second first resonator 210b and the third first resonator 210c; 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 first resonator 210c and the output end 100B.

[0086] As shown in FIG4 , the first jumper branch 130 includes a third resonator 231 and a fourth resonator 232 connected in series. The first jumper branch 130 includes a third end 130A and a fourth end 130B. The first node 110P of the series branch 110 is located between the input terminal 100A and the first first resonator 210a. The third end 130A of the first jumper branch 130 is connected to the first node 110P, and the fourth end 130B of the first jumper branch 130 is connected to the second end 120B of the second parallel branch 122.

[0087] As shown in FIG4 , the second jumper branch 140 includes a fifth resonator 240. The second jumper branch 140 includes a fifth end 140A and a sixth end 140B. The fifth end 140A is connected between the third resonator 231 and the fourth resonator 232 of the first jumper branch 130. The sixth end 140B of the second jumper branch 140 is connected to the second end 120B of the first parallel branch 121.

[0088] In some examples, as shown in FIG4 , the filter 100 further includes a shunt inductor 310, which is arranged in parallel with the third first resonator 210c of the series branch 110. The shunt inductor 310 can be arranged in parallel with any first resonator 210c of the series branch 110, and the present disclosure is not limited thereto. The shunt inductor 310 arranged in parallel can introduce a zero point on the left side of the passband, further improving out-of-band suppression while also reducing insertion loss and ripple within the passband.

[0089] In some examples, the inductance of the parallel inductor 310 ranges from 4 nH to 8 nH.

[0090] Figure 5 is a graph showing the transmission coefficient of the filter shown in Figure 4 over a wide frequency band, while Figure 6 is a graph showing the transmission coefficient of the filter shown in Figure 4 at its center frequency. As shown in Figures 5 and 6, by adjusting the parameters of the resonators of filter 100 and the inductance of shunt inductor 310, an optimal transmission coefficient can be achieved. The insertion loss of filter 100 is approximately 0.8 dB better than that of a conventional bulk acoustic wave filter 100, and out-of-band rejection is significantly improved.

[0091] FIG7 is a schematic diagram of another filter provided by an embodiment of the present disclosure. As shown in FIG7 , the filter 100 further includes multiple parallel inductors 310. For example, the multiple parallel inductors 310 include a first parallel inductor 311 and a second parallel inductor 312. The series branch 110 includes an input terminal 100A and an output terminal 100B that are oppositely disposed. M first resonators 210 are disposed between the input terminal 100A and the output terminal 100B. The first parallel inductor 311 is disposed in parallel with one first resonator 210 in the series branch 110, and the second parallel inductor 312 is disposed in parallel with another first resonator 210 in the series branch 110. The multiple parallel inductors 310 can improve out-of-band suppression while also reducing insertion loss and ripple within the passband.

[0092] In some examples, as shown in FIG. 7 , a first parallel inductor 311 is provided in parallel with the first resonator 210 of the series branch 110 adjacent to the input terminal 100A, and a second parallel inductor 312 is provided in parallel with the first resonator 210 of the series branch 110 adjacent to the output terminal 100B.

[0093] In some examples, as shown in FIG7 , the series branch 110 of the filter 100 includes three first resonators 210, and the filter 100 includes three parallel branches 120. The first node 110P is located between the input terminal 100A and the first first resonator 210a. The fourth end 130B of the first jumper branch 130 is connected to the second end 120B of the second parallel branch 122. The sixth end 140B of the second jumper branch 140 is connected to the second end 120B of the first parallel branch 121. The first parallel inductor 311 is arranged in parallel with the first first resonator 210a of the series branch 110, and the second parallel inductor 312 is arranged in parallel with the third first resonator 210c.

[0094] In some examples, as shown in FIG7 , the inductance of the first parallel inductor 311 ranges from 5 nH to 9 nH.

[0095] In some examples, as shown in FIG. 7 , the inductance of the second parallel inductor 312 ranges from 2 nH to 4 nH.

[0096] For example, the series branch 110 of the filter 100 includes M first resonators 210 , and the filter 100 may further include q parallel inductors 310 , where q is a positive integer greater than or equal to 1 and less than or equal to M. For example, the values ​​of q and M may be equal.

[0097] Figure 8 is a graph showing the transmission coefficient of the filter shown in Figure 7 over a wide frequency band; Figure 9 is a graph showing the transmission coefficient of the filter shown in Figure 7 at its center frequency. As shown in Figures 8 and 9, by adjusting the parameters of the resonators of filter 100 and the inductance of the multiple parallel inductors 310, the insertion loss of filter 100 is approximately 0.8 dB better than that of a conventional bulk acoustic wave filter 100, and the out-of-band rejection of filter 100 is significantly improved.

[0098] Figure 10 is a schematic diagram of another filter provided by an embodiment of the present disclosure. As shown in Figure 10, the filter 100 further includes a first series inductor 321, which is arranged in series with the second resonator 220 of the parallel branch 120. The series arrangement of the first series inductor 321 introduces a zero point on the right side of the passband and shifts the zero point on the left side of the passband to the left, further improving out-of-band suppression while also reducing in-band insertion loss.

