LC band-pass filter based on ltcc technology

Abstract

The application discloses an LC band-pass filter based on LTCC technology and relates to the microwave technical field, and at least comprises nine conductor layers; the first conductor layer is a grounding layer, the second conductor layer is an inductance circuit layer, the third conductor layer, the fourth conductor layer, the fifth conductor layer, the sixth conductor layer, the seventh conductor layer, the eighth conductor layer and the ninth conductor layer are all capacitance circuit layers, and the conductor layers are connected through metal through holes. The third conductor layer and the ninth conductor layer are input and output layers of the capacitance circuit and are electrically coupled with the fourth conductor layer and the eighth conductor layer; the second conductor layer and the fourth conductor layer to the eighth conductor layer form a resonator. The application solves the technical problem that the LC band-pass filter occupies a large space, and reduces the volume of the LC band-pass filter.

Description

Technical Field

[0001] This invention relates to the field of microwave technology, and in particular to an LC bandpass filter based on LTCC technology. Background Technology

[0002] With the continuous development of communication technology, wireless signals in space are becoming increasingly complex, and people have higher and higher requirements for the frequency selectivity of hardware. Bandpass filters can provide superior narrowband signals for radio frequency systems, and their design types are diverse and their applications are wide-ranging.

[0003] LTCC technology, or Low Temperature Co-fired Ceramic Technology, is a thick-film process with high stability, high quality factor, and high integration. Compared with other materials, ceramic materials have high stability and a wide range of dielectric constant variations, making them suitable for the manufacture of microwave devices.

[0004] LC bandpass filters are derived from lowpass filters. They have many auxiliary design tools, simple circuits, but are difficult to simulate in three dimensions, require a large space, and are difficult to design. Summary of the Invention

[0005] To address the drawback of large space occupation of LC bandpass filters, this invention provides an LC bandpass filter based on LTCC technology. By employing a resonant coupling method with a resonant capacitor, the technical problem of large space occupation of LC bandpass filters is solved, thereby reducing the size of the LC bandpass filter.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] An LC bandpass filter based on LTCC technology includes at least nine conductor layers, all of which are printed using LTCC technology and connected through metal vias. The first conductor layer is a ground layer, the second conductor layer is an inductor layer, and the third, fourth, fifth, sixth, seventh, eighth, and ninth conductor layers are all capacitor layers.

[0008] The metal through hole is provided with a first connecting post (19), a second connecting post (20) and a third connecting post (21);

[0009] The first conductor layer includes a metal grounding plate (1);

[0010] The second conductor layer comprises, from left to right, a first inductor strip (2), a second inductor strip (3), and a third inductor strip (4);

[0011] The third conductor layer, from left to right, includes a first input capacitor plate (5), a first coupling capacitor plate (6), a first connecting block (22), a second coupling capacitor plate (7), and a first output capacitor plate (8);

[0012] The fourth conductor layer, from left to right, includes a first capacitor layer plate (9), a second capacitor layer plate (10), and a third capacitor layer plate (11).

[0013] The fifth conductor layer includes a first grounding capacitor plate (12); a first circular opening (18) is provided in the middle of the first grounding capacitor plate (12), a first rectangular opening (16) is provided in the left part of the first grounding capacitor plate (12), and a second rectangular opening (17) is provided in the right part of the first grounding capacitor plate (12); a third connecting block (24) is provided in the first circular opening (18), a second connecting block (23) is provided in the first rectangular opening (16), and a fourth connecting block (25) is provided in the second rectangular opening (17);

[0014] The sixth conductor layer, from left to right, includes a first capacitor layer three-plate (13), a second capacitor layer three-plate (14), and a third capacitor layer three-plate (15);

[0015] The seventh conductor layer includes a second grounding capacitor plate (26); a second circular opening (29) is provided in the middle of the second grounding capacitor plate (26), a third rectangular opening (27) is provided in the left part of the second grounding capacitor plate (26), and a fourth rectangular opening (28) is provided in the right part of the second grounding capacitor plate (26); a sixth connecting block (31) is provided in the second circular opening (29), a fifth connecting block (30) is provided in the third rectangular opening (27), and a seventh connecting block (32) is provided in the fourth rectangular opening (28);

[0016] The eighth conductor layer, from left to right, includes a first capacitor layer five plates (33), a second capacitor layer five plates (34), and a third capacitor layer five plates (35);

[0017] The ninth conductor layer, from left to right, includes a second input capacitor plate (36), a third coupling capacitor plate (37), an eighth connecting block (40), a fourth coupling capacitor plate (38), and a second output capacitor plate (39).

