Filtering unit, thin film filter, preparation method of thin film filter and radio frequency transceiving system

Abstract

The invention provides a filtering unit, a thin film filter, a preparation method of the thin film filter and a radio frequency transceiving system. The filtering unit comprises a plurality of resonance units. The plurality of resonance units are parallel to each other and are arranged at intervals; each resonance unit comprises a high-impedance strip line and a low-impedance strip line which are connected with each other, and adjacent resonance units are mutually spaced at one end provided with the low-impedance strip line to form an open-circuit end and connected at one end provided with the high-impedance strip line to form a short-circuit end; the end, away from the low-impedance strip line, of the high-impedance strip line is connected with the middle metal layer, and the joint is in a step shape.

Description

Technical Field

[0001] The present application relates to the field of microwave technology, and particularly to a filtering unit, a thin-film filter and a preparation method thereof, and a radio frequency transceiver system. Background Art

[0002] As one of the key components of a radio frequency transceiver system, a filter plays an important role in filtering out clutter and transmitting effective signals therein. Therefore, the performance of the filter will affect the performance of the entire radio frequency transceiver system. With the continuous improvement of system integration, high integration and miniaturization are important directions for the development and design of filters. The microstrip filter replaces the traditional waveguide and coaxial transmission line structures with transmission lines, greatly reducing the size of the filter, and being compatible with the traditional printed circuit board (PCB) manufacturing process, being easy to integrate with other circuits, and having advantages such as small size, low production cost, and easy integration, and is a currently widely adopted technical solution.

[0003] With the development of system-on-chip and microelectromechanical system (MEMS) technologies, the functions of chips have become increasingly rich, and more and more devices are integrated on the same chip. The combination of MEMS technology and radio frequency / microwave technology has become a new direction for a new generation of integrated high-performance filter technologies. In order to facilitate the design and manufacturing of MEMS processes, the structures of MEMS filters are mostly relatively simple and need to meet the process manufacturing requirements. Currently, people have used MEMS technology to etch dielectrics and manufacture metal thin films to realize microstrip thin-film filters and strip thin-film filters, but the structures of these filters are single and the selectivity is poor. If a higher filter order is required, it will result in a relatively large size of the filter and be not easy to process and manufacture. Summary of the Invention

[0004] To solve the existing technical problems, the present application provides a filtering unit, a thin-film filter and a preparation method thereof, and a radio frequency transceiver system that can flexibly control the position of transmission zeros, achieve good passband selectivity, can reduce the size and is easy to integrate.

[0005] In a first aspect, an embodiment of the present application provides a filtering unit, including a plurality of resonant units; the plurality of resonant units are arranged parallel to and spaced apart from each other;

[0006] Each of the resonant units includes a high-impedance transmission line and a low-impedance transmission line connected to each other. Adjacent resonant units are spaced apart from each other at one end provided with the low-impedance transmission line to form an open end, and are connected to each other at one end provided with the high-impedance transmission line to form a short circuit end. One end of the high-impedance transmission line far from the low-impedance transmission line is connected to the same metal, and the connection part is in a stepped shape.

[0007] In a second aspect, a thin film filter is provided, which includes a first metal layer, a first dielectric layer, an intermediate metal layer, a second dielectric layer, and a second metal layer that are sequentially stacked and arranged;

[0008] The intermediate metal layer is divided into a first part and a second part that are spaced apart from each other, and the first part is provided with the filtering unit described in any embodiment of the present application.

[0009] In a third aspect, a radio frequency transceiver system is provided, which includes the thin film filter described in any embodiment of the present application.

[0010] In a fourth aspect, a method for manufacturing a thin film filter includes:

[0011] Providing a first wafer, preparing an intermediate metal layer on a first surface of the first wafer, the intermediate metal layer including the filtering unit described in any one of claims 1 to 4, preparing a first metal layer on a second surface of the first wafer, and preparing metallized vias;

[0012] Providing a second wafer, preparing a second metal layer on one of the surfaces of the second wafer, and preparing metallized vias;

[0013] Bonding the first wafer and the second wafer, and the other surface of the second wafer away from the second metal layer is in contact with the intermediate metal layer of the first wafer.

[0014] The filtering unit provided in the above embodiments includes a plurality of resonant units that are parallel to each other and arranged at intervals. Each resonant unit is composed of a high-impedance strip line and a low-impedance strip line. The low-impedance strip line forms an open end, the high-impedance strip line is connected to the intermediate metal layer, and they are connected to each other to form a short circuit end. In this way, the resonant unit has the strongest electric field at the open end and the strongest magnetic field at the short circuit end. Energy coupling is carried out between two adjacent resonant units through hybrid electromagnetic coupling. The hybrid electromagnetic coupling realizes coexisting electric coupling and magnetic coupling between two adjacent resonant units, thereby physically forming a multipath coupling with a 180-degree phase difference, and thus generating a transmission zero point with a controllable position near the passband, facilitating flexible control of the position of the transmission zero point and achieving good passband selectivity. The overall structure adopts a strip line design, thus having the advantages of miniaturization and easy integration.

[0015] The thin film filter, its manufacturing method, and the radio frequency transceiver system provided in the above embodiments belong to the same concept as the corresponding filtering unit embodiments, and thus have the same technical effects as the corresponding filtering unit embodiments, which will not be elaborated here. Description of the Drawings

[0016] Figure 1 It is a schematic structural diagram of a filtering unit in an embodiment.

[0017] Figure 2 Schematic diagram of a hybrid electromagnetic coupling structure in an embodiment.

[0018] Figure 3 Three-dimensional schematic diagram of a thin-film filter in an embodiment.

[0019] Figure 4 For Figure 3 Schematic diagram of the first metal layer or the second metal layer in the thin-film filter shown.

[0020] Figure 5 For Figure 3 Schematic diagram of the intermediate metal layer of the thin-film filter shown.

[0021] Figure 6 For Figure 3 Side schematic diagram of the thin-film filter shown.

[0022] Figure 7 For Figure 3 Schematic diagram of the first dielectric layer or the second dielectric layer in the thin-film filter shown.

[0023] Figure 8 Schematic diagram of the planar structure of a second-order resonant filter and the equivalent circuit diagram of resonator coupling in an embodiment.

[0024] Figure 9 Frequency response curve of a second-order resonant filter in an embodiment.

[0025] Figure 10 Bandwidth control response curve of a second-order resonant filter in an embodiment.

