Notch filter

Abstract

Provided in the present invention is a notch filter. The notch filter comprises a signal input end, first laterally excited bulk acoustic wave resonators connected in series with the signal input end, resonator assemblies connected in parallel to the first laterally excited bulk acoustic wave resonators, and a signal output end connected in series with the first laterally excited bulk acoustic wave resonators, wherein each resonator assembly comprises two second laterally excited bulk acoustic wave resonators that are respectively grounded; a first laterally excited bulk acoustic wave resonator is connected between two second laterally excited bulk acoustic wave resonators in a resonator assembly, and the three laterally excited bulk acoustic wave resonators are jointly arranged in a T shape; and the resonant frequency of each first laterally excited bulk acoustic wave resonator is less than the resonant frequency of each second laterally excited bulk acoustic wave resonator. In the present invention, by means of designing first laterally excited bulk acoustic wave resonators that are connected in series and resonator assemblies that are connected in parallel, a notch filter for realizing high-frequency, high-degree-of-suppression and large-bandwidth filtering is obtained.

Description

Notch filter TECHNICAL FIELD

[0001] The present application relates to the technical field of filter, in particular to a notch filter. BACKGROUND

[0002] Filters are key components for radio frequency (RF) front-ends, especially in WIFI 6 and 5G communication technologies, which are used to select signals of specific frequencies and suppress unwanted signals, and as the development of communication technologies, the demand for high performance of filters is increasing, which need to have low insertion loss, high selectivity and good linearity.

[0003] In the related art, an integrated passive device (IPD) filter is usually used to realize the wideband filtering of WIFI 6 and 5G, and the technical principle of the integrated passive device filter is similar to that of the traditional LC filter, mainly using semiconductor photolithography process to form a capacitance and inductance structure on a substrate or a substrate, then realizing a resonant cavity through a via and a metal wire, and finally realizing the reflection and transmission of signals through the coupling between the resonant cavities, and then packaging and testing.

[0004] Although the integrated passive device filter can realize the wideband filtering of WIFI 6 and 5G, as the 5G frequency reaches 4.4-5.0GHz and the WIFI 6 frequency reaches 5.85GHz, the precision requirement for the filter is also increasing, and because the quality factor of the passive device filter is low, it cannot realize the large bandwidth bandpass filtering with high frequency and high suppression degree, such as the WIFI 5G frequency band 5.15-5.85GHz filter cannot realize the strong suppression of the N79 frequency band 4.4-5.0GHz. SUMMARY

[0005] In view of the above problems in the related art, the present application provides a notch filter to solve the problem that the filter in the related art cannot realize high frequency and high suppression degree and large bandwidth filtering.

[0006] The present application provides a notch filter, which comprises a signal input end, a first transverse excitation bulk acoustic resonator arranged in series with the signal input end, a resonator assembly arranged in parallel with the first transverse excitation bulk acoustic resonator, and a signal output end arranged in series with the first transverse excitation bulk acoustic resonator; the resonator assembly comprises two second transverse excitation bulk acoustic resonators respectively grounded, the first transverse excitation bulk acoustic resonator is connected between the two second transverse excitation bulk acoustic resonators in the resonator assembly and arranged in a T shape together, and the resonant frequency of the first transverse excitation bulk acoustic resonator is less than the resonant frequency of the second transverse excitation bulk acoustic resonator.

[0007] Preferably, the first transverse excitation bulk acoustic wave resonator comprises a plurality of resonators connected in series between the signal input terminal and the signal output terminal; the resonator assembly comprises a plurality of assemblies, the plurality of resonator assemblies and the plurality of first transverse excitation bulk acoustic wave resonators are arranged alternately, one resonator assembly is arranged between two adjacent second transverse excitation bulk acoustic wave resonators, and two second transverse excitation bulk acoustic wave resonators in each resonator assembly and two first transverse excitation bulk acoustic wave resonators adjacent to the two second transverse excitation bulk acoustic wave resonators are arranged in a cross shape.

[0008] Preferably, the resonant frequencies of the plurality of first transverse excitation bulk acoustic wave resonators are different.

[0009] Preferably, the first transverse excitation bulk acoustic wave resonator is connected to the middle point of the two second transverse excitation bulk acoustic wave resonators in the resonator assembly.

