A bandpass filter with both high selectivity and broadband suppression capability

Abstract

The present invention discloses a bandpass filter with both high selectivity and broadband suppression capability, and relates to the technical field of bandpass filters, comprising a filter body (1) and a mark (2), wherein the mark (2) is located on the outer wall of the filter body (1), and the filter body (1) comprises a multilayer dielectric body, wherein the dielectric body comprises a circuit layer in the dielectric body and an external electrode on the outer wall of the dielectric body, wherein the external electrode comprises an input port (3), an output port (4) and a ground port (5), wherein the input port (3), the ground port (5) and the output port (4) are located in the same plane and are arranged in sequence. The present invention solves the problems of the existing filter being too large in size, too large in line loss and poor out-of-band suppression capability.

Description

Technical Field

[0001] The present invention relates to the technical field of bandpass filters, and in particular to a bandpass filter having both high selectivity and broadband suppression capability. Background Art

[0002] Today's highly integrated advanced radio frequency (RF) designs and developments have performance levels that exceed those of previous RF systems. In RF systems, harmful RF signals at or near the system's required operating frequency may affect the receiver's ability to accurately modulate the required RF data packets. Traditional filters can use a coupled line structure, which allows two transmission lines to couple with each other by setting parallel transmission lines together. When the RF signal passes through, it can block low-frequency signals. However, the filtering effect of a single set of coupled lines is limited. In order to achieve good filtering characteristics, multiple sets of coupled transmission lines need to be connected, resulting in the filter size being too large. The more the number of transmission lines connected in series, the greater the line loss. In addition, it is more difficult for filters with coupled line structures to produce transmission zeros, and the ability to suppress out-of-band is poor, making it difficult to meet the circuit requirements of high-frequency wireless communication technology. Summary of the invention

[0003] In view of the above-mentioned deficiencies in the prior art, the present invention provides a bandpass filter with both high selectivity and broadband suppression capability, which solves the problems of the existing filter being too large in size, too large in line loss, and poor out-of-band suppression capability.

[0004] In order to achieve the above-mentioned purpose of the invention, the technical solution adopted by the present invention is: a bandpass filter with both high selectivity and broadband suppression capability, including a filter body and a mark, the mark is located on the outer wall of the filter body, the filter body includes a multilayer dielectric body, the dielectric body includes a circuit layer in the dielectric body and an external electrode on the outer wall of the dielectric body, the external electrode includes an input port, an output port and a ground port, the input port, the ground port and the output port are located in the same plane and are arranged in sequence.

[0005] The beneficial effect of the above scheme is: the present invention provides a bandpass filter with both high selectivity and broadband suppression capability, which has the advantages of small size, low cost, small insertion loss, high isolation, good stability, high reliability, etc., and is easy to integrate with other circuits and modules. It can be widely used in wireless communication systems and equipment with high requirements on volume, electrical performance, temperature stability and anti-interference, and solves the problems of existing filters being too large in size, too large in line loss and poor out-of-band suppression capability.

[0006] Furthermore, the circuit layer in the dielectric body includes an LC resonance unit, a co-directional coupling resonance unit and a reverse coupling resonance unit.

[0007] The beneficial effect of the above further scheme is: by reasonably selecting the equivalent component values ​​of the filter resonant unit and optimizing the coupling relationship of its equivalent components in the vertical space, the present invention can introduce transmission zeros near both ends of the passband to achieve a higher rectangular coefficient, while achieving a good suppression effect in a wider stopband range.

[0008] Further, the LC resonant unit includes a resonant capacitor and a resonant inductor, one end of the resonant capacitor is connected to one end of the resonant inductor and serves as a signal input end, the other end of the resonant capacitor is connected to the other end of the resonant inductor, and is respectively connected to one end of the first coupling path CL1, one end of the ground capacitor Cg1, and one end of the first coupling capacitor C1, the other end of the first coupling path CL1 and the other end of the ground capacitor Cg1 are both grounded, the other end of the first coupling capacitor C1 is respectively connected to one end of the second coupling path CL2, one end of the ground capacitor Cg2, and one end of the second coupling capacitor C2, the other end of the second coupling path CL2 and the other end of the ground capacitor Cg2 are both grounded, the other end of the second coupling path CL2 is respectively connected to one end of the third coupling path CL3 and one end of the ground capacitor Cg3, and serves as a signal output end, the other end of the third coupling path CL3 and the other end of the ground capacitor Cg3 are both grounded.

