Coaxial lumped capacitor structure, high-pass filter and continuous duplexer

Abstract

The invention discloses a coaxial lumped capacitor structure, a high-pass filter and a continuous duplexer, and belongs to the technical field of microwave measurement. The coaxial lumped capacitor structure comprises a parallel-plate-like capacitor structure, an upper conductor, a lower conductor and an outer conductor, the parallel-plate-like capacitor structure, the upper conductor and the lower conductor jointly form an inner conductor and are arranged in the outer conductor, and the parallel-plate-like capacitor structure adopts a metal-medium-metal laminated structure; two ends of the parallel-plate-like capacitor structure are respectively connected with the upper conductor and the lower conductor. The capacitance value can be adjusted by changing the area of the similar parallel plate capacitor structure; the invention further provides a high-pass filter and a continuous duplexer based on the coaxial lumped capacitor structure, the problem that a series capacitor structure cannot be realized in a filter in a coaxial transmission line form by using open-circuit or short-circuit branches which are connected in series and in parallel is solved, and the coaxial lumped capacitor structure is easy to integrate with various active and passive devices based on the design of an additive manufacturing technology. The method can be applied to a broadband probe and a broadband vector network analyzer.

Description

Technical Field

[0001] The invention belongs to the technical field of communication equipment measurement, and in particular relates to a coaxial lumped capacitor structure, a high-pass filter and a continuous duplexer. Background Art

[0002] With the rapid development of 5G and IoT technologies, wireless communication systems and sensor systems play an important role and require wider operating bandwidths. Therefore, systems and high-performance devices in the microwave and millimeter wave frequency range play a key role. At millimeter wave frequencies, on-chip measurements of passive and active circuits (such as millimeter wave integrated circuits) require the use of vector network analyzers, frequency extension modules, and on-chip measurement probes. The waveguide or coaxial cable connecting the probe to the extension module, as well as the measurement equipment itself, are the main limiting factors for the measurement bandwidth.

[0003] In order to fully acquire data within the required frequency range, on-chip measurements of millimeter-wave devices and circuits typically require multiple measurement setups with different frequency bands. This approach requires reconfiguring the probes and repeating the warm-up and calibration process. In addition, different probes are required for each band, and the calibration methods and substrates used may also be different. Repeated measurements increase the contact of the probes with the device under test (DUT) and the calibration sheet, resulting in additional wear on the pads and changes in the probe contact position. Therefore, the frequency-band measurement method is not only time-consuming, but also produces additional errors, uncertainties, and discontinuities in the measurement, while also increasing the wear on the DUT.

[0004] To solve this problem, one solution is to develop an ultra-wideband vector network analyzer, in which frequency synthesis is performed through a directional coupler or a broadband continuous duplexer. Another solution is to integrate a broadband continuous duplexer and an on-chip probe, combined with traditional frequency-dividing measurement equipment, so that signals of two different frequency bands can be input into the duplexer together, and the duplexer outputs a broadband signal to the tip of the GSG probe. Therefore, broadband continuous duplexers play an important role in ultra-wideband test systems.

[0005] However, most of the duplexers reported in the public literature have low operating frequencies, narrow bandwidths or discontinuous frequency bands. The Chinese patent with publication number: CN117766963A provides a duplexer design with broadband spectrum continuity based on microstrip lines. The invention uses a high-low impedance microstrip line structure as a low-pass filter, and a double-layer metal coupling structure and a microstrip-waveguide transition structure as a high-pass filter. Through the double-layer metal coupling circuit and the high-impedance branch, the decoupling effect between the high-pass filter and the low-pass filter is improved to form a complementary filter, thereby realizing a broadband continuous duplexer. However, the stopband suppression effect of the low-pass filter in the invention is poor, and the steep drop characteristics of the filter response curve are poor; in addition, there is a transition from non-standard waveguide to standard waveguide in the high-pass filter, which causes inconvenience in processing, and the non-standard waveguide end face makes it difficult to directly integrate the chip with other devices, and it is impossible to truly realize a miniaturized ultra-wideband measurement system. Coaxial transmission lines have the advantