Superconducting filter working in short-wave frequency band

Abstract

The invention relates to the technical field of filters, in particular to a superconducting filter working in a short-wave frequency band, which comprises a metal shielding shell and a plurality of sub-filters connected in sequence, every two adjacent sub-filters are connected through a gold wire bonding wire, and each sub-filter comprises a plurality of resonance units. A plurality of resonance units in one sub-filter are coupled to form a resonance circuit, one end of each resonance unit is grounded, the other end of each resonance unit is connected with a capacitor, the sub-filters are interconnected in a gold wire bonding mode to form a complete filter, the larger the number of the sub-filters is, the better the out-of-band rejection degree of the filter is, and the more the sub-filters are, the better the out-of-band rejection degree of the filter is. The out-of-band rejection performance of the superconducting filter is effectively improved, and the design period is shortened; moreover, the working frequency of the superconducting filter is effectively reduced, and the application scene is expanded.

Description

Technical Field

[0001] The present invention relates to the technical field of filters, and in particular to a superconducting filter operating in a shortwave frequency band. Background Art

[0002] Compared with filters made of ordinary materials, superconducting filters have the advantages of high band edge steepness, high out-of-band suppression, low insertion loss, and the ability to work with low-noise amplifiers to improve the sensitivity of microwave systems. They have broad application prospects in military and civilian fields such as radar guidance, astronomical detection, and communication base stations, and are attracting more and more attention and research.

[0003] The size of the filter is closely related to its operating frequency. Generally, the lower the operating frequency and the longer the wavelength, the larger the filter size. On the one hand, due to the processing technology of superconducting film and substrate materials, the maximum size of a single film is only a disk with a diameter of 3 inches; on the other hand, the size of the filter resonant unit is usually one-quarter wavelength or one-half wavelength of the center operating frequency; therefore, the lowest operating frequency of the traditional superconducting filter actually manufactured is in the ultra-short wave band (above 30MHz); in addition, the out-of-band suppression performance of the filter is closely related to the order of the filter. In order to obtain high out-of-band suppression performance, the order of the filter must be increased, which further limits the working performance of the low-frequency filter; the simulation optimization design of high-order filters is highly dependent on the experience of designers, especially as the order of the filter increases, the circuit topology becomes more and more complex, and more and more variables are involved. The energy and time spent by traditional simulation optimization methods are also getting longer and longer, sometimes even up to several months, which is unacceptable in actual engineering applications. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a superconducting filter operating in a shortwave frequency band, which can effectively reduce the operating frequency of the superconducting filter and effectively improve the out-of-band suppression performance of the superconducting filter.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] A superconducting filter working in a shortwave frequency band comprises a metal shielding shell and a plurality of sub-filters connected in sequence, wherein the plurality of filters are encapsulated in the metal shielding shell, two adjacent sub-filters are connected via gold wire bonding lines, each sub-filter comprises a plurality of resonant units, a plurality of resonant units in a sub-filter are coupled to form a resonant circuit, one end of the resonant unit is grounded, and the other end of the resonant unit is connected to a capacitor.

[0007] The beneficial effects of the present invention are:

[0008] This solution connects two adjacent sub-filters through gold wire bonding lines. Each sub-filter includes a number of resonance units. The several resonance units in a sub-filter are coupled to form a resonance circuit. One end of the resonance unit is grounded, and the other end of the resonance unit is connected to a capacitor. Each sub-filter is interconnected by gold wire bonding to form a complete filter. The more sub-filters there are, the better the out-of-band suppression of the filter is, which effectively improves the out-of-band suppression performance of the superconducting filter and speeds up the design cycle. It also effectively reduces the operating frequency of the superconducting filter and expands its application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a structural side view of the superconducting filter working in the short-wave frequency band of the present invention;

[0010] Figure 2 A structural side view of a resonant unit of a superconducting filter operating in a short-wave frequency band of the present invention;

[0011] Figure 3 It is a schematic structural diagram of a comb-shaped resonance unit of a superconducting filter working in a short-wave frequency band of the present invention;

