Miniaturized low-loss millimeter wave filter and radio frequency front-end equipment

Abstract

The invention discloses a miniaturized low-loss millimeter wave filter and radio frequency front-end equipment, which comprises a dielectric substrate, the dielectric substrate is provided with a metal layer, the metal layer is provided with a coplanar waveguide, and the coplanar waveguide comprises a central conductor belt and metal floors arranged on two sides of the central conductor belt. The central conductor belt is symmetrically provided with a first feed structure and a second feed structure; the metal layer is also provided with N resonators, N is greater than or equal to 2, and the N resonators are respectively coupled with the first feed structure and the second feed structure. According to the invention, low loss of the filter can be realized.

Description

Technical Field

[0001] This invention relates to the field of communications, and in particular to a miniaturized, low-loss millimeter-wave filter and radio frequency front-end device. Background Technology

[0002] Filters are key passive components in wireless radio frequency (RF) front-end systems, and their performance directly affects the overall efficiency, power consumption, and size of the entire communication system. In the RF front-end architecture, filters play a crucial role in frequency selection and out-of-band interference suppression; therefore, their insertion loss and physical size become critical design parameters. Traditionally, filters designed using microstrip lines or LC lumped-parameter structures offer advantages such as compact structure and ease of fabrication, meeting the miniaturization requirements of systems to a certain extent. However, limited by conductor losses, dielectric losses, and radiation losses, these filters generally achieve relatively low Q values, resulting in high passband insertion loss and poor frequency selectivity, making them unsuitable for low-power and high-efficiency applications.

[0003] To improve filter performance, SIW (Self-Induced Waveguide) has been introduced as one solution. SIW structures combine the advantages of high Q-values, high power capacity, and easy integration with planar circuits found in metallic waveguides. Their unloaded Q-values ​​can typically reach several hundred or even higher, significantly outperforming microstrip structures. However, SIW resonators are generally large, making it difficult for filters built based on SIW resonators to meet the high integration requirements of modern RF systems.

[0004] To address these challenges, academia and industry have proposed various miniaturization techniques for filters in recent years. For example, methods such as defective ground structures (DGS), low-temperature co-fired ceramics (LTCC), and substrate integrated cavities (SIC) have been used to compress filter size while maintaining a high Q value.

[0005] In summary, miniaturization and low-loss design of filters are key aspects of achieving high performance and high integration in current RF front-end systems. In particular, technological breakthroughs in this area will have a profound impact on the miniaturization, low power consumption, and spectral efficiency of the entire wireless device. Summary of the Invention

[0006] In order to overcome the above-mentioned shortcomings and deficiencies of the prior art, the purpose of this invention is to provide a miniaturized low-loss millimeter-wave filter and radio frequency front-end device.

[0007] This invention employs a resonator based on a defective ground structure, which has a higher Q value than traditional microstrip or LC resonators, thereby enabling low-loss filters. Compared to SIW resonators, it has a smaller size while maintaining a high Q value, thus exhibiting miniaturization and low-loss characteristics, demonstrating inventiveness and novelty.

[0008] Another object of the present invention is to provide a radio frequency front-end device.

[0009] The objective of this invention is achieved through the following technical solution: A miniaturized low-loss millimeter-wave filter includes a dielectric substrate, a metal layer disposed on the dielectric substrate, a coplanar waveguide disposed on the metal layer, the coplanar waveguide including a central conductor strip and metal ground planes disposed on both sides of the central conductor strip, and a first feeding structure and a second feeding structure symmetrically disposed on the central conductor strip. N resonators are also disposed on the metal layer, where N is greater than or equal to 2, and the N resonators are coupled to the first feeding structure and the second feeding structure, respectively.

[0010] Furthermore, each of the resonators is specifically a pair of spiral defect ground structures, which are symmetrically arranged on both sides of the central conductor strip.

[0011] Furthermore, the N resonators are divided into two parts, and the two parts are coupled to the first feed structure or the second feed structure that is close to each other, respectively.

[0012] Furthermore, the first power supply structure and the second power supply structure include two interconnected first metal lines and second metal lines.

