CN216794959U - Chebyshev band-pass filter circuit and radio frequency front end module - Google Patents

Abstract

The utility model discloses a Chebyshev band-pass filter circuit, which comprises an input end, an output end and a grounding end, wherein at least one LC series resonance circuit is connected in series between the input end and the output end; at least two LC parallel resonance circuits are arranged between the serial path formed by the at least one LC series resonance circuit and the grounding port; wherein at least one of the LC series resonant circuits is an acoustic wave resonator. According to the technical scheme, the high bandwidth of the Chebyshev band-pass filter circuit is met, the rectangular coefficient and the out-of-band rejection capability of the Chebyshev band-pass filter circuit can be improved, and the overall performance of the Chebyshev band-pass filter circuit is further improved.

Description

Chebyshev band-pass filter circuit and radio frequency front end module

Technical Field

The utility model relates to the technical field of filters, in particular to a Chebyshev band-pass filter circuit and a radio frequency front-end module.

Background

In a radio frequency communication device, a filter is a device for filtering harmonic signals, and is a circuit that allows signals within a certain pass band to pass through, while preventing signals outside the pass band from passing through. The filter can maximize the spectrum utilization rate, and for radio frequency signals of a 5G high-frequency band (for example, an N77/N78/N79 band), the filter needs to simultaneously meet the characteristics of high bandwidth, low loss, high rectangular coefficient, high out-of-band rejection and the like. At present, IPD (Integrated Product Development, IPD for short) technology or ceramic dielectric filter technology is mainly adopted for a filter applied to ultra-wideband scenes such as N77/78 and the like. However, the filter adopting the IPD technology or the ceramic dielectric filter technology has a poor rectangular coefficient, which is not favorable for the suppression of out-of-passband harmonic signals, and thus the application of the filter is finally greatly limited.

SUMMERY OF THE UTILITY MODEL

The embodiment of the utility model provides a Chebyshev band-pass filter circuit, which aims to solve the problem that the existing filter cannot well realize high bandwidth and high out-of-band rejection characteristics.

A Chebyshev band-pass filter circuit comprises an input end, an output end and a grounding end; at least one LC series resonant circuit connected in series between the input and the output; at least two LC parallel resonance circuits are arranged between the series path formed by the at least one LC series resonance circuit and the grounding port;

wherein at least one of the LC series resonant circuits is an acoustic wave resonator.

Further, the acoustic wave resonator is a SAW resonator or a BAW resonator.

Further, the chebyshev band-pass filter circuit further comprises at least one first capacitor, and each first capacitor is connected with one LC parallel resonance circuit in series.

The first LC series resonant circuit is connected in series between the input end and the output end, a first node is arranged between the input end and the first LC series resonant circuit, a second node is arranged between the first LC series resonant circuit and the output end, a first LC parallel resonant circuit is arranged between the first node and the grounding end, and a second LC parallel resonant circuit is arranged between the second node and the grounding end; wherein the first LC series resonant circuit is a first acoustic resonator.

Further, the first LC parallel resonant circuit includes a second capacitor and a first inductor connected in parallel, and the second LC parallel resonant circuit includes a third capacitor and a second inductor connected in parallel.

Further, the first LC parallel resonant circuit is a second acoustic wave resonator, and the second LC parallel resonant circuit includes a third capacitor and a second inductor connected in parallel;

or the second LC parallel resonant circuit is a second acoustic wave resonator, and the first LC parallel resonant circuit includes a second capacitor and a first inductor connected in parallel.

Further, the chebyshev band-pass filter circuit further comprises a first capacitor, and the first capacitor is connected with the second acoustic resonator in series.

Further, a first LC series resonant circuit and a second LC series resonant circuit are included, the first LC series resonant circuit and the second LC series resonant circuit are connected in series between the input end and the output end; a first node is arranged between the input end and the first LC series resonant circuit, a second node is arranged between the first LC series resonant circuit and the second LC series resonant circuit, a third node is arranged between the second LC series resonant circuit and the output end, a first LC parallel resonant circuit is arranged between the first node and the grounding end, a second LC parallel resonant circuit is arranged between the second node and the grounding end, and a third LC parallel resonant circuit is arranged between the third node and the grounding end;

the first LC series resonance circuit is a first acoustic resonator, and the second LC series resonance circuit is a second acoustic resonator.