[0026] Figure 11 Transmission zero control response curve of a second-order resonant filter in an embodiment.

[0027] Figure 12 Schematic diagram of the topological structure of an electromagnetic hybrid coupling structure in an embodiment.

[0028] Figure 13 Frequency response curve of a sixth-order resonant filter in an embodiment.

[0029] Figure 14 Stopband characteristic response curve of a sixth-order resonant filter in an embodiment.

[0030] Figure 15 Flowchart of the manufacturing method of a thin-film filter in an embodiment.

[0031] Explanation of component symbols:

[0032] Filter unit 10, low impedance stripline 11, high impedance stripline 12, resonant unit 13, open end 131, short circuit end 132, thin film filter 20, first metal layer 21, second metal layer 22, intermediate metal layer 23, first dielectric layer 24, second dielectric layer 25, shielding cavity 26, through hole 261, coupling window 262, feeding electrode window 263, input electrode 271, output electrode 272, grounding electrode 273, input ohmic stripline 281, output ohmic stripline 282, feeding electrode transition structure 29. DETAILED DESCRIPTION

[0033] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0034] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings. The described embodiments should not be regarded as limiting the present application. All other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of this application.

[0035] In the following description, the expression "some embodiments" is involved, which describes a subset of all possible embodiments. It should be noted that "some embodiments" may be the same subset or different subsets of all possible embodiments, and may be combined with each other without conflict.

[0036] In the following description, the terms "first, second, third" involved are merely used to distinguish similar objects and do not represent a specific ordering of the objects. It can be understood that "first, second, third" can be interchanged with a specific order or sequence where permitted, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein.

[0037] The inventor of the present application proposes a filter unit 10 with a controllable hybrid electromagnetic coupling structure. Through the design of the controllable hybrid electromagnetic coupling structure, position-controllable transmission zeros can be introduced on both sides of the passband to achieve high frequency selectivity. The inventor of the present application further proposes a thin film filter 20 including the filter unit 10, so that the thin film filter 20 can control the size of the electric coupling and magnetic coupling by controlling the length and spacing of the high impedance strip line 12 and the low impedance strip line 11 in the filter unit 10, thereby introducing position-controllable transmission zeros; in addition, the entire structure of the thin film filter 20 is designed with strip lines, so that the overall structure of the thin film filter 20 has the advantages of ultra-wide stopband, full closure, miniaturization, easy integration, simple design, and easy use.

[0038] See also Figure 1, the filtering unit 10 provided by an embodiment of the present application includes a plurality of resonant units 13; the plurality of resonant units 13 are arranged parallel to each other and at intervals; each resonant unit 13 includes a high-impedance strip line 12 and a low-impedance strip line 11 connected to each other. Adjacent resonant units 13 are spaced apart at one end provided with the low-impedance strip line 11 to form an open end 131, and are connected at one end provided with the high-impedance strip line 12 to form a short circuit end 132. One end of the high-impedance strip line 12 away from the low-impedance strip line 11 is connected to the same metal, and the connection part is in a stepped shape.

[0039] Among them, each resonant unit 13 is composed of a high-impedance strip line 12 and a low-impedance strip line 11 connected to each other. The plurality of resonant units 13 are arranged at intervals in pairs. Adjacent two resonant units 13 are connected at one end provided with the high-impedance strip line 12, so as to form a comb-like arrangement.

[0040] The connection of the high-impedance strip line 12 to the same metal may mean that the high-impedance strip line 12 and the metal to be connected are formed on the same metal layer. For the convenience of understanding and description, in the embodiments of the present application, the metal layer where the high-impedance strip line 12 and the low-impedance strip line 11 are located is taken as an example of the intermediate metal layer 23 for illustration.

[0041] The connection part of the high-impedance strip line 12 to the same metal is in a stepped shape, which means that the connecting lines formed by connecting each high-impedance strip line 12 to the metal layer are not on the same straight line. In an optional example, the number of the high-impedance strip lines 12 includes a plurality. The connection part of the high-impedance strip line 12 to the same metal is in a stepped shape, which may mean that the connecting lines formed by connecting each high-impedance strip line 12 to the metal layer are not on the same straight line, so as to form a stepped shape; it may also mean that the connecting lines formed by connecting some high-impedance strip lines 12 to the metal layer are not on the same straight line, while the connecting lines formed by connecting another part of the high-impedance strip lines 12 to the metal layer are on the same straight line, and the stepped shape can also be formed.

[0042] In the above embodiment, please refer to Figure 2 , the resonant unit 13 of the filtering unit 10 has the strongest electric field at the open end 131 and the strongest magnetic field at the short circuit end 132. The energy is coupled between two adjacent resonant units 13 through a hybrid electromagnetic coupling structure. The hybrid electromagnetic coupling structure realizes coexisting electric coupling and magnetic coupling between two adjacent resonant units 13, so as to physically form a multi-path coupling with a 180-degree phase difference, thereby generating a transmission zero point with a controllable position near the passband, facilitating the flexible control of the position of the transmission zero point, realizing good passband selectivity, and the overall structure adopts a strip line design, so as to have the advantages of miniaturization and easy integration.

[0043] Optionally, one end 121 of the high-impedance strip line 12 connected to the low-impedance strip line 11 is located on the same straight line DL1; among different resonant units 13, the lengths of the high-impedance strip lines 12 are different. Among multiple resonant units 13, one end of the high-impedance strip line 12 connected to the low-impedance strip line 11 is flush, while among different resonant units 13, the lengths of the high-impedance strip lines 12 are different, so that the connection points of the high-impedance strip lines 12 and the intermediate metal layer 23 are arranged in a stepped manner in a staggered manner based on the different lengths of the high-impedance strip lines 12. In this embodiment, by controlling the length of the high-impedance strip line 12 in adjacent resonant units 13, the magnitude of the magnetic coupling coefficient can be controlled.