[0013] Furthermore, it also includes a resonator with a U-shaped defect ground structure, which forms a CT structure with two adjacent resonators with spiral defect ground structures.

[0014] Furthermore, there are three resonators, specifically a first resonator, a second resonator, and a third resonator. The first and third resonators have a spiral defect structure, and the second resonator has a U-shaped defect structure.

[0015] Furthermore, the first feeding structure controls the coupling amount between the first feeding structure and the resonator, i.e. the external quality factor of the filter input, by controlling the length and width of the two metal lines.

[0016] Furthermore, the second feeding structure controls the coupling amount between the second feeding structure and the resonator, i.e. the external quality factor at the output of the filter, by the length and width of the two metal lines. Furthermore, the dielectric substrate is made of high-resistivity silicon wafer, ceramic, or printed circuit board (PCB) material.

[0017] An RF front-end device includes the miniaturized low-loss millimeter-wave filter described above.

[0018] Compared with the prior art, the present invention has the following advantages and beneficial effects: This invention employs a resonator based on a defect-ground structure, which has a higher Q value compared to traditional microstrip or LC resonators, thus enabling low-loss filters. Compared to SIW resonators, it has a smaller size while maintaining a high Q value, thus exhibiting miniaturization and low-loss characteristics. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a miniaturized low-loss millimeter-wave filter structure employing a defective ground structure according to the present invention. Figure 2 This is a schematic diagram of the response of the miniaturized low-loss millimeter-wave filter with a defective ground structure according to the present invention. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to the embodiments, but the implementation of the present invention is not limited thereto.

[0021] like Figure 1 As shown, a miniaturized, low-loss millimeter-wave filter includes a dielectric substrate with a metal layer disposed thereon. The metal layer contains a coplanar waveguide, which includes a central conductor strip and metal ground planes 1 disposed on both sides of the central conductor strip. A first feed structure 2 and a second feed structure 3 are symmetrically disposed on the central conductor strip about its centerline. The dielectric substrate is made of high-resistivity silicon wafer, ceramic, or printed circuit board (PCB) material.

[0022] N resonators, where N is greater than or equal to 2, are also disposed on the metal layer. The N resonators are coupled to the first feed structure and the second feed structure, respectively. Each of the N resonators consists of a pair of defect ground structures, including spiral defect ground structures and U-shaped defect ground structures.

[0023] If the N resonators include N1 spiral defect-ground structure resonators and N2 U-shaped defect-ground structure resonators, each U-shaped defect-ground structure resonator forms a CT structure with two adjacent spiral defect-ground structure resonators.

[0024] Among the N resonators, the resonator with the spiral defect structure is divided into two parts, which are coupled to the first or second feed structure that is close to each other, respectively.

[0025] In this embodiment, three resonators are disposed on the metal layer, including a first resonator 4, a second resonator 5, and a third resonator 6; a first feeding structure is coupled to the first resonator, and the first, second, and third resonators are coupled sequentially, with the first resonator and the third resonator forming a cross coupling.

[0026] The first, second, and third resonators are all composed of a pair of defect-ground structures. Specifically, the first and third resonators are a pair of spiral defect-ground structures, symmetrically arranged on both sides of the central conductor strip, as shown below. Figure 1 As shown, the second resonator is a pair of U-shaped defect ground structures, which are located on both sides of the two pairs of spiral defect ground structures and form a CT structure with the spiral defect ground structures.

[0027] The first power supply structure and the second power supply structure include a first metal line and a second metal line. In this embodiment, the first metal line and the second metal line are connected to each other. Both the first metal line and the second metal line are rectangular structures, and their sizes may be different.

[0028] The first feeding structure controls the coupling amount between the first feeding structure and the first resonator, i.e., the external quality factor of the filter input, by controlling the length and width of the two metal lines.

[0029] The second feeding structure controls the coupling amount between the second feeding structure and the third resonator, i.e. the external quality factor at the output of the filter, by the length and width of the two metal lines.

