On-chip integrated band elimination filter chip

Abstract

According to the on-chip integrated band elimination filter chip provided by the invention, the two ends of the double-end open-circuit branch knot of the dual-mode resonance structure are folded, so that the size can be reduced, capacitance coupling is formed, the position of a transmission zero point is convenient to regulate and control, signals in a specific frequency range are effectively inhibited, and the stop band attenuation characteristic of the filter is enhanced; in addition, a plurality of dual-mode resonant structures are arranged to be coupled and connected through a feed structure, and a plurality of transmission zero points are introduced into a stop band, so that the filtering performance is improved; moreover, the dual-mode resonant structures can be connected through the microstrip structures to realize magnetoelectric hybrid coupling, and the positions of reflection zero points on the two sides can be adjusted by adjusting the connection position, impedance and length of the microstrip structures, so that the out-of-band rejection stop-band range of the filter is adjusted. The filter has the characteristics of small size, strong stop band suppression and large bandwidth, in-band noise and interference can be effectively filtered, the anti-interference capability of a communication system is improved, the dynamic range of the communication system is expanded, and the filter has good application prospects in the fields of satellite communication, radar, electronic countermeasure and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of passive integrated devices, and relates to a chip-integrated band-stop filter chip. Background Art

[0002] In radio frequency circuit design, filters are often used to suppress interference during signal transmission. With the transformation of communication technologies, more stringent requirements for miniaturization, low loss, high suppression, etc. have been put forward for filters.

[0003] Filters can be implemented in various forms. Traditional ones include waveguide filters, dielectric filters, etc. As the volume of communication systems shrinks, planar filters are currently mostly adopted. For high-frequency band-stop filters, common planar structures include classical microstrip structures (parallel coupled line structure, hairpin structure), split-ring resonator structure, defected ground structure, etc. Among them, the classical microstrip structure usually uses quarter-wavelength or half-wavelength resonators to couple with each other. Its advantages are easy design and processing, but its size is large and the rectangularity coefficient is not high; the split-ring resonator structure is evolved from the folding of half-wavelength resonators, which reduces the size to a certain extent, but its suppression of higher harmonics is poor and the transmission zeros are difficult to control; the defected ground structure changes the distributed current on the ground plane by etching a specific pattern on the ground plane, thereby changing the characteristics of the transmission line. This structure improves the sideband suppression and reduces the size, but it is difficult to process, incompatible with semiconductor processes, and there is a risk of electromagnetic leakage.

[0004] Therefore, how to provide a chip-integrated band-stop filter chip to reduce the device size, improve the stopband suppression ability, and reduce the process difficulty has become an urgent technical problem for those skilled in the art. Summary of the Invention

[0005] In view of the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a chip-integrated band-stop filter chip, which is used to solve the problems of large size, poor stopband suppression ability, and difficult processing of filters in the prior art.

[0006] To achieve the above purpose and other related purposes, the present invention provides a chip-integrated band-stop filter chip, including: A GaAs substrate, the GaAs substrate has a first surface and a second surface disposed opposite to each other, and a ground metal layer is disposed on the first surface of the GaAs substrate; A patterned top metal layer, located on the second surface of the GaAs substrate, the top metal layer includes a feeding structure and a dual-mode resonance structure, the dual-mode resonance structure and the feeding structure are spaced apart, wherein, the dual-mode resonance structure includes a double-ended open stub and a short-circuit stub connected to each other, and the two ends of the double-ended open stub are folded close to each other to form a capacitive coupling; The metallized vias electrically connect the shorting stub and the ground metal layer through the GaAs substrate.

[0007] Optionally, the two - terminal open stub includes a body portion and two double - folded portions. The body portion is in a "П" shape, and the double - folded portions are in an "L" shape. The two double - folded portions are respectively located at both ends of the body portion and are symmetrically arranged.

[0008] Optionally, in the dual - mode resonant structure, the shorting stub and the two - terminal open stub are centrally connected.

[0009] Optionally, the number of the dual - mode resonant structures is multiple, and the multiple dual - mode resonant structures are coupled and connected through the feeding structure.

