A YIG thin film resonator based on coplanar waveguide

Abstract

The invention discloses a YIG thin film resonator based on a coplanar waveguide, which comprises a substrate, a YIG thin film, an open resonant ring, and a coplanar waveguide; the YIG thin film and the open resonant ring are arranged on the top surface of the substrate, the open resonant ring is located outside the YIG thin film and surrounds the YIG thin film; the coplanar waveguide is arranged on the bottom surface of the substrate. The resonator uses the YIG thin film to replace the existing YIG small ball, and thus does not need to adjust the crystal orientation, simplifies the circuit assembly process, reduces the assembly time, and the YIG thin film is more convenient to be installed on a flat circuit board.

Description

Technical Field

[0001] The present application relates to the field of radio frequency microwave technology, and in particular to a YIG thin film resonator based on a coplanar waveguide. Background Art

[0002] Gadolinium gallium garnet is abbreviated as "GGG" and yttrium iron garnet is abbreviated as "YIG".

[0003] Yttrium iron garnet (YIG) is a microwave gyromagnetic material that has both insulating and gyromagnetic properties. By changing the bias magnetic field applied to the YIG film, the gyromagnetic tensor in the YIG material can be changed within an ultra-wideband frequency band, thereby affecting the electromagnetic field characteristics in the film. Therefore, the YIG film has an ultra-wideband magnetic tuning characteristic. The resonator made of YIG film can change its resonant frequency by adjusting the bias magnetic field on the YIG film.

[0004] YIG resonator is a tunable device with excellent performance, which has an unparalleled super-octave tuning range, extremely low loss and extremely high unloaded quality factor. YIG resonator can be used in the design and production of YIG tuned filters and YIG tuned oscillators. Filters and oscillators designed with YIG resonators can be tuned super-octave, and are widely used in ultra-wideband instruments and meters. They are essential key components for the RF front end of high-performance instruments and meters.

[0005] Existing YIG resonators generally use a YIG ball structure. The YIG ball is a YIG material that is cut into small cubic particles with a side length of about 1.5 mm. The YIG ball is processed by a ball forming equipment to become a YIG ball. The YIG ball can only become a qualified device material after being polished.

[0006] The YIG ball structure is more difficult to assemble during the circuit assembly process. During assembly, the angle of the ball needs to be repeatedly adjusted to determine the crystal orientation of the YIG ball in order to achieve the best performance. The entire assembly process is complicated and time-consuming, and it is not convenient to install the spherical surface on a flat circuit board. Summary of the invention

[0007] The purpose of the present invention is to provide a YIG thin film resonator based on coplanar waveguide to solve the above-mentioned problems. The resonator uses YIG thin film to replace the existing YIG balls, thereby eliminating the need to adjust the crystal orientation, simplifying the circuit assembly process, reducing the assembly time, and making it easier to install the YIG film on a flat circuit board.

[0008] The technical solution adopted by the present invention is as follows:

[0009] A YIG thin film resonator based on a coplanar waveguide comprises a substrate, a YIG thin film, an open resonant ring and a coplanar waveguide; the YIG thin film and the open resonant ring are arranged on the top surface of the substrate, the open resonant ring is located outside the YIG thin film and surrounds the YIG thin film; the coplanar waveguide is arranged on the bottom surface of the substrate.

[0010] Furthermore, the coplanar waveguide includes a coplanar waveguide center conductor and two coplanar waveguide ground conductors arranged on the bottom surface of the substrate; the coplanar waveguide center conductor is located below the open resonant ring; the two coplanar waveguide ground conductors are symmetrically arranged on both sides of the coplanar waveguide center conductor and are spaced apart from the coplanar waveguide center conductor.

[0011] Furthermore, the top surface of the coplanar waveguide central conductor is connected to the bottom surface of the substrate, and in the horizontal direction, the geometric center of the open resonant ring is located in the top surface area of ​​the coplanar waveguide central conductor.