[0030] The entire filter structure is symmetrical. The first, second, and third resonators may be cross-coupled to generate transmission zeros; the second resonator may be omitted to achieve a second-order filter response; or more resonators may be added and coupled to one or more of the first, second, or third resonators to achieve a higher-order filter response or to increase transmission zeros.

[0031] The dielectric substrate can be made of high-resistivity silicon wafer, ceramic, or conventional printed circuit board (PCB) material.

[0032] This embodiment also provides an RF front-end device, including the filter in this embodiment.

[0033] The lengths of the two metal lines in the first and second feed structures are 0.31 mm and 0.36 mm, respectively, and their widths are 0.1 mm and 0.2 mm, respectively. Good matching results can be achieved under these preferred values. In this embodiment, the side lengths of the spiral defect ground structure, from longest to shortest, are 0.35 mm, 0.35 mm, 0.3 mm, 0.23 mm, 0.18 mm, and 0.11 mm, respectively, and the width is 0.07 mm for all sides. The width of the U-shaped defect ground structure is 0.06 mm, and the lengths of its three sections are 0.38 mm, 1.35 mm, and 0.38 mm, respectively. The U-shaped and spiral defect ground structures generate three transmission poles. Simultaneously, there is cross-coupling and source-load coupling between the resonator and the feed structure of these defect ground structures, achieving three transmission zeros out of band. In this embodiment, the dielectric substrate is a high-resistivity silicon wafer with a dielectric constant of 11.9 and a thickness of 0.6 mm.

[0034] like Figure 2 The image shows the filter response of one embodiment of the present invention. The filter operates in the 24-30GHz range, which can meet the requirements of the 5G millimeter-wave communication band. The return loss is greater than 17dB and the loss is less than 0.5dB. Three transmission zeros are generated at 19.5GHz below the passband and 32.7GHz and 41.2GHz above the passband, which enhances selectivity.

[0035] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the embodiments described above. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A miniaturized, low-loss millimeter-wave filter, characterized in that, The device includes a dielectric substrate, a metal layer disposed on the dielectric substrate, a coplanar waveguide disposed on the metal layer, the coplanar waveguide including a central conductor strip and metal ground planes disposed on both sides of the central conductor strip, and a first feeding structure and a second feeding structure symmetrically disposed on the central conductor strip; N resonators are also disposed on the metal layer, where N is greater than or equal to 2, and the N resonators are coupled to the first feeding structure and the second feeding structure, respectively.

2. The miniaturized low-loss millimeter-wave filter according to claim 1, characterized in that, Each of the resonators is specifically a pair of spiral defect structures, which are symmetrically arranged on both sides of the central conductor strip.

3. The miniaturized low-loss millimeter-wave filter according to claim 2, characterized in that, The N resonators are divided into two parts, which are coupled to the first and second feed structures located close to each other, respectively.

4. The miniaturized low-loss millimeter filter according to claim 1, characterized in that, The first and second power supply structures each include two interconnected first and second metal lines.

5. The miniaturized low-loss millimeter filter according to claim 2, characterized in that, It also includes a resonator with a U-shaped defective ground structure, which forms a CT structure with two adjacent resonators with spiral defective ground structures.

6. The miniaturized low-loss millimeter filter according to claim 5, characterized in that, There are three resonators, specifically a first resonator, a second resonator, and a third resonator. The first and third resonators have a spiral defect structure, and the second resonator has a U-shaped defect structure.

7. The miniaturized low-loss millimeter filter according to claim 4, characterized in that, The first feeding structure controls the coupling amount between the first feeding structure and the resonator, i.e., the external quality factor of the filter input, by controlling the length and width of the two metal lines.

8. The miniaturized low-loss millimeter filter according to claim 4, characterized in that, The second feeding structure controls the coupling amount between the second feeding structure and the resonator, i.e. the external quality factor at the output of the filter, by the length and width of the two metal lines.

9. The miniaturized low-loss millimeter filter according to claim 1, characterized in that, The dielectric substrate is made of high-resistivity silicon wafer, ceramic, or printed circuit board (PCB) material.

10. A radio frequency front-end device, characterized in that, Includes the miniaturized low-loss millimeter-wave filter as described in any one of claims 1-9.

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