Further, the first LC parallel resonant circuit comprises a second capacitor and a first inductor which are connected in parallel, the second LC parallel resonant circuit comprises a third capacitor and a second inductor which are connected in parallel, and the third LC parallel resonant circuit comprises a fourth capacitor and a third inductor which are connected in parallel;

or any one of the first LC parallel resonance circuit, the second LC parallel resonance circuit and the third LC parallel resonance circuit is an acoustic wave resonator;

or any two of the first LC parallel resonant circuit, the second LC parallel resonant circuit and the third LC parallel resonant circuit are acoustic wave resonators.

The embodiment further provides a radio frequency front end module, which comprises the Chebyshev band-pass filter circuit.

The chebyshev band-pass filter circuit comprises an input end, an output end and a grounding end; at least one LC series resonant circuit connected in series between the input and the output; by the series connection route that at least one LC series resonance circuit constitutes with be equipped with two at least LC parallel resonance circuits between the ground connection port, this application sets up at least one LC series resonance circuit among the chebyshev band-pass filter circuit into the sound wave syntonizer to make the chebyshev band-pass filter circuit of this application when having high bandwidth performance, still have lower loss, better rectangle coefficient and higher outband rejection ability, realize the high performance filter of ultra wide band, high rectangle coefficient, high outband rejection.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments of the present invention will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without inventive labor.

FIG. 1 is a schematic circuit diagram of a Chebyshev bandpass filter circuit in accordance with an embodiment of the present invention;

FIG. 2 is another circuit schematic of a Chebyshev bandpass filter circuit in accordance with an embodiment of the utility model;

FIG. 3 is another circuit schematic of a Chebyshev bandpass filter circuit in accordance with an embodiment of the utility model;

FIG. 4 is another circuit schematic of a Chebyshev bandpass filter circuit in accordance with an embodiment of the utility model;

FIG. 5 is another circuit schematic of a Chebyshev bandpass filter circuit in accordance with an embodiment of the utility model;

FIG. 6 is another circuit schematic of a Chebyshev bandpass filter circuit in accordance with an embodiment of the utility model;

FIG. 7 is another circuit schematic of a Chebyshev bandpass filter circuit in accordance with an embodiment of the utility model;

FIG. 8 is another circuit schematic of a Chebyshev bandpass filter circuit in accordance with an embodiment of the utility model;

FIG. 9 is another circuit schematic of a Chebyshev bandpass filter circuit in accordance with an embodiment of the utility model;

FIG. 10 is another circuit schematic of a Chebyshev bandpass filter circuit in accordance with an embodiment of the utility model;

FIG. 11 is another circuit schematic of a Chebyshev bandpass filter circuit in accordance with an embodiment of the utility model;

FIG. 12 is a schematic diagram of a simulation of a conventional Chebyshev bandpass filter circuit in accordance with an embodiment of the present invention;

FIG. 13 is a schematic diagram of a simulation of a Chebyshev bandpass filter circuit in accordance with an embodiment of the present invention.

In the figure: 10. an input end; 20. an output end; 31. a first LC series resonant circuit; 32. a second LC series resonant circuit; 41. a first LC parallel resonant circuit; 42. a second LC parallel resonant circuit; 43. a third LC parallel resonant circuit; 50. an acoustic wave resonator; 51. a first acoustic wave resonator; 52. a second acoustic wave resonator; 53. a third acoustic wave resonator; 54. a fourth acoustic wave resonator; 55. a fifth acoustic wave resonator; 61. an LC series resonant circuit; 62. an LC parallel resonance circuit.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It is to be understood that the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the utility model to those skilled in the art. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity to indicate like elements throughout.