[0012] Figure 4 It is a schematic structural diagram of a zigzag resonant unit of a superconducting filter working in a short-wave frequency band of the present invention;

[0013] Figure 5 It is a structural schematic diagram of a spiral resonant unit of a superconducting filter working in a short-wave frequency band of the present invention;

[0014] Figure 6 It is a schematic structural diagram of a superconducting filter working in the shortwave frequency band of the present invention;

[0015] Description of labels:

[0016] 1. Metal shielding shell; 2. Gold bonding wire; 3. Sub-filter; 31. Resonant unit; 311. First superconducting film layer; 312. Substrate layer; 313. Second superconducting film layer; 314. First gold layer; 315. Second gold layer; 4. RF connector; 5. Inner conductor. DETAILED DESCRIPTION

[0017] In order to explain the technical content, achieved objectives and effects of the present invention in detail, the following is an explanation in combination with the implementation modes and the accompanying drawings.

[0018] Please refer to Figure 1 , the technical solution adopted by the present invention is:

[0019] A superconducting filter working in a shortwave frequency band comprises a metal shielding shell and a plurality of sub-filters connected in sequence, wherein the plurality of filters are encapsulated in the metal shielding shell, two adjacent sub-filters are connected via gold wire bonding lines, each sub-filter comprises a plurality of resonant units, a plurality of resonant units in a sub-filter are coupled to form a resonant circuit, one end of the resonant unit is grounded, and the other end of the resonant unit is connected to a capacitor.

[0020] From the above description, it can be seen that the beneficial effects of the present invention are:

[0021] This solution connects two adjacent sub-filters through gold wire bonding lines. Each sub-filter includes a number of resonance units. The several resonance units in a sub-filter are coupled to form a resonance circuit. One end of the resonance unit is grounded, and the other end of the resonance unit is connected to a capacitor. Each sub-filter is interconnected by gold wire bonding to form a complete filter. The more sub-filters there are, the better the out-of-band suppression of the filter is, which effectively improves the out-of-band suppression performance of the superconducting filter and speeds up the design cycle. It also effectively reduces the operating frequency of the superconducting filter and expands its application scenarios.

[0022] Furthermore, the resonance unit includes a first superconducting film layer, a substrate layer, and a second superconducting film layer stacked in sequence, the first superconducting film layer is used for grounding, and the second superconducting film layer is used for etching a resonance circuit.

[0023] Furthermore, the first superconducting film layers of the resonant circuits in two adjacent sub-filters are connected via a gold bonding wire, and the second superconducting film layers of the resonant circuits in two adjacent sub-filters are connected via a gold bonding wire.

[0024] From the above description, it can be seen that the gold-plated superconducting thin film layers used to etch the resonant circuit of adjacent sub-filters are connected by gold bonding wires, and the gold-plated superconducting thin film layers serving as the ground of adjacent sub-filters are connected by gold bonding wires, which can effectively reduce the ground resistance of the resonant unit and maintain the boundary conditions for electromagnetic field propagation.

[0025] Furthermore, the two resonant circuits located at the head and the tail are respectively connected to feeder lines, and two radio frequency connectors are installed on the outer wall of the metal shielding shell, and the two radio frequency connectors are respectively connected to the two feeder lines in a one-to-one correspondence.

[0026] Furthermore, the feeder is connected to the inner conductor of the RF connector via a gold bonding wire.

[0027] Furthermore, the resonance unit also includes a first gold layer and a second gold layer, the first gold layer is arranged on a side of the first superconducting film layer away from the substrate layer, the second gold layer is arranged on a side of the second superconducting film layer away from the substrate layer, the first gold layer is connected to the metal shielding shell, and the second gold layer is used to connect the feeder.

[0028] Furthermore, the substrate layer is made of lanthanum aluminate, and the thickness of the substrate layer is in the range of 0.4 mm to 0.6 mm.

[0029] Furthermore, the material of the first superconducting film layer is yttrium barium copper oxide, and the thickness of the first superconducting film layer is in the range of 500nm-650nm.

