Substrate integrated waveguide bandpass filter based on glass substrate process

Abstract

The application discloses a kind of based on glass substrate process's substrate integrated waveguide band-pass filter, including input port, output port and main body area;Main body area is located between input port and output port, including glass substrate and being located on the top layer metal of glass substrate upper and lower two faces, bottom layer metal, glass substrate is equipped with several metallized through holes, several metallized through holes connect the top layer metal and bottom layer metal and are formed by arrangement and enclosure band-pass filter resonant cavity, band-stop filter resonant cavity and transition cavity, band-pass filter resonant cavity and transition cavity are connected to form the signal transmission main path of input port to output port, and band-stop filter resonant cavity is hung on the bypass outside signal transmission main path in transition cavity.This application is based on glass through hole and constructs band-pass resonant cavity and band-stop resonant cavity, does not use any inductance or capacitance structure, constitutes equivalent filter structure, its structure is compact, performance is good, is convenient for integration, and design is flexible.

Description

Technical Field

[0001] This invention belongs to the technical field of filters, specifically relating to a substrate integrated waveguide bandpass filter based on glass substrate technology. Background Technology

[0002] Substrate integrated waveguide bandpass filter (SIW BPF) is a novel microwave device that utilizes the transmission characteristics of microstrip electromagnetic waves in a substrate integrated waveguide to achieve a high-performance, small-size, low-loss bandpass filter. SIW BPF has important applications in communications, radar, satellite, and biomedicine.

[0003] Traditional waveguide filters typically use metallic waveguides, which offer high quality factors and low losses, but their fabrication process is complex, resulting in large size and heavy weight. With the continuous advancement of microelectronics technology, the development of substrate-integrated waveguides (SIWBPFs) has provided new options for device fabrication. Compared to traditional waveguide filters, SIWBPFs are small, lightweight, operate over a wide frequency range, and have a high quality factor, making them suitable for implementing high-performance multi-communication standard interfaces in space-constrained devices.

[0004] An LC filter is a filter circuit designed using a combination of inductors, capacitors, and resistors to filter out one or more harmonics. Existing LC filter integration technology uses forward and reverse multilayer redistribution layers (RDLs) on a substrate to form capacitors and inductors. However, due to the parasitic effects of the capacitors and inductors, this type of filter cannot achieve a good filtering response at high frequencies. Summary of the Invention

[0005] This invention addresses the shortcomings of existing technologies by providing a substrate-integrated waveguide bandpass filter based on glass substrate technology.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] A substrate-integrated waveguide bandpass filter based on glass substrate technology includes an input port, an output port, and a main body region. The main body region is located between the input port and the output port and includes a glass substrate and top and bottom metals on the upper and lower surfaces of the glass substrate. The glass substrate has a plurality of metallized vias, which connect the top and bottom metals and are arranged to form a bandpass filter resonant cavity, a bandstop filter resonant cavity, and a transition cavity. The bandpass filter resonant cavity and the transition cavity are connected to form a main signal transmission path from the input port to the output port. The bandstop filter resonant cavity is attached to the transition cavity as a bypass outside the main signal transmission path.

[0008] Optionally, the transition cavity includes a first transition cavity and a second transition cavity, the first transition cavity is connected to the input port, the second transition cavity is connected to the output port, and at least one of the bandpass filter resonant cavities is coupled between the first transition cavity and the second transition cavity through a coupling window.

[0009] Optionally, no metallized vias are provided between the first transition cavity and the input port, or between the second transition cavity and the output port, to form a transmission channel. Instead, discontinuous metallized vias are provided between the first transition cavity, the second transition cavity, and the bandpass filter resonant cavity to form the coupling window.

[0010] Optionally, a plurality of bandpass filter resonant cavities are provided between the first transition cavity and the second transition cavity, and the plurality of bandpass filter resonant cavities are connected in series through a coupling window.

[0011] Optionally, the coupling window of the first transition cavity and the bandpass filter resonant cavity is located on the side opposite to the input port, and the coupling window of the second transition cavity and the bandpass filter resonant cavity is located on the side opposite to the output port.

[0012] Optionally, the coupling windows of each bandpass filter resonator are located on adjacent sides.

[0013] Optionally, the band-stop filter resonant cavity is coupled to the side of the main signal transmission path of the transition cavity through a coupling window.

[0014] Optionally, the first transition cavity and the second transition cavity are respectively attached to at least one of the band-stop filter resonant cavities. The band-stop filter resonant cavities attached to the first transition cavity and the second transition cavity are located on opposite sides of the main signal transmission path and are centrally symmetrically arranged around the thickness direction of the glass substrate.

