Low-loss LTCC millimeter wave band-pass filter

Abstract

The invention relates to a low-loss LTCC millimeter wave band-pass filter. The filter comprises six ceramic dielectric layers, and the six ceramic dielectric layers are stacked from top to bottom and are respectively an input feed layer, a first grounding shielding layer, a main resonance layer, an auxiliary resonance layer, a second grounding shielding layer and an output feed layer. The main resonance layer and the auxiliary resonance layer are respectively provided with an elliptical ring-shaped resonance unit, and a cross coupling window is arranged between the main resonance layer and the auxiliary resonance layer; the input feed layer and the output feed layer adopt gradient coplanar waveguides, and the line width is gradually changed from 50 ohms to 20 ohms; the first grounding shielding layer and the second grounding shielding layer are provided with periodic electromagnetic band gap structures, and the first grounding shielding layer and the second grounding shielding layer are provided with a plurality of coupling holes. According to the invention, the Q value of the elliptical annular resonance unit is increased to 120, and meanwhile, the surface wave loss is reduced by 40% by the EBG ground structure; the elliptical ring-shaped resonance units are rotationally coupled by 40-50 degrees, so that the 3dB bandwidth fluctuation is less than 5%; the size of the filter is reduced by 30%, and meanwhile, the integration level of the whole filter is improved.

Description

Technical Field

[0001] This invention relates to the field of microwave communication technology, and more particularly to a low-loss LTCC millimeter-wave bandpass filter. Background Technology

[0002] With the rapid development of wireless communication technology, millimeter-wave communication technology has become a key technology in mobile communication and low-Earth orbit satellite communication due to its abundant spectrum resources and high data transmission rates. As a critical component of communication systems, filters face even more stringent requirements in millimeter-wave systems. High-reliability equipment demands that millimeter-wave filters possess characteristics such as high performance, small size, and lightweight design. Among these, small size and low loss are crucial performance indicators for millimeter-wave filters.

[0003] In the millimeter-wave band, distributed microstrip filters are easier to miniaturize compared to other structures. However, the microstrip filters currently used in communication systems are designed based on PCB (Printed Circuit Board) technology. Filters designed based on single-layer PCB technology result in a larger circuit area because the microstrip lines can only be designed on the same plane.

[0004] The performance of microstrip filters relies on the coupling between microstrip lines. Traditional filters designed using single-layer PCB technology adjust the coupling by changing the distance between adjacent transmission lines; however, the small spacing between these lines makes fabrication difficult. Furthermore, cross-coupling techniques can introduce more transmission zeros to improve passband and out-of-band performance. However, implementing cross-coupling in traditional single-layer PCB designs requires additional circuitry, leading to increased filter losses. Summary of the Invention

[0005] The purpose of this invention is to provide a low-loss LTCC millimeter-wave bandpass filter to solve the problems of high loss and poor bandwidth stability in the millimeter-wave band in the prior art.

[0006] The technical solution of the present invention is: a low-loss LTCC millimeter-wave bandpass filter, wherein the filter comprises six ceramic dielectric layers, and the six ceramic dielectric layers are stacked from top to bottom as an input feed layer, a ground shield layer one, a main resonant layer, a secondary resonant layer, a ground shield layer two, and an output feed layer; Elliptical ring resonant units are provided on the main resonant layer and the secondary resonant layer respectively, and a cross coupling window is provided between the main resonant layer and the secondary resonant layer; The input and output feed layers employ a gradient coplanar waveguide with a linewidth that gradually decreases from 50Ω to 20Ω. The first and second grounding shields are provided with periodic electromagnetic bandgap structures, and the first and second grounding shields are provided with multiple coupling holes.

[0007] Preferably, the elliptical ring resonant units on the main resonant layer and the secondary resonant layer are arranged in a staggered rotational manner, with a rotation angle of 40°-50° between them.

[0008] Preferably, the major axis of the elliptical ring resonant unit is 0.7-0.9λg, and the minor axis is 0.4-0.6λg.

[0009] Preferably, the cross-shaped coupling window has a width of 0.1-0.2 mm and a depth of λg / 10-λg / 6.

[0010] Preferably, a gold bridging wire is provided between the main resonant layer and the secondary resonant layer.

[0011] Preferably, the elliptical ring resonant units on the main resonant layer and the secondary resonant layer are surrounded by an array of metal through holes that penetrate the first grounding shield layer, the main resonant layer, the secondary resonant layer, and the second grounding shield layer.

[0012] The beneficial effects of this invention are: (1) Reduced loss: The Q value of the elliptical ring resonator unit is increased to 120, and at the same time, the EBG ground structure reduces the surface wave loss by 40%; (2) Stable bandwidth: The elliptical ring resonator unit is rotated and coupled at 40°-50°, so that the 3dB bandwidth fluctuation is <5%; (3) Reduced volume: The overall volume is reduced by 30%, while the integration of the entire filter is improved. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the structure of the present invention.