[0044] For the convenience of description and understanding, two adjacent resonant units 13 are respectively referred to as a first resonant unit and a second resonant unit. The length of the high-impedance strip line 12 in each resonant unit 13 is l1, the width is w1, the length of the low-impedance strip line 11 is l2, and the width is w2. The interval between the high-impedance strip lines 12 of the first resonant unit and the second resonant unit is s1, and the interval between the low-impedance strip lines 11 of the first resonant unit and the second resonant unit is s2. The length l1, width w1 of the high-impedance strip line 12, the length l2, width w2 of the low-impedance strip line 11 jointly determine the resonant frequency of the filtering unit 10. The interval s1 between the high-impedance strip lines 12 and the interval s2 between the low-impedance strip lines 11 can control the magnitude of the hybrid electromagnetic coupling between the corresponding two resonant units 13. In this embodiment, the first resonant unit and the second resonant unit are different in at least one of the following: different length l1, different width w1, different interval s1, different length l2, different width w2, different interval s2. The multiple resonant units 13 are arranged in a comb shape, and the distances between two adjacent resonant units 13 can be different. For example, the distances between some adjacent resonant units 13 are the same, while the distances between other adjacent resonant units 13 are different; or the distances between any two adjacent resonant units 13 are different; to adjust and control the number and position of transmission zeros.

[0045] For the filtering unit 10 composed of a plurality of resonant units 13 arranged in a comb shape, the maximum electric field intensity exists at the open end 131; the magnetic field is dual to the electric field, so correspondingly, the maximum magnetic field intensity exists at the short - circuit end 132. If two resonant units 13 are arranged in a comb shape, electrical coupling is generated through the gap at the open end 131 between the two resonant units 13, and magnetic coupling is generated through the gap at the short - circuit end 132 and the short - circuit ground plane. Thus, the coupling mode of the entire structure of the filtering unit 10 is a hybrid electromagnetic coupling mode with both electrical coupling and magnetic coupling. Energy coupling is carried out between every two adjacent resonant units 13 arranged in a comb shape through the hybrid electromagnetic coupling mode. The hybrid electromagnetic coupling mode can achieve co - existing electrical coupling and magnetic coupling between every two adjacent resonant units 13, thereby physically forming a multipath coupling with a 180 - degree phase difference, and thus generating a transmission zero with a controllable position near the passband. When the magnetic coupling coefficient is greater than the electrical coupling coefficient, the magnetic coupling dominates, and at this time the total coupling coefficient is positive, and a transmission zero will be generated in the upper stopband of the passband; when the electrical coupling coefficient is greater than the magnetic coupling coefficient, the electrical coupling dominates, and at this time the total coupling coefficient is negative, and a transmission zero will be generated in the lower stopband of the passband. In this embodiment, the filtering unit 10 is composed of 1 / 4 - wavelength SIR resonant units. By controlling the size of the interval s2 between the low - impedance transmission lines 11 of two 1 / 4 - wavelength SIR resonant units, the size of the electrical coupling coefficient can be controlled, and by controlling the length l1 of the high - impedance transmission lines 12 of two 1 / 4 - wavelength SIRs, the size of the magnetic coupling coefficient can be controlled. It should be noted that in this embodiment, the interval between the resonant units 13 is represented by the size of the interval s2 between the low - impedance transmission lines 11. By adjusting the two parameters of the interval s2 between the SIR resonant units and the length l1 of the high - impedance transmission lines 12, the position of the transmission zero can be flexibly controlled to achieve good passband selectivity.

[0046] The hybrid electromagnetic coupling structure can achieve co - existing electrical coupling and magnetic coupling between two adjacent resonant units 13, thereby physically constructing a multipath coupling with a 180 - degree phase difference, and thus generating a transmission zero with a controllable position near the passband. The position of the transmission zero is determined based on the following formula (1):

[0047]

[0048] where Ec refers to the electrical coupling coefficient, Mc refers to the magnetic coupling coefficient, g refers to the frequency - varying coupling coefficient of the filter, refers to the resonant frequency of the first resonant unit, which is related to the length l1 and width w1 of the first resonant unit; It refers to the resonant frequency of the second resonant unit, which is related to the length l2 and width w2 of the second resonant unit. In this embodiment, the frequency-varying coupling coefficient of the filtering unit 10 is designed to be negative. When the magnetic coupling coefficient is greater than the electric coupling coefficient, the magnetic coupling dominates, and at this time the total coupling coefficient is positive, which will generate a transmission zero point in the upper stopband of the passband. Moreover, the larger the Mc / Ec, the farther the position of the transmission zero point is from the passband; when the electric coupling coefficient is greater than the magnetic coupling coefficient, the electric coupling dominates, and at this time the total coupling coefficient is negative, which will generate a transmission zero point in the lower stopband of the passband. Moreover, the smaller the Mc / Ec, the farther the position of the transmission zero point is from the passband. Based on the above principle, the position of the transmission zero point can be independently controlled.

[0049] Please refer to Figures 3 to 6 for reference. On the other hand, in another aspect of the embodiments of the present application, a high-selectivity wide-stopband thin-film filter 20 is provided, which includes the filtering unit 10 provided in any embodiment of the present application.

[0050] As Figure 3 shown, Figure 3 is a three-dimensional schematic diagram of a thin-film filter in an embodiment. The thin-film filter 20 includes a first metal layer 21, a first dielectric layer 24, an intermediate metal layer 23, a second dielectric layer 25, and a second metal layer 22 that are sequentially stacked; the intermediate metal layer 23 is divided into a first part and a second part that are spaced apart from each other, and the first part is provided with the filtering unit 10 provided in the foregoing embodiment.

[0051] The thin-film filter 20 is provided with a plurality of through holes 261, and each through hole 261 penetrates the first metal layer 21, the first dielectric layer 24, the intermediate metal layer 23, the second dielectric layer 25, and the second metal layer 22. In this embodiment, the plurality of through holes 261 provided in the middle of the thin-film filter 20 are arranged in a substantially rectangular shape. The through holes 261 are metallized through holes with a metal layer on the inner surface. Each through hole 261 penetrates the first metal layer 21, the first dielectric layer 24, the intermediate metal layer 23, the second dielectric layer 25, and the second metal layer 22, and the metal layer on the inner surface of the through hole 261 is connected to the first metal layer 21, the second metal layer 22, and the intermediate metal layer 23. In some embodiments, the plurality of through holes 261 can be arranged periodically to surround and form an area for placing the filtering unit 10, and the filtering unit 10 can be shielded through the through holes 261.

[0052] Thus, the overall structure of the thin-film filter 20 is designed using a multi-order resonator with a layered structure combined with a strip line. The filtering unit 10 is located in the central part of a plurality of stacked layered structures. The filtering unit 10 uses a plurality of resonator units 13 arranged in a comb shape to achieve high frequency selectivity and at the same time can reduce the overall size of the filter. In this embodiment, the thin-film filter 20 is a layered structure with a rectangular outer contour formed by sequentially stacking a first metal layer 21, a first dielectric layer 24, an intermediate metal layer 23, a second dielectric layer 25, and a second metal layer 22. The filtering unit 10 is disposed on the intermediate metal layer 23.