[0099] For example, as shown in FIG. 10 , the first series inductor 321 may be connected in series to a side of the second resonator 220 close to the first end 120A, or may be connected in series to a side of the second resonator 220 close to the second end 120B.

[0100] In some examples, as shown in FIG10 , the fourth end 130B of the first jumper branch 130 is connected to the second end 120B of the i-th parallel branch 120, the sixth end 140B of the second jumper branch 140 is connected to the second end 120B of the j-th parallel branch 120, and the first series inductor 321 is arranged in series with the second resonator 220 of the k-th parallel branch 120, where i, j, and k are all different.

[0101] In some examples, as shown in FIG10 , the series branch 110 of the filter 100 includes three first resonators 210 , the filter 100 includes three parallel branches 120 , the first node 110P is located between the input terminal 100A and the first first resonator 210 , the fourth end 130B of the first jumper branch 130 is connected to the second end 120B of the second parallel branch 122 , the sixth end 140B of the second jumper branch 140 is connected to the second end 120B of the first parallel branch 121 , and the first series inductor 321 is connected in series with the second resonator 220 of the third parallel branch 123 .

[0102] In some examples, as shown in FIG10 , the inductance of the first series inductor 321 ranges from 6 nH to 10 nH.

[0103] In some examples, as shown in FIG10 , the figure schematically illustrates a first series inductor 321 connected in series with the second resonator 220 of the third parallel branch 123. However, the present disclosure is not limited to this. For example, if the filter 100 includes N parallel branches 120, the first series inductor 321 can be connected in series with the second resonator 220 of any one of the N parallel branches 120.

[0104] For example, the filter 100 further includes a plurality of first series inductors 321 , and the plurality of first series inductors 321 are respectively connected in series with the second resonators 220 of the plurality of parallel branches 120 in a one-to-one correspondence.

[0105] For example, the filter 100 may include r first series inductors 321 and N parallel branches 120, where r is a positive integer greater than or equal to 1 and less than or equal to N. The r first series inductors 321 are respectively connected in series with the second resonators 220 of r of the N parallel branches 120 in a one-to-one correspondence. For example, the values ​​of r and M may be equal.

[0106] Figure 11 is a graph showing the transmission coefficient of the filter shown in Figure 10 over a wide frequency band; Figure 12 is a graph showing the transmission coefficient of the filter shown in Figure 10 at its center frequency. As shown in Figures 11 and 12, by adjusting the resonator parameters and the inductance of first series inductor 321 of filter 100 shown in Figure 10, the insertion loss of filter 100 is approximately 0.8 dB better than that of a conventional bulk acoustic wave filter 100, and the out-of-band rejection of filter 100 is significantly improved.

[0107] Figure 13 is a schematic diagram of another filter provided by an embodiment of the present disclosure. As shown in Figure 13, the filter 100 further includes a second series inductor 322, which is connected in series with the third resonator 231 of the first jumper branch 130. The series connection of the second series inductor 322 can further improve out-of-band suppression, resulting in even better out-of-band suppression.

[0108] In some examples, as shown in FIG13 , the first jumper branch 130 includes a second node 130P, and the fifth end 140A of the second jumper branch 140 is connected to the second node 130P. The second series inductor 322 can be located between the second node 130P and the third resonator 231. Of course, the embodiments of the present disclosure are not limited to this. For example, the second series inductor 322 can also be located between the third resonator 231 and the fourth end 130B.

[0109] In some examples, as shown in FIG13 , the series branch 110 of the filter 100 includes three first resonators 210, the filter 100 includes three parallel branches 120, the first node 110P is located between the input terminal 100A and the first first resonator 210, the fourth end 130B of the first jumper branch 130 is connected to the second end 120B of the second parallel branch 122, the sixth end 140B of the second jumper branch 140 is connected to the second end 120B of the first parallel branch 121, and the second series inductor 322 is located between the second node 130P and the third resonator 231.

[0110] In some examples, the inductance of the second series inductor 322 ranges from 6 nH to 10 nH.

[0111] Figure 14 is a graph showing the transmission coefficient of the filter shown in Figure 13 over a wide frequency band, and Figure 15 is a graph showing the transmission coefficient of the filter shown in Figure 13 at its center frequency. As shown in Figures 14 and 15 , by adjusting the parameters of the resonator of filter 100 and the inductance of second series inductor 322, filter 100 can simultaneously reduce insertion loss and improve out-of-band rejection performance.

[0112] FIG16 is a schematic diagram of another filter provided by an embodiment of the present disclosure. As shown in FIG16 , the filter 100 further includes a parallel inductor 310 and a first series inductor 321. The parallel inductor 310 is arranged in parallel with the first resonator 210 of the series branch 110, and the first series inductor 321 is arranged in series with the second resonator 220 of the parallel branch 120. The parallel inductor 310 can introduce a zero point on the left side of the passband to further improve out-of-band suppression, while also reducing the insertion loss and ripple within the passband; the first series inductor 321 can introduce a zero point on the right side of the passband and shift the zero point position on the left side of the passband to the left, further improving out-of-band suppression, while also reducing the insertion loss within the band. Thus, the resonator can have smaller insertion loss and better out-of-band suppression.