[0010] Preferably, the static capacitance of the first transverse excitation bulk acoustic wave resonator is greater than the static capacitance of the second transverse excitation bulk acoustic wave resonator.

[0011] Preferably, the resonant frequencies of the two second transverse excitation bulk acoustic wave resonators in the resonator assembly are different.

[0012] Preferably, the notch filter further comprises an inductor corresponding to each resonator assembly, each inductor is connected in series with one of the second transverse excitation bulk acoustic wave resonators in the corresponding resonator assembly and grounded.

[0013] Preferably, the inductance value of the inductor is 0.1-5nH.

[0014] Preferably, the notch filter further comprises a first capacitor corresponding to each first transverse excitation bulk acoustic wave resonator, each first capacitor is arranged in parallel with the corresponding first transverse excitation bulk acoustic wave resonator.

[0015] Preferably, the notch filter further comprises a second capacitor corresponding to each resonator assembly, each second capacitor is arranged in parallel with one of the second transverse excitation bulk acoustic wave resonators in the corresponding resonator assembly.

[0016] Compared with the related art, the application designs the first transverse excitation bulk acoustic resonator in series with the signal input end and the resonator assembly in parallel with the first transverse excitation bulk acoustic resonator, limits the resonator assembly to include two second transverse excitation bulk acoustic resonators respectively grounded, arranges the two second transverse excitation bulk acoustic resonators in the resonator assembly in a T shape with the first transverse excitation bulk acoustic resonator, and limits the resonant frequency of the first transverse excitation bulk acoustic resonator to be less than the resonant frequency of the second transverse excitation bulk acoustic resonator, thereby obtaining a high-frequency high-suppression high-bandwidth filtering notch filter, and solving the problem that the filter in the related art cannot realize high-frequency high-suppression high-bandwidth filtering. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiments description. Obviously, the drawings in the following description are only some embodiments of the application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0018] Fig. 1 is a circuit structure diagram of a first notch filter provided by the embodiment of the application;

[0019] Fig. 2 is a circuit simulation diagram of the first notch filter provided by the embodiment of the application;

[0020] Fig. 3 is a circuit structure diagram of a band-stop filter provided by the related art;

[0021] Fig. 4 is a circuit simulation diagram of the band-stop filter provided by the related art;

[0022] Fig. 5 is a comparison diagram of the circuit simulation of the band-stop filter in the related art and the circuit simulation of the band-stop filter in the embodiment of the application;

[0023] Fig. 6 is a comparison diagram of the circuit simulation of the band-stop filter in the related art and the circuit simulation of the first notch filter in the embodiment of the application;

[0024] Fig. 7 is a circuit structure diagram of a second notch filter provided by the embodiment of the application;

[0025] Fig. 8 is a circuit structure diagram of a third notch filter provided by the embodiment of the application;

[0026] Fig. 9 is a circuit simulation diagram of a fourth notch filter provided by the embodiment of the application. DETAILED DESCRIPTION

[0027] 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 application belongs; the terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application; the description herein and the claims of the application and the above description of the drawings herein are not to be construed as limiting upon the entire scope of the application, unless otherwise specifically indicated; the description herein and the claims of the application and the above description of the drawings herein use the term "comprising" and "comprises" and "having" and "has" and "including" and "includes" and "containing" and "contains" and their variations thereof to mean "including but not limited to", unless otherwise specifically indicated.

[0028] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase "in an embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily all directed to the same embodiment, or to a single alternative embodiment.

[0029] It should be noted that the terms "upper", "lower", "left", "right", etc. mentioned in the embodiments of the present application are described with reference to the placement state in the drawings, and should not be interpreted as limiting embodiments of the present application. In addition, it should also be understood that in the text, when referring to an element "above" or "below" another element, it is possible that the element is directly "above" or "below" the other element, or it is possible that the element is "above" or "below" the other element through an intermediate element.

[0030] The technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0031] The embodiment of the present application provides a wave filter 100, which is shown in combination with FIG. 1, comprising a signal input end IN, a first transverse excitation bulk acoustic resonator arranged in series with the signal input end IN, a resonator assembly arranged in parallel with the first transverse excitation bulk acoustic resonator, and a signal output end OUT arranged in series with the first transverse excitation bulk acoustic resonator, the resonator assembly comprising two second transverse excitation bulk acoustic resonators respectively grounded, the first transverse excitation bulk acoustic resonator being connected between the two second transverse excitation bulk acoustic resonators in the resonator assembly and being arranged in a T shape together.