It will be understood that when an element or layer is referred to as being "on …", "adjacent …", "connected to" or "coupled to" another element or layer, it can be directly on, adjacent, connected or coupled to the other element or layer or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on …", "directly adjacent to …", "directly connected to" or "directly coupled to" other elements or layers, there are no intervening elements or layers present. It will be understood that, although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention.

Spatially relative terms, such as "under …," "under …," "below," "under …," "over …," "above," and the like, may be used herein for ease of description to describe one element or feature's relationship to another element or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, then elements or features described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary terms "below …" and "below …" can encompass both an orientation of up and down. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatial descriptors used herein interpreted accordingly.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the utility model. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of the associated listed items.

In the following description, for purposes of explanation, specific details are set forth in order to provide a thorough understanding of the present invention. The following detailed description of the preferred embodiments of the utility model, however, the utility model is capable of other embodiments in addition to those detailed.

As shown in fig. 1, the present embodiment provides a chebyshev band-pass filter circuit, which includes an input terminal 10, an output terminal 20, and a ground terminal; at least one LC series resonant circuit 61 is connected in series between the input terminal 10 and the output terminal 20; at least two LC parallel resonant circuits 62 are provided between a series path constituted by at least one LC series resonant circuit 61 and a ground port; at least one of the LC series resonant circuits 61 is an acoustic wave resonator 50.

The series path formed by at least one LC series resonant circuit 61 is a path formed by the input terminal 10, the LC series resonant circuit 61, and the output terminal 20. At least one LC series resonant circuit 61 is provided between the input 10 and the output 20. The present embodiment does not specifically limit the number of the LC series resonant circuits 61 connected in series between the input terminal 10 and the output terminal 20.

In a specific embodiment, at least two LC parallel resonant circuits 62 are provided between the series path formed by at least one LC series resonant circuit 61 and the ground port. For example: if the chebyshev band-pass filter circuit includes an LC series resonant circuit 61, and the LC series resonant circuit 61 is connected in series between the input terminal 10 and the output terminal 20, an LC parallel resonant circuit 62 is provided between a connection node between the input terminal 10 and the LC series resonant circuit 61 and the ground terminal, and an LC parallel resonant circuit 62 is provided between a connection node between the LC series resonant circuit 61 and the output terminal 20 and the ground terminal. If the chebyshev band-pass filter circuit includes two LC series resonant circuits 61, the two LC series resonant circuits 61 being connected in series between the input terminal 10 and the output terminal 20, an LC parallel resonant circuit 62 is provided between a connection node between the input terminal 10 and the first LC series resonant circuit 61 and the ground terminal, an LC parallel resonant circuit 62 is provided between a connection node between the two LC series resonant circuits 61 connected in series and the ground terminal, and an LC parallel resonant circuit 62 is provided between a connection node between the second LC series resonant circuit 61 and the output terminal 20 and the ground terminal. At least one of the LC series resonant circuits 61 connected in series between the input terminal 10 and the output terminal 20 is an acoustic wave resonator 50, which can be selected by a user according to actual situations. The number of the acoustic wave resonators 50 in the Chebyshev band-pass filter circuit can be selected according to actual circuits, and the more the number of the acoustic wave resonators 50 is, the better the out-of-band rejection characteristic of the Chebyshev band-pass filter circuit is.

Further, as shown in fig. 2, the chebyshev band-pass filter circuit further includes at least one first capacitor C10, one first capacitor C10 is connected in series with one LC parallel resonant circuit 62, and the connected first capacitor C10 can enable the chebyshev band-pass filter circuit to appear a transmission zero point outside the passband, thereby improving the out-of-band rejection capability of the chebyshev band-pass filter circuit.