[0113] In some examples, as shown in FIG16 , the series branch 110 of the filter 100 includes three first resonators 210, and the filter 100 includes three parallel branches 120. The first node 110P is located between the input terminal 100A and the first first resonator 210. The fourth end 130B of the first jumper branch 130 is connected to the second end 120B of the second parallel branch 122. The sixth end 140B of the second jumper branch 140 is connected to the second end 120B of the first parallel branch 121. The parallel inductor 310 is arranged in parallel with the third first resonator 210 of the series branch 110. The first series inductor 321 is arranged in series with the second resonator 220 of the first parallel branch 120.

[0114] In some examples, the inductance of the parallel inductor 310 ranges from 7 nH to 11 nH.

[0115] In some examples, the inductance of the first series inductor 321 ranges from 9 nH to 14 nH.

[0116] In some examples, the parallel inductor 310 may be connected in parallel with any first resonator 210 of the series branch 110 , and the first series inductor 321 may be connected in series with any second resonator 220 of the parallel branch 120 , which will not be described in detail here.

[0117] For example, the filter 100 may include q parallel inductors 310 and r first series inductors 321, the q parallel inductors 310 are arranged in parallel with the q first resonators 210 of the series branch 110 in a one-to-one correspondence, and the r first series inductors 321 are arranged in series with the r second resonators 220 of the parallel branch 120 in a one-to-one correspondence. The q parallel inductors 310 and the r first series inductors 321 can enable the resonator to have smaller insertion loss and better out-of-band suppression, q is a positive integer greater than or equal to 1 and less than or equal to M, and r is a positive integer greater than or equal to 1 and less than or equal to N.

[0118] Figure 17 is a graph showing the transmission coefficient of the filter shown in Figure 16 over a wide frequency band; Figure 18 is a graph showing the transmission coefficient of the filter shown in Figure 16 at its center frequency. As shown in Figures 17 and 18 , by adjusting the parameters of the resonator of filter 100 and the inductance values ​​of shunt inductor 310 and first series inductor 321, the insertion loss of filter 100 is approximately 0.8 dB better than that of a conventional bulk acoustic wave filter 100. Furthermore, the out-of-band rejection of filter 100 is significantly improved.

[0119] Figure 19 is a schematic diagram of another filter provided by an embodiment of the present disclosure. As shown in Figure 19, the filter 100 may further include a third series inductor 323, which is arranged in series with the fifth resonator 240 of the second jumper branch 140. The third series inductor 323 and the fifth resonator 240 arranged in series can further improve out-of-band suppression, resulting in even better out-of-band suppression.

[0120] For example, as shown in FIG. 19 , the third series inductor 323 may be connected in series to a side of the second resonator 220 close to the fifth end 140A, or may be connected in series to a side of the second resonator 220 close to the sixth end 140B.

[0121] In some examples, in order to improve the out-of-band suppression of the filter 100, at least one of the parallel inductor 310, the first series inductor 321, the second series inductor 322 and the third series inductor 323 can be added to the circuit structure composed of the series branch 110, N parallel branches 120, the first jumper branch 130 and the second jumper branch 140. By adjusting the parameters of the resonator and each inductor, the out-of-band suppression of the filter 100 can be improved, which will not be repeated here.

[0122] FIG20 is a schematic diagram of another filter provided by an embodiment of the present disclosure. As shown in FIG20 , the filter 100 may further include a third jumper branch 150, which includes a sixth resonator 250. The third jumper branch 150 includes a seventh end 150A and an eighth end 150B. The seventh end 150A is connected between the third resonator 231 and the fourth resonator 232 of the first jumper branch 130. The eighth end 150B of the third jumper branch 150 is connected to the second end 120B of the p-th parallel branch 120, where p is a positive integer greater than or equal to 1 and less than or equal to N. The introduction of the first jumper branch 130, the second jumper branch 140, and the third jumper branch 150 improves the impedance matching between the input end 100A and the output end 100B of the series branch 110, thereby reducing insertion loss.

[0123] In some examples, as shown in Figure 20, the fourth end 130B of the first jumper branch 130 is connected to the second end 120B of the i-th parallel branch 120, the sixth end 140B of the second jumper branch 140 is connected to the second end 120B of the j-th parallel branch 120, and the eighth end 150B of the third jumper branch 150 is connected to the second end 120B of the p-th parallel branch 120, and i, j and p are all different.

[0124] In some examples, as shown in FIG20 , the filter 100 further includes a shunt inductor 310, which is arranged in parallel with the first resonator 210 of the series branch 110 of the series branch 110. The figure schematically illustrates the shunt inductor 310 being arranged in parallel with the third first resonator 210 of the series branch 110 of the series branch 110. The disclosed embodiments are not limited to this, and the shunt inductor 310 can be arranged in parallel with any first resonator 210 of the series branch 110. The shunt inductor 310 arranged in parallel can introduce a zero point on the left side of the passband, further improving out-of-band suppression while also reducing insertion loss and ripple within the passband.