[0032] Wherein, the other end of the signal input end is grounded, and the other end of the signal output end is grounded.

[0033] The first transverse excitation bulk acoustic resonator includes a plurality of resonators connected in series between the signal input end and the signal output end; the resonator assembly includes a plurality of resonator assemblies, the plurality of resonator assemblies and the plurality of first transverse excitation bulk acoustic resonators are arranged alternately, one resonator assembly is arranged between two adjacent second transverse excitation bulk acoustic resonators, and two second transverse excitation bulk acoustic resonators in each resonator assembly and two first transverse excitation bulk acoustic resonators adjacent to the two second transverse excitation bulk acoustic resonators are arranged in a cross shape.

[0034] In the embodiment, the first transverse excitation bulk acoustic resonator includes three resonators, which are a first transverse excitation bulk acoustic resonator S1, a first transverse excitation bulk acoustic resonator S2 and a first transverse excitation bulk acoustic resonator S3, and the resonator assembly includes two resonator assemblies, which are a first resonator assembly 1 and a second resonator assembly 2, wherein the two second transverse excitation bulk acoustic resonators in the first resonator assembly 1 are a second transverse excitation bulk acoustic resonator P1 and a second transverse excitation bulk acoustic resonator P2, and the two second transverse excitation bulk acoustic resonators in the second resonator assembly 2 are a second transverse excitation bulk acoustic resonator P3 and a second transverse excitation bulk acoustic resonator P4.

[0035] The resonant frequency of the first transverse excitation bulk acoustic resonator is less than the resonant frequency of the second transverse excitation bulk acoustic resonator. Such a design can design the notch filter 100 as a band-stop filter, that is, a BSF, which can achieve a higher suppression degree in a certain frequency band. If the resonant frequency of the first transverse excitation bulk acoustic resonator is greater than the resonant frequency of the second transverse excitation bulk acoustic resonator, the notch filter 100 will form a band-pass filter in the related art, which is referred to as a BPF.

[0036] As shown in FIG. 5, the frequency range of the band-pass filter in the related art between the m3 position point and the m4 position point is 4.6-5.0 GHz, and the insertion loss range is-1.884 to-2.298 dB; while the frequency range of the notch filter 100 in the embodiment of the present application between the m3 position point and the m4 position point is 4.6-5.0 GHz, and the insertion loss range of the edge is-35.649 to-44.318 dB, which completely presents a band-stop filter.

[0037] The first transverse excitation bulk acoustic resonator is connected to the middle point of the two second transverse excitation bulk acoustic resonators in the resonator assembly; the resonant frequencies of the plurality of first transverse excitation bulk acoustic resonators are different.

[0038] The static capacitance of the first transverse excitation bulk acoustic resonator is greater than the static capacitance of the second transverse excitation bulk acoustic resonator.

[0039] The resonant frequencies of the two second laterally driven bulk acoustic wave resonators in each resonator assembly are different; but the static capacitances of the two second laterally driven bulk acoustic wave resonators in each resonator assembly can be the same or different.

[0040] The circuit structure of the band-stop filter in the related art is shown in FIG. 3, and the circuit simulation is shown in FIG. 4. The frequencies of the m5-m8 position points are 5.020 GHz, 5.150 GHz, 5.850 GHz and 4.620 GHz, respectively, and the insertion losses are -21.116 dB, -2.150 dB, -1.422 dB and -17.167 dB, respectively. The band-stop filter in the embodiment is implemented in a manner of alternating arrangement of series resonators and parallel resonators, and the worst rejection point in the frequency range of 4.62-5.02 GHz is -17.16 dB, and the worst insertion loss in the frequency range of 5.15-5.85 GHz is -2.15 dB. The band-stop filter 100 in the embodiment can achieve higher out-of-band rejection without increasing the number of first laterally driven bulk acoustic wave resonators in a manner of cross arrangement. As shown in FIG. 2, the frequencies of the m1-m5 position points are 4.620 GHz, 5.020 GHz, 5.150 GHz, 5.850 GHz and 4.820 GHz, respectively, and the insertion losses are -35.649 dB, -55.430 dB, -1.626 dB, -1.782 dB and -30.619 dB, respectively. The worst rejection point in the frequency range of 4.62-5.02 GHz is -30.62 dB, and the worst insertion loss in the frequency range of 5.15-5.85 GHz is -1.78 dB. That is, the band-stop filter 100 in the embodiment not only achieves high-frequency high-rejection and large-bandwidth filtering, but also maintains the insertion loss in the passband from deteriorating. The comparison between the circuit simulation of the band-stop filter in the related art and the circuit simulation of the band-stop filter 100 in the embodiment is shown in FIG. 6. Specifically, compared with the band-stop filter in the related art, the band-stop filter 100 in the embodiment can achieve a steeper out-of-band rejection level than the Chebyshev polynomial, while maintaining the insertion loss in the passband from deteriorating. That is, the out-of-band steep drop is enhanced and the stopband is lowered quickly by adjusting the parameters.