[0030] Furthermore, the material of the second superconducting film layer is yttrium barium copper oxide, and the thickness of the second superconducting film layer is in the range of 500nm-650nm.

[0031] Furthermore, the capacitor is a capacitor with a high quality factor.

[0032] Please refer to Figures 1 to 6 As shown, the first embodiment of the present invention is:

[0033] Please refer to Figure 1 and Figure 6 A superconducting filter operating in a short-wave frequency band comprises a metal shielding shell 1 and a plurality of sub-filters 3 connected in sequence, wherein the plurality of filters are encapsulated in the metal shielding shell 1, and two adjacent sub-filters 3 are connected by gold wire bonding wires 2, and each sub-filter 3 comprises a plurality of resonant units 31 (see Figure 3 , Figure 4 and Figure 5 The resonance unit 31 may be a compact shape such as a comb-shaped resonance unit, a zigzag resonance unit, or a spiral resonance unit), and a plurality of resonance units 31 in a sub-filter 3 are coupled to form a resonance circuit, one end of the resonance unit 31 is grounded, and the other end of the resonance unit 31 is connected to a capacitor.

[0034] Please refer to Figure 2 The resonance unit 31 includes a first superconducting film layer 311, a substrate layer 312, and a second superconducting film layer 313 which are stacked in sequence. The first superconducting film layer 311 is used for grounding, and the second superconducting film layer 313 is used for etching a resonance circuit.

[0035] The first superconducting film layers 311 of the resonant circuits in two adjacent sub-filters 3 are connected via a gold bonding wire 2 , and the second superconducting film layers 313 of the resonant circuits in two adjacent sub-filters 3 are connected via a gold bonding wire 2 .

[0036] Please refer to Figure 1 The two resonant circuits located at the head and tail are respectively connected to feed lines, and two RF connectors 4 are installed on the outer wall of the metal shielding shell 1. The two RF connectors 4 are respectively connected to the two feed lines in a one-to-one correspondence.

[0037] Please refer to Figure 1 The feed line is connected to the inner conductor 5 of the RF connector 4 via a gold bonding wire 2 .

[0038] Please refer to Figure 2 The resonance unit 31 also includes a first gold layer 314 and a second gold layer 315, the thickness of the first gold layer 314 and the second gold layer 315 are both 200nm, the first gold layer 314 is arranged on a side of the first superconducting film layer 311 away from the substrate layer 312, and the second gold layer 315 is arranged on a side of the second superconducting film layer 313 away from the substrate layer 312, the first gold layer 314 is connected to the metal shielding shell 1, the first gold layer 314 can be connected and fixed to the metal shielding shell 1 through an indium layer or a silver glue layer to play a grounding role, and the second gold layer 315 is used to connect the feeder.

[0039] The substrate layer 312 is made of lanthanum aluminate (with a dielectric constant of about 23.75) or magnesium oxide (with a dielectric constant of about 9.7), and the thickness of the substrate layer 312 is 0.5 mm.

[0040] The material of the first superconducting film layer 311 is yttrium barium copper oxide (superconducting transition temperature is about 92K), and the thickness of the first superconducting film layer 311 is 600nm.

[0041] The material of the second superconducting film layer 313 is yttrium barium copper oxide (superconducting transition temperature is about 92K), and the thickness of the second superconducting film layer 313 is 600nm.

[0042] The capacitor is a capacitor with a high quality factor.

[0043] Please refer to Figure 6 Each of the sub-filters 3 can be composed of a spiral resonant unit. In order to ensure the power capacity of the sub-filter 3 and reduce the mutual coupling between the spiral lines, the line width and the line spacing are both 0.5mm, the line length at the outermost part is about 53mm, and it is wound 26 times. Based on this, the total line length can reach 3m; combined with the compensation effect of the capacitor, the equivalent length of the resonant unit 31 can reach 4m, and its resonant frequency is 5MHz.

[0044] In order to achieve the requirement of high out-of-band suppression, each sub-filter 3 is interconnected by gold wire bonding to form a complete filter. The more sub-filters 3 there are, the better the out-of-band suppression of the filter.