[0125] For example, in order to improve the out-of-band suppression of the filter 100, at least one of the parallel inductor 310, the first series inductor 321, the second series inductor 322 and the third series inductor 323 can be added to the circuit structure consisting of the series branch 110, the N parallel branches 120, the first jumper branch 130, the second jumper branch 140 and the third jumper branch 150. By adjusting the parameters of the resonator and each inductor, the out-of-band suppression of the filter 100 can be improved. The details will not be repeated here.

[0126] FIG21 is a schematic diagram of another filter provided by an embodiment of the present disclosure. As shown in FIG21 , the filter 100 includes a series branch 110 , four parallel branches 120 , a first jumper branch 130 , and a second jumper branch 140 .

[0127] The filter 100 includes an input terminal 100A and an output terminal 100B, with a series branch 110 disposed between the input terminal 100A and the output terminal 100B. The series branch 110 includes four first resonators 210 arranged in series, namely a first first resonator 210a, a second first resonator 210b, a third first resonator 210c, and a fourth first resonator 210d.

[0128] As shown in FIG21 , the four parallel branches 120 include a first parallel branch 121, a second parallel branch 122, a third parallel branch 123, and a fourth parallel branch 124. Each parallel branch 120 includes a second resonator 220, and each parallel branch 120 includes a first end 120A and a second end 120B opposite to each other. The first end 120A of the first parallel branch 121 is grounded, and the second end 120B of the first parallel branch 121 is connected between the first first resonator 210a and the second first resonator 210b. The first end 120A of the second parallel branch 122 is grounded, and the second end 120B of the first parallel branch 121 is connected between the first first resonator 210a and the second first resonator 210b. One end 120A is grounded, and the second end 120B of the second parallel branch 122 is connected between the second first resonator 210b and the third first resonator 210c; 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 first resonator 210c and the fourth first resonator 210d; the first end 120A of the fourth parallel branch 124 is grounded, and the second end 120B of the fourth parallel branch 124 is connected between the fourth first resonator 210d and the output end 100B.

[0129] As shown in FIG21 , the first jumper branch 130 includes a third resonator 231 and a fourth resonator 232 connected in series. For example, the first jumper branch 130 includes a third end 130A and a fourth end 130B. The first node 110P of the series branch 110 is located between the input terminal 100A and the first first resonator 210a. The third end 130A of the first jumper branch 130 is connected to the first node 110P, and the fourth end 130B of the first jumper branch 130 is connected to the second end 120B of the second parallel branch 122.

[0130] 21 , the second jumper branch 140 includes a fifth resonator 240. For example, the second jumper branch 140 includes a fifth end 140A and a sixth end 140B. The fifth end 140A is connected between the third resonator 231 and the fourth resonator 232 of the first jumper branch 130, and the sixth end 140B of the second jumper branch 140 is connected to the second end 120B of the first parallel branch 121.

[0131] In this example, the introduction of the first jumper branch 130 and the second jumper branch 140 improves the impedance matching between the input end 100A and the output end 100B of the series branch 110, thereby reducing the insertion loss; in addition, the filter 100 has a four-step ladder topology structure, which can achieve better out-of-band suppression.

[0132] It is worth noting that the filter 100 provided in the embodiment of the present disclosure includes but is not limited to the above-mentioned three-step ladder topology structure and four-step ladder topology structure, and may also include a higher-step ladder topology structure, which will not be described in detail here.

[0133] In some examples, as shown in FIG21 , the filter 100 further includes a parallel inductor 310, which is arranged in parallel with the third first resonator 210 of the series branch 110. The parallel inductor 310 can introduce a zero point on the left side of the passband to further improve out-of-band suppression, while also reducing insertion loss and ripple within the passband.

[0134] FIG22 is a schematic diagram of another filter provided by an embodiment of the present disclosure. As shown in FIG22 , the filter 100 includes a series branch 110 , four parallel branches 120 , a first jumper branch 130 , and a second jumper branch 140 .

[0135] As shown in FIG22 , the filter 100 may further include a first series inductor 321. For example, the first series inductor 321 is connected in series with the second resonator 220 of the third parallel branch 123. Thus, the first series inductor 321 can introduce a zero point on the right side of the passband and shift the position of the zero point on the left side of the passband to the left, further improving out-of-band suppression while also reducing in-band insertion loss.

[0136] In some examples, at least one of the parallel inductor 310, the first series inductor 321, the second series inductor 322, and the third series inductor 323 described above can be added to the filter 100 shown in Figures 21 and 22. By adjusting the parameters of the resonator and each inductor, the out-of-band suppression of the filter 100 can be improved, which will not be described in detail here.

[0137] In some examples, at least one of the first resonator 210, the second resonator 220, the third resonator 231, the fourth resonator 232, and the fifth resonator 240 described above is a bulk acoustic wave resonator. Thus, the filter 100 can have advantages such as lower insertion loss, a high Q value, a steeper roll-off characteristic, and greater power handling.

[0138] For example, the first resonator 210 , the second resonator 220 , the third resonator 231 , the fourth resonator 232 , and the fifth resonator 240 are all bulk acoustic wave resonators.

[0139] For example, the BAW resonator may be at least one of a film bulk acoustic resonator (FBAR) and a solid-state mount resonator (SMR).

