A LTCC millimeter wave filter

Abstract

The present invention relates to an LTCC millimeter wave filter, comprising an LTCC ceramic body, a composite feed structure, a plurality of resonant units, a shielding layer, a shielding hole array, an isolation hole array, a coupling capacitor sheet, a parallel capacitor sheet, and a cross-coupling unit; the bottom of the LTCC ceramic body is provided with two input and output ports, the two input and output ports are respectively connected to the resonant units via the composite feed structure, the plurality of resonant units are sequentially arranged adjacent to each other inside the ceramic body, and the plurality of resonant units are capacitively coupled via coupling capacitor sheets, the shielding layers are respectively arranged at the bottom and inside the ceramic body and connected via a plurality of shielding holes and a plurality of isolation holes, the resonant units at the input port and the output port are further provided with parallel capacitor sheets, wherein a cross-coupling unit is further provided between the two resonant units. The filter structure of the present invention has the characteristics of wide bandwidth and high suppression.

Description

Technical Field

[0001] The present invention relates to the technical field of filters, and in particular to an LTCC millimeter wave filter. Background Art

[0002] Currently, 5G communication technology continues to develop, and research into millimeter-wave technologies is a future trend in the global communications industry. Millimeter-wave filters are a key component in this area. Many companies and related researchers have conducted extensive research in this area. For example, TDK Corporation's patent (publication number CN 110137654 A) describes a main structure composed of multiple dielectric resonators, with the resonators and the surrounding dielectric components having different dielectric constants and temperature coefficients. TDK Corporation's patent (publication number CN 110401000 A) also describes a main structure composed of multiple dielectric resonators, with the resonators and the surrounding dielectric components having different dielectric constants and temperature coefficients. The resonator body consists of multiple separate elements, with the distance between adjacent elements being less than one-quarter of the wavelength corresponding to the resonant frequency of the dielectric resonator within the surrounding electrical cutoff portion. Jingde Electronics' patent (TW 1751892 B) includes four resonant units, each with one end grounded and the other open.

[0003] The filter disclosed by TDK, mentioned above, faces significant manufacturing difficulties and sensitivity, particularly due to the different dielectric constants between the resonant units and the surrounding dielectric medium. The filter disclosed by Jingde Electronics has a smaller number of resonant units, making it difficult to achieve high rejection and wide bandwidth. Therefore, how to make millimeter-wave filters more convenient to manufacture and achieve better performance has become an urgent challenge for those skilled in the art. Summary of the Invention

[0004] In order to solve the above technical problems, an object of the present invention is to provide an LTCC millimeter wave filter, which is easy to produce and has good performance.

[0005] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0006] A LTCC millimeter wave filter comprises an LTCC ceramic body, a composite feeding structure, a plurality of resonant units, a shielding layer, a shielding hole array, an isolation hole array, a coupling capacitor sheet, a parallel capacitor sheet, and a cross-coupling unit. Two input and output ports are provided at the bottom of the LTCC ceramic body, and the two input and output ports are respectively connected to the resonant units via the composite feeding structure. The plurality of resonant units are sequentially arranged adjacent to each other inside the ceramic body, and the plurality of resonant units are capacitively coupled via the coupling capacitor sheet. The shielding layers are respectively provided at the bottom and inside the ceramic body and are connected via the plurality of shielding holes and the plurality of isolation holes. Parallel capacitor sheets are further provided at the resonant units at the input port and the output port, respectively, and a cross-coupling unit is further provided between the two resonant units.

[0007] As a preferred solution: the composite feeding structure is composed of a single via, a capacitor plate, and multiple vias connected in series; the single via connects the output port and the capacitor plate, or the single via connects the input port and the capacitor plate, and the multiple vias connect the first-stage resonant unit and the capacitor plate, or the last-stage resonant unit and the capacitor plate.

[0008] As a preferred solution: there are 7 resonance units, and each resonance unit is a resonance unit with open ends.

[0009] As a preferred solution: capacitive coupling is formed between the first resonant unit and the second resonant unit, between the second resonant unit and the third resonant unit, between the third resonant unit and the fourth resonant unit, between the fourth resonant unit and the fifth resonant unit, between the fifth resonant unit and the sixth resonant unit, and between the sixth resonant unit and the seventh resonant unit through coupling capacitors.

[0010] As a preferred solution: one end of the first resonance unit is directly connected to the composite feeding structure, and the other end forms a capacitive coupling with the second resonance unit through a coupling capacitor; parallel capacitors are provided at the head and tail of the first resonance unit.