In one embodiment, as shown in fig. 4, the chebyshev band-pass filter circuit includes an LC series resonant circuit 61 connected in series between the input terminal 10 and the output terminal 20. The Chebyshev band-pass filter circuit comprises an input end 10, an output end 20 and a grounding end, wherein a first LC series resonance circuit 31 is arranged between the input end 10 and the output end 20, a first node is arranged between the input end 10 and the first LC series resonance circuit 31, a second node is arranged between the first LC series resonance circuit 31 and the output end 20, a first LC parallel resonance circuit 41 is arranged between the first node and the grounding end, and a second LC parallel resonance circuit 42 is arranged between the second node and the grounding end; the first LC series resonant circuit 31 is an acoustic wave resonator 50, that is, the first LC series resonant circuit 31 in the chebyshev band-pass filter circuit is replaced with the acoustic wave resonator 50. The first LC parallel resonant circuit 41 includes a second capacitor C411 and a first inductor L411 connected in parallel, and the second LC parallel resonant circuit 42 includes a third capacitor C421 and a second inductor L421 connected in parallel.

In another embodiment, as shown in fig. 2, a first capacitor C10 of the chebyshev bandpass filter circuit is connected in series to the first LC parallel resonant circuit 41, and the chebyshev bandpass filter circuit has a corresponding transmission zero outside the passband; a first capacitor C10 in the Chebyshev band-pass filter circuit is connected in series to the first LC parallel resonance circuit 41, a first capacitor C10 is connected in series to the second LC parallel resonance circuit 42, and the Chebyshev band-pass filter circuit has two corresponding transmission zeros outside a pass band; therefore, the number of transmission zeros outside the pass band of the chebyshev band-pass filter circuit is positively correlated with the number of the first capacitors C10. It should be noted that the transmission zero includes a high-band transmission zero and a low-band transmission zero outside the passband.

In the present embodiment, the chebyshev band-pass filter circuit includes an input terminal 10, an output terminal 20, and a ground terminal; at least one LC series resonant circuit 61 is connected in series between the input terminal 10 and the output terminal 20; at least two LC parallel resonant circuits 62 are provided between a series path constituted by at least one LC series resonant circuit 61 and a ground port; at least one of the LC series resonant circuits 61 is the acoustic wave resonator 50, and at least one of the LC series resonant circuits 61 is replaced with the acoustic wave resonator 50, so that the out-of-band high-frequency suppression performance is better than that of a chebyshev band-pass filter circuit in which the LC parallel resonant circuit 62 is replaced with the acoustic wave resonator 50; therefore, the Chebyshev band-pass filter circuit has high bandwidth performance, low loss, good rectangular coefficient and high out-of-band rejection capability, and realizes a high-performance filter with ultra wide band, high rectangular coefficient and high out-of-band rejection.

In a particular embodiment, the acoustic wave resonator 50 is a SAW resonator or a BAW resonator. The Acoustic Wave ResONator 50 may be a SAW (Surface Acoustic Wave, SAW filter for short) ResONator or a BAW (Film Bulk Acoustic ResONator filter for short) ResONator. The SAW resonator and the BAW resonator can realize the performances of low loss, high rectangular coefficient, high out-of-band rejection and the like, and the volumes of the SAW resonator and the BAW resonator are smaller. Therefore, in this example, at least one LC series resonant circuit 61 in the chebyshev band-pass filter circuit is set as a SAW resonator or a BAW resonator, so that the chebyshev band-pass filter circuit of the present application has high bandwidth performance, low loss, good squareness factor and high out-of-band rejection capability, and a high-performance filter with ultra-wideband, high squareness factor and high out-of-band rejection is realized.

It should be noted that the acoustic wave resonator 50 in the present application is not limited to the SAW resonator or the BAW resonator, and may be any existing type of acoustic wave resonator 50.