[0140] FIG23 is a schematic diagram of the structure of a BAW resonator provided in one embodiment of the present disclosure. As shown in FIG23 , the BAW resonator 260 includes a substrate 261, a piezoelectric film 263 located on the substrate 261, and a first drive electrode 264 and a second drive electrode 265. The first drive electrode 264 and the second drive electrode 265 are located on the substrate 261 and on either side of the piezoelectric film 263. For example, the first drive electrode 264 is located on the side of the piezoelectric film 263 closest to the substrate 261, while the second drive electrode 265 is located on the side of the piezoelectric film 263 away from the substrate 261. The BAW resonator 260 also includes an air gap 262 located within the substrate 261.

[0141] For example, as shown in FIG23 , the air gap 262 of the BAW resonator 260 is located on the side of the substrate 261 near the first driving electrode 264 and can be obtained by etching from the side of the substrate 261 near the first driving electrode 264. Thus, the BAW resonator 260 can convert electrical signals into BAWs that propagate along the thickness direction of the piezoelectric film 263, and utilize the air gap to achieve total reflection of the interfacial acoustic waves.

[0142] Figure 24 is a schematic diagram of the structure of another BAW resonator provided in one embodiment of the present disclosure. As shown in Figure 24, the air gap 262 of BAW resonator 260 is located on the side of substrate 1261 away from the first drive electrode 264. This gap can be etched from the side of substrate 261 away from the first drive electrode 264. Thus, BAW resonator 260 can convert electrical signals into BAWs that propagate along the thickness of piezoelectric film 263, and utilize the air gap to achieve total reflection of interfacial acoustic waves.

[0143] FIG25 is a schematic diagram of the structure of another BAW resonator provided in accordance with an embodiment of the present disclosure. As shown in FIG25 , the BAW resonator 270 includes a substrate 271, a piezoelectric film 274 located on the substrate 271, a first drive electrode 275, and a second drive electrode 276. The first drive electrode 275 and the second drive electrode 276 are located on the substrate 271 and on either side of the piezoelectric film 274. For example, the first drive electrode 275 is located on the side of the piezoelectric film 274 that is close to the substrate 271, and the second drive electrode 276 is located on the side of the piezoelectric film 274 that is away from the substrate 271. The BAW resonator 270 also includes alternating high acoustic impedance layers 272 and low acoustic impedance layers 273. The high acoustic impedance layers 272 and the low acoustic impedance layers 273 are located on the side of the piezoelectric film 274 that is close to the substrate 271. Thus, the BAW resonator 270 can convert electrical signals into BAWs that propagate along the thickness direction of the piezoelectric film 274 and achieve total reflection using the Bragg reflection layer composed of the alternating high acoustic impedance layers 272 and the low acoustic impedance layers 273 .

[0144] In some examples, at least one of the first resonator 210, the second resonator 220, the third resonator 231, the fourth resonator 232, and the fifth resonator 240 may be a resonator as shown in FIG23, a resonator as shown in FIG24, or a resonator as shown in FIG25. Of course, the embodiments of the present disclosure include but are not limited to the above, and at least one of the first resonator 210, the second resonator 220, the third resonator 231, the fourth resonator 232, and the fifth resonator 240 may also be a resonator of other types.

[0145] Figure 26 is a schematic diagram of a series-connected BAW resonator structure provided by one embodiment of the present disclosure. As shown in Figure 26, the structure includes a first BAW resonator 260A and a second BAW resonator 260B. The first BAW resonator 260A includes a substrate 261, an air gap 262A located within the substrate 261, a piezoelectric film 263, and first and second drive electrodes 264A and 265A located on either side of the piezoelectric film 263. The second BAW resonator 260B includes a substrate 261, an air gap 262B located within the substrate 261, a piezoelectric film 263, and first and second drive electrodes 264B and 265B located on either side of the piezoelectric film 263. The first BAW resonator 260A and the second BAW resonator 260B may share the substrate 261 and the piezoelectric film 263.

[0146] As shown in Figure 26, the structure may also include an insulating layer 266 and a first connecting electrode 267A, a second connecting electrode 268A, a third connecting electrode 267B and a fourth connecting electrode 268B located on the side of the insulating layer 266 away from the substrate 261; the first connecting electrode 267A is electrically connected to the first driving electrode 264A in the first bulk acoustic wave resonator 260A through a via hole passing through the insulating layer 266 and the piezoelectric film 263, and the second connecting electrode 268A is electrically connected to the second driving electrode 265A in the first bulk acoustic wave resonator 260A through a via hole passing through the insulating layer 266; the third connecting electrode 267B is electrically connected to the first driving electrode 264B in the second bulk acoustic wave resonator 260B through a via hole passing through the insulating layer 266 and the piezoelectric film 263, and the fourth connecting electrode 292B is electrically connected to the second driving electrode 265B in the second bulk acoustic wave resonator 260B through a via hole passing through the insulating layer 280. At this time, the first BAW resonator 260A and the second BAW resonator 260B can be connected in series by connecting the third connection electrode 267B and the second connection electrode 268A. For example, any two adjacent resonators in the series branch of the filter provided by the embodiment of the present disclosure can be connected in series in the above manner. The resonator in any parallel branch of the filter can also be connected to the resonator in the series branch in the above manner. The third and fourth resonators arranged in series in the first jumper branch can also be connected in series in the above manner. The fifth resonator in the second jumper branch can also be connected to the third resonator in the above manner.