[0011] As a preferred solution: one end of the seventh resonant unit is directly connected to the composite feeding structure, and the other end forms capacitive coupling with the sixth resonant unit through a coupling capacitor; parallel capacitors are provided at the head and tail of the seventh resonant unit.

[0012] As a preferred solution: a plurality of isolation rows of holes are arranged between the second resonance unit and the sixth resonance unit, and between the third resonance unit and the fifth resonance unit.

[0013] As a preferred solution, the second resonant unit, the third resonant unit, the fourth resonant unit, the fifth resonant unit, and the sixth resonant unit are shaped as line segments with constant width, or dumbbell shapes with two wide segments and a thin middle.

[0014] As a preferred solution: the cross-coupling unit is arranged between the second resonance unit and the sixth resonance unit, and the cross-coupler is in a square shape.

[0015] As a preferred solution: the resonant unit, the isolation hole array, the shielding layer, the coupling capacitor sheet, the composite feeding structure, and the cross-coupling unit are all metal conductors.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The filter of the present invention includes an LTCC ceramic body, a composite feeding structure, multiple resonant units, a shielding layer, a shielding hole array, an isolation hole array, a coupling capacitor sheet, a parallel capacitor sheet, and a cross-coupling unit. Adjacent resonant units are sequentially capacitively coupled by the coupling capacitor sheets, and non-adjacent resonant units are cross-magnetically coupled or electrically coupled. The shielding layers are directly connected by holes, and some non-adjacent resonant units are arranged with isolation holes to generate electromagnetic isolation or control cross-coupling. The above structure enables the millimeter wave filter of the present invention to have wide bandwidth and high suppression characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings in the specification, which constitute a part of this application, are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute a limitation on this application.

[0019] Figure 1 is an equivalent circuit diagram of the millimeter wave bandpass filter of the present invention;

[0020] Figure 2 is a three-dimensional diagram of the millimeter wave bandpass filter structure of the present invention;

[0021] Figure 3 This is a schematic diagram of the internal explosion structure of the millimeter wave bandpass filter of the present invention;

[0022] Figure 4 A schematic diagram of the bottom layer pattern formation surface of the millimeter wave bandpass filter of the present invention;

[0023] Figure 5 Schematic diagram of the printed pattern forming surface and via holes of the first ceramic layer of the millimeter wave bandpass filter of the present invention;

[0024] Figure 6 A schematic diagram of a printed pattern forming surface of a second ceramic layer of a millimeter wave bandpass filter according to the present invention;

[0025] Figure 7 Schematic diagram of the printed pattern forming surface and via holes of the third ceramic layer of the millimeter wave bandpass filter of the present invention;

[0026] Figure 8Schematic diagram of the printed pattern forming surface of the fourth ceramic layer of the millimeter wave bandpass filter of the present invention;

[0027] Figure 9 Schematic diagram of the printed pattern forming surface of the fifth ceramic layer of the millimeter wave bandpass filter of the present invention;

[0028] Figure 10 A schematic diagram of a via connecting two shielding layers in the millimeter wave bandpass filter of the present invention;

[0029] Figure 11 This is a simulation diagram of the millimeter wave bandpass filter of the present invention. DETAILED DESCRIPTION

[0030] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0031] In order to explain the technical implementation scheme of the present invention more clearly and in detail, the present invention will be further described in detail below with reference to the accompanying drawings.

[0032] like Figure 1 As shown in FIG, it is an equivalent circuit diagram of the millimeter wave bandpass filter of the present invention; Figure 2 and Figure 3 As shown, the LTCC millimeter wave filter described in the present invention includes an LTCC ceramic body 1, input and output ports A2 and B3, a composite feeding structure, two large-area shielding layers 6 and 7, shielding holes 8 and isolation holes 9, a coupling capacitor layer 10, a parallel capacitor layer 11, a cross coupler 12, and seven resonant units. The above structures are all integrated.

[0033] In terms of circuit structure, the first input and output port of the present invention is directly connected to the composite feeding structure, the composite feeding structure is directly connected to the first resonant unit, the second resonant unit and the third resonant unit are capacitively coupled through a portion of the coupling capacitor layer, the third resonant unit and the fourth resonant unit are capacitively coupled through a portion of the coupling capacitor layer, the fourth resonant unit and the fifth resonant unit are capacitively coupled through a portion of the coupling capacitor layer, the fifth resonant unit and the sixth resonant unit are capacitively coupled through a portion of the coupling capacitor layer, the sixth resonant unit and the seventh resonant unit are capacitively coupled through a portion of the coupling capacitor layer, the seventh resonant unit is directly connected to the composite feeding structure, and the composite feeding structure is directly connected to the second input and output port.