[0053] The plurality of resonator units 13 of the filtering unit 10 are arranged in a comb shape. The high-impedance strip line 12 is coplanar with the intermediate metal layer 23 and connected to the intermediate metal layer 23. It should be noted that the filtering unit 10 is correspondingly located within the region formed by surrounding the center of the thin-film filter 20 by the through hole 261. The positions of the first metal layer 21, the first dielectric layer 24, the second dielectric layer 25, and the second metal layer corresponding to this region are all solid. In some embodiments, the filtering unit 10 is fabricated using the intermediate metal layer 23.

[0054] In this embodiment, the dielectric layer refers to a structural layer formed using a silicon-based material as the insulating dielectric material, and the thin-film filter 20 is a silicon-based thin-film filter. It should be noted that in other embodiments, the dielectric layer may also refer to insulating dielectric materials such as glass, gallium arsenide, and gallium nitride, which are not limited herein.

[0055] In some embodiments, such as Figure 4 and Figure 5 , Figure 4 is Figure 3 a schematic diagram of the first metal layer 21 or the second metal layer 22 in the thin-film filter 20 shown. Figure 5 is Figure 3 a schematic diagram of the intermediate metal layer 23 of the thin-film filter 20 shown. Since the structures of the first metal layer 21 and the second metal layer 22 are the same, only the first metal layer 21 will be described as an example below. As Figure 4 shown, the first metal layer 21 includes a metal part and a hollowed-out part. The metal part is in an I shape, and the through hole 261 is disposed in the metal part. The hollowed-out part is symmetrically disposed relative to the metal part, which can be equivalent to etching away the position where the hollowed-out part is formed from a rectangular metal layer and retaining the rest. The corresponding position of the hollowed-out part is the coupling window 262.

[0056] Optionally, as Figure 5As shown, the thin-film filter 20 includes coupling windows 262 provided on opposite sides, and an input electrode 271 and an output electrode 272 located within the coupling windows 262; the coupling windows 262 are located on opposite sides of the filtering unit 10, and the two outermost resonant units 13 of the filtering unit 10 are respectively connected to an input ohmic strip line 281 and an output ohmic strip line 282. The input ohmic strip line 281 and the output ohmic strip line 282 are respectively connected to the high-impedance strip lines 12 of the corresponding resonant units 13, and pass through the coupling windows 262 on the corresponding sides and are correspondingly connected to the input electrode 271 and the output electrode 272. Among them, the intermediate metal layer 23 includes a first part and a second part that are not connected, for example Figure 5 the upper and lower parts in. The positions corresponding to the coupling windows 262 do not have metal except for the input ohmic strip line 281, the output ohmic strip line 282, the input electrode 271, and the output electrode 272. The first part has a filtering unit. The positions where the first part and the second part are disconnected include the coupling window 262 and the feeding electrode window 263. The input ohmic strip line 281 and the output ohmic strip line 282 extend outward from the disconnection between the first part and the second part, and pass through the coupling window 262 and the feeding electrode window 263. Preferably, it extends outward from the middle position of the coupling window 262 and the feeding electrode window 263. The distance between the first part and the second part of the intermediate metal layer 23 at the feeding electrode window 263 is smaller than the distance at the coupling window 262.

[0057] In some embodiments, the input ohmic strip line 281 and the output ohmic strip line 282 are respectively connected to the high-impedance strip lines 12 of the two outermost resonant units 13 in the filtering unit 10, and form an integral structure with the filtering unit 10. For example, the input ohmic strip line 281, the output ohmic strip line 282, and the filtering unit 10 are all made of the intermediate metal layer 23. In some embodiments, the distance between the position where the input ohmic strip line 281 is connected to the high-impedance strip line 12 and the intermediate metal layer 23 is a first distance, and the distance between the position where the output ohmic strip line 282 is connected to the high-impedance strip line 12 and the intermediate metal layer 23 is a second distance. Among them, the magnitudes of the first distance and the second distance can be the same or different. In this embodiment, the first distance and the second distance are the same and both are p, so as to control the coupling magnitude between the input / output ports and the filter. The distances between the positions where the input ohmic strip line 281 and the output ohmic strip line 282 are connected to the high-impedance strip line 12 and the intermediate metal layer 23 are equal, so that the input and output can be interchanged in practical applications.

[0058] In some other embodiments, input electrodes 271 and output electrodes 272 are respectively disposed in the coupling windows 262 on the opposite sides of the thin film filter 20. The input electrodes 271 and the output electrodes 272 penetrate through the thin film filter 20 along the stacking direction to connect the first metal layer 21, the second metal layer 22 and the intermediate metal layer 23. The input electrodes 271 and the output electrodes 272 penetrate through the entire structure of the thin film filter 20 to connect the first metal layer 21 and the second metal layer 22 on the upper and lower surfaces and the intermediate metal layer 23 in the middle, so that input and output ports exist on the side walls of the filter and the metal layers on the upper and lower surfaces, thereby avoiding the drawback of wire bonding required to connect external circuits during use, and making the overall structure of the thin film filter 20 have the advantages of ultra-wide stopband, fully enclosed, easy integration and easy use. It should be noted that the input electrodes 271 and the output electrodes 272 may also refer to the metal layers reserved at corresponding positions on the first metal layer 21, the second metal layer 22 and the intermediate metal layer 23. In addition, it should be noted that the coupling window 262 refers to a rectangular three-dimensional space respectively disposed on the opposite sides of the thin film filter 20. In one example, the positions of the first metal layer 21, the second metal layer 22 and the intermediate metal layer 23 corresponding to the coupling window 262 are respectively hollowed-out regions, and the parts of the first metal layer 21 and the second metal layer 22 corresponding to the input electrodes 271 and the output electrodes 272 are metal columns filled in the corresponding through holes. The intermediate metal layer 23 has a hollowed-out region at the position corresponding to the coupling window 262 except for the input ohmic strip line 281 and the output ohmic strip line 282. In another example, the positions of the first metal layer 21 and the second metal layer 22 corresponding to the coupling window 262 retain the metal as the input electrodes 271 and the output electrodes 272, and the regions except for the input electrodes 271 and the output electrodes 272 are respectively hollowed-out regions. The intermediate metal layer 23 has a hollowed-out region at the position corresponding to the coupling window 262 except for the input ohmic strip line 281 and the output ohmic strip line 282. It should be noted that, similar to the shielding cavity 26, the regions of the first dielectric layer 24 and the second dielectric layer 25 corresponding to the coupling window 262 are both solid.