[0010] Optionally, in the direction from the first surface of the GaAs substrate pointing to the second surface perpendicular to the GaAs substrate, the feeding structure has a first opening, a second opening, and a third opening arranged in sequence. The opening directions of the first opening and the third opening are the same, and the opening direction of the second opening is opposite to that of the third opening; The number of the dual - mode resonant structures is four. One dual - mode resonant structure is located in the first opening, two dual - mode resonant structures are located in the second opening, and one dual - mode resonant structure is located in the third opening; Wherein, the top metal layer further includes a microstrip structure, and the microstrip structure connects the two dual - mode resonant structures located in the second opening, enabling the dual - mode resonant structures in the second opening to be magnetoelectrically hybrid - coupled to form a triple - mode resonant structure.

[0011] Optionally, the feeding structure is in a "W" shape.

[0012] Optionally, the materials of the ground metal layer, the top metal layer, and the metallized vias are gold.

[0013] Optionally, a passivation layer is further provided between the top metal layer and the second surface of the GaAs substrate, and the metallized vias also penetrate through the passivation layer.

[0014] Optionally, the material of the passivation layer is silicon nitride.

[0015] Optionally, a protective layer is further included, and the protective layer covers the surface of the top metal layer.

[0016] As described above, in the on-chip integrated band-stop filter chip of the present invention, the two open-ended stubs at both ends of the dual-mode resonant structure are folded, which can not only reduce the size, but also form capacitive coupling, facilitating the regulation of the transmission zero position, effectively suppressing signals within a specific frequency range, and enhancing the stopband attenuation characteristics of the filter. In addition, multiple dual-mode resonant structures are arranged to be coupled and connected through a feeding structure, introducing multiple transmission zeros within the stopband to improve the filtering performance. Moreover, the dual-mode resonant structures can be connected through a microstrip structure to achieve magnetoelectric hybrid coupling. By adjusting the position, impedance, and length of the microstrip structure connection, the positions of the bilateral reflection zeros can be adjusted, thereby adjusting the out-of-band rejection stopband range of the filter. It has the characteristics of small size, strong stopband suppression, and large bandwidth, can effectively filter out in-band noise and interference, improve the anti-interference ability of the communication system, expand the dynamic range of the communication system, and has good application prospects in the fields of satellite communication, radar, electronic countermeasure, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It shows a cross-sectional view of the on-chip integrated band-stop filter chip in an embodiment of the present invention.

[0018] Figure 2 It shows a top view of the patterned top metal layer in an embodiment of the present invention.

[0019] Figure 3 It shows an S-parameter simulation result diagram of the on-chip integrated band-stop filter chip in an embodiment of the present invention.

[0020] Description of Component Labels: 1 - GaAs substrate; 2 - ground metal layer; 3 - top metal layer, 30 - first metal layer, 31 - second metal layer, 32 - feeding structure, 320 - first opening, 321 - second opening, 322 - third opening, 33 - dual-mode resonant structure, 330 - two open-ended stubs, 331 - short-circuit stub, 34 - microstrip structure, 35 - triple-mode resonant structure; 4 - metallized via; 5 - passivation layer; 6 - protective layer, 60 - first protective layer, 61 - second protective layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] The following describes the embodiments of the present invention through specific specific examples. Those skilled in the art can easily understand the other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0022] Please refer to Figures 1 to 3It should be noted that the illustrations provided in this embodiment only schematically illustrate the basic concept of the present invention. Therefore, only the components related to the present invention are shown in the drawings, rather than being drawn according to the number, shape, and size of the components in actual implementation. The type, quantity, and ratio of each component in actual implementation can be arbitrarily changed, and the component layout type may also be more complex.

[0023] This embodiment provides an on-chip integrated band-stop filter chip. Please refer to Figure 1 and Figure 2 . The on-chip integrated band-stop filter chip includes a GaAs substrate 1, a ground metal layer 2, a patterned top metal layer 3, and a metallized via 4. The GaAs substrate 1 has a first surface and a second surface disposed opposite to each other. The ground metal layer 2 is located on the first surface of the GaAs substrate 1. The top metal layer 3 is located on the second surface of the GaAs substrate 1. The top metal layer 3 includes a feeding structure 32 and a dual-mode resonance structure 33. The dual-mode resonance structure 33 and the feeding structure 32 are spaced apart. Among them, the dual-mode resonance structure 33 includes a dual-ended open stub 330 and a short-circuit stub 331 connected to each other. The two ends of the dual-ended open stub 330 are folded close to each other to form capacitive coupling. The metallized via 4 penetrates through the GaAs substrate 1 to electrically connect the short-circuit stub 331 and the ground metal layer 2.

[0024] As an example, the GaAs substrate 1 has extremely low dielectric loss, so that the filter based on the GaAs substrate can effectively reduce energy loss during high-frequency signal transmission and improve device performance. Moreover, the GaAs substrate supports the integrated passive device (IPD) process, which can reduce the volume of the filter and make it more suitable for the miniaturization requirements of modern electronic systems.

[0025] As an example, in the dual-mode resonance structure 33, by loading the short-circuit stub 331 on the dual-ended open stub 330, the short-circuit stub 331 will introduce a perturbation of the electromagnetic field, splitting the degenerate mode into two different resonance frequencies to achieve dual-mode characteristics. Since one dual-mode resonance structure 33 can support two resonance frequencies at the same time, it can replace two single-mode resonators, reducing the number of resonators and thus reducing the device size. Preferably, the center of the short-circuit stub 331 and the dual-ended open stub 330 are connected for easy simulation calculation. When the non-center positions of the short-circuit stub 331 and the dual-ended open stub 330 are connected, an analysis method of asymmetric stub loading needs to be used for simulation calculation.

[0026] As an example, the dual-open-circuit stub 330 includes a body portion and two double-folded portions. The body portion is in a "П" shape, and the double-folded portions are in an "L" shape. The two double-folded portions are respectively arranged at both ends of the body portion and symmetrically arranged. The double-folded portions are connected to the body portion, and the double-folded portions are located in the opening space of the body portion. That is, both ends of the dual-open-circuit stub 330 are folded on both sides, further reducing the size. Moreover, after folding, the dual-open-circuit stub 330 is close to each other in space, forming capacitive coupling. By adjusting the capacitive coupling, the position of the transmission zero can be conveniently controlled, effectively suppressing signals in a specific frequency range, thereby enhancing the stopband attenuation characteristic of the filter.

[0027] As an example, in this embodiment, the number of the dual-mode resonant structures 33 is set to be multiple, and the multiple dual-mode resonant structures 33 are coupled and connected through the feeding structure 32, introducing multiple transmission zeros in the stopband to improve the filtering performance.

[0028] Specifically, in this embodiment, the feeding structure 32 is in a "W" shape. In the direction perpendicular to the first surface of the GaAs substrate 1 and pointing to the second surface, the feeding structure 32 has a first opening 320, a second opening 321, and a third opening 322 arranged in sequence. The opening directions of the first opening 320 and the third opening 322 are the same, and the opening direction of the second opening 321 is opposite to that of the third opening 322. Among them, the first opening 320, the second opening 321, and the third opening 322 are all rectangular openings, and the size of the second opening 321 is larger than that of the first opening 320 and the third opening 322. The number of the dual-mode resonant structures 33 is four. One dual-mode resonant structure 33 is located in the first opening 320, two dual-mode resonant structures 33 are located in the second opening 321, and one dual-mode resonant structure 33 is located in the third opening 322. Since the opening directions of the first opening 320 and the third opening 322 are opposite to that of the second opening 321, the dual-mode resonant structures 33 located in the first opening 320 and the third opening 322 are in the opposite direction to the dual-mode resonator structures 33 located in the second opening 321. The "W"-shaped feeding structure can achieve effective coupling between the multiple dual-mode resonant structures 33 to accurately control the coupling strength between the dual-mode resonant structures 33. Moreover, the "W"-shaped feeding structure makes the overall structure of the filter more compact, meeting the requirements of modern communication devices for miniaturization and high integration.