[0018] The first inductor strip (2), the first capacitor layer plate (9), the first ground capacitor plate (12), the first capacitor layer plate (13), the second ground capacitor plate (26), and the first capacitor layer plate (33) are combined to form the first resonator through the first connecting post (19);

[0019] The second inductor strip (3), the second capacitor layer plate 1 (10), the first ground capacitor plate (12), the second capacitor layer plate 3 (14), the second ground capacitor plate (26), and the second capacitor layer plate 5 (34) are combined into a second resonator through the second connecting post (20);

[0020] The third inductor strip (4), the third capacitor layer plate 1 (11), the first ground capacitor plate (12), the third capacitor layer plate 3 (15), the second ground capacitor plate (26), and the third capacitor layer plate 5 (35) are combined into a third resonator through the third connecting post (21);

[0021] The first resonator and the second resonator are arranged symmetrically.

[0022] Optionally, the first input capacitor plate (5) is coupled to the first capacitor layer plate (9), the first coupling capacitor plate (6) is coupled to the second capacitor layer plate (10), the second coupling capacitor plate (7) is coupled to the second capacitor layer plate (10), and the first output capacitor plate (8) is coupled to the third capacitor layer plate (11).

[0023] The second input capacitor plate (36) is coupled to the first capacitor layer plate (33), the third coupling capacitor plate (37) is coupled to the second capacitor layer plate (34), the fourth coupling capacitor plate (38) is coupled to the second capacitor layer plate (34), and the second output capacitor plate (39) is coupled to the third capacitor layer plate (35).

[0024] The first coupling capacitor plate (6) and the third coupling capacitor plate (37) are both connected to the first resonator through the first connecting post (19);

[0025] The second coupling capacitor plate (7) and the fourth coupling capacitor plate (38) are connected to the third resonator through the third connecting post (21).

[0026] Optionally, the fifth conductor layer and the seventh conductor layer adopt a defective ground structure.

[0027] Optionally, the printed circuits of the third conductor layer and the ninth conductor layer are identical, the printed circuits of the fourth conductor layer and the eighth conductor layer are identical, and the printed circuits of the fifth conductor layer and the seventh conductor layer are identical.

[0028] Optionally, the first connecting post (19) includes a first post, a second post, and a third post; one end of the first post is connected to the first inductor strip (2), and the other end of the first post passes through the first input capacitor plate (5) and the first capacitor layer plate (9) in sequence and is connected to one side of the second connecting block (23); one end of the second post is connected to the other side of the second connecting block (23); the other end of the second post passes through the first capacitor layer plate (13) and is connected to one side of the fifth connecting block (30); one end of the third post is connected to the other side of the fifth connecting block (30); and the other end of the third post passes through the first capacitor layer plate (33) and is connected to the third coupling capacitor plate (37).

[0029] The second connecting post (19) includes a fourth post, a fifth post, a sixth post, and a seventh post; one end of the fourth post is connected to the third inductor strip (4), and the other end of the fourth post is connected to one side of the first connecting block (22); one end of the fifth post is connected to the other side of the first connecting block (22), and the other end of the fifth post passes through the second capacitor layer plate (10) and is connected to one side of the third connecting block (24); one end of the sixth post is connected to the other side of the third connecting block (24), and the other end of the sixth post passes through the second capacitor layer plate (14) and is connected to one side of the sixth connecting block (31); one end of the seventh post is connected to the other side of the sixth connecting block (31), and the other end of the seventh post passes through the second capacitor layer plate (34) and is connected to the eighth connecting block (40);

[0030] The third connecting post (21) includes an eighth post, a ninth post, and a tenth post; one end of the eighth post is connected to the third inductor strip (4), and the other end of the eighth post passes through the second coupling capacitor plate (7), the third capacitor layer plate (11), and is connected to one side of the fourth connecting block (25); one end of the ninth post is connected to the other side of the fourth connecting block (25), and the other end of the ninth post passes through the third capacitor layer plate (15) and is connected to one side of the seventh connecting block (32); one end of the tenth post is connected to the other side of the seventh connecting block (32), and the other end of the tenth post passes through the third capacitor layer plate (35) and is connected to the fourth coupling capacitor plate (38).