For example, taking the filtering of the signal in the N78 frequency band as an example, the bandwidth that can be realized by the conventional chebyshev band-pass filter circuit is 3300Mhz to 3800Mhz, i.e. about 500Mhz, but the rectangular coefficient and the out-of-band rejection capability are poor. Although the realized bandwidth of the acoustic wave resonator 50 is only about 300Mhz, the rectangular coefficient of the acoustic wave resonator is high, and the out-of-band rejection performance is good, therefore, at least one LC series resonance circuit 61 in the Chebyshev band-pass filter circuit is set as the acoustic wave resonator 50, namely, at least one LC series resonance circuit in the Chebyshev band-pass filter circuit is replaced by the acoustic wave resonator 50, so that the Chebyshev band-pass filter circuit has high bandwidth performance, low loss, good rectangular coefficient and high out-of-band rejection capability, and realizes a high-performance filter with ultra wide band, high rectangular coefficient and high out-of-band rejection.

As shown in fig. 3, in an embodiment, the equivalent circuit of the acoustic wave resonator 50 includes a sixth capacitor C51, a seventh capacitor C52, and a fourth inductor L51, a second terminal of the sixth capacitor C51 is connected to a first terminal of the fourth inductor L51, a first terminal of the seventh capacitor C52 is connected to a first terminal of the sixth capacitor C51, and a second terminal of the seventh capacitor C52 is connected to a second terminal of the fourth inductor L51.

In this embodiment, at least one LC series resonant circuit 61 in the chebyshev band-pass filter circuit is replaced with the acoustic wave resonator 50 corresponding to the equivalent circuit, and compared with the existing chebyshev band-pass filter circuit, the chebyshev band-pass filter circuit of the present application has a high bandwidth performance, and at the same time, has a low loss, a good rectangular coefficient and a high out-of-band rejection capability, and realizes a high-performance filter with ultra-wideband, high rectangular coefficient and high out-of-band rejection.

Referring to fig. 4, in a specific embodiment, the chebyshev band-pass filter circuit includes a first LC series resonant circuit 31, the first LC series resonant circuit 31 is connected in series between an input terminal 10 and an output terminal 20, a first node is provided between the input terminal 10 and the first LC series resonant circuit 31, a second node is provided between the first LC series resonant circuit 31 and the output terminal 20, a first LC parallel resonant circuit 41 is provided between the first node and a ground terminal, and a second LC parallel resonant circuit 42 is provided between the second node and the ground terminal; here, the first LC series resonant circuit 31 is a first acoustic wave resonator 51.

In the present embodiment, the chebyshev band-pass filter circuit includes the first LC series resonant circuit 31 by replacing the first LC series resonant circuit 31 with the acoustic wave resonator 50; therefore, the Chebyshev band-pass filter circuit has high bandwidth performance, low loss, good rectangular coefficient and high out-of-band rejection capability, and a high-performance filter with ultra-wide band, high rectangular coefficient and high out-of-band rejection is realized.

Referring to fig. 4, in a specific embodiment, the first LC parallel resonant circuit 41 includes a second capacitor C411 and a first inductor L411 connected in parallel, and the second LC parallel resonant circuit 42 includes a third capacitor C421 and a second inductor L421 connected in parallel.

As shown in fig. 5, in a specific embodiment, the first LC parallel resonant circuit 41 is a second acoustic wave resonator 52, and the second LC parallel resonant circuit 42 includes a third capacitor C421 and a second inductor L421 connected in parallel. As an example, the first LC series resonant circuit 31 is a first acoustic wave resonator 51, the first LC parallel resonant circuit 41 is a second acoustic wave resonator 52, and the second LC parallel resonant circuit 42 includes a third capacitor C421 and a second inductor L421 connected in parallel, so that the chebyshev band-pass filter circuit has two transmission zeros outside the passband, thereby achieving high bandwidth performance and further improving the out-of-band rejection capability of the chebyshev band-pass filter circuit.

In this embodiment, the first LC series resonant circuit 31 is the first acoustic wave resonator 51, and the first LC parallel resonant circuit 41 is the second acoustic wave resonator 52, compared with the case where only the first LC series resonant circuit 31 is set as the first acoustic wave resonator 51, the out-of-band rejection capability of the chebyshev band-pass filter circuit is further improved while the high bandwidth performance is achieved.