[0045] Since superconducting film materials cannot be punched, the grounding of the filter in this scheme is achieved by a gold wire bonding process, that is, a wedge welding machine is used to weld a gold wire at the grounding point of the resonance unit 31, and the other end of the gold wire is welded and fixed to the metal shielding shell 1; wherein, the diameter of the gold wire bonding line 2 is 18μm-76μm, and the termination position is the edge of the superconducting film ground. The gold wires are evenly distributed and spaced apart from each other at the millimeter level to ensure the grounding continuity and reliable stability of the high-frequency signal.

[0046] In summary, the present invention provides a superconducting filter operating in a shortwave frequency band, wherein two adjacent sub-filters are connected by gold wire bonding lines, each sub-filter includes a plurality of resonance units, and a plurality of resonance units in a sub-filter are coupled to form a resonance circuit, one end of the resonance unit is grounded, and the other end of the resonance unit is connected to a capacitor, and each sub-filter is interconnected by gold wire bonding to form a complete filter. The more sub-filters there are, the better the out-of-band suppression of the filter is, which effectively improves the out-of-band suppression performance of the superconducting filter and speeds up the design cycle; and the operating frequency of the superconducting filter is also effectively reduced, thereby expanding its application scenarios.

[0047] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention's specification and drawings, or directly or indirectly applied in related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A superconducting filter operating in a shortwave frequency band, characterized in that: It includes a metal shielding shell and a plurality of sub-filters connected in sequence, wherein the plurality of filters are encapsulated in the metal shielding shell, two adjacent sub-filters are connected via gold bonding wires, each sub-filter includes a plurality of resonant units, and a plurality of resonant units in a sub-filter are coupled to form a resonant circuit, wherein one end of the resonant unit is grounded, and the other end of the resonant unit is connected to a capacitor.

2. The superconducting filter operating in the shortwave frequency band according to claim 1, characterized in that: The resonance unit comprises a first superconducting film layer, a substrate layer and a second superconducting film layer which are stacked in sequence, the first superconducting film layer is used for grounding, and the second superconducting film layer is used for etching a resonance circuit.

3. The superconducting filter operating in the shortwave frequency band according to claim 2, characterized in that: The first superconducting film layers of the resonant circuits in two adjacent sub-filters are connected via a gold bonding wire, and the second superconducting film layers of the resonant circuits in two adjacent sub-filters are connected via a gold bonding wire.

4. The superconducting filter operating in the shortwave frequency band according to claim 2, characterized in that: The two resonant circuits located at the head and the tail are respectively connected with feeder lines, and two radio frequency connectors are installed on the outer wall of the metal shielding shell, and the two radio frequency connectors are respectively connected with the two feeder lines in a one-to-one correspondence.

5. The superconducting filter operating in the shortwave frequency band according to claim 4, characterized in that: The feeder is connected to the inner conductor of the radio frequency connector via a gold bonding wire.

6. The superconducting filter operating in the shortwave frequency band according to claim 4, characterized in that: The resonance unit also includes a first gold layer and a second gold layer, the first gold layer is arranged on a side of the first superconducting film layer away from the substrate layer, the second gold layer is arranged on a side of the second superconducting film layer away from the substrate layer, the first gold layer is connected to the metal shielding shell, and the second gold layer is used to connect the feeder.

7. The superconducting filter operating in the shortwave frequency band according to claim 2, characterized in that: The substrate layer is made of lanthanum aluminate, and the thickness of the substrate layer is in the range of 0.4 mm to 0.6 mm.

8. The superconducting filter operating in the shortwave frequency band according to claim 2, characterized in that: The material of the first superconducting film layer is yttrium barium copper oxide, and the thickness of the first superconducting film layer is in the range of 500nm-650nm.

9. The superconducting filter operating in the shortwave frequency band according to claim 2, characterized in that: The material of the second superconducting film layer is yttrium barium copper oxide, and the thickness of the second superconducting film layer is in the range of 500nm-650nm.

10. The superconducting filter operating in the shortwave frequency band according to claim 1, characterized in that: The capacitor is a capacitor with a high quality factor.

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