[0041] In the related art, the band-stop filter is calculated by the following formula:

[0042] The band-stop filter 100 in the embodiment is calculated by the following formula:

[0043] ε is the passband ripple coefficient, ω is the normalized frequency, ω c is the cutoff frequency, T is the Chebyshev polynomial, and R is the Jacobi polynomial.

[0044] As an optional embodiment of the notch filter 100, as shown in FIG. 7, the notch filter 100 further comprises a first capacitor corresponding to each first lateral excitation bulk acoustic resonator, and each second capacitor is arranged in parallel with the corresponding first lateral excitation bulk acoustic resonator. This design can improve the suppression degree of the passband near end. Of course, according to actual needs, one first capacitor can also be designed, and then the plurality of first lateral excitation bulk acoustic resonators are arranged in parallel with each other and then in series with the first capacitor.

[0045] In this embodiment, the first capacitor includes three, which are the first capacitor C1, the first capacitor C2 and the first capacitor C3.

[0046] In addition, if the notch filter 100 is not designed with the first capacitor, the notch filter 100 can also be designed to include a second capacitor corresponding to each resonator assembly, and each second capacitor is arranged in parallel with one of the second lateral excitation bulk acoustic resonators in the corresponding resonator assembly. Of course, according to actual needs, one second capacitor can also be designed, and then one of the second lateral excitation bulk acoustic resonators in each resonator assembly is arranged in parallel with each other and then in series with the first capacitor.

[0047] Correspondingly, according to actual needs, the second capacitor can be designed to have a number corresponding to each second lateral excitation bulk acoustic resonator, and each second capacitor is arranged in parallel with the corresponding second lateral excitation bulk acoustic resonator.

[0048] As another optional embodiment of the notch filter 100, as shown in FIG. 8, the notch filter 100 further comprises an inductor corresponding to each resonator assembly, and each inductor is arranged in series with one of the second lateral excitation bulk acoustic resonators in the corresponding resonator assembly and then grounded. Of course, according to actual needs, one inductor can also be designed, and then one of the second lateral excitation bulk acoustic resonators in each resonator assembly is arranged in parallel with each other and then in series with the inductor.

[0049] The inductor can be realized by a wire-wound inductor on the same layer as the resonator assembly or an inductor attached to the external surface.

[0050] In this embodiment, the inductor includes two, which are the inductor L1 and the inductor L2.

[0051] In this embodiment, the inductance value of the inductor is 0.1-5nH.

[0052] Regarding the design of the first capacitor or the second capacitor and the design of the inductor, it is not limited to including any one of the first capacitor, the second capacitor and the inductor alone, but can also be designed to include a combination of capacitors and inductors, which can include the first capacitor, the second capacitor and the inductor, or the first capacitor and the inductor, or the second capacitor and the inductor, or the first capacitor and the second capacitor.

[0053] As another optional embodiment of the notch filter 100, the notch filter 100 further comprises the first capacitor and the first inductor as described above, and both the first capacitor and the first inductor are multiple. The first capacitor and the first inductor can form a second resonance section, and form a better notch at the far end of the passband. As shown in FIG. 9, the frequencies of the m1-m6 points are 2.400 GHz, 2.483 GHz, 4.400 GHz, 5.000 GHz, 5.150 GHz and 5.850 GHz, and the insertion losses are -34.345 dB, -34.469 dB, -33.043 dB, -30.541 dB, -1.598 dB and -0.742 dB, respectively. The second notch section is realized in the frequency range of 2.400-2.483 GHz, and the suppression level reaches -34.3 dB.