[0031] Optionally, the first inductor strip (2) and the third inductor strip (4) are symmetrically arranged; the first coupling capacitor plate (6) and the second coupling capacitor plate (7) are symmetrically arranged; the first input capacitor plate (5) and the first output capacitor plate (8) are symmetrically arranged; the first capacitor layer plate (9) and the third capacitor layer plate (11) are symmetrically arranged; the second connecting block (23) and the fourth connecting block (25) are symmetrically arranged; the first capacitor layer plate (13) and the third capacitor layer plate (15) are symmetrically arranged; the sixth connecting block (31) and the seventh connecting block (32) are symmetrically arranged; the first capacitor layer plate (33) and the third capacitor layer plate (35) are symmetrically arranged; the second input capacitor plate (36) and the second output capacitor plate (39) are symmetrically arranged; and the third coupling capacitor plate (37) and the fourth coupling capacitor plate (38) are symmetrically arranged.

[0032] Optionally, the LC bandpass filter further includes an external electrode; the external electrode includes an input port, a first ground port, an output port, and a second ground port;

[0033] The input ports are connected to the first input capacitor plate (5) and the second input capacitor plate (36) respectively. The output ports are connected to the first output capacitor plate (8) and the second output capacitor plate (39) respectively. The first grounding port is connected to the first grounding capacitor plate (12) and the second grounding capacitor plate (26) respectively. The second grounding port is connected to the first grounding capacitor plate (12), the second grounding capacitor plate (26), the first inductor strip (2), the second inductor strip (3), and the third inductor strip (4) respectively.

[0034] Optionally, the input port and the output port are symmetrically arranged, and the first ground port and the second ground port are symmetrically arranged; wherein, both the input port and the output port are 50-ohm impedance ports.

[0035] Optionally, the LC bandpass filter further includes at least eight dielectric substrate layers; all dielectric substrate layers are LTCC ceramic dielectric substrates.

[0036] Optionally, the dimensions of the LC bandpass filter are 3.2mm × 1.6mm × 0.94mm;

[0037] The inner conductor linewidth is not less than 100μm;

[0038] The conductor spacing shall be not less than 100μm;

[0039] The diameter of the metal through hole is not less than 100 μm;

[0040] The distance between the conductor layers is not less than 20 μm.

[0041] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0042] The present invention provides an LC bandpass filter based on LTCC technology, which adopts a lumped structure design. By optimizing the spatial position of the capacitors, the size of the LC bandpass filter is reduced and the performance of the LC bandpass filter is improved.

[0043] Furthermore, the present invention adopts a symmetrical design, and the circuit structure is simple and symmetrical, which is convenient for design and development. The microwave devices manufactured by the present invention using LTCC process have good high temperature resistance and can carry large current. The LTCC process can fabricate dozens of substrates to embed passive devices, which reduces interference from other assembled components and improves integration.

[0044] Therefore, this invention achieves the characteristics of small size, simple structure, good stability, high reliability, high temperature resistance, and good material consistency of the components while meeting the electrical performance requirements of the filter. Attached Figure Description

[0045] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0046] Figure 1 This is a schematic diagram of the layering of an LC bandpass filter provided in an embodiment of the present invention;

[0047] Figure 2 This is a top view of the first conductor layer of an LC bandpass filter provided in an embodiment of the present invention;

[0048] Figure 3 This is a top view schematic diagram of the second conductor layer of an LC bandpass filter provided in an embodiment of the present invention;

[0049] Figure 4 A top view of the third conductor layer / ninth conductor layer of the LC bandpass filter provided in an embodiment of the present invention;

[0050] Figure 5 A top view of the fourth conductor layer / eighth conductor layer of the LC bandpass filter provided in an embodiment of the present invention;

[0051] Figure 6 A top view of the fifth conductor layer / seventh conductor layer of the LC bandpass filter provided in an embodiment of the present invention;