[0059] Optionally, as Figure 5As shown, on the opposite sides of the filtering unit 10, between two adjacent through-holes 261, there is a feeding electrode window 263. The size of the feeding electrode window 263 is set such that the input ohmic strip line 281 and the output ohmic strip line 282 can have a 50-ohm impedance characteristic. On the intermediate metal layer 23, the part other than the input ohmic strip line 281 and the output ohmic strip line 282 at the position where the feeding electrode window 263 is formed is a hollowed-out area. The setting of the feeding electrode window 263 realizes the impedance matching of the input and output ports, and the size of the feeding electrode window 263 is used to ensure the 50-ohm impedance characteristic of the input ohmic strip line 281 and the output ohmic strip line 282. Optionally, a feeding electrode transition structure 29 is respectively provided at the connection between the input ohmic strip line 281 and the input electrode 271, and at the connection between the output ohmic strip line 282 and the output electrode 272. It should be noted that the feeding electrode window 263 refers to a rectangular three-dimensional space provided on the opposite sides of the filtering unit 10 and located between two adjacent through-holes. The part other than the input ohmic strip line 281 and the output ohmic strip line 282 at the position corresponding to the feeding electrode window 263 on the intermediate metal layer 23 is a hollowed-out area, while the areas corresponding to the feeding electrode window 263 on the first dielectric layer 24 and the second dielectric layer 25 are both solid.

[0060] In this embodiment, the intermediate metal layer 23 is divided into a first part and a second part that are spaced apart from each other. The feeding electrode window 263 refers to the part with a relatively small interval between the first part and the second part, and the coupling window 262 refers to the part with a relatively large interval between the first part and the second part. The size of the feeding electrode window 263 is smaller than that of the coupling window 262, and their specific sizes can be adjusted according to actual application requirements. Optionally, between the first part and the second part of the intermediate metal layer 23, the distance at the feeding electrode window 263 is greater than a first preset multiple of the diameter of the through-hole 261. This first preset multiple is usually greater than 1.5 and less than 3. Secondly, between the first part and the second part of the intermediate metal layer 23, the distance at the coupling window 262 is greater than the distance at the feeding electrode window 263. The size of the coupling window 262 should be at least greater than the size of the feeding electrode window 263. In actual applications, the size of the coupling window 262 can be specifically determined through simulation calculations with the goal of enabling the input ohmic strip line 281 and the output ohmic strip line 282 to have a 50-ohm impedance characteristic.

[0061] Optionally, the thin-film filter 20 further includes a plurality of ground electrodes 273, and the ground electrodes 273 are respectively located on the opposite sides of the corresponding input electrode 271 and output electrode 272 to form a GSG radio frequency connection structure. In this embodiment, as Figure 6As shown, the grounding electrodes 273 respectively refer to semi-cylindrical metals within semi-circular through holes 261 that are located on the outermost sides of the opposite two sides of the thin-film filter 20 and are on the same straight line as the corresponding input electrode 271 and output electrode 272, and form an integral electrode in the direction of sequential stacking of the multiple layered structures of the thin-film filter 20. Among them, the feeding electrodes include the input electrode 271, the output electrode 272, and the grounding electrode 273, and the input electrode 271, the output electrode 272, and the grounding electrode 273 respectively penetrate the entire structure of the thin-film filter 20 in the direction of sequential stacking of the multiple layered structures of the thin-film filter 20, connecting the first metal layer 21 and the second metal layer 22 on the upper and lower surfaces to the intermediate metal layer 23 in the middle, so that input and output ports exist on the side walls and the upper and lower metal surfaces of the filter, and wire bonding operations during use can be avoided.

[0062] As Figure 7 shown, it is a plan view of the dielectric layer. Since the structures of the first dielectric layer 24 and the second dielectric layer 25 are the same, only the first dielectric layer 24 will be described and illustrated. In the embodiment of the present application, the part of the first dielectric layer 24 except for the through holes 261 provided is a solid.

[0063] In order to have a more overall understanding of the filtering unit 10 provided in the embodiment of the present application and the thin-film filter 20 including the filtering unit 10, please refer to Figure 8 , taking the second-order resonant filter composed of 1 / 4 wavelength SIR resonant units as an example, to illustrate the implementation method and principle of the thin-film filter.

[0064] Figure 8(a1) and (a2) respectively show schematic diagrams of the intermediate metal layers of two different second-order resonant filters, and (b) shows the corresponding equivalent circuit diagrams of these two second-order resonant filters. Similar to the structure of the aforementioned resonant filter, the second-order resonant filter includes a first metal layer 21, a first dielectric layer 24, an intermediate metal layer 23, a second dielectric layer 25, and a second metal layer 22 arranged in sequence from top to bottom. A plurality of metallized vias arranged in a circular periodic interval are provided between the first metal layer 21 and the second metal layer 22, and a shielding cavity 26 is formed by surrounding these metallized vias. A second-order resonator composed of quarter-wavelength SIR resonant units arranged in a comb shape and having different sizes is located in the shielding cavity 26. The second-order resonator includes a first resonant unit and a second resonant unit. Each resonant unit 13 is composed of a high-impedance strip line 12 and a low-impedance strip line 11 connected. The low-impedance strip line 11 is located at the open end 131, the length of the low-impedance strip line 11 is l2, and the width is w2. The interval between the low-impedance strip lines 11 of the first resonant unit and the second resonant unit is s2. The high-impedance strip line 12 is located at the short circuit end 132, the length of the high-impedance strip line 12 is l1, and the width is w1. The interval between the high-impedance strip lines 12 of the first resonant unit and the second resonant unit is s1. The first resonant unit and the second resonant unit form a quarter-wavelength SIR in the shape of a paddle structure. By changing the length l1 of the high-impedance strip line 12 and the interval s2 between the low-impedance strip lines 11 of the two resonant units 13, the position of the transmission zero point can be adjusted and controlled. Figure 7 (a1) and (a2) respectively show the second-order resonant filters, that is, different positions of the transmission zero point can be realized. Coupling windows 262 are respectively arranged on both sides of the shielding cavity 26. The input ohmic strip line 281 and the output ohmic strip line 282 are respectively led out from the outermost resonant unit 13 of the filtering unit 10 and connected to the feeding electrodes arranged outside the thin film filter 20. Feeding electrode windows 263 are respectively arranged between the shielding cavity 26 and the corresponding coupling windows 262. The size of the feeding electrode windows 263 ensures the 50-ohm impedance characteristics of the input electrode 271 and the output electrode 272. The edge of the coupling window 262 further includes grounding electrodes 273 arranged in sequence and spaced at intervals along the extending directions of the input ohmic strip line 281 and the output ohmic strip line 282. The grounding electrodes 273 are arranged on the opposite sides of the corresponding input electrode 271 and output electrode 272, forming a radio frequency connection structure in the ground-signal-ground (GSG) bonding mode.