[0054] The notch filter 100 in the embodiment is calculated by using the following formula:

[0055] freq is the resonance frequency, L is the inductance, and C is the capacitance.

[0056] The embodiment designs the first transverse excitation bulk acoustic resonator in series with the signal input end IN and the resonator assembly in parallel with the first transverse excitation bulk acoustic resonator, limits that the resonator assembly comprises two second transverse excitation bulk acoustic resonators respectively grounded, the two second transverse excitation bulk acoustic resonators in the resonator assembly are arranged in a T shape with the first transverse excitation bulk acoustic resonator, and limits that the resonance frequency of the first transverse excitation bulk acoustic resonator is less than the resonance frequency of the second transverse excitation bulk acoustic resonator, thereby obtaining a high-frequency high-suppression-level and large-bandwidth filtering notch filter 100, solving the problem that the filter in the related art cannot realize high-frequency high-suppression-level and large-bandwidth filtering. At the same time, the integrated passive device filter in the related art is avoided, and the performance of the overall system is provided.

[0057] It should be noted that the above-described various embodiments with reference to the accompanying drawings are only used to illustrate the present application and not to limit the scope of the present application. Those skilled in the art should understand that the modifications or equivalent replacements to the present application without departing from the spirit and scope of the present application should be covered within the scope of the present application. In addition, unless the context indicates otherwise, the word in singular form includes the plural form, and vice versa. In addition, unless specifically stated, all or part of any embodiment can be used in combination with all or part of any other embodiment.

Claims

1. A notch filter, characterized by, The notch filter comprises a signal input end, a first transverse excitation bulk acoustic resonator arranged in series with the signal input end, a resonator assembly arranged in parallel with the first transverse excitation bulk acoustic resonator, and a signal output end arranged in series with the first transverse excitation bulk acoustic resonator; the resonator assembly comprises two second transverse excitation bulk acoustic resonators each grounded, and the first transverse excitation bulk acoustic resonator is connected between the two second transverse excitation bulk acoustic resonators in the resonator assembly and arranged in a T shape together; the resonant frequency of the first transverse excitation bulk acoustic resonator is less than the resonant frequency of the second transverse excitation bulk acoustic resonator.

2. The wave filter of claim 1, wherein, The first transverse excitation bulk acoustic resonator comprises a plurality of first transverse excitation bulk acoustic resonators arranged in series between the signal input end and the signal output end; the resonator assembly comprises a plurality of resonator assemblies, the plurality of resonator assemblies and the plurality of first transverse excitation bulk acoustic resonators are arranged alternately, one resonator assembly is arranged between two adjacent second transverse excitation bulk acoustic resonators, and two second transverse excitation bulk acoustic resonators in each resonator assembly and two first transverse excitation bulk acoustic resonators adjacent to the resonator assembly are arranged in a cross shape.

3. The wave trap filter of claim 2, wherein, The resonant frequencies of the plurality of first transverse excitation bulk acoustic resonators are different.

4. The wave filter of claim 2, wherein, The first transverse excitation bulk acoustic resonator is connected to the middle point of the two second transverse excitation bulk acoustic resonators in the resonator assembly.

5. The wave filter of claim 1, wherein, The static capacitance of the first transverse excitation bulk acoustic resonator is greater than the static capacitance of the second transverse excitation bulk acoustic resonator.

6. The wave filter of claim 1, wherein, The resonant frequencies of the two second transverse excitation bulk acoustic resonators in the resonator assembly are different.

7. The wave filter of claim 1, wherein, The notch filter further comprises an inductor corresponding to each resonator assembly, each inductor is connected in series with one of the second transverse excitation bulk acoustic resonators in the corresponding resonator assembly and then grounded.

8. The wave filter of claim 7, wherein, The inductance value of the inductor is 0.1-5nH.

9. The wave filter of claim 1, wherein, The notch filter further comprises a first capacitor corresponding to each first transverse excitation bulk acoustic resonator, each first capacitor is arranged in parallel with the corresponding first transverse excitation bulk acoustic resonator.

10. The wave filter of claim 1, wherein, The notch filter further comprises a second capacitor corresponding to each resonator assembly, each second capacitor is arranged in parallel with one of the second transverse excitation bulk acoustic resonators in the corresponding resonator assembly.

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