As shown in fig. 7, in a specific embodiment, the second LC parallel resonant circuit 42 is a second acoustic wave resonator 52, and the first LC parallel resonant circuit 41 includes a second capacitor C411 and a first inductor L411 connected in parallel. As another example, the first LC series resonant circuit 31 is a first acoustic wave resonator 51, the second LC parallel resonant circuit 42 is a second acoustic wave resonator 52, and the first LC parallel resonant circuit 41 includes a second capacitor C411 and a first inductor L411 connected in parallel, so that there are two transmission zeros outside the passband of the chebyshev band-pass filter circuit, thereby achieving high bandwidth performance and further improving the out-of-band rejection capability of the chebyshev band-pass filter circuit.

Furthermore, as shown in fig. 6, the chebyshev band-pass filter circuit further includes a first capacitor C40, and the first capacitor C40 is connected in series with the second acoustic wave resonator 52, so that the chebyshev band-pass filter circuit can also realize a transmission zero outside the pass band, and the out-of-band rejection capability of the chebyshev band-pass filter circuit is improved.

In this embodiment, the first LC series resonant circuit 31 is the first acoustic resonator 51, and the second LC parallel resonant circuit 42 is the second acoustic resonator 52, compared with the case where only the first LC series resonant circuit 31 is set as the first acoustic resonator 51, the out-of-band rejection capability of the chebyshev band-pass filter circuit is further improved while the high bandwidth performance is achieved.

In another specific embodiment, the first LC series resonant circuit 31 may be set as the first acoustic wave resonator 51, the first LC parallel resonant circuit 41 may be set as the second acoustic wave resonator 52, and the second LC parallel resonant circuit 42 may be set as the third acoustic wave resonator 53, that is, all LC resonant circuits in the chebyshev band-pass filter circuit are replaced by the acoustic wave resonator 50, so that the out-of-band rejection capability of the chebyshev band-pass filter circuit is further improved while the high bandwidth performance is achieved; the high-performance filter with ultra-wide band, high rectangular coefficient and high out-of-band rejection is realized.

In a specific embodiment, as shown in fig. 8, the chebyshev band-pass filter circuit includes a first LC series resonant circuit 31 and a second LC series resonant circuit 32 provided between an input terminal 10 and an output terminal 20, a first node is provided between the input terminal 10 and the first LC series resonant circuit 31, a second node is provided between the first LC series resonant circuit 31 and the second LC series resonant circuit 32, a third node is provided between the second LC series resonant circuit 32 and the output terminal 20, a first LC parallel resonant circuit 41 is provided between the first node and a ground terminal, a second LC parallel resonant circuit 42 is provided between the second node and the ground terminal, and a third LC parallel resonant circuit 43 is provided between the third node and the ground terminal; the first LC series resonant circuit 31 is a first acoustic resonator 51, and the second LC series resonant circuit 32 is a second acoustic resonator 52.

In this embodiment, the first LC series resonant circuit 31 is replaced with the first acoustic resonator 51, and the second LC series resonant circuit 32 is replaced with the second acoustic resonator 52, so that the chebyshev band-pass filter circuit of the present application has high bandwidth performance, and at the same time, has low loss, good rectangular coefficient and high out-of-band rejection capability, thereby realizing a high-performance filter with ultra-wideband, high rectangular coefficient and high out-of-band rejection.

As an example, fig. 12 is a graph showing a frequency-gain simulation of a conventional chebyshev band-pass filter circuit. Fig. 13 is a simulation diagram of frequency-gain of the chebyshev band-pass filter circuit in this example, in which the first LC series resonant circuit 31 is replaced with the first acoustic wave resonator 51, and the second LC series resonant circuit 32 is replaced with the second acoustic wave resonator 52. Compared with the existing Chebyshev band-pass filter circuit, the Chebyshev band-pass filter circuit in the example has high bandwidth performance, good rectangular coefficient and high out-of-band rejection capability.

Alternatively, as shown in fig. 8, the first LC parallel resonant circuit 41 includes a second capacitor C411 and a first inductor L411 connected in parallel, the second LC parallel resonant circuit 42 includes a third capacitor C421 and a second inductor L421 connected in parallel, and the third LC parallel resonant circuit 43 includes a fourth capacitor C431 and a third inductor L431 connected in parallel.