[0147] FIG27 is a schematic diagram of another structure of a series connection of BAW resonators provided by an embodiment of the present disclosure. As shown in FIG27 , the structure includes a third BAW resonator 270A and a fourth BAW resonator 270B. The third BAW resonator 270A includes a substrate 271, a plurality of alternating high-acoustic impedance layers 272 and low-acoustic impedance layers 273 disposed on the substrate 271, a piezoelectric film 274, and a first drive electrode 275A and a second drive electrode 276A disposed on either side of the piezoelectric film 274. The fourth BAW resonator 270B includes a substrate 271, a plurality of alternating high-acoustic impedance layers 272 and low-acoustic impedance layers 273 disposed on the substrate 271, a piezoelectric film 274, and a first drive electrode 275B and a second drive electrode 276B disposed on either side of the piezoelectric film 274. The third BAW resonator 270A and the fourth BAW resonator 270B may share a substrate 271 , a plurality of alternating high acoustic impedance layers 272 and low acoustic impedance layers 273 , and a piezoelectric film 274 .

[0148] As shown in FIG27 , the first driving electrode 275A of the third BAW resonator 270A is located on the side of the piezoelectric thin film 274 away from the substrate 271, and the second driving electrode 276A of the third BAW resonator 270A is located on the side of the piezoelectric thin film 274 closer to the substrate 271. Furthermore, the first driving electrode 275B of the fourth BAW resonator 270B is located on the side of the piezoelectric thin film 274 closer to the substrate 271, and the second driving electrode 276B of the fourth BAW resonator 270B is located on the side of the piezoelectric thin film 274 away from the substrate 271. Thus, the second driving electrode 276A of the third BAW resonator 270A and the first driving electrode 275B of the fourth BAW resonator 270B can be disposed on the same layer and electrically connected, thereby achieving a series connection between the third BAW resonator 270A and the fourth BAW resonator 270A. For example, any two adjacent resonators in the series branch of the filter provided in the embodiment of the present disclosure can be connected in series in the above-mentioned manner, and the resonator in any parallel branch of the filter can also be connected to the resonator in the series branch in the above-mentioned manner. The third resonator and the fourth resonator arranged in series in the first jumper branch can also be connected in series in the above-mentioned manner, and the fifth resonator in the second jumper branch can also be connected to the third resonator in the above-mentioned manner.

[0149] For example, as shown in FIG. 27 , the second driving electrode 276A of the third BAW resonator 270A and the first driving electrode 275B of the fourth BAW resonator 270B may be integrally formed.

[0150] FIG28 is a schematic diagram of a structure for connecting a BAW resonator and an inductor according to an embodiment of the present disclosure. As shown in FIG28 , the structure includes a fifth BAW resonator 260C, a sixth BAW resonator 260D, and an inductor 300. The fifth BAW resonator 260C includes a substrate 261, an air gap 262C located within the substrate 261, a piezoelectric film 263, and first and second drive electrodes 264C and 265C located on either side of the piezoelectric film 263. The sixth BAW resonator 260D includes a substrate 261, an air gap 262D located within the substrate 261, a piezoelectric film 263, and first and second drive electrodes 264D and 265D located on either side of the piezoelectric film 263. The fifth and sixth BAW resonators 260C and 260D may share the substrate 261 and piezoelectric film 263.

[0151] As shown in Figure 28, the structure may also include an insulating layer 266 and a fifth connecting electrode 267C, a sixth connecting electrode 268C, a seventh connecting electrode 267D and an eighth connecting electrode 268D located on the side of the insulating layer 266 away from the substrate 261; the fifth connecting electrode 267C is electrically connected to the first driving electrode 264C in the fifth bulk acoustic wave resonator 260C through a via hole passing through the insulating layer 266 and the piezoelectric film 263, and the sixth connecting electrode 268C is electrically connected to the second driving electrode 265C in the fifth bulk acoustic wave resonator 260C through a via hole passing through the insulating layer 266; the seventh connecting electrode 267D is electrically connected to the first driving electrode 264D in the sixth bulk acoustic wave resonator 260D through a via hole passing through the insulating layer 266 and the piezoelectric film 263, and the eighth connecting electrode 268D is electrically connected to the second driving electrode 265D in the sixth bulk acoustic wave resonator 260D through a via hole passing through the insulating layer 266. For example, the inductor 300 can be a single-layer inductor, located on the side of the insulating layer 269 away from the substrate 261, and connected to the sixth connection electrode 268C and the eighth connection electrode 268D respectively, with the insulating layer 269 provided between each connection electrode and the inductor 240. For example, the resonator and inductor in the filter provided by the embodiment of the present disclosure can be connected in the manner described above. For example, the inductor 322 shown in Figure 13 can be connected to the resonator 232 and the resonator 231 in the manner described above.