[0065] Combined with the aforementioned formula (1), it can be known that when the magnetic coupling coefficient is greater than the electric coupling coefficient, magnetic coupling dominates. At this time, the total coupling coefficient is positive, and a transmission zero will be generated in the upper stopband of the passband. Moreover, the larger the Mc / Ec, the farther the transmission zero is from the passband. When the electric coupling coefficient is greater than the magnetic coupling coefficient, electric coupling dominates. At this time, the total coupling coefficient is negative, and a transmission zero will be generated in the lower stopband of the passband. And the smaller the Mc / Ec, the farther the transmission zero is from the passband. Based on the above principle, different size parameters of the high-impedance transmission line 12 and the low-impedance transmission line 11 in the resonant unit 13 can be designed to achieve independent control of the position of the transmission zero, and its equivalent circuit is as Figure 8 shown in (b).

[0066] As Figures 9 to 11 shown, it is the frequency response curve of the second-order resonant filter, Figure 9 is the bandwidth control response curve of the second-order resonant filter, Figure 10 and Figure 11 are the transmission zero control response curves of the second-order resonant filters with the same bandwidth. It can be seen from Figure 10 that the transmission zero is located in the upper stopband of the passband and magnetic coupling dominates. By controlling the length l1 of the high-impedance transmission line 12 of the two 1 / 4-wavelength SIR resonant units, the magnitude of the magnetic coupling coefficient can be controlled. And the smaller the length l1 of the high-impedance transmission line 12, the larger the magnetic coupling coefficient, the electric coupling coefficient remains unchanged, the farther the transmission zero is from the passband, the larger the absolute value of the total coupling coefficient, and the larger the bandwidth. When the length l1 of the high-impedance transmission line 12 is larger, the magnetic coupling coefficient is smaller, the electric coupling coefficient remains unchanged, the closer the transmission zero is to the passband, the smaller the absolute value of the total coupling coefficient, and the smaller the bandwidth. In order to control the position of the transmission zero of the filter and keep the bandwidth unchanged, it is necessary to control the magnitudes of both the electric coupling coefficient and the magnetic coupling coefficient simultaneously to keep the total coupling coefficient unchanged. It can be seen from Figure 10 that the position of the transmission zero is located in the upper stopband of the passband. When the length l1 of the high-impedance transmission line 12 is increased, the magnetic coupling coefficient becomes smaller. It is necessary to simultaneously increase the width s between the two resonant units (it should be noted that since an open end is formed between the low-impedance transmission lines 12, the width s between the two resonant units can be equivalently determined according to the interval s1 between the low-impedance transmission lines 12) to reduce the magnitude of the electric coupling coefficient to ensure that the total coupling coefficient remains basically unchanged. At this time, Mc / Ec becomes larger, causing the transmission zero to move away from the passband. It can be seen from Figure 11 that the transmission zero is located in the lower stopband of the passband and electric coupling dominates. When the length l1 of the high-impedance transmission line 12 is increased, the magnetic coupling coefficient becomes smaller. It is necessary to simultaneously increase the magnitude of the width s between the two resonant units to reduce the magnitude of the electric coupling coefficient. At this time, Mc / Ec will also become larger, causing the transmission zero to move away from the passband.

[0067] Based on the above principle, the 1 / 4-wavelength SIR resonant units are cascaded in a comb shape. By changing the length l1 of the high-impedance strip line 12 and the interval s1 between the low-impedance strip lines 11 of the two resonant units 13, the magnitude of the hybrid electromagnetic coupling between the two filter units 10 can be controlled, thereby controlling the position of the transmission zero. Its topological structure is as Figure 12 shown. Theoretically, for an Nth-order electromagnetic hybrid coupling filter structure, N - 1 transmission zeros with independently controllable positions can be generated.

[0068] Taking again Figure 3 the sixth-order resonant filter composed of 1 / 4-wavelength SIR resonant units shown as an example, Figure 13 is the frequency response curve of the sixth-order resonant filter. As Figure 13 can be seen, the center frequency of this filter is 17.3 GHz, the -3dB bandwidth is 1.8 GHz (relative bandwidth 10.4%), the insertion loss is -2 dB, and the reflection coefficient in the passband is less than -18 dB. For the sixth-order resonant filter, two transmission zeros are generated on each side of the passband. Among them, transmission zero 1 and transmission zero 2 are generated by the hybrid coupling link dominated by electric coupling, located at 15.5 GHz and 15.8 GHz respectively; transmission zero 3 and transmission zero 4 are generated by the hybrid coupling link dominated by magnetic coupling, located at 18.64 GHz and 19.4 GHz respectively. Thus, the frequency selectivity of the sixth-order resonant filter is greatly improved.

[0069] Figure 14 is the stopband characteristic response curve of the sixth-order resonant filter. The second resonant mode of the 1 / 4-wavelength SIR is three times the fundamental frequency. Therefore, the sixth-order resonant filter based on the cascading of 1 / 4-wavelength SIR resonant units has an ultra-wide stopband characteristic. As Figure 14 can be seen, this filter has a parasitic passband near 55 GHz, and the frequency of this parasitic passband is three times the center frequency, which conforms to the design theory.

[0070] Combined with the above embodiments, it can be known that the thin-film filter 20 provided in the embodiments of the present application and including the filter unit 10 has at least the following characteristics:

[0071] First, the filter unit 10 is composed of 1 / 4-wavelength SIR resonant units arranged in a comb shape, reducing the overall size of the filter.

[0072] Second, the thin-film filter 20 using this filter unit 10 has an ultra-wide stopband bandwidth and no parasitic passband exists in the frequency range of 0 - 54 GHz, which is three times the center frequency.

[0073] Third, there are two transmission zeros on each side of the passband, very close to the passband, improving the frequency selectivity of the filter.