[0052] Figure 7 This is a top view of the sixth conductor layer of the LC bandpass filter provided in an embodiment of the present invention;

[0053] Figure 8 This is a schematic diagram of the external electrodes of an LC bandpass filter provided in an embodiment of the present invention;

[0054] Figure 9 The frequency response characteristic curve of the LC bandpass filter provided in the embodiment of the present invention is shown. Detailed Implementation

[0055] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0056] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0057] This embodiment provides an LC bandpass filter based on LTCC technology. The aforementioned filter structure is an improvement on the lumped filter. This invention addresses the drawbacks of traditional LC filters, such as large size and high design complexity, by simplifying simulation and reducing size.

[0058] like Figure 1 As shown, the LC bandpass filter provided in this example includes at least eight dielectric substrate layers and nine conductor layers, all of which are printed using LTCC technology. The dielectric substrate layers are all LTCC ceramic dielectric substrates. The conductor layers are connected via metal vias; wherein, the first conductor layer is a ground layer, the second conductor layer is an inductor circuit layer, and the third, fourth, fifth, sixth, seventh, eighth, and ninth conductor layers are all capacitor circuit layers.

[0059] The capacitor circuit uses wide-side coupling to transfer electromagnetic energy. The third and ninth conductor layers are the input and output layers of the capacitor circuit, and they are electrically coupled with the fourth and eighth conductor layers to form a resonator; the second conductor layer and the fourth to eighth conductor layers form a resonator.

[0060] like Figures 2-7 As shown, the first conductor layer L1 includes a metal grounding plate 1.

[0061] The second conductor layer L2 includes, from left to right, a first inductor strip 2, a second inductor strip 3, and a third inductor strip 4.

[0062] The third conductor layer L3, from left to right, includes a first input capacitor plate 5, a first coupling capacitor plate 6, a first connecting block 22, a second coupling capacitor plate 7, and a first output capacitor plate 8.

[0063] The fourth conductor layer L4 includes, from left to right, a first capacitor layer plate 9, a second capacitor layer plate 10, and a third capacitor layer plate 11.

[0064] The fifth conductor layer L5 includes a first grounding capacitor plate 12; a first circular opening 18 is provided in the middle of the first grounding capacitor plate 12, a first rectangular opening 16 is provided in the left part of the first grounding capacitor plate 12, and a second rectangular opening 17 is provided in the right part of the first grounding capacitor plate 12; a third connecting block 24 is provided in the first circular opening 18, a second connecting block 23 is provided in the first rectangular opening 16, and a fourth connecting block 25 is provided in the second rectangular opening 17.

[0065] The sixth conductor layer L6 includes, from left to right, a first capacitor layer plate 13, a second capacitor layer plate 14, and a third capacitor layer plate 15.

[0066] The seventh conductor layer L7 includes a second grounding capacitor plate 26; a second circular opening 29 is provided in the middle of the second grounding capacitor plate 26, a third rectangular opening 27 is provided in the left part of the second grounding capacitor plate 26, and a fourth rectangular opening 28 is provided in the right part of the second grounding capacitor plate 26; a sixth connecting block 31 is provided in the second circular opening 29, a fifth connecting block 30 is provided in the third rectangular opening 27, and a seventh connecting block 32 is provided in the fourth rectangular opening 28.

[0067] The eighth conductor layer L8 includes, from left to right, a first capacitor layer plate 33, a second capacitor layer plate 34, and a third capacitor layer plate 35.

[0068] The ninth conductor layer L9, from left to right, includes a second input capacitor plate 36, a third coupling capacitor plate 37, an eighth connecting block 40, a fourth coupling capacitor plate 38, and a second output capacitor plate 39.

[0069] The first inductor strip 2, the first capacitor layer plate 9, the first ground capacitor plate 12, the first capacitor layer plate 3 13, the second ground capacitor plate 26, and the first capacitor layer plate 5 33 are combined to form the first resonator through the first connecting post 19.

[0070] The second inductor strip 3, the second capacitor layer plate 10, the first ground capacitor plate 12, the second capacitor layer plate 34, the second ground capacitor plate 26, and the second capacitor layer plate 5 are combined through the second connecting post 20 to form the second resonator.