[0015] Optionally, the metallized via is formed by TGV process and filled with metal material, the filter has a filtering frequency band of millimeter wave, TGV aperture < 100 μm, aperture depth > 200 μm, and aperture spacing > 100 μm.

[0016] Optionally, the glass substrate is a quartz glass substrate.

[0017] The beneficial effects of this invention are as follows:

[0018] Based on the metallized glass through-hole, a bandpass filter resonant cavity and a bandstop filter resonant cavity are constructed without using any inductor or capacitor structure to form an equivalent filter structure. (1) The structure is compact and can effectively reduce the size of existing filters; (2) It is easy to integrate and interconnect; (3) It has good performance and is suitable for mass production; (4) The number and position of the zeros and poles of the filter response are adjustable and controllable, and the design is flexible; (5) It can introduce a good filtering effect in the millimeter wave band. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the layered structure of the substrate-integrated waveguide bandpass filter in an embodiment.

[0020] Figure 2 This is a half-section schematic diagram of the substrate-integrated waveguide bandpass filter used in this embodiment.

[0021] Figure 3 This is a schematic diagram of the planar structure of the substrate-integrated waveguide bandpass filter in the embodiment;

[0022] Figure 4 This is a schematic diagram of the topology of the substrate-integrated waveguide bandpass filter in an embodiment;

[0023] Figure 5 This is a schematic diagram of the simulated S-parameters of the substrate-integrated waveguide bandpass filter in the embodiment. Detailed Implementation

[0024] The present invention will be further explained below with reference to the accompanying drawings and specific embodiments. The accompanying drawings are merely illustrative to facilitate understanding of the invention, and their specific proportions can be adjusted according to design requirements. The vertical relationships of relative elements and the definitions of front / back in the graphics described herein should be understood by those skilled in the art to refer to the relative positions of the components; therefore, they can all be flipped to present the same component, and all of this should fall within the scope disclosed in this specification.

[0025] The three-dimensional Cartesian coordinate system established in the embodiment has the x-axis, y-axis, and z-axis directions perpendicular to each other.

[0026] Terminology: Re-Distribution Layer (RDL); Through Glass Via (TGV); Non-resonating Note (NRN); Bandpass Resonator (BPR); Bandstop Resonator (BSR).

[0027] refer to Figures 1 to 3The substrate-integrated waveguide bandpass filter based on glass substrate technology in this embodiment comprises three layers along the z-axis: a top metal layer 1, a bottom metal layer 2, and a glass substrate 3, with the glass substrate 3 disposed between the top metal layer 1 and the bottom metal layer 2. Depending on design requirements, either the top metal layer 1 or the bottom metal layer 2 can be a patterned metal layer, the other a solid metal layer, or both can be patterned metal layers; the patterned metal layer includes an RDL structure. The glass substrate 3 has several glass vias that penetrate the glass substrate and are filled with metal to form metallized glass vias 4. The metallized glass vias 4 connect the top metal layer 1 and the bottom metal layer 2, and their horizontal arrangement within the glass substrate 3 constructs a resonant cavity structure including a bandpass resonant cavity and a bandstop resonant cavity, thereby eliminating the need for any inductor or capacitor structures and forming an equivalent filter structure.

[0028] refer to Figure 3 The planar structure of the substrate-integrated waveguide bandpass filter in this embodiment, based on glass substrate technology, is a sixth-order filter. It includes an input port 5, an output port 6, and a main region located between the input port 5 and the output port 6. The main region includes a first transition cavity a, a second transition cavity d, bandpass filter resonant cavities b and c, and bandstop filter resonant cavities e, f, g, and h. The first transition cavity a, bandpass filter resonant cavity b, bandpass filter resonant cavity c, and second transition cavity d are connected sequentially to form the main signal transmission path from the input port 5 to the output port 6. The first transition cavity a and the second transition cavity d are non-resonant node structures. Bandstop filter resonant cavities e and f are connected to the bypass of the first transition cavity a, and bandstop filter resonant cavities g and h are connected to the bypass of the second transition cavity d. All cavities are connected to the top layer metal 1 and the bottom layer metal 2 through metallized glass through-holes 4 and arranged in a parallel enclosure.