[0034] These non-adjacent resonant units generate cross-electromagnetic coupling, also known as cross-coupling in electromagnetic field theory. By adjusting the density of the isolation holes, the strength of the cross-coupling can be controlled, thereby controlling the filter's out-of-band zeros. The second, third, fourth, fifth, and sixth resonant units can be shaped as line segments with a constant width or as dumbbells with two wide segments and a narrow center.

[0035] To enhance the filter's high-frequency rejection, a capacitor is connected in parallel between the first and seventh resonant units to create a resonant zero outside the band. To enhance the filter's out-of-band rejection, a cross-coupling unit is placed between the second and sixth resonant units to adjust the position of the out-of-band resonant zero, thereby controlling the steepness of the out-of-band rejection. In this invention, the resonant units, shielding and isolation holes, shielding layer, capacitive coupling layer, and composite feed structure are all metallic conductors, integrated into the ceramic body.

[0036] The specific structure of the present invention is as follows: LTCC ceramic body 1 is a rectangular parallelepiped, composed of multiple stacked bodies, such as Figure 4 As shown, the bottom of the LTCC ceramic body 1 is printed with input / output port A2, input / output port B3 and a large-area first shielding layer 6.

[0037] like Figure 5 The first stack 101 shown is filled with via A401 and via B501, and circular patterns A402 and B502 are printed on the stack 101. Via A401 is located in the center of the circular pattern A402 and is electrically connected to via A401. Via B501 is located in the center of the circular pattern B502 and is electrically connected to via B501.

[0038] like Figure 6 The second stack 102 is printed with a circular pattern C403 and a circular pattern D503; Figure 7 The third stack 103 shown is filled with a number of vias C404 and vias D504, and the first resonance unit 1301, the second resonance unit 1302, the third resonance unit 1303, the fourth resonance unit 1304, the fifth resonance unit 1305, the sixth resonance unit 1306, and the seventh resonance unit 1307 are printed on the third stack 103. One end of the via C404 is connected to the circular pattern C403, and the other end of the via C404 is connected to the first resonance unit 1301. One end of the via D504 is connected to the circular pattern D503, and the other end of the via D504 is connected to the seventh resonance unit 1307.

[0039] According to this embodiment, the first resonance unit 1301 , the second resonance unit 1302 , the third resonance unit 1303 , the fourth resonance unit 1304 , the fifth resonance unit 1305 , the sixth resonance unit 1306 , and the seventh resonance unit 1307 are electrically adjacent and electromagnetically coupled.

[0040] like Figure 7As shown, the third stack 103 is printed with a cross-coupler 12, which is located between the open-circuit end of the second resonance unit 2 and the open-circuit end of the sixth resonance unit 6. Electrically, the cross-coupler is close to the first resonance unit 1 and the seventh resonance unit 7, and on the contrary, far away from the third resonance unit 3 and the fifth resonance unit 5.

[0041] like Figure 8 As shown, the fourth stack 104 is printed with a coupling capacitor pattern A1001, a coupling capacitor pattern B1002, a coupling capacitor pattern C1003, a coupling capacitor pattern D1004, a coupling capacitor pattern E1005, and a coupling capacitor pattern F1006; through the coupling capacitor pattern A1001, the first resonance unit 1 and the second resonance unit 2 are electromagnetically coupled; through the coupling capacitor pattern B1002, the second resonance unit 2 and the third resonance unit 3 are electromagnetically coupled; through the coupling capacitor pattern C1003, the third resonance unit 3 and the fourth resonance unit 4 are electromagnetically coupled; through the coupling capacitor pattern D1004, the fourth resonance unit 4 and the fifth resonance unit 5 are electromagnetically coupled; through the coupling capacitor pattern E1005, the fifth resonance unit 5 and the sixth resonance unit 6 are electromagnetically coupled; the fourth stack 104 is also printed with a parallel capacitor pattern A1101 and a parallel capacitor pattern B1102. The two ends of the parallel capacitor pattern A1101 are electrically connected in parallel with the two ends of the first resonant unit 1301, thereby generating a resonance zero point; the two ends of the parallel capacitor pattern B1102 are electrically connected in parallel with the two ends of the seventh resonant unit 1307, thereby generating a resonance zero point.

[0042] One end of the third resonance unit 3 is perpendicular to the second resonance unit, and the other end is perpendicular to the fourth resonance unit. One end of the fifth resonance unit is perpendicular to the fourth resonance unit, and the other end is perpendicular to the sixth resonance unit.

[0043] like Figure 9 As shown, the fifth laminate 105 is printed with a large area of ​​the second shielding layer 7. Figure 10 As shown, shielding holes 8 and isolation holes 9 are arranged throughout the first stack 101 , the second stack 102 , the third stack 103 , the fourth stack 104 , and the fifth stack 105 .