In one embodiment, any one of the first LC parallel resonant circuit 41, the second LC parallel resonant circuit 42, and the third LC parallel resonant circuit 43 is an acoustic wave resonator 50;

alternatively, any two of the first LC parallel resonant circuit 41, the second LC parallel resonant circuit 42, and the third LC parallel resonant circuit 43 are acoustic wave resonators 50.

In a specific embodiment, at least one of the first LC parallel resonance circuit 41, the second LC parallel resonance circuit 42, and the third LC parallel resonance circuit 43 is an acoustic wave resonator 50. According to the application, on the basis that at least one of at least two LC series resonance circuits 61 in the Chebyshev band-pass filter circuit is replaced by a SAW resonator or a BAW resonator, at least one of the LC parallel resonance circuits 62 is replaced by an acoustic wave resonator 50 (such as the SAW resonator or the BAW resonator), so that high bandwidth performance is achieved, and the out-of-band rejection capability of the Chebyshev band-pass filter circuit is further improved.

As an example, as shown in fig. 9, the first LC series resonant circuit 31 is a first acoustic wave resonator 51, the second LC series resonant circuit 32 is a second acoustic wave resonator 52, the third LC parallel resonant circuit 43 is a third acoustic wave resonator 53, and the first LC parallel resonant circuit 41 includes a second capacitor C411 and a first inductor L411 connected in parallel; the second LC parallel resonant circuit 42 includes a third capacitor C421 and a second inductor L421 connected in parallel; in this example, compared with the case where only the LC series resonant circuit 61 on the series branch is set as the wave resonator, the second LC series resonant circuit 32 on the series branch is set as the second wave resonator, and the third LC parallel resonant circuit 43 on the parallel branch is set as the third acoustic wave resonator 53, so that the rectangular coefficient and the out-of-band rejection capability of the chebyshev band-pass filter circuit are further improved while the chebyshev band-pass filter circuit is ensured to have high bandwidth performance.

As another example, as shown in fig. 10, the first LC series resonant circuit 31 is a first acoustic wave resonator 51, the second LC series resonant circuit 32 is a second acoustic wave resonator 52, the first LC parallel resonant circuit 41 is a third acoustic wave resonator 53, the second LC parallel resonant circuit 42 is a fourth acoustic wave resonator 54, and the third LC parallel resonant circuit 43 includes a fourth capacitance C431 and a third inductance L431 connected in parallel.

As another example, as shown in fig. 11, the first LC series resonant circuit 31 is a first acoustic wave resonator 51, the second LC series resonant circuit 32 is a second acoustic wave resonator 52, the first LC parallel resonant circuit 41 is a third acoustic wave resonator 53, the second LC parallel resonant circuit 42 is a fourth acoustic wave resonator 54, and the third LC parallel resonant circuit 43 is a fifth acoustic wave resonator 55.

In the present embodiment, at least one of the LC parallel resonant circuits 62 is replaced with a SAW resonator or a BAW resonator on the basis of replacing at least one of the at least two LC series resonant circuits 61 in the chebyshev band pass filter circuit with a SAW resonator or a BAW resonator, thereby achieving high bandwidth performance and further improving the out-of-band rejection capability of the chebyshev band pass filter circuit.

Preferably, the first LC series resonant circuit 31 in the chebyshev band-pass filter circuit is an acoustic wave resonator 50. In a specific embodiment, the chebyshev band-pass filter circuit of which the first LC series resonant circuit 31 is the acoustic wave resonator 50 has better out-of-band high frequency suppression performance than the chebyshev band-pass filter circuit of which the first LC parallel resonant circuit 41 or the second LC parallel resonant circuit 42 is the acoustic wave resonator 50.

The number of acoustic wave resonators 50 in the chebyshev band-pass filter circuit may be selected according to an actual circuit, and the larger the number of acoustic wave resonators 50, the better the suppression characteristics of the chebyshev band-pass filter circuit.