[0029] As an example, the top metal layer 3 further includes a microstrip structure 34, and the microstrip structure 34 connects two of the dual-mode resonant structures 33 located in the second opening 321, enabling the dual-mode resonant structures 33 in the second opening 321 to achieve magnetoelectric hybrid coupling, thereby forming a triple-mode resonant structure 35. By adjusting the connection position of the microstrip structure 34 and the impedance and length of the microstrip structure 34, the positions of the bilateral reflection zeros can be adjusted, causing the reflection zeros to move towards higher or lower frequencies, or affecting the out-of-band level, etc., so as to adjust the out-of-band rejection stopband range of the filter.

[0030] As an example, the patterned top metal layer 3 is axially symmetrically arranged about the center of the microstrip structure 34.

[0031] As an example, the top metal layer 3 is composed of a stacked first metal layer 30 and the second metal layer 31. Using two layers of metal stacking can improve the over-power capability and reduce the insertion loss; of course, in other examples, the top metal layer 3 can also use a single-layer metal or more than two layers of metal stacking, which is not limited to this embodiment.

[0032] As an example, a passivation layer 5 is provided between the top metal layer 3 and the GaAs substrate 1. The passivation layer 3 insulates and isolates the top metal layer 3 and the GaAs substrate 1 to prevent leakage; in this embodiment, the material of the passivation layer 5 is silicon nitride, and the metallized via 4 also penetrates through the passivation layer 5.

[0033] As an example, a protective layer 6 is further included, and the protective layer 6 covers the surface of the top metal layer 3 to prevent the top metal layer 3 from being oxidized; specifically, in this embodiment, the protective layer 6 includes a first protective layer 60 and a second protective layer 61. The first protective layer 60 covers the surface of the first metal layer 30, and the second protective layer 61 covers the surface of the second metal layer 31. The materials of the first protective layer 60 and the second protective layer 61 are silicon nitride. Among them, the protective layer 6 also fills the patterned gaps of the top metal layer 3. For areas where MIM capacitors are required, the protective layer 6 can be used as the dielectric layer of the capacitor.

[0034] As an example, the materials of the ground metal layer 2, the top metal layer 3, and the metallized via 4 are gold. Gold has strong chemical stability, which can ensure that the filter maintains stable performance during long-term use. At the same time, it can significantly reduce the loss during signal transmission; moreover, gold has good compatibility with the GaAS substrate, reducing the process difficulty.

[0035] Specifically, in this embodiment, the thickness of the GaAs substrate 1 is 100 μm, the thickness of the ground metal layer 2 is 4 μm, the thickness of the first metal layer 30 is 1.06 μm, the thickness of the second metal layer 31 is 3.5 μm, the diameter of the metallization via 4 is 50 μm, the thickness of the passivation layer 5 is 0.41 μm, the thickness of the first protective layer 60 is 0.3 μm, and the thickness of the second protective layer 61 is 0.1 μm. The width W1 of the feeding structure 3 is 35 μm, the length L1 of one side of the first opening 320 is 490 μm, and the common side length L2 of the first opening 320 and the second opening 321 is 550 μm; the width W2 of the dual-open-circuit stub 330 is 30 μm, the side length L3 of the dual-open-circuit stub 330 is 300 μm, the length L4 of one of the folded stubs of the dual-open-circuit stub 330 is 100 μm, and the length L5 of the other folded stub is 230 μm. The side spacing S1 between the dual-open-circuit stub 330 and the opening is 15 μm, and the spacing S2 between the two double-folded parts is 15 μm; the short-circuit stub 331 is in a "T" shape, and the longitudinal part length L6 of the short-circuit stub 331 is 40 μm; the width W3 of the microstrip structure 34 is 60 μm, the length L7 of the microstrip structure 34 is 20 μm, and the length L8 of the dual-open-circuit stub below the microstrip structure 34 is 150 μm.

[0036] As an example, please refer to Figure 3 , which shows the S-parameter simulation result diagram of the on-chip integrated band-stop filter chip in the embodiment of the present invention. As can be seen from Figure 3 , in the frequency band of 27.5 - 31 GHz, a notch depth exceeding 30 dBc is achieved, and the 3 dB opening width is only 6.5 GHz.

[0037] As an example, the size of the on-chip integrated band-stop filter chip in this embodiment is only 1.8 mm * 1.3 mm.