[0152] FIG29 is a schematic diagram of another embodiment of the present disclosure, illustrating another connection method between a BAW resonator and an inductor. As shown in FIG29 , unlike the connection method shown in FIG28 , inductor 300 can be a three-dimensional inductor, comprising sub-conductive portions 300A and 300B located in multiple film layers. Sub-conductive portion 240A is located on the side of insulating layer 269A away from substrate 261, and sub-conductive portion 240B is located on the side of insulating layer 269B away from sub-conductive portion 240A.

[0153] FIG30 is a schematic diagram of a structure of a resonator and an inductor connected in parallel, provided in accordance with an embodiment of the present disclosure. As shown in FIG30 , the structure includes a seventh bulk acoustic wave resonator 260E and an inductor 300; the seventh bulk acoustic wave resonator 260E includes a substrate 261, an air gap 262E located in the substrate 261, a piezoelectric film 263, and a first drive electrode 264E and a second drive electrode 265E located on both sides of the piezoelectric film 263; the inductor 300 may be a three-dimensional inductor, and may include sub-conductive portions located in multiple film layers (for a specific description, see the relevant description in FIG29 ). The structure may also include a ninth connecting electrode 267E and a tenth connecting electrode 268E; the ninth connecting electrode 267E is connected to the first drive electrode 264E, and the tenth connecting electrode 268E is connected to the second drive electrode 265E; one end of the inductor 300 is connected to the ninth connecting electrode 267E, and the other end is connected to the tenth connecting electrode 268E, thereby achieving the parallel connection of the inductor 300 and the seventh bulk acoustic wave resonator 260E. For example, the parallel inductor 310 and the resonator described in the previous embodiment can be arranged in parallel in the above manner.

[0154] In some examples, the first resonator 210 , the second resonator 220 , the third resonator 231 , the fourth resonator 232 , or the fifth resonator 240 may also be a surface acoustic wave resonator (SAW), which has lower cost and has the advantage of impedance transformation.

[0155] Figure 31 is a schematic diagram of the structure of a surface acoustic wave resonator provided in one embodiment of the present disclosure. As shown in Figure 31, the surface acoustic wave resonator 280 includes an interdigital transducer 282 disposed on a piezoelectric film 281 and reflection gratings 283 disposed on either side of the interdigital transducer 282. One end of the interdigital transducer 282 can be directly or indirectly connected to the input port O1, and the other end of the interdigital transducer 282 can be directly or indirectly connected to the output port O2.

[0156] For example, multiple IDTs 282 may be connected in series to form a series branch. For example, one end of the IDT 282 may be grounded to form a parallel branch. In some examples, the piezoelectric film described above may include a piezoelectric crystal or a piezoelectric ceramic. Of course, the disclosed embodiments include but are not limited to these, and the piezoelectric material layer may also be other types of piezoelectric materials.

[0157] In some examples, the material of the piezoelectric film described above may be one or more of aluminum nitride (AlN), doped aluminum nitride (doped ALN), zinc oxide (ZnO), lead zirconate titanate (PZT), lithium niobate (LiNbO3), quartz, potassium niobate (KNbO3), and lithium tantalate (LiTaO3). Of course, the embodiments of the present disclosure include but are not limited to these. The piezoelectric material layer may also be a piezoelectric film composite structure, such as a composite structure of lithium tantalate piezoelectric film / silicon dioxide / silicon substrate.

[0158] At least one embodiment of the present disclosure further provides a radio frequency device. Figure 32 is a schematic diagram of a radio frequency device provided by one embodiment of the present disclosure. As shown in Figure 32, the radio frequency device 400 includes the aforementioned filter 100. Because the filter 100 can reduce insertion loss and improve out-of-band rejection performance, the radio frequency device 400 including the filter 100 has better performance.

[0159] In some examples, the RF device 400 includes but is not limited to a RF front-end module.

[0160] At least one embodiment of the present disclosure further provides an electronic device. FIG33 is a schematic diagram of an electronic device provided by one embodiment of the present disclosure. As shown in FIG33 , the electronic device 500 includes the aforementioned RF device 400. The electronic device 500 also has high performance and low cost.

[0161] In some examples, the electronic device 500 may be a terminal product such as a smart phone, WIFI, or a drone.

[0162] There are a few points to note:

[0163] (1) The drawings of the embodiments of the present disclosure only relate to the structures related to the embodiments of the present disclosure, and other structures may refer to conventional designs.

[0164] (2) Unless there is any conflict, the features of the same embodiment and different embodiments of the present disclosure may be combined with each other.

[0165] The above are only specific embodiments of the present disclosure, but the scope of protection of the present disclosure is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this disclosure should be included in the scope of protection of the present disclosure. Therefore, the scope of protection of the present disclosure should be based on the scope of protection of the claims.

Claims

1. A filter comprising: A series branch comprising M first resonators arranged in series; N parallel branches, each of the parallel branches comprising a second resonator; and The first jumper branch includes a third resonator and a fourth resonator arranged in series, Each of the parallel branches includes a first end and a second end opposite to each other, the first end of each of the parallel branches is grounded, and the second end of each of the parallel branches is connected to the series branch. The first jumper branch includes a third end and a fourth end, the third end is located at an end of the fourth resonator of the first jumper branch away from the third resonator, and the fourth end is located at an end of the third resonator of the first jumper branch away from the fourth resonator, the series branch includes a first node, and there is at least one first resonator between the first node and the second end of each parallel branch, the third end of the first jumper branch is connected to the first node, and the fourth end of the first jumper branch is connected to the second end of the parallel branch, and M and N are both positive integers greater than or equal to 2.