[0014] In the diagram, 1 is the input feed layer, 2 is the first grounding shield layer, 3 is the main resonant layer, 4 is the secondary resonant layer, 5 is the second grounding shield layer, 6 is the output feed layer, 7 is the elliptical ring resonant unit, and 8 is the metal via. Detailed Implementation

[0015] A low-loss LTCC millimeter-wave bandpass filter, the filter comprising six ceramic dielectric layers, the six ceramic dielectric layers being stacked from top to bottom as an input feed layer 1, a first ground shield layer 2, a main resonant layer 3, a secondary resonant layer 4, a second ground shield layer 5, and an output feed layer 6. Elliptical ring resonant units 7 are respectively provided on the main resonant layer 3 and the secondary resonant layer 4, and a cross coupling window is provided between the main resonant layer 3 and the secondary resonant layer 4. The input feed layer 1 and the output feed layer 6 adopt a gradient coplanar waveguide with a linewidth that gradually changes from 50Ω to 20Ω. The grounding shield layer 2 and the grounding shield layer 5 are provided with periodic electromagnetic bandgap structures, and the grounding shield layer 2 and the grounding shield layer 5 are provided with multiple coupling holes.

[0016] The elliptical ring resonant units 7 on the main resonant layer 3 and the secondary resonant layer 4 are arranged in a staggered rotational manner, with a rotation angle of 40°-50° between them.

[0017] The major axis of the elliptical ring resonant unit 7 is 0.7-0.9λg, and the minor axis is 0.4-0.6λg.

[0018] The cross-shaped coupling window has a width of 0.1-0.2mm and a depth of λg / 10-λg / 6.

[0019] A gold bridging wire is provided between the main resonant layer 3 and the secondary resonant layer 4.

[0020] The elliptical ring resonant unit 7 on the main resonant layer 3 and the secondary resonant layer 4 is surrounded by an array of metal through holes 8 that penetrate the grounding shield layer 1 2, the main resonant layer 3, the secondary resonant layer 4, and the grounding shield layer 2 5.

[0021] In the description of this invention, it should be understood that the indicated orientation or positional relationship is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description, and is not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0022] In this invention, unless otherwise explicitly specified and limited, for example, it can be a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two elements or an interaction between two elements. Unless otherwise explicitly limited, those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0023] All standard parts used in this invention can be purchased from the market, and irregular parts can be customized according to the description and drawings.

[0024] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A low-loss LTCC millimeter-wave bandpass filter, characterized in that: The filter comprises six ceramic dielectric layers, which are stacked from top to bottom as follows: input feed layer (1), ground shield layer one (2), main resonant layer (3), secondary resonant layer (4), ground shield layer two (5), and output feed layer (6). Elliptical ring resonant units (7) are provided on the main resonant layer (3) and the secondary resonant layer (4), and a cross coupling window is provided between the main resonant layer (3) and the secondary resonant layer (4); The input feed layer (1) and the output feed layer (6) adopt a gradient coplanar waveguide with a linewidth that gradually changes from 50Ω to 20Ω. The grounding shield layer one (2) and the grounding shield layer two (5) are provided with periodic electromagnetic bandgap structures, and the grounding shield layer one (2) and the grounding shield layer two (5) are provided with multiple coupling holes.

2. The low-loss LTCC millimeter-wave bandpass filter according to claim 1, characterized in that: The elliptical ring resonant units (7) on the main resonant layer (3) and the secondary resonant layer (4) are arranged in a staggered rotation, with a rotation angle of 40°-50° between them.

3. The low-loss LTCC millimeter-wave bandpass filter according to claim 2, characterized in that: The major axis of the elliptical ring resonant unit (7) is 0.7-0.9λg, and the minor axis is 0.4-0.6λg.

4. The low-loss LTCC millimeter-wave bandpass filter according to claim 1, characterized in that: The cross-shaped coupling window has a width of 0.1-0.2mm and a depth of λg / 10-λg / 6.

5. A low-loss LTCC millimeter-wave bandpass filter according to claim 1, characterized in that: A gold bridging wire is provided between the main resonant layer (3) and the secondary resonant layer (4).

6. The low-loss LTCC millimeter-wave bandpass filter according to claim 1, characterized in that: The elliptical ring resonant unit (7) on the main resonant layer (3) and the secondary resonant layer (4) is provided with an array of metal through holes (8) that penetrate the grounding shield layer one (2), the main resonant layer (3), the secondary resonant layer (4) and the grounding shield layer two (5).

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