[0009] The beneficial effect of the above further solution is: through the above technical solution, an equivalent circuit of a bandpass filter is provided.

[0010] Further, the resonant capacitor includes an eighth electrode of the sixth layer of the circuit layer, a thirteenth electrode of the fourth layer of the circuit layer, and a ninth electrode of the third layer of the circuit layer, wherein the eighth electrode is connected to the thirteenth electrode of the fourth layer of the circuit layer via an eleventh via hole located in the fifth layer of the circuit layer and an eleventh via hole located in the sixth layer of the circuit layer, and forms a resonant capacitor with the ninth electrode of the third layer of the circuit layer;

[0011] The resonant inductor includes an eighth electrode of the sixth circuit layer, a twelfth electrode of the fifth circuit layer, a twelfth electrode of the fourth circuit layer and a first electrode of the first circuit layer. The eighth electrode is connected to the twelfth electrode via an eleventh via hole located on the fifth circuit layer, the twelfth electrode is connected to the twelfth electrode via the twelfth via hole located on the fifth circuit layer, and the twelfth electrode is connected to the first electrode via the first via hole located on the third circuit layer.

[0012] The beneficial effect of the above further solution is: through the above technical solution, a specific structure of the LC resonance unit is provided, and the characteristics of the resonance unit are used to minimize the mutual coupling between the lumped components and reduce the influence of parasitic parameters.

[0013] Furthermore, the co-directional coupling resonance unit includes a first electrode of the first layer of the circuit layer and a second electrode of the first layer of the circuit layer, the first electrode is vertically connected to the ninth electrode of the third layer of the circuit layer via a first via hole located in the first layer of the circuit layer, and forms a first coupling capacitor C1 with the second electrode vertically connected to the tenth electrode of the fourth layer of the circuit layer via a second via hole located in the first layer of the circuit layer, the first electrode is connected to the fourth electrode of the second layer of the circuit layer via a fourth via hole located in the first layer of the circuit layer, and is connected to the sixth electrode of the sixth layer of the circuit layer via an eighth via hole located in the second layer of the circuit layer and is conducted to the ground, the second electrode is connected to the fourth electrode via a fifth via hole located in the first layer of the circuit layer, and is connected to the sixth electrode of the sixth layer of the circuit layer via an eighth via hole located in the second layer of the circuit layer and is conducted to the ground.

[0014] The beneficial effect of the above further solution is that: through the above technical solution, a co-directional coupling resonance unit is formed.

[0015] Furthermore, the first electrode is vertically connected to the ninth electrode of the third layer of the circuit layer through a first via hole located in the first layer of the circuit layer, and forms a capacitor Cg1 to ground with the fifth electrode of the fifth layer of the circuit layer, and the second electrode is vertically connected to the tenth electrode of the fourth layer of the circuit layer through a second via hole located in the first layer of the circuit layer, and forms a capacitor Cg2 to ground with the fifth electrode of the fifth layer of the circuit layer.

[0016] The beneficial effect of the above further solution is that: through the above technical solution, ground capacitors Cg1 and Cg2 are formed.

[0017] Further, the reverse coupling resonance unit includes a third electrode of the first layer of the circuit layer, the third electrode is connected to the seventh electrode of the sixth layer of the circuit layer via a third via located in the first layer of the circuit layer and a thirty-first via located in the fourth layer of the circuit layer, the third electrode is connected to the fourth electrode of the second layer of the circuit layer via the sixth via located in the first layer of the circuit layer, and is connected to the fifth electrode of the fifth layer of the circuit layer via the seventh via located in the second layer of the circuit layer, the fifth electrode is conducted to the ground via a ninth via located in the fifth layer of the circuit layer, the third electrode is connected to the eleventh electrode of the fourth layer of the circuit layer via the third via located in the first layer of the circuit layer, and forms a second coupling capacitor C2 with the tenth electrode of the fourth layer of the circuit layer.

[0018] The beneficial effect of the above further solution is that a reverse coupling resonance unit is formed through the above technical solution.

[0019] Furthermore, the third electrode is connected to the eleventh electrode on the fourth layer of the circuit layer through the third via hole on the first layer of the circuit layer, and forms a capacitor Cg3 to ground with the fifth electrode on the fifth layer of the circuit layer.

[0020] The beneficial effect of the above further solution is that: a capacitance to ground is formed based on the third electrode, the eleventh electrode and the fifth electrode through the above technical solution.