[0012] Furthermore, the geometric center of the open resonant ring coincides with the geometric center of the coplanar waveguide central conductor in the vertical direction.

[0013] Furthermore, an open resonant ring is arranged outside the YIG film, and the geometric center of the YIG film coincides with the geometric center of the open resonant ring in the vertical direction.

[0014] Furthermore, a plurality of open resonant rings are arranged outside the YIG film, and the plurality of open resonant rings form concentric rings on the top surface of the substrate; and the geometric center of the YIG film coincides with the geometric center of the concentric rings in the vertical direction.

[0015] Furthermore, the shape of the split resonant ring matches the shape of the YIG film.

[0016] Furthermore, the YIG film is arranged at the bottom of the GGG substrate, and the bottom surface of the YIG film is arranged on the top surface of the substrate.

[0017] Furthermore, a YIG film is also arranged on the top of the GGG substrate.

[0018] Furthermore, the YIG thin film is grown on the GGG substrate by liquid phase epitaxial growth, and the YIG thin film has a single crystal structure.

[0019] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention include at least one of the following:

[0020] 1. The YIG thin film resonator based on coplanar waveguide of the present invention uses YIG thin film to replace the existing YIG balls. Since the YIG thin film is a planar structure, it is no longer necessary to repeatedly adjust the angle of the YIG thin film to determine the crystal orientation during assembly, thereby simplifying the entire circuit assembly process and reducing the assembly time. At the same time, the YIG thin film is a planar structure, and the YIG thin film can be more conveniently installed on a flat circuit board.

[0021] 2. The coplanar waveguide-based YIG thin film resonator of the present invention utilizes an open resonant ring to directly excite the YIG thin film, thereby reducing the excitation of clutter and effectively suppressing high-order modes in the YIG thin film.

[0022] 3. Compared with other types of planar transmission circuits, the coplanar waveguide structure has a left-right symmetrical ground plane, which allows the electromagnetic field to maintain a quasi-TEM mode at a higher frequency. The quasi-TEM mode has a linear dispersion characteristic and a more superior frequency response characteristic. In addition, the coplanar waveguide has a smaller radiation loss, which enables the overall device to work in a higher frequency band. The coplanar waveguide itself can maintain a single quasi-TEM mode without generating other high-order mode characteristics, and can also make the distribution of the RF current excited on the open ring more uniform, so that the high-order mode of the static magnetostatic wave will not be excited, so that the clutter suppression ability of the overall device is optimized.

[0023] 4. By setting the YIG film by liquid phase epitaxial growth, the thickness of the YIG film can be easily adjusted, and then the coupling energy intensity between the YIG film and the coplanar waveguide structure can be effectively adjusted, reducing the design difficulty of the ultra-wideband resonator.

[0024] 5. The YIG film grown by liquid phase epitaxy is a single crystal structure. It can grow according to the crystal orientation of the GGG substrate as the substrate. After the growth is completed, the YIG single crystal film has a single fixed crystal orientation. No additional adjustment of the crystal orientation is required during assembly, which is convenient for assembly and debugging. The YIG single crystal film grown according to the crystal orientation of the temperature stable axis of YIG has better temperature performance and can improve the temperature drift characteristics of the final device. In addition, the YIG single crystal structure has a good lattice, few internal defects, uniform impurity distribution, and low stress. Therefore, the YIG single crystal film has lower ferromagnetic resonance loss, which is beneficial to reduce the loss of the device and improve the quality factor of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A perspective view of the present invention;

[0026] Figure 2 A top view of the present invention;

[0027] Figure 3 A bottom view of the present invention;

[0028] Figure 4 A structural diagram showing a YIG film disposed on the bottom of a GGG substrate. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0030] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0032] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0033] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the product of the invention is usually placed when in use, or the positions or positional relationships commonly understood by those skilled in the art, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0034] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0035] like Figures 1 to 4 As shown, the present invention discloses a YIG thin film resonator based on a coplanar waveguide, which includes a substrate 4, a YIG thin film 1, an open resonant ring 3, and a coplanar waveguide; the YIG thin film 1 and the open resonant ring 3 are arranged on the top surface of the substrate 4, the open resonant ring 3 is located outside the YIG thin film 1 and surrounds the YIG thin film 1; the coplanar waveguide is arranged on the bottom surface of the substrate 4.