[0071] The third inductor strip 4, the third capacitor layer plate 11, the first ground capacitor plate 12, the third capacitor layer plate 15, the second ground capacitor plate 26, and the third capacitor layer plate 35 are combined into a third resonator through the third connecting post 21.

[0072] Specifically, the first and second resonators are symmetrically arranged as follows: the first inductor stripline 2 and the third inductor stripline 4 are symmetrically arranged; the first coupling capacitor plate 6 and the second coupling capacitor plate 7 are symmetrically arranged; the first input capacitor plate 5 and the first output capacitor plate 8 are symmetrically arranged; the first capacitor layer plate 9 and the third capacitor layer plate 11 are symmetrically arranged; the second connecting block 23 and the fourth connecting block 25 are symmetrically arranged; the first capacitor layer plate 13 and the third capacitor layer plate 15 are symmetrically arranged; the sixth connecting block 31 and the seventh connecting block 32 are symmetrically arranged; the first capacitor layer plate 33 and the third capacitor layer plate 35 are symmetrically arranged; the second input capacitor plate 36 and the second output capacitor plate 39 are symmetrically arranged; and the third coupling capacitor plate 37 and the fourth coupling capacitor plate 38 are symmetrically arranged.

[0073] Furthermore, the first input capacitor plate 5 is coupled to the first capacitor layer plate 9, the first coupling capacitor plate 6 is coupled to the second capacitor layer plate 10, the second coupling capacitor plate 7 is coupled to the second capacitor layer plate 10, and the first output capacitor plate 8 is coupled to the third capacitor layer plate 11.

[0074] The second input capacitor plate 36 is coupled to the first capacitor layer plate 33, the third coupling capacitor plate 37 is coupled to the second capacitor layer plate 34, the fourth coupling capacitor plate 38 is coupled to the second capacitor layer plate 34, and the second output capacitor plate 39 is coupled to the third capacitor layer plate 35.

[0075] The first coupling capacitor plate 6 and the third coupling capacitor plate 37 are both connected to the first resonator via the first connecting post 19. The second coupling capacitor plate 7 and the fourth coupling capacitor plate 38 are connected to the third resonator via the third connecting post 21.

[0076] Furthermore, the fifth conductor layer L5 and the seventh conductor layer L7 employ a defective ground structure. This defective ground structure shielding layer suppresses higher harmonics of the signal.

[0077] The printed circuits of the third conductor layer L3 and the ninth conductor layer L9 are identical, the printed circuits of the fourth conductor layer L4 and the eighth conductor layer L8 are identical, and the printed circuits of the fifth conductor layer L5 and the seventh conductor layer L7 are identical.

[0078] Further, the first connecting post 19 includes a first post, a second post, and a third post; one end of the first post is connected to the first inductor strip 2, and the other end of the first post passes through the first input capacitor plate 5 and the first capacitor layer plate 9 in sequence and connects to one side of the second connecting block 23; one end of the second post is connected to the other side of the second connecting block 23, and the other end of the second post passes through the first capacitor layer plate 33 and connects to one side of the fifth connecting block 30; one end of the third post is connected to the other side of the fifth connecting block 30, and the other end of the third post passes through the first capacitor layer plate 33 and connects to the third coupling capacitor plate 37.

[0079] The second connecting post 19 includes a fourth post, a fifth post, a sixth post, and a seventh post; one end of the fourth post is connected to the third inductor strip 4, and the other end of the fourth post is connected to one side of the first connecting block 22; one end of the fifth post is connected to the other side of the first connecting block 22, and the other end of the fifth post passes through the second capacitor layer plate 10 and connects to one side of the third connecting block 24; one end of the sixth post is connected to the other side of the third connecting block 24, and the other end of the sixth post passes through the second capacitor layer plate 14 and connects to one side of the sixth connecting block 31; one end of the seventh post is connected to the other side of the sixth connecting block 31, and the other end of the seventh post passes through the second capacitor layer plate 34 and connects to the eighth connecting block 40.