2. The filter according to claim 1, further comprising: The second jumper branch includes a fifth resonator, The second jumper branch includes a fifth end and a sixth end, and the fifth end is connected between the third resonator and the fourth resonator of the first jumper branch. The fourth end of the first jumper branch is connected to the second end of the i-th parallel branch, and the sixth end of the second jumper branch is connected to the second end of the j-th parallel branch, i and j are both positive integers greater than or equal to 1 and less than or equal to N, and i is greater than or equal to j.

3. The filter according to claim 2, wherein The difference between the value of i and the value of j is equal to 1.

4. The filter according to claim 2, wherein The first resonator, the third resonator, and the fifth resonator have the same resonant frequency and anti-resonant frequency, and the second resonator and the fourth resonator have the same resonant frequency and anti-resonant frequency.

5. The filter according to any one of claims 2 to 4, wherein: The series branch includes an input end and an output end that are oppositely arranged, and the M first resonators are arranged between the input end and the output end. The third end of the first jumper branch is connected between the input end and the first end of the series branch. one between the first resonators. The filter according to claim 5 , wherein: The second end of the first parallel branch is connected between the first first resonator and the second first resonator of the series branch, the second end of the kth parallel branch is connected between the kth first resonator and the k+1th first resonator of the series branch, and the second end of the Nth parallel branch is connected to the end of the Nth first resonator in the series branch away from the (N-1)th first resonator, where k is a positive integer greater than or equal to 1 and less than N.

7. The filter according to claim 6, wherein The values ​​of M and N are equal.

8. The filter according to claim 7, wherein The fourth end of the first jumper branch is connected to the second end of the second parallel branch, and the sixth end of the second jumper branch is connected to the second end of the first parallel branch.

9. The filter according to any one of claims 1 to 8, wherein: The values ​​of M and N are both 3.

10. The filter according to any one of claims 1 to 9, further comprising at least one shunt inductor, wherein: The parallel inductor is arranged in parallel with the first resonator of the series branch.

11. The filter according to claim 10, wherein The inductance of the parallel inductor ranges from 4nH to 8nH.

12. The filter according to claim 10, wherein The at least one parallel inductor includes a first parallel inductor and a second parallel inductor, the series branch includes an input end and an output end that are oppositely arranged, and the M first resonators are arranged between the input end and the output end. The first parallel inductor is connected in parallel with the first resonator of the series branch adjacent to the output end, and the inductance of the first parallel inductor ranges from 5nH to 9nH. The second parallel inductor is arranged in parallel with the first resonator of the series branch adjacent to the input end, and the inductance of the second parallel inductor ranges from 2nH to 4nH.

13. The filter according to any one of claims 1 to 12, further comprising at least one first series inductor, wherein: The first series inductor is arranged in series with the second resonator of the parallel branch.

14. The filter according to claim 13, wherein The inductance of the first series inductor ranges from 6nH to 10nH.

15. The filter according to any one of claims 1 to 14, further comprising: A second series inductor is arranged in series with the third resonator of the first jumper branch.

16. The filter according to claim 15, wherein The inductance of the second series inductor ranges from 6nH to 10nH.

17. The filter according to claim 6, further comprising: a parallel inductor, arranged in parallel with the first resonator of the series branch; as well as A first series inductor is arranged in series with the second resonator of the parallel branch, The inductance of the parallel inductor ranges from 7nH to 11nH, and the inductance of the first series inductor ranges from 9nH to 14nH.

18. The filter according to any one of claims 2 to 17, further comprising: The third jumper branch includes a sixth resonator, The third jumper branch includes a seventh end and an eighth end, the seventh end is connected between the third resonator and the fourth resonator of the first jumper branch, and the eighth end of the third jumper branch is connected to the second end of the pth parallel branch, where p is a positive integer greater than or equal to 1 and less than or equal to N.

19. The filter according to any one of claims 1 to 18, wherein: At least one of the first resonator, the second resonator, the third resonator, and the fourth resonator is a bulk acoustic wave resonator.

20. The filter according to claim 19, wherein The bulk acoustic wave resonator comprises: substrate; a piezoelectric film located on the substrate; and A first driving electrode and a second driving electrode are located on the substrate and on both sides of the piezoelectric film, Wherein, the bulk acoustic wave resonator further includes an air gap located in the substrate.

21. The filter according to claim 19, wherein The bulk acoustic wave resonator comprises: substrate; a piezoelectric film located on the substrate; and A first driving electrode and a second driving electrode are located on the substrate and on both sides of the piezoelectric film, The bulk acoustic wave resonator further includes high acoustic impedance layers and low acoustic impedance layers that are alternately arranged, and the high acoustic impedance layers and the low acoustic impedance layers are located on a side of the piezoelectric film close to the substrate.

22. A radio frequency device comprising the filter according to any one of claims 1 to 21.

23. An electronic device comprising the radio frequency device according to claim 22.

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