[0021] Furthermore, the dielectric body is formed by stacking multiple layers of substrates, the dielectric body is manufactured based on a multi-layer printed circuit board process or a low-temperature co-fired ceramic technology, and the circuit layer adopts an embedded metal material.

[0022] The beneficial effects of the above further scheme are as follows: the present invention has a multi-layer circuit structure, and by using corresponding dielectric materials in different circuit layer areas, the dual-channel function can be realized in a very small package volume. Based on the low-temperature co-fired ceramic process, the multi-layer circuit of the frequency divider is built into the ceramic dielectric body, and various equivalent components are integrated on the three-dimensional circuit substrate to achieve miniaturization and high density of the circuit. Metal materials with high electrical conductivity, such as silver and copper, can be used as conductor materials, which is beneficial to improve the quality factor of the circuit system. For example, silver can be used as the embedded metal material, which will not oxidize during the sintering process and does not require electroplating protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The figure is a schematic diagram of the appearance structure of a bandpass filter with both high selectivity and broadband suppression capability.

[0024] Figure 2 This is a schematic diagram of the internal structure of a bandpass filter with both high selectivity and broadband suppression capabilities.

[0025] Figure 3 This is a schematic diagram of the first-layer circuit structure inside the bandpass filter.

[0026] Figure 4 This is a schematic diagram of the second-layer circuit structure inside the bandpass filter.

[0027] Figure 5 This is a schematic diagram of the third-layer circuit structure inside the bandpass filter.

[0028] Figure 6 This is a schematic diagram of the fourth layer circuit structure inside the bandpass filter.

[0029] Figure 7 This is a schematic diagram of the fifth layer circuit structure inside the bandpass filter.

[0030] Figure 8 This is a schematic diagram of the sixth layer circuit structure inside the bandpass filter.

[0031] Fig. 9 It is an equivalent schematic diagram of a bandpass filter with both high selectivity and broadband suppression capability.

[0032] Fig.10 This is a simulated response curve of a bandpass filter with both high selectivity and broadband suppression capabilities.

[0033] Fig.11This is a measured response curve of a bandpass filter with both high selectivity and broadband suppression capabilities.

[0034] Among them: 1. filter body; 2. marking; 3. input port; 4. output port; 5. ground port; P1. first electrode; P2. second electrode; P3. third electrode; P4. fourth electrode; P5. fifth electrode; P6. sixth electrode; P7. seventh electrode; P8. eighth electrode; P9. ninth electrode; P10. tenth electrode; P11. eleventh electrode; P12. twelfth electrode; P121. twelfth-first electrode; P13. thirteenth electrode; H1. first via hole; H2. second via hole; H3. third via hole; H31. third-first via hole; H4. fourth via hole; H5. fifth via hole; H6. sixth via hole; H7. seventh via hole; H8. eighth via hole; H9. ninth via hole; H10. tenth via hole; H11. eleventh via hole; H111. eleventh-first via hole; H12. twelfth via hole; H13. thirteenth via hole. DETAILED DESCRIPTION

[0035] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0036] like Figure 1 As shown, a bandpass filter with both high selectivity and broadband suppression capability includes a filter body 1 and a mark 2, wherein the mark 2 is located on the outer wall of the filter body 1, and the filter body 1 includes a multilayer dielectric body, wherein the dielectric body includes a circuit layer in the dielectric body and an external electrode on the outer wall of the dielectric body, wherein the external electrode includes an input port 3, an output port 4 and a ground port 5, wherein the input port 3, the ground port 5 and the output port 4 are located in the same plane and are arranged in sequence. In this embodiment, the multilayer circuit is built into the dielectric body of 1.6 mm×0.8 mm×0.6 mm.

[0037] The circuit layer in the dielectric body includes an LC resonance unit, a co-directional coupling resonance unit and a reverse coupling resonance unit, such as Figure 2 to Figure 8 As shown, Figure 2 is a schematic diagram of the internal structure of the bandpass filter. Figure 3 to Figure 8They are schematic diagrams of the first to sixth layers of the circuit diagram, wherein the first layer includes the first via H1, the second via H2, the third via H3, the fourth via H4, the fifth via H5, and the sixth via H6; the second layer includes the first via H1, the second via H2, the third via H3, the fourth via H4, the fifth via H5, the sixth via H6, the seventh via H7, and the eighth via H8; the third layer includes the first via H1, the second via H2, the third via H3, the seventh via H7, the eighth via H8, The eighth via H8 and the eleventh via H11; the fourth layer includes the second via H2, the fifth via H5, the eighth via H8, the ninth via H9, and the third via H31; the fifth layer includes the seventh via H7, the eighth via H8, the ninth via H9, the tenth via H10, the eleventh via H11, the twelfth via H12 and the third via H31; the sixth layer includes the third via H31, the ninth via H9, the tenth via H10 and the eleventh via H111.