[0080] The third connecting post 21 includes an eighth post, a ninth post, and a tenth post; one end of the eighth post is connected to the third inductor strip 4, and the other end of the eighth post passes through the second coupling capacitor plate 7 and the third capacitor layer plate 11 in sequence and connects to one side of the fourth connecting block 25; one end of the ninth post is connected to the other side of the fourth connecting block 25, and the other end of the ninth post passes through the third capacitor layer plate 15 and connects to one side of the seventh connecting block 32; one end of the tenth post is connected to the other side of the seventh connecting block 32, and the other end of the tenth post passes through the third capacitor layer plate 35 and connects to the fourth coupling capacitor plate 38.

[0081] Furthermore, the LC bandpass filter also includes an external electrode; such as Figure 8 As shown, the external electrode adopts a four-port structure; the external electrode includes an input port P1, a first ground port P2, an output port P3, and a second ground port P4.

[0082] The input port P1 is connected to the first input capacitor plate 5 and the second input capacitor plate 36 respectively. The output port P3 is connected to the first output capacitor plate 8 and the second output capacitor plate 39 respectively. The first ground port P2 is connected to the first ground capacitor plate 12 and the second ground capacitor plate 26 respectively. The second ground port P4 is connected to the first ground capacitor plate 12, the second ground capacitor plate 26, the first inductor strip 2, the second inductor strip 3, and the third inductor strip 4 respectively.

[0083] The input port P1 and the output port P3 are symmetrically arranged, and the first grounding port P2 and the second grounding port P4 are symmetrically arranged.

[0084] The metal grounding plate 1 is connected to the first grounding port P2 and the second grounding port (P4), serving as a shielding layer. Both the input port P1 and the output port P3 are 50-ohm impedance ports.

[0085] Furthermore, the LC bandpass filter adopts a 9-layer printed circuit structure based on LTCC technology. The dimensions of the LC bandpass filter are 3.2mm × 1.6mm × 0.94mm; the inner conductor linewidth (i.e., the width of all conductor lines inside the device) is not less than 100μm; the conductor line spacing (i.e., the spacing of all conductor lines inside the device) is not less than 100μm; the diameter of the metal via is not less than 100μm; and the distance between the conductor layers is not less than 20μm.

[0086] Figure 9 This is a frequency response characteristic curve of the LC bandpass filter provided in this embodiment of the invention. The horizontal axis represents frequency, and the vertical axis represents loss. The test curve shows that the LC bandpass filter operates in the frequency band of 2.4GHz to 2.55GHz, with an insertion loss better than -2dB, a return loss at the input port better than -20dB, attenuation less than -20dB in the upper stopband range of DC to 2GHz, and attenuation less than -20dB in the lower stopband range of 3.8GHz to 8GHz.

[0087] The LC bandpass filter provided by this invention improves the filter's integration density by adjusting the position and size of the capacitor in the resonant device. It is manufactured using LTCC technology and offers advantages such as small component size, high temperature resistance, low processing cost, good operational stability, good material consistency, and environmental friendliness. It can be widely used in microwave base stations and the Internet of Things (IoT) and other fields.

[0088] The various embodiments described in this specification are presented in a progressive manner. Each embodiment focuses on the differences from other embodiments, and the same or similar parts between the embodiments can be referred to each other.

[0089] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this description should not be construed as a limitation of the present invention.