[0036] Due to the above structure, since the YIG film 1 is a planar structure, it is no longer necessary to repeatedly adjust the angle of the YIG film 1 to determine the crystal orientation during assembly, thereby simplifying the entire circuit assembly process and reducing the assembly time. At the same time, the YIG film 1 is a planar structure, and the YIG film 1 can be more conveniently installed on a flat circuit board.

[0037] Due to the above structure, when an external bias magnetic field perpendicular to the YIG film 1 is added, the split resonant ring 3 will be coupled with the YIG film 1. When the coplanar waveguide receives an external input signal to generate an electromagnetic field, the split resonant ring 3 excites a radio frequency current under the action of the electromagnetic field. Under the action of the external bias magnetic field, the radio frequency current on the split resonant ring 3 excites the YIG film 1 to generate a static magneto-wave resonance. The resonant frequency can be determined by the magnitude of the bias magnetic field applied to the YIG film 1.

[0038] Compared with other types of planar transmission circuits, the coplanar waveguide structure has a left-right symmetrical ground plane, which allows the electromagnetic field to maintain a quasi-TEM mode at a higher frequency. The quasi-TEM mode has a linear dispersion characteristic and a more superior frequency response characteristic. In addition, the coplanar waveguide has a smaller radiation loss, which enables the overall device to operate in a higher frequency range. The coplanar waveguide itself can maintain a single quasi-TEM mode without generating other high-order mode characteristics, and can also make the distribution of the RF current excited on the open ring more uniform, so that the high-order mode of the static magnetostatic wave will not be excited, so that the clutter suppression ability of the overall device is optimized.

[0039] Furthermore, the coplanar waveguide includes a coplanar waveguide center conductor 6 and two coplanar waveguide ground conductors 5 arranged on the bottom surface of the substrate 4; the coplanar waveguide center conductor 6 is located below the open resonant ring 3; the two coplanar waveguide ground conductors 5 are symmetrically arranged on both sides of the coplanar waveguide center conductor 6, and are spaced apart from the coplanar waveguide center conductor 6.

[0040] like Figure 3 As shown, the coplanar waveguide center conductor 6 and the two coplanar waveguide ground conductors 5 are in plate shape, and the axes of the coplanar waveguide center conductor 6 and the two coplanar waveguide ground conductors 5 in the length direction are parallel to each other.

[0041] Since the coplanar waveguide central conductor 6 is located below the open resonant ring 3, when the coplanar waveguide central conductor 6 receives an external input signal to generate an electromagnetic field, the open resonant ring 3 can be fully located in the electromagnetic field, which is more conducive to the open resonant ring 3 to generate radio frequency current. The symmetrical current distribution can better suppress the generation of high-order static magnetomodes, thereby obtaining a purer spectrum resonance effect.

[0042] Furthermore, the top surface of the coplanar waveguide center conductor 6 is connected to the bottom surface of the substrate 4, and in the horizontal direction, the geometric center of the open resonant ring 3 is located in the top surface area of ​​the coplanar waveguide center conductor 6, that is, the geometric center of the open resonant ring 3 cannot be located outside the top surface area of ​​the coplanar waveguide center conductor 6.

[0043] Since the geometric center of the split resonant ring 3 is located in the top surface area of ​​the coplanar waveguide central conductor 6 , it can be ensured that the split resonant ring 3 is fully located in the electromagnetic field generated by the coplanar waveguide central conductor 6 .

[0044] The best way is to make the geometric center of the split resonant ring 3 coincide with the geometric center of the coplanar waveguide central conductor 6 in the vertical direction. This can reduce the excitation of clutter and make the static magnetoelectric wave generated by the YIG film 1 more symmetrical, thereby effectively suppressing the high-order modes in the YIG film 1.