[0038] like Fig. 9 As shown, the LC resonance unit includes a resonant capacitor and a resonant inductor, one end of the resonant capacitor is connected to one end of the resonant inductor and serves as a signal input end, the other end of the resonant capacitor is connected to the other end of the resonant inductor, and is respectively connected to one end of the first coupling path CL1, one end of the ground capacitor Cg1 and one end of the first coupling capacitor C1, the other end of the first coupling path CL1 and the other end of the ground capacitor Cg1 are both grounded, the other end of the first coupling capacitor C1 is respectively connected to one end of the second coupling path CL2, one end of the ground capacitor Cg2 and one end of the second coupling capacitor C2, the other end of the second coupling path CL2 and the other end of the ground capacitor Cg2 are both grounded, the other end of the second coupling path CL2 is respectively connected to one end of the third coupling path CL3 and one end of the ground capacitor Cg3, and serves as a signal output end, the other end of the third coupling path CL3 and the other end of the ground capacitor Cg3 are both grounded.

[0039] The resonant capacitor includes an eighth electrode P8 on the sixth layer of the circuit layer, a thirteenth electrode P13 on the fourth layer of the circuit layer, and a ninth electrode P9 on the third layer of the circuit layer. The eighth electrode P8 is connected to the thirteenth electrode P13 on the fourth layer of the circuit layer via an eleventh via hole H11 on the fifth layer of the circuit layer and an eleventh via hole H111 on the sixth layer of the circuit layer, and forms a resonant capacitor with the ninth electrode P9 on the third layer of the circuit layer.

[0040] The resonant inductor includes an eighth electrode P8 of the sixth layer of the circuit layer, a twelfth electrode P12 of the fifth layer of the circuit layer, a twelfth electrode P121 of the fourth layer of the circuit layer and a first electrode (P1) of the first layer of the circuit layer. The eighth electrode P8 is connected to the twelfth electrode P12 via an eleventh via hole H11 located on the fifth layer of the circuit layer, the twelfth electrode P12 is connected to the twelfth electrode P121 via a twelfth via hole H12 located on the fifth layer of the circuit layer, and the twelfth electrode P121 is connected to the first electrode P1 via a first via hole H1 located on the third layer of the circuit layer.

[0041] The co-directional coupling resonance unit includes a first electrode P1 of the first layer of the circuit layer and a second electrode P2 of the first layer of the circuit layer. The first electrode P1 is vertically connected to the ninth electrode P9 of the third layer of the circuit layer via a first via hole H1 located in the first layer of the circuit layer, and is vertically connected to the tenth electrode P10 of the fourth layer of the circuit layer via the second via hole H2 located in the first layer of the circuit layer to form a first coupling capacitor C1. The first electrode P1 is connected to the fourth electrode P4 of the second layer of the circuit layer via a fourth via hole H4 located in the first layer of the circuit layer, and is connected to the sixth electrode P6 of the sixth layer of the circuit layer via an eighth via hole H8 located in the second layer of the circuit layer and is conducted to the ground. The second electrode P2 is connected to the fourth electrode P4 via a fifth via hole H5 located in the first layer of the circuit layer, and is connected to the sixth electrode P6 of the sixth layer of the circuit layer via an eighth via hole H8 located in the second layer of the circuit layer and is conducted to the ground.

[0042] The first electrode P1 is vertically connected to the ninth electrode P9 on the third layer of the circuit layer through the first via hole H1 located on the first layer of the circuit layer, and forms a capacitor Cg1 to ground with the fifth electrode P5 on the fifth layer of the circuit layer. The second electrode P2 is vertically connected to the tenth electrode P10 on the fourth layer of the circuit layer through the second via hole H2 located on the first layer of the circuit layer, and forms a capacitor Cg2 to ground with the fifth electrode P5 on the fifth layer of the circuit layer.