[0074] Fourth, the input electrode 271, the output electrode 272, and the ground electrode 273 are designed such that electrode structures are provided on the upper and lower surfaces and the side surfaces of the thin film filter 20 at the input and output ports, eliminating the need for wire bonding and making it easy to use.

[0075] Fifth, it has a completely enclosed structure, reducing radiation loss and interference with other circuits.

[0076] Sixth, the circuit structure is simple, easy to expand, without a bridging structure, and easy to process and manufacture.

[0077] On the other hand, an embodiment of the present application further provides a radio frequency transceiver system, including the thin film filter 20 of any embodiment of the present application.

[0078] Please refer to Figure 15 , on the other hand, an embodiment of the present application further provides a method for manufacturing a thin film filter 20, including the following steps:

[0079] Step A: Provide a first wafer, prepare an intermediate metal layer on the first surface of the first wafer, prepare a first metal layer on the second surface of the first wafer, and prepare metallized vias.

[0080] Step B: Provide a second wafer, prepare a second metal layer on one of the surfaces of the second wafer, and prepare metallized vias;

[0081] Step C: Bond the first wafer and the second wafer, and the other surface of the second wafer away from the second metal layer contacts the intermediate metal layer of the first wafer.

[0082] Among them, Step A includes:

[0083] S1. Polish and clean.

[0084] As Figure 15 , first take a wafer, that is, the first wafer, polish and clean it to make the wafer surface clean and flat and reach the required thickness; among them, the cleaning process can use inorganic cleaning, organic cleaning, plasma cleaning and other methods to remove particles, metals, organic substances and other stains on the wafer surface. In the subsequent wafer processing processes, the cleaning process will be used multiple times for cleaning, and this will not be elaborated here.

[0085] Send the wafer that has been thinned and cleaned to the yellow light room. First, accurately make the circuit pattern of the first part corresponding to the intermediate metal layer on the first surface, apply HMDS (hexamethyldisilazane) on the first surface, and bake it in an environment of heating (200 - 250 °C) and pressurization to keep it dry and form hydrophobicity, improving the adhesion between the photoresist and the silicon wafer.

[0086] S2, Glue Coating and Pre-baking: After forming the bottom film by vapor deposition using HMDS coating, glue is coated on the first surface. A spin coater is used to evenly spin-coat the photoresist on the wafer, and then the wafer with the coated photoresist is transferred to a hot plate for pre-baking to improve the adhesion of the photoresist.

[0087] S3, Exposure and Post-baking: In step S3, first, the circuit pattern of the intermediate metal layer is transferred to a mask, and then the mask is placed in a lithography machine. Under the action of the lithography machine, ultraviolet light will pass through the part of the mask with the circuit, so that the photoacid generator in the photoresist will react with the protecting group in the resin.

[0088] S4, Development and Hard-baking: The exposed wafer is placed in a developer. The photoresist irradiated by the lithography machine will be decomposed when it encounters the developer, thus transferring the circuit pattern on the mask to the wafer. Among them, the circuit pattern on the mask corresponds to the pattern on the intermediate metal layer, which can be the same as or complementary to the pattern on the intermediate metal layer.

[0089] S5, Metal Electroplating: After step S3, metal thin film growth can be carried out at the position developed by the photoresist. Since metals with good conductivity have poor adhesion on the dielectric, it is necessary to sputter a metal seed layer on the wafer, using metals such as titanium and titanium tungsten as the adhesion layer, then attach a thin gold layer, and electroplate to thicken it.

[0090] S6, Resist Removal: After metal electroplating, cleaning is carried out to remove the photoresist.

[0091] S7, ICP Deep Silicon Etching: The same lithography scheme is used to etch the periodically arranged metallized vias. In this embodiment, based on the second surface of the wafer, after sequentially completing the processes of glue coating, pre-baking, exposure, development, and hard-baking, ICP etching of the vias is carried out based on the via positions determined by development; first, use C 4 F 8 gas to fill the reaction chamber. C 4 F 8 will be decomposed into CF 2 , active groups, and F ions. CF 2 will form a passivation layer on the sidewalls of the etched vias to prevent further lateral etching of the sidewalls. Then, SF6 gas is introduced into the reaction chamber to etch the vertical direction of the vias. The above two steps are cycled to etch layer by layer downward, so as to ensure the uniformity of the aspect ratio and shape of the vias.

[0092] S8, Resist Removal: After step S7, next, the cleaning process is again used to remove the photoresist and sputter the metal seed layer.

[0093] S9, Metal Electroplating: Electroplating is carried out to metallize the sidewalls of the vias.

[0094] S10. Etching of the first metal layer; At this time, on the other side opposite to the intermediate metal layer, that is, the second surface of the first wafer is entirely covered with a metal thin film, which needs to be etched to form the first metal layer. The same processes such as spin coating, pre-baking, exposure, development, and hard baking are carried out on it, and etching cleaning is performed to form the circuit pattern corresponding to the first metal layer.

[0095] S11. Removing the photoresist; Through the above process flow, the processing of the first wafer is achieved.

[0096] Step B includes:

[0097] S12. Polishing and cleaning; Similarly, select a wafer, that is, the second wafer, and perform polishing and cleaning on it.

[0098] S13. ICP deep silicon etching; After sequentially completing the processes of spin coating, pre-baking, exposure, development, and hard baking, directly perform ICP etching of the through holes.

[0099] S14. Removing the photoresist; Cleaning the photoresist.

[0100] S15. Metal electroplating; Electroplating is carried out to metallize the side walls of the through holes.

[0101] S16. Etching of the second metal layer; Next, etch the metal pattern of the second metal layer. Based on the second surface of the second wafer, perform the same processes such as spin coating, pre-baking, exposure, development, and hard baking on it, and perform etching cleaning to form the circuit pattern of the second metal layer.

[0102] S17. Removing the photoresist; Through the above process flow, the processing of the second wafer is achieved.

[0103] Step C includes:

[0104] S18. Bonding; After processing the circuit patterns on the first wafer and the second wafer, perform bonding and dicing to complete the process manufacturing of the entire thin film filter.

[0105] The first surface of the first wafer and the first surface of the second wafer are arranged facing each other and are bonded to each other. Bond the first wafer and the second wafer. Among them, in the two orthogonal XY directions of the first surface, the X direction is parallel to the electrode, and the dicing lane can be arranged at the corresponding position of the through hole, for example, in the middle of the through hole, which can be used as the input and output electrodes correspondingly; the Y direction is perpendicular to the electrode of the filtering unit, and the dicing lane is located between two through holes.