[0044] The shielding holes are distributed around the first resonant unit 1, the second resonant unit 2, the third resonant unit 3, the fourth resonant unit 4, the fifth resonant unit 5, the sixth resonant unit 6, and the seventh resonant unit 7; the first shielding layer of the present invention is located at the bottom of the ceramic body, and the second shielding layer is located inside the ceramic body. The shielding holes connect the first shielding layer and the second shielding layer, and surround the composite feeding structure, the seven resonant units, and the coupling capacitor layer.

[0045] The isolation holes connect the first and second shielding layers. A portion of the isolation holes separates the second resonant unit from the sixth resonant unit, a portion of the isolation holes separates the third resonant unit from the fifth resonant unit, a portion of the isolation holes separates the third resonant unit from the fourth resonant unit, and a portion of the isolation holes separates the fourth resonant unit from the fifth resonant unit. Specifically, the isolation holes A901 are arranged between the second resonant unit 2 and the sixth resonant unit 6; the isolation holes A901 are arranged between the third resonant unit 3 and the fifth resonant unit 5; the isolation holes B902 are arranged between the third resonant unit 3 and the fourth resonant unit 4; and the isolation holes B902 are arranged between the fourth resonant unit 4 and the fifth resonant unit 5.

[0046] The above description is an embodiment of the present invention and is a preferred embodiment of the present invention. The present invention is not limited to the above embodiment. Based on the embodiment of the present invention, any modification, equivalent replacement, or improvement made by a person of ordinary skill in the art based on the present invention without creative work should be included in the scope of protection described in the claims.

Claims

1. An LTCC millimeter wave filter, characterized in that: The invention comprises an LTCC ceramic body, a composite feeding structure, a plurality of resonant units, a shielding layer, a shielding hole array, an isolation hole array, a coupling capacitor sheet, a parallel capacitor sheet, and a cross-coupling unit. The bottom of the LTCC ceramic body is provided with two input and output ports, the two input and output ports are respectively connected to the resonant units through the composite feeding structure, the plurality of resonant units are sequentially arranged adjacent to each other inside the ceramic body, and the plurality of resonant units are capacitively coupled through the coupling capacitor sheet. The shielding layers are respectively arranged at the bottom and inside the ceramic body and are connected through the plurality of shielding holes and the plurality of isolation holes. The first resonant unit and the seventh resonant unit at the two input and output ports are further provided with parallel capacitor sheets, respectively. A cross-coupling unit is further provided between the two resonant units. The composite feeding structure is composed of a single via, a capacitor plate, and multiple vias connected in series; the single via is connected to the output port and the capacitor plate, or the single via is connected to the input port and the capacitor plate, and the multiple vias are connected to the first-stage resonant unit and the capacitor plate, or the last-stage resonant unit and the capacitor plate; There are 7 resonance units, and each resonance unit is an open-ended resonance unit; A plurality of isolation holes are arranged between the second resonance unit and the sixth resonance unit, and between the third resonance unit and the fifth resonance unit; The cross-coupling unit is arranged between the second resonance unit and the sixth resonance unit, and the cross-coupler is in a square shape; Capacitive coupling is formed between the first resonant unit and the second resonant unit, between the second resonant unit and the third resonant unit, between the third resonant unit and the fourth resonant unit, between the fourth resonant unit and the fifth resonant unit, between the fifth resonant unit and the sixth resonant unit, and between the sixth resonant unit and the seventh resonant unit through the coupling capacitor sheet.

2. The LTCC millimeter wave filter according to claim 1, characterized in that: One end of the first resonant unit is directly connected to the composite feeding structure, and the other end forms capacitive coupling with the second resonant unit through a coupling capacitor plate; parallel capacitor plates are provided at the head and tail of the first resonant unit.

3. The LTCC millimeter wave filter according to claim 1, wherein: One end of the seventh resonant unit is directly connected to the composite feeding structure, and the other end forms capacitive coupling with the sixth resonant unit through a coupling capacitor plate; parallel capacitor plates are provided at the head and tail of the seventh resonant unit.

4. The LTCC millimeter wave filter according to claim 1, characterized in that: The second resonance unit, the third resonance unit, the fourth resonance unit, the fifth resonance unit, and the sixth resonance unit are shaped like line segments with constant width, or like dumbbells with two wide segments and a thin middle.

5. The LTCC millimeter wave filter according to claim 1, characterized in that: The resonant unit, the isolation hole array, the shielding layer, the coupling capacitor sheet, the composite feeding structure, and the cross-coupling unit are all metal conductors.

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