[0043] The reverse coupling resonance unit includes a third electrode P3 of the first layer of the circuit layer, the third electrode P3 is connected to the seventh electrode P7 of the sixth layer of the circuit layer via the third via hole H3 located in the first layer of the circuit layer and the thirty-first via hole H31 located in the fourth layer of the circuit layer, the third electrode P3 is connected to the fourth electrode P4 of the second layer of the circuit layer via the sixth via hole H6 located in the first layer of the circuit layer, and is connected to the fifth electrode P5 of the fifth layer of the circuit layer via the seventh via hole H7 located in the second layer of the circuit layer, the fifth electrode P5 is conducted to the ground via the ninth via hole H9 located in the fifth layer of the circuit layer, the third electrode P3 is connected to the eleventh electrode P11 of the fourth layer of the circuit layer via the third via hole H3 located in the first layer of the circuit layer, and forms a second coupling capacitor C2 with the tenth electrode P10 of the fourth layer of the circuit layer.

[0044] The third electrode P3 is connected to the eleventh electrode P11 on the fourth layer of the circuit layer through the third via hole H3 on the first layer of the circuit layer, and forms a ground capacitor Cg3 with the fifth electrode P5 on the fifth layer of the circuit layer.

[0045] The dielectric body is formed by stacking multiple layers of substrates. The dielectric body is manufactured based on a multi-layer printed circuit board process or a low-temperature co-fired ceramic technology, and the circuit layer adopts an embedded metal material.

[0046] In this embodiment, the dielectric body is composed of a plurality of layers of substrate stacked and electrically connected by a plurality of conductive holes. The plurality of layers of substrates include a first substrate to a sixth substrate from top to bottom. The first substrate has two long strips of coupling strips formed on its surface. The second capacitive coupling surface (the tenth electrode P10) of the coupling strip is coupled with two third capacitive coupling surfaces (the eleventh electrode P11) on the fourth substrate to form the second coupling capacitor C2. Two contact surfaces are formed on the surface of the first substrate, and three sections of zigzag horizontal coupling surfaces are formed to respectively form the horizontal coupling sections of the first coupling path CL1, the second coupling path CL2 and the third coupling path CL3; an independent first capacitive coupling surface (the ninth electrode P9) is formed on the surface of the second substrate; two independent first ground planes and a resonant inductor are formed on the surface of the fifth substrate; the ground plane is coupled with the fourth substrate to form a grounding capacitor; a ground plane, an input port and an output port are formed on the surface of the sixth substrate.

[0047] The first coupling path CL1 and the second coupling path CL2 are connected in parallel with each other and the third coupling path CL3 is connected in reverse parallel. The two ends of the parallel connection are connected to the first inductor and the second inductor respectively. The other ends of the first inductor and the second inductor are grounded. The LC resonance unit is connected to the first coupling path as a signal input end. The third coupling line CL3 is composed of a transmission line segment and a ground capacitor in parallel. The third reverse coupling transmission line is placed in the second coupling path as a signal output end. The first coupling path CL1, the second coupling path CL2 and the third coupling path CL3 each include a first capacitor, a first vertical coupling segment, a horizontal coupling segment and a second vertical coupling segment connected in series in sequence.

[0048] In one embodiment of the present invention, Fig. 9 As shown, the bandpass filter provided by the present invention is equivalent to a third-order circuit structure, and the third-order circuit structure includes a resonant capacitor, a resonant inductor, a first coupling capacitor C1, a second coupling capacitor C2, a ground capacitor Cg1, a ground capacitor Cg2, a ground capacitor Cg3, a first coupling path CL1, a second coupling path CL2 and a third coupling path CL3.

[0049] The first coupling path CL1, the first coupling capacitor C1 and the second coupling path CL2 are electromagnetically coupled to form a first electromagnetic coupling unit; the second coupling path CL2, the second coupling capacitor C2 and the third coupling path CL3 are electromagnetically coupled to form a second electromagnetic coupling unit; the third coupling path CL3 forms a third electromagnetic coupling unit. The circuit order of the present invention corresponds to the number of coupling lines. The first to third coupling paths CL3 have three coupling lines in total, so it is the three-order circuit architecture.