[0045] One open resonant ring 3 may be arranged outside the YIG film 1, or a plurality of open resonant rings 3 may be arranged, for example, 2, 3 or 4;

[0046] When the open resonant ring 3 is set as one, the geometric center of the YIG film 1 coincides with the geometric center of the open resonant ring 3 in the vertical direction, which can reduce the excitation of the clutter and make the static magnetoelectric wave waveform generated by the YIG film 1 more symmetrical, thereby effectively suppressing the high-order modes in the YIG film 1.

[0047] When multiple open resonant rings 3 are provided, multiple open resonant rings 3 form concentric rings on the top surface of the substrate 4; the geometric center of the YIG film 1 coincides with the geometric center of the concentric rings in the vertical direction, which can reduce the excitation of clutter and make the static magnetic wave waveform generated by the YIG film 1 more symmetrical, thereby effectively suppressing the high-order modes in the YIG film 1.

[0048] The YIG film 1 and the open resonant ring 3 are arranged at intervals, and the concentric rings are equally spaced concentric rings. In the concentric rings, the opening position of each open resonant ring 3 can be set arbitrarily.

[0049] In order to ensure that the open resonant ring 3 is excited by the coplanar waveguide, the open resonant ring 3 should be made as large as possible so that the open resonant ring 3 can fully cover the larger area of ​​the coplanar waveguide central conductor 6. When a single open resonant ring 3 is set, if the open resonant ring 3 is made too large, the gap between the open resonant ring 3 and the YIG film 1 will be enlarged, thereby affecting the excitation effect of the open resonant ring 3 on the YIG film 1; in order to reduce the gap between the YIG film 1 and the open resonant ring 3, the size of the YIG film 1 needs to be increased. If the size of the YIG film 1 is increased, the coplanar waveguide will directly excite the YIG film 1, and more clutter will be generated. When multiple open resonant rings 3 are set, multiple open resonant rings 3 can fully cover the larger area of ​​the coplanar waveguide central conductor 6, and the YIG film 1 is located at the center of the inner ring of the concentric ring, and the gap between the YIG film 1 and the inner ring is small, then there is no need to increase the size of the YIG film 1, thereby avoiding the generation of more clutter.

[0050] The best setting is Figure 2 As shown, the optimal number of split resonant rings 3 is two, and the openings of the inner split resonant ring 3 and the outer split resonant ring 3 differ by 180°.

[0051] Furthermore, the shape of the split resonant ring 3 matches that of the YIG film 1 , which can reduce the excitation of clutter and make the waveform of the static magnetoelectric wave generated by the YIG film 1 more symmetrical, thereby effectively suppressing the high-order modes in the YIG film 1 .

[0052] In the present invention, the YIG film 1 can be arranged in a circular shape, a square shape, etc. When the YIG film 1 can be arranged in a circular shape, all the split resonant rings 3 are circular rings, and when the YIG film 1 can be arranged in a square shape, all the split resonant rings 3 are square rings.

[0053] Furthermore, the YIG film 1 is arranged at the bottom of the GGG substrate 2 , and the bottom surface of the YIG film 1 is arranged on the top surface of the substrate 4 .

[0054] In specific implementation, the YIG film 1 is grown on the bottom of the GGG substrate 2 by liquid phase epitaxial growth; the bottom surface of the YIG film 1 is bonded to the top surface of the substrate 4 by using non-conductive adhesive.

[0055] The GGG substrate 2 is used to fix the YIG film 1. The YIG film 1 is set by liquid phase epitaxial growth, which can facilitate the adjustment of the thickness of the YIG film 1, and further effectively adjust the coupling energy intensity between the YIG film 1 and the coplanar waveguide structure, thereby reducing the design difficulty of the ultra-wideband resonator.