The embodiment further provides a radio frequency front end module, which comprises the chebyshev band-pass filter circuit in any one of the embodiments. It is understood that the rf front-end module integrates two or more discrete devices, such as an rf switch, a low noise amplifier, a filter, a duplexer, and a power amplifier, into one module. Alternatively, the rf front end module may be, but is not limited to, FEMiD, PAMiD, LPAMiD, dfem, LFEM, etc.

The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the embodiments of the present invention, and they should be construed as being included therein.

Claims (10)

1. A Chebyshev band-pass filter circuit is characterized by comprising an input end, an output end and a grounding end; at least one LC series resonant circuit connected in series between the input and the output; at least two LC parallel resonance circuits are arranged between the series path formed by the at least one LC series resonance circuit and the grounding end;

wherein at least one of the LC series resonant circuits is an acoustic wave resonator.

2. The chebyshev bandpass filter circuit as recited in claim 1, wherein the acoustic wave resonator is a SAW resonator or a BAW resonator.

3. The chebyshev bandpass filter circuit as recited in claim 1, further comprising at least one first capacitor, each of the first capacitors being connected in series with one of the LC parallel resonant circuits.

4. The chebyshev bandpass filter circuit according to claim 1, comprising a first LC series resonant circuit connected in series between the input terminal and the output terminal, a first node being provided between the input terminal and the first LC series resonant circuit, a second node being provided between the first LC series resonant circuit and the output terminal, a first LC parallel resonant circuit being provided between the first node and the ground terminal, and a second LC parallel resonant circuit being provided between the second node and the ground terminal; wherein the first LC series resonant circuit is a first acoustic resonator.

5. The chebyshev bandpass filter circuit according to claim 4, wherein the first LC parallel resonant circuit comprises a second capacitor and a first inductor connected in parallel, and the second LC parallel resonant circuit comprises a third capacitor and a second inductor connected in parallel.

6. The chebyshev bandpass filter circuit according to claim 4, wherein the first LC parallel resonant circuit is a second acoustic resonator, the second LC parallel resonant circuit comprising a third capacitor and a second inductor connected in parallel;

or the second LC parallel resonant circuit is a second acoustic wave resonator, and the first LC parallel resonant circuit includes a second capacitor and a first inductor connected in parallel.

7. The chebyshev bandpass filter circuit as recited in claim 6, further comprising a first capacitor connected in series with the second acoustic resonator.

8. The chebyshev bandpass filter circuit of claim 1 comprising a first LC series resonant circuit and a second LC series resonant circuit, the first LC series resonant circuit and the second LC series resonant circuit being connected in series between the input terminal and the output terminal; a first node is arranged between the input end and the first LC series resonant circuit, a second node is arranged between the first LC series resonant circuit and the second LC series resonant circuit, a third node is arranged between the second LC series resonant circuit and the output end, a first LC parallel resonant circuit is arranged between the first node and the grounding end, a second LC parallel resonant circuit is arranged between the second node and the grounding end, and a third LC parallel resonant circuit is arranged between the third node and the grounding end;

the first LC series resonance circuit is a first acoustic resonator, and the second LC series resonance circuit is a second acoustic resonator.

9. The chebyshev bandpass filter circuit of claim 8 wherein the first LC parallel resonant circuit comprises a second capacitor and a first inductor connected in parallel, the second LC parallel resonant circuit comprises a third capacitor and a second inductor connected in parallel, the third LC parallel resonant circuit comprises a fourth capacitor and a third inductor connected in parallel;

or any one of the first LC parallel resonance circuit, the second LC parallel resonance circuit and the third LC parallel resonance circuit is an acoustic wave resonator;

or any two of the first LC parallel resonant circuit, the second LC parallel resonant circuit and the third LC parallel resonant circuit are acoustic wave resonators.

10. A radio frequency front end module comprising a chebyshev bandpass filter circuit according to any one of claims 1-9.

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