[0050] like Fig.10 and Fig.11 As shown in FIG. 1 , a schematic frequency response characteristic curve of a bandpass filter in an embodiment of the present invention is shown. The insertion loss of the channel filter in the operating frequency band of 1805 to 2025 MHz is only 1.4 dB, and at the same time, an out-of-band suppression of more than 30 dB can be achieved in the channel frequency band of 3600 to 12150 MHz. The return loss response is shown in FIG. Fig.10 and Fig.11 As shown in the figure, the return loss of the two channels is above 15dB. The above indicators reflect the good transmission characteristics and high noise suppression ability of the frequency divider.

[0051] The bandpass filter with high selectivity and broadband suppression capability provided by the present invention has the following technical advantages: (1) Small size. The multilayer interconnection technology based on low-temperature co-fired ceramics makes the present invention compact and repeatable. By using vertical coupling, a larger capacitance can be achieved in a smaller volume. At the same time, the use of dielectric materials with higher dielectric constants in the via regions between the circuit layers can further reduce its physical size. Since there is no circuit pattern in the via region, the parasitic effect caused by its high dielectric constant can be ignored. (2) Small insertion loss. The use of dielectric materials with lower dielectric constants in the circuit layer regions can minimize the influence of parasitic parameters generated by the lumped component circuit. At the same time, the use of a reasonable topological structure to block the coupling of circuit components of different layers as much as possible can also effectively improve the quality factor of its filter circuit, and achieve a maximum insertion loss of only 1.6 dB in a smaller volume. The suppression capability of up to 30 dB can effectively reduce the interference of mobile phone applications. (3) Suitable for mass production. The design of the entire frequency divider maximizes the tolerance of the processing technology while ensuring that its electrical performance is not affected. For example, the two vertical coupling plates of the equivalent capacitor are in the form of "big package small", sufficient distance is reserved from the internal pattern of the frequency divider to the external cutting frame, and Monte Carlo simulation analysis is used for the sensitive layer circuit components to ensure that the impact of their process deviation on the electrical performance of the entire frequency divider is within an acceptable range. This improves the process stability and consistency of the frequency divider in the mass production stage.

[0052] The present invention has excellent properties such as high Q value, small size, low insertion loss, wide suppression bandwidth, etc. At the same time, under the premise of ensuring that its electrical performance is not affected, the tolerance of the processing technology is maximized, high process stability and consistency are achieved, and it is easy to integrate with other circuit modules, and has broad application prospects in the field of new generation wireless communications.

[0053] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the principles of the present invention, and should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific variations and combinations that do not deviate from the essence of the present invention based on the technical revelations disclosed by the present invention, and these variations and combinations are still within the protection scope of the invention.

Claims

1. A bandpass filter having both high selectivity and broadband suppression capability, characterized in that: The invention comprises a filter body (1) and a mark (2), wherein the mark (2) is located on the outer wall of the filter body (1), the filter body (1) comprises a multilayer dielectric body, the dielectric body comprises a circuit layer in the dielectric body and an external electrode on the outer wall of the dielectric body, the external electrode comprises an input port (3), an output port (4) and a ground port (5), and the input port (3), the ground port (5) and the output port (4) are located in the same plane and are arranged in sequence; The circuit layer in the dielectric body includes an LC resonance unit, a co-directional coupling resonance unit and a reverse coupling resonance unit; The LC resonance unit includes a resonant capacitor and a resonant inductor, one end of the resonant capacitor is connected to one end of the resonant inductor and serves as a signal input end, the other end of the resonant capacitor is connected to the other end of the resonant inductor, and is respectively connected to one end of the first coupling path CL1, one end of the ground capacitor Cg1 and one end of the first coupling capacitor C1, the other end of the first coupling path CL1 and the other end of the ground capacitor Cg1 are both grounded, the other end of the first coupling capacitor C1 is respectively connected to one end of the second coupling path CL2, one end of the ground capacitor Cg2 and one end of the second coupling capacitor C2, the other end of the second coupling path CL2 and the other end of the ground capacitor Cg2 are both grounded, the other end of the second coupling capacitor C2 is respectively connected to one end of the third coupling path CL3 and one end of the ground capacitor Cg3 and serves as a signal output end, the other end of the third coupling path CL3 and the other end of the ground capacitor Cg3 are both grounded; The co-directional coupling resonance unit comprises a first electrode (P1) of a first layer of the circuit layer and a second electrode (P2) of the first layer of the circuit layer, the first electrode (P1) is vertically connected to a ninth electrode (P9) of a third layer of the circuit layer via a first via hole (H1) located in the first layer of the circuit layer, and forms a first coupling capacitor C1 with the second electrode (P2) vertically connected to a tenth electrode (P10) of a fourth layer of the circuit layer via a second via hole (H2) located in the first layer of the circuit layer, the first electrode (P1) is connected to a fourth electrode (P4) of a second layer of the circuit layer via a fourth via hole (H4) located in the first layer of the circuit layer, and is connected to a sixth electrode (P6) of a sixth layer of the circuit layer via an eighth via hole (H8) located in the second layer of the circuit layer and is connected to the ground, the second electrode (P2) is connected to the fourth electrode (P4) via a fifth via hole (H5) located in the first layer of the circuit layer, and is connected to a sixth electrode (P6) of a sixth layer of the circuit layer via an eighth via hole (H8) located in the second layer of the circuit layer and is connected to the ground; The reverse coupling resonance unit includes a third electrode (P3) of the first layer of the circuit layer, the third electrode (P3) is connected to the seventh electrode (P7) of the sixth layer of the circuit layer via a third via hole (H3) located in the first layer of the circuit layer and a thirty-first via hole (H31) located in the fourth layer of the circuit layer, the third electrode (P3) is connected to the fourth electrode (P4) of the second layer of the circuit layer via a sixth via hole (H6) located in the first layer of the circuit layer, and is connected to the fifth electrode (P5) of the fifth layer of the circuit layer via a seventh via hole (H7) located in the second layer of the circuit layer, the fifth electrode (P5) is connected to the ground via a ninth via hole (H9) located in the fifth layer of the circuit layer, the third electrode (P3) is connected to the eleventh electrode (P11) of the fourth layer of the circuit layer via a third via hole (H3) located in the first layer of the circuit layer, and forms a second coupling capacitor C2 with the tenth electrode (P10) of the fourth layer of the circuit layer.