Claims

1. An LC bandpass filter based on LTCC technology, characterized in that, It includes at least nine conductor layers, all of which are printed using LTCC technology and connected through metal vias; wherein, the first conductor layer is a ground layer, the second conductor layer is an inductor circuit layer, and the third, fourth, fifth, sixth, seventh, eighth, and ninth conductor layers are all capacitor circuit layers; The metal through hole is provided with a first connecting post (19), a second connecting post (20) and a third connecting post (21); The first conductor layer includes a metal grounding plate (1); The second conductor layer comprises, from left to right, a first inductor strip (2), a second inductor strip (3), and a third inductor strip (4); The third conductor layer, from left to right, includes a first input capacitor plate (5), a first coupling capacitor plate (6), a first connecting block (22), a second coupling capacitor plate (7), and a first output capacitor plate (8); The fourth conductor layer, from left to right, includes a first capacitor layer plate (9), a second capacitor layer plate (10), and a third capacitor layer plate (11). The fifth conductor layer includes a first grounding capacitor plate (12); a first circular opening (18) is provided in the middle of the first grounding capacitor plate (12), a first rectangular opening (16) is provided in the left part of the first grounding capacitor plate (12), and a second rectangular opening (17) is provided in the right part of the first grounding capacitor plate (12); a third connecting block (24) is provided in the first circular opening (18), a second connecting block (23) is provided in the first rectangular opening (16), and a fourth connecting block (25) is provided in the second rectangular opening (17); The sixth conductor layer, from left to right, includes a first capacitor layer three-plate (13), a second capacitor layer three-plate (14), and a third capacitor layer three-plate (15); The seventh conductor layer includes a second grounding capacitor plate (26); a second circular opening (29) is provided in the middle of the second grounding capacitor plate (26), a third rectangular opening (27) is provided in the left part of the second grounding capacitor plate (26), and a fourth rectangular opening (28) is provided in the right part of the second grounding capacitor plate (26); a sixth connecting block (31) is provided in the second circular opening (29), a fifth connecting block (30) is provided in the third rectangular opening (27), and a seventh connecting block (32) is provided in the fourth rectangular opening (28); The eighth conductor layer, from left to right, includes a first capacitor layer five plates (33), a second capacitor layer five plates (34), and a third capacitor layer five plates (35); The ninth conductor layer, from left to right, includes a second input capacitor plate (36), a third coupling capacitor plate (37), an eighth connecting block (40), a fourth coupling capacitor plate (38), and a second output capacitor plate (39). The first inductor strip (2), the first capacitor layer plate (9), the first ground capacitor plate (12), the first capacitor layer plate (13), the second ground capacitor plate (26), and the first capacitor layer plate (33) are combined to form the first resonator through the first connecting post (19); The second inductor strip (3), the second capacitor layer plate 1 (10), the first ground capacitor plate (12), the second capacitor layer plate 3 (14), the second ground capacitor plate (26), and the second capacitor layer plate 5 (34) are combined into a second resonator through the second connecting post (20); The third inductor strip (4), the third capacitor layer plate 1 (11), the first ground capacitor plate (12), the third capacitor layer plate 3 (15), the second ground capacitor plate (26), and the third capacitor layer plate 5 (35) are combined into a third resonator through the third connecting post (21); The first resonator and the second resonator are arranged symmetrically.

2. The LC bandpass filter based on LTCC technology according to claim 1, characterized in that, The first input capacitor plate (5) is coupled to the first capacitor layer plate (9), the first coupling capacitor plate (6) is coupled to the second capacitor layer plate (10), the second coupling capacitor plate (7) is coupled to the second capacitor layer plate (10), and the first output capacitor plate (8) is coupled to the third capacitor layer plate (11). The second input capacitor plate (36) is coupled to the first capacitor layer plate (33), the third coupling capacitor plate (37) is coupled to the second capacitor layer plate (34), the fourth coupling capacitor plate (38) is coupled to the second capacitor layer plate (34), and the second output capacitor plate (39) is coupled to the third capacitor layer plate (35). The first coupling capacitor plate (6) and the third coupling capacitor plate (37) are both connected to the first resonator through the first connecting post (19); The second coupling capacitor plate (7) and the fourth coupling capacitor plate (38) are connected to the third resonator through the third connecting post (21).

3. An LC bandpass filter based on LTCC technology according to claim 1 or 2, characterized in that, The fifth conductor layer and the seventh conductor layer adopt a defective ground structure.

4. An LC bandpass filter based on LTCC technology according to claim 1 or 2, characterized in that, The printed circuits of the third conductor layer and the ninth conductor layer are identical, the printed circuits of the fourth conductor layer and the eighth conductor layer are identical, and the printed circuits of the fifth conductor layer and the seventh conductor layer are identical.