[0056] The YIG film 1 grown by liquid phase epitaxy is a single crystal structure, and it can grow according to the crystal orientation of the GGG substrate 2 as a substrate. After the growth is completed, the YIG single crystal film has a single fixed crystal orientation, and no additional crystal orientation adjustment is required during assembly, which is convenient for assembly and debugging. The YIG single crystal film grown according to the temperature stable axis crystal orientation of YIG has better temperature performance and can improve the temperature drift characteristics of the final device. The YIG single crystal structure has a good lattice, few internal defects, uniform impurity distribution, and low stress, so the YIG single crystal film has lower ferromagnetic resonance loss, which is beneficial to reduce the loss of the device and improve the quality factor of the device.

[0057] Furthermore, a YIG film 1 may be disposed on the top of the GGG substrate 2. That is, the YIG film 1 is disposed on both the top and the bottom of the GGG substrate 2.

[0058] During the liquid phase epitaxial growth process, the GGG substrate 2 is immersed in the melt, and the YIG film 1 will grow on both the bottom and top surfaces of the GGG substrate 2. With a double-sided structure, there is no need to remove the YIG film 1 on the top surface, which can simplify the process.

[0059] In the present invention, the substrate 4 is a PCB board.

[0060] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A YIG thin film resonator based on a coplanar waveguide, characterized in that: It comprises a substrate (4), a YIG film (1), an open resonant ring (3), and a coplanar waveguide; the YIG film (1) and the open resonant ring (3) are arranged on the top surface of the substrate (4), the open resonant ring (3) is located outside the YIG film (1) and surrounds the YIG film (1); and the coplanar waveguide is arranged on the bottom surface of the substrate (4).

2. The YIG thin film resonator based on coplanar waveguide according to claim 1, characterized in that: The YIG film (1) is arranged at the bottom of a GGG substrate (2), and the bottom surface of the YIG film (1) is arranged on the top surface of a substrate (4); the YIG film (1) is grown on the GGG substrate (2) by liquid phase epitaxial growth, and the YIG film (1) is a single crystal structure.

3. The YIG thin film resonator based on coplanar waveguide according to claim 2, characterized in that: The coplanar waveguide comprises a coplanar waveguide center conductor (6) and two coplanar waveguide grounding conductors (5) arranged on the bottom surface of a substrate (4); the coplanar waveguide center conductor (6) is located below the open resonant ring (3); and the two coplanar waveguide grounding conductors (5) are symmetrically arranged on both sides of the coplanar waveguide center conductor (6) and are spaced apart from the coplanar waveguide center conductor (6).

4. The YIG thin film resonator based on coplanar waveguide according to claim 3, characterized in that: The top surface of the coplanar waveguide central conductor (6) is connected to the bottom surface of the substrate (4), and in the horizontal direction, the geometric center of the open resonant ring (3) is located in the top surface area of ​​the coplanar waveguide central conductor (6).

5. The YIG thin film resonator based on coplanar waveguide according to claim 4, characterized in that: The geometric center of the open resonant ring (3) coincides with the geometric center of the coplanar waveguide central conductor (6) in the vertical direction.

6. The YIG thin film resonator based on coplanar waveguide according to any one of claims 2 to 5, characterized in that: An open resonant ring (3) is arranged outside the YIG film (1), and the geometric center of the YIG film (1) coincides with the geometric center of the open resonant ring (3) in the vertical direction.

7. The YIG thin film resonator based on coplanar waveguide according to any one of claims 2 to 5, characterized in that: A plurality of open resonant rings (3) are arranged outside the YIG film (1), and the plurality of open resonant rings (3) form concentric rings on the top surface of the substrate (4); the geometric center of the YIG film (1) and the geometric center of the concentric rings coincide with each other in the vertical direction.

8. The YIG thin film resonator based on coplanar waveguide according to any one of claims 2 to 5, characterized in that: The shape of the open resonant ring (3) matches the shape of the YIG film (1).

9. The YIG thin film resonator based on coplanar waveguide according to claim 2, characterized in that: A YIG film (1) is also arranged on the top of the GGG substrate (2).

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