[0029] The first transition cavity a is connected to the input port 5 and the bandpass filter resonant cavity b at opposite ends in the main signal transmission path direction (y-axis direction), respectively. The second transition cavity d is connected to the bandpass filter resonant cavity c and the output port 6 at opposite ends in the main signal transmission path direction (y-axis direction), respectively. No metallized vias 4 are provided in the x-axis direction between the first transition cavity a and the input port 5, and between the second transition cavity d and the output port 6 to form a transmission channel. Discontinuously arranged metallized vias are provided between the first transition cavity a and the bandpass filter resonant cavity b, between the second transition cavity d and the bandpass filter resonant cavity c, and between the bandpass filter resonant cavity b and the bandpass filter resonant cavity c, forming slots as coupling windows to achieve coupling. The coupling windows between the bandpass filter resonator b and the first transition cavity a and the bandpass filter resonator c are located on adjacent sides. The coupling windows between the bandpass filter resonator c and the bandpass filter resonator b and the second transition cavity d are located on adjacent sides. That is, the bandpass filter resonators b and c are arranged along the x-axis direction, so the first transition cavity a and the second transition cavity d have the same transmission direction (y-axis direction) on the main signal transmission path.

[0030] The band-stop filter resonators e, f, g, and h are also coupled to the sides of the main signal transmission path of the transition cavity through the aforementioned coupling window. The band-stop filter resonators e, f and g, h are located on opposite sides of the main signal transmission path and are symmetrical about the z-axis. Specifically, the band-stop filter resonators f and g are symmetrical, and the band-stop filter resonators e and h are symmetrical.

[0031] Input port 5 and output port 6 can employ a GSG-to-microstrip transmission structure, for example, with tapered transmission lines. The transmission line width at input port 5 gradually increases along the signal transmission direction, while the transmission line width at output port 6 gradually decreases along the signal transmission direction. This tapering size is used to match the internal and external impedances of the devices. Furthermore, other conventional transmission structures can also be applied depending on design requirements.

[0032] Figure 4 The diagram shows the topology of a sixth-order filter in this embodiment. The main signal transmission path is a(NRN1+NRN2)-b(BPR1)-c(BPR2)-d(NRN3+NRN4). Depending on their placement, each resonant cavity can produce different bandpass and bandstop filtering responses. In the transmission path, the first transition cavity 'a' is denoted as a(NRN1+NRN2), and the second transition cavity 'd' is denoted as d(NRN3+NRN4). The bandpass filter resonators b-b(BPR1) and c-c(BPR2) in the main path introduce two poles for the filter. The bandstop filter resonators e, f, g, and h, which are directly connected to a(NRN1+NRN2) and d(NRN3+NRN4) but are not in the main path but are attached to the bypass, are all connected to the first transition cavity a and the second transition cavity d. However, due to the different attachment positions, the topology reflects that they are attached to different non-resonant nodes, introducing a total of two zeros and four poles.

[0033] In this embodiment, the operating frequency band is in the millimeter-wave band. The preferred glass substrate is a quartz glass substrate, which has low dielectric loss and greater advantages at high frequencies. Through-holes (TGVs) are formed in the glass substrate using TGV technology and filled with metal to form metallized vias. The TGV aperture is <100μm, the aperture depth is >200μm, and the aperture spacing is >100μm. Several TGVs can be arranged in an encircling pattern within the glass substrate, forming different cavities. In the millimeter-wave band, the TGV aperture is much smaller than the wavelength, and benefits from the low dielectric constant and loss factor of the glass at high frequencies, resulting in low substrate loss and low cost. Combined with current high aspect ratio glass via technology, this allows for increasingly miniaturized filter designs, enabling advancements to higher operating frequency bands.

[0034] Figure 5The diagram shows the simulated S-parameters of the sixth-order filter in this embodiment. The horizontal axis X represents the response frequency (unit: GHz), and the vertical axis Y represents the return loss and insertion loss of the filter (unit: dB). From the simulated S-parameters of this sixth-order filter, it can be seen that the filter designed in this embodiment has a minimum in-band insertion loss of 1.23 dB, a center frequency of 67.85 GHz, a 3 dB passband of 65.82 GHz to 69.88 GHz, a bandwidth of 4.06 GHz, and a return loss greater than 15 dB in the passband. As can be seen from the S-parameters, a transmission zero is generated on each side of the passband. One transmission zero is generated by the band-stop resonator pair formed by band-stop filter resonators e and h, which simultaneously introduces two poles into the passband. The other transmission zero is generated by the band-stop resonator pair formed by band-stop filter resonators f and g, which also simultaneously introduces two poles into the passband. In fact, each band-stop filter introduces a zero into the system. Since the band-stop filters in this embodiment overlap in pairs, the zeros they introduce into the system also overlap in pairs, thus deepening the zeros, which is reflected in the S-parameters as two zeros. The last two poles are introduced by the band-pass resonators formed by the two band-pass filter resonators b and c. The first transition cavity a and the second transition cavity d are non-resonant nodes and do not introduce zeros or poles themselves, ultimately achieving a single passband filter response with 6 poles (m1~m6) + 2 zeros (m7~m8). Modifying the resonant frequency of the resonator can adjust the center frequency of the embodiment, which can be widely used in millimeter-wave wireless communication fields such as wireless communication and automotive radar.