[0106] In the method for preparing the thin film filter 20 provided in the above embodiment, in step A, the preparation of the first metal layer on the first wafer is completed by transferring the overall circuit pattern formed by the first part and the second part of the intermediate metal layer to the first wafer using a mask plate.

[0107] Optionally, in some other embodiments, it may also be to transfer the circuit pattern of the first part of the intermediate metal layer to the first wafer through step A respectively, and transfer the circuit pattern of the second part of the intermediate metal layer to the second wafer through step B. Correspondingly, the preparation method of the thin film filter 20 includes:

[0108] Step A: Provide a first wafer, prepare the first part of the intermediate metal layer on the first surface of the first wafer, prepare a first metal layer on the second surface of the first wafer, and prepare metallized vias.

[0109] Step B: Provide a second wafer, prepare the second part of the intermediate metal layer on the first surface of the second wafer, prepare a second metal layer on the second surface of the second wafer, and prepare metallized vias.

[0110] Step C: Bond the first wafer and the second wafer, and the first surface of the first wafer is in contact with the first surface of the second wafer.

[0111] In the above embodiments, at this time, S4 can be adjusted to first transfer the pattern of the first part of the intermediate metal layer to the first wafer through a mask; and S15 and S16 are adjusted to first perform via etching and then combine electroplating process and etching process on the two surfaces of the second wafer to obtain the pattern of the second part of the intermediate metal layer and the pattern of the second metal layer. It should be noted that in this embodiment, the preparation method of separately fabricating the first part and the second part of the intermediate metal layer on the first wafer and the second wafer should also fall within the protection scope of the present application.

[0112] It should be noted that in this article, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of additional identical elements in the process, method, article or device including that element.

[0113] The above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of changes or substitutions, which should all be covered by the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A filtering unit, characterized in that: It comprises a plurality of resonance units; the plurality of resonance units are arranged parallel to each other and spaced apart from each other; Each of the resonant units includes a high-impedance stripline and a low-impedance stripline connected to each other. Adjacent resonant units are spaced apart from each other at one end where the low-impedance stripline is provided to form an open-circuit end, and are connected at one end where the high-impedance stripline is provided to form a short-circuit end. The end of the high-impedance stripline away from the low-impedance stripline is connected to the same metal, and the connection is in a stepped shape.

2. The filter unit according to claim 1, characterized in that One end of the high impedance strip line connected to the low impedance strip line is located on the same straight line; In different resonant units, at least two of the high-impedance strip lines have different lengths.

3. The filter unit according to claim 2, characterized in that The adjacent resonance units include a first resonance unit and a second resonance unit, the length of the high-impedance strip line is l1, the width is w1, and the interval between the high-impedance strip lines of the first resonance unit and the second resonance unit is s1; the length of the low-impedance strip line is l2, the width is w2, and the interval between the low-impedance strip lines of the first resonance unit and the second resonance unit is s2; The first resonant unit and the second resonant unit are different in at least one of the following: the length l1 is different, the width w1 is different, the interval s1 is different, the length l2 is different, the width w2 is different, and the interval s2 is different.

4. The filter unit according to claim 3, characterized in that The location of the transmission zero of the filter unit Determined based on the following formula: Among them, Ec refers to the electric coupling coefficient, Mc refers to the magnetic coupling coefficient, and g refers to the frequency-dependent coupling coefficient of the filter. It refers to the resonance frequency of the first resonance unit, which is related to the length l1 and the width w1 of the first resonance unit; It refers to the resonance frequency of the second resonance unit, which is related to the length l2 and the width w2 of the second resonance unit.

5. A thin film filter, characterized in that: It includes a first metal layer, a first dielectric layer, an intermediate metal layer, a second dielectric layer and a second metal layer which are stacked in sequence; The intermediate metal layer is divided into a first part and a second part which are spaced apart from each other, and the first part is provided with a filter unit as claimed in any one of claims 1 to 4.

6. The thin film filter according to claim 5, characterized in that: The thin film filter is provided with a plurality of through holes, each of which penetrates the first metal layer, the first dielectric layer, the intermediate metal layer, the second dielectric layer and the second metal layer, and the through holes are arranged in an annular manner and surround to form a shielding cavity.

7. The thin film filter according to claim 6, characterized in that: The thin film filter comprises coupling windows arranged on two opposite sides, and an input electrode and an output electrode located in the coupling windows; The coupling window is located on opposite sides of the filter unit, and the two outermost resonance units of the filter unit are respectively connected to the input ohmic stripline and the output ohmic stripline, and the input ohmic stripline and the output ohmic stripline are respectively connected to the high-impedance stripline of the corresponding resonance unit, and are passed through the coupling window on the corresponding side and connected to the input electrode and the output electrode accordingly.

8. The thin film filter according to claim 7, characterized in that: The thin film filter further comprises a plurality of ground electrodes, wherein the ground electrodes are respectively located on opposite sides of the corresponding input electrode and the output electrode to form a radio frequency connection structure of GSG; and / or, Feeding electrode windows are provided on opposite sides of the filter unit and between two adjacent through holes, and the size of the feeding electrode windows is set so that the input ohmic stripline and the output ohmic stripline have a 50 ohm impedance characteristic; and / or, A feeding electrode switching structure is provided at the connection point between the input ohmic stripline and the input electrode, and at the connection point between the output ohmic stripline and the output electrode.

9. The thin film filter according to claim 7, characterized in that: The input electrode and the output electrode are respectively arranged along the stacking direction to penetrate the thin film filter, and connect the first metal layer, the second metal layer, the input ohmic stripline and the output ohmic stripline.

10. A radio frequency transceiver system, characterized in that: The method comprises the thin film filter according to any one of claims 5 to 9.

11. A method for preparing a thin film filter, characterized in that: include: Providing a first wafer, preparing an intermediate metal layer on a first surface of the first wafer, the intermediate metal layer comprising a filter unit according to any one of claims 1 to 4, preparing a first metal layer on a second surface of the first wafer, and preparing a metallized through hole; Providing a second wafer, preparing a second metal layer on one surface of the second wafer, and preparing a metallized through hole; The first wafer and the second wafer are bonded together, and another surface of the second wafer away from the second metal layer is in contact with the middle metal layer of the first wafer.

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