[0038] In summary, in the on-chip integrated band-stop filter chip of the present invention, the two open ends of the dual-mode resonant structure are folded, which can not only reduce the size, but also form capacitive coupling, facilitating the regulation of the transmission zero position, effectively suppressing signals within a specific frequency range, and enhancing the stop-band attenuation characteristics of the filter. In addition, multiple dual-mode resonant structures are coupled and connected through a feeding structure to introduce multiple transmission zeros in the stop band, improving the filtering performance. Moreover, the dual-mode resonant structures can be connected through a microstrip structure to achieve magnetoelectric hybrid coupling. By adjusting the position, impedance, and length of the microstrip structure connection, the positions of the bilateral reflection zeros can be adjusted, thereby adjusting the out-of-band rejection stop-band range of the filter. It has the characteristics of small size, strong stop-band suppression, and large bandwidth, can effectively filter out in-band noise and interference, improve the anti-interference ability of the communication system, expand the dynamic range of the communication system, and has good application prospects in the fields of satellite communication, radar, electronic countermeasure, etc. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has high industrial utilization value.

[0039] The above embodiments are only illustrative of the principles and effects of the present invention, and are not used to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes completed by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. An on-chip integrated band-stop filter chip, characterized in that, Comprising: A GaAs substrate having a first surface and a second surface disposed opposite to each other, and a ground metal layer is provided on the first surface of the GaAs substrate; A patterned top metal layer is located on the second surface of the GaAs substrate. The top metal layer includes a feeding structure and a dual-mode resonant structure. The dual-mode resonant structure and the feeding structure are spaced apart. Wherein, the dual-mode resonant structure includes a dual-ended open stub and a short-circuit stub connected to each other. The two ends of the dual-ended open stub are folded close to each other to form capacitive coupling; A metallized via penetrates the GaAs substrate to electrically connect the short-circuit stub and the ground metal layer.

2. The on-chip integrated band-stop filter chip according to claim 1, wherein: The dual-ended open stub includes a body portion and two double-folded portions. The body portion is in a "П" shape, and the double-folded portions are in an "L" shape. The two double-folded portions are respectively located at both ends of the body portion and are symmetrically arranged.

3. The on-chip integrated band-stop filter chip according to claim 1, characterized in that: In the dual-mode resonant structure, the short-circuit stub and the center of the dual-ended open stub are connected.

4. The on-chip integrated band-stop filter chip according to claim 1, characterized in that: The number of the dual-mode resonant structures is multiple, and the multiple dual-mode resonant structures are coupled and connected through the feeding structure.

5. The on-chip integrated band-stop filter chip according to claim 4, characterized in that: In the direction perpendicular to the first surface of the GaAs substrate pointing to the second surface, the feeding structure has a first opening, a second opening, and a third opening arranged in sequence. The opening directions of the first opening and the third opening are the same, and the opening direction of the second opening is opposite to that of the third opening; The number of the dual-mode resonant structures is four. One dual-mode resonant structure is located in the first opening, two dual-mode resonant structures are located in the second opening, and one dual-mode resonant structure is located in the third opening; Wherein, the top metal layer further includes a microstrip structure, and the microstrip structure connects the two dual-mode resonant structures located in the second opening, so that the dual-mode resonant structures in the second opening are magnetoelectrically hybrid-coupled to form a triple-mode resonant structure.

6. The on-chip integrated band-stop filter chip according to claim 5, characterized in that: The feeding structure is in a "W" shape.

7. The on-chip integrated band-stop filter chip according to claim 1, wherein: The materials of the ground metal layer, the top metal layer, and the metallized via are gold.

8. The on-chip integrated band-stop filter chip according to claim 1, characterized in that: A passivation layer is further provided between the top metal layer and the second surface of the GaAs substrate, and the metallized via also penetrates the passivation layer.

9. The on-chip integrated band-stop filter chip according to claim 8, characterized in that: The material of the passivation layer is silicon nitride.

10. The on-chip integrated band-stop filter chip according to claim 1, characterized in that: It further includes a protective layer that covers the surface of the top metal layer.

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