[0035] By employing a different connection method than non-resonant nodes, the resonant cavity constructed through the metallized glass via 4 differentiates into bandpass and bandstop filter resonant cavities. Coupling between different resonant cavities is achieved through slots formed by the metallized glass via 4. Testing and interconnection with other devices can be implemented using transmission lines at input port 5 and output port 6. Current manufacturing processes can achieve metallized glass via 4 structures at the micron and even submicron scales. The flexibly adjustable metallized glass via 4 at the micron scale represents a flexibly adjustable resonant cavity and slot at the micron scale. The bandpass and bandstop filter resonant cavities obtained through this design can introduce flexibly adjustable zeros and poles into the system, bringing the following beneficial effects:

[0036] (1) It can effectively reduce the size of existing filters; (2) It is easy to integrate and interconnect; (3) It is suitable for mass production; (4) The number and position of the zeros and poles of the filter response are adjustable and controllable; (5) It can introduce good filtering effect in the millimeter wave band.

[0037] The above embodiments are only used to further illustrate a substrate integrated waveguide bandpass filter based on glass substrate technology according to the present invention. However, the present invention is not limited to the embodiments. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A substrate-integrated waveguide bandpass filter based on glass substrate technology, characterized in that: The system includes an input port, an output port, and a main body region. The main body region is located between the input and output ports and includes a glass substrate and top and bottom metal layers on the upper and lower surfaces of the glass substrate. The glass substrate has several metallized vias that connect the top and bottom metal layers and are arranged to form a band-pass filter resonant cavity, a band-stop filter resonant cavity, and a transition cavity. The band-pass filter resonant cavity and the transition cavity are connected to form the main signal transmission path from the input port to the output port. The band-stop filter resonant cavity is attached to the transition cavity as a bypass outside the main signal transmission path. The transition cavity includes a first transition cavity and a second transition cavity. The first transition cavity is connected to the input port, and the second transition cavity is connected to the output port. At least one bandpass filter resonant cavity is coupled between the first transition cavity and the second transition cavity through a coupling window. No metallized vias are provided between the first transition cavity and the input port, and between the second transition cavity and the output port to form a transmission channel. Discontinuously arranged metallized vias are provided between the first transition cavity, the second transition cavity, and the bandpass filter resonant cavity to form the coupling window. At least one bandstop filter resonant cavity is attached to the first transition cavity and the second transition cavity respectively. The bandstop filter resonant cavities attached to the first transition cavity and the second transition cavity are located on opposite sides of the main signal transmission path and are symmetrically arranged around the thickness direction of the glass substrate.

2. The substrate-integrated waveguide bandpass filter based on glass substrate technology according to claim 1, characterized in that: A plurality of bandpass filter resonant cavities are provided between the first transition cavity and the second transition cavity, and the plurality of bandpass filter resonant cavities are connected in series through a coupling window.

3. The substrate-integrated waveguide bandpass filter based on glass substrate technology according to claim 2, characterized in that: The coupling window of the first transition cavity and the bandpass filter resonant cavity is located on the side opposite to the input port, and the coupling window of the second transition cavity and the bandpass filter resonant cavity is located on the side opposite to the output port.

4. The substrate-integrated waveguide bandpass filter based on glass substrate technology according to claim 2, characterized in that: The coupling windows of each bandpass filter resonant cavity are located on adjacent sides.

5. The substrate-integrated waveguide bandpass filter based on glass substrate technology according to claim 1, characterized in that: The band-stop filter resonant cavity is coupled to the side of the main signal transmission path of the transition cavity through a coupling window.

6. The substrate-integrated waveguide bandpass filter based on glass substrate technology according to claim 1, characterized in that: The metallized vias are formed by the TGV process and filled with metallic material. The filter has a millimeter-wave frequency band, a TGV aperture of <100 μm, an aperture depth of >200 μm, and an aperture spacing of >100 μm.

7. The substrate-integrated waveguide bandpass filter based on glass substrate technology according to claim 1, characterized in that: The glass substrate is a quartz glass substrate.

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