5. An LC bandpass filter based on LTCC technology according to claim 1 or 2, characterized in that, The first connecting post (19) includes a first post, a second post, and a third post; one end of the first post is connected to the first inductor strip (2), and the other end of the first post passes through the first input capacitor plate (5) and the first capacitor layer plate (9) in sequence and is connected to one side of the second connecting block (23); one end of the second post is connected to the other side of the second connecting block (23); the other end of the second post passes through the first capacitor layer plate (13) and is connected to one side of the fifth connecting block (30); one end of the third post is connected to the other side of the fifth connecting block (30); and the other end of the third post passes through the first capacitor layer plate (33) and is connected to the third coupling capacitor plate (37). The second connecting post (20) includes a fourth post, a fifth post, a sixth post, and a seventh post; one end of the fourth post is connected to the third inductor strip (4), and the other end of the fourth post is connected to one side of the first connecting block (22); one end of the fifth post is connected to the other side of the first connecting block (22), and the other end of the fifth post passes through the second capacitor layer plate (10) and is connected to one side of the third connecting block (24); one end of the sixth post is connected to the other side of the third connecting block (24), and the other end of the sixth post passes through the second capacitor layer plate (14) and is connected to one side of the sixth connecting block (31); one end of the seventh post is connected to the other side of the sixth connecting block (31), and the other end of the seventh post passes through the second capacitor layer plate (34) and is connected to the eighth connecting block (40); The third connecting post (21) includes an eighth post, a ninth post, and a tenth post; one end of the eighth post is connected to the third inductor strip (4), and the other end of the eighth post passes through the second coupling capacitor plate (7), the third capacitor layer plate (11), and is connected to one side of the fourth connecting block (25); one end of the ninth post is connected to the other side of the fourth connecting block (25), and the other end of the ninth post passes through the third capacitor layer plate (15) and is connected to one side of the seventh connecting block (32); one end of the tenth post is connected to the other side of the seventh connecting block (32), and the other end of the tenth post passes through the third capacitor layer plate (35) and is connected to the fourth coupling capacitor plate (38).

6. An LC bandpass filter based on LTCC technology according to claim 1 or 2, characterized in that, The first inductor strip (2) and the third inductor strip (4) are symmetrically arranged; the first coupling capacitor plate (6) and the second coupling capacitor plate (7) are symmetrically arranged; the first input capacitor plate (5) and the first output capacitor plate (8) are symmetrically arranged; the first capacitor layer plate (9) and the third capacitor layer plate (11) are symmetrically arranged; the second connecting block (23) and the fourth connecting block (25) are symmetrically arranged; the first capacitor layer plate (13) and the third capacitor layer plate (15) are symmetrically arranged; the sixth connecting block (31) and the seventh connecting block (32) are symmetrically arranged; the first capacitor layer plate (33) and the third capacitor layer plate (35) are symmetrically arranged; the second input capacitor plate (36) and the second output capacitor plate (39) are symmetrically arranged; the third coupling capacitor plate (37) and the fourth coupling capacitor plate (38) are symmetrically arranged.

7. An LC bandpass filter based on LTCC technology according to claim 1 or 2, characterized in that, The LC bandpass filter further includes an external electrode; the external electrode includes an input port, a first ground port, an output port, and a second ground port; The input ports are connected to the first input capacitor plate (5) and the second input capacitor plate (36) respectively. The output ports are connected to the first output capacitor plate (8) and the second output capacitor plate (39) respectively. The first grounding port is connected to the first grounding capacitor plate (12) and the second grounding capacitor plate (26) respectively. The second grounding port is connected to the first grounding capacitor plate (12), the second grounding capacitor plate (26), the first inductor strip (2), the second inductor strip (3), and the third inductor strip (4) respectively.

8. An LC bandpass filter based on LTCC technology according to claim 7, characterized in that, The input port and the output port are symmetrically arranged, and the first ground port and the second ground port are symmetrically arranged; wherein, both the input port and the output port are 50-ohm impedance ports.

9. An LC bandpass filter based on LTCC technology according to claim 1 or 2, characterized in that, The LC bandpass filter further includes at least eight dielectric substrate layers; all of the dielectric substrate layers are LTCC ceramic dielectric substrates.

10. An LC bandpass filter based on LTCC technology according to claim 1 or 2, characterized in that, The dimensions of the LC bandpass filter are 3.2mm × 1.6mm × 0.94mm; The inner conductor linewidth is not less than 100μm; The conductor spacing shall be not less than 100μm; The diameter of the metal through hole is not less than 100 μm; The distance between the conductor layers is not less than 20 μm.

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