2. The bandpass filter having both high selectivity and broadband suppression capability according to claim 1, characterized in that: The resonant capacitor comprises an eighth electrode (P8) of the sixth layer of the circuit layer, a thirteenth electrode (P13) of the fourth layer of the circuit layer and a ninth electrode (P9) of the third layer of the circuit layer, wherein the eighth electrode (P8) is connected to the thirteenth electrode (P13) of the fourth layer of the circuit layer via an eleventh via hole (H11) of the fifth layer of the circuit layer and an eleventh via hole (H111) of the sixth layer of the circuit layer, and forms a resonant capacitor with the ninth electrode (P9) of the third layer of the circuit layer; The resonant inductor comprises an eighth electrode (P8) of the sixth layer of the circuit layer, a twelfth electrode (P12) of the fifth layer of the circuit layer, a twelfth electrode (P121) of the fourth layer of the circuit layer and a first electrode (P1) of the first layer of the circuit layer, the eighth electrode (P8) is connected to the twelfth electrode (P12) via an eleventh via hole (H11) located on the fifth layer of the circuit layer, the twelfth electrode (P12) is connected to the twelfth electrode (P121) via a twelfth via hole (H12) located on the fifth layer of the circuit layer, and the twelfth electrode (P121) is connected to the first electrode (P1) via a first via hole (H1) located on the third layer of the circuit layer.

3. The bandpass filter with high selectivity and broadband suppression capability according to claim 1, characterized in that: The first electrode (P1) is vertically connected to the ninth electrode (P9) of the third layer of the circuit layer through a first via hole (H1) located in the first layer of the circuit layer, and forms a capacitor Cg1 to ground with the fifth electrode (P5) of the fifth layer of the circuit layer. The second electrode (P2) is vertically connected to the tenth electrode (P10) of the fourth layer of the circuit layer through a second via hole (H2) located in the first layer of the circuit layer, and forms a capacitor Cg2 to ground with the fifth electrode (P5) of the fifth layer of the circuit layer.

4. The bandpass filter with high selectivity and broadband suppression capability according to claim 1, characterized in that: The third electrode (P3) is connected to the eleventh electrode (P11) of the fourth circuit layer through the third via hole (H3) located in the first circuit layer, and forms a ground capacitor Cg3 with the fifth electrode (P5) of the fifth circuit layer.

5. The bandpass filter with high selectivity and broadband suppression capability according to claim 1, characterized in that: The dielectric body is formed by stacking multiple layers of substrates. The dielectric body is manufactured based on a multi-layer printed circuit board process or a low-temperature co-fired ceramic technology. The circuit layer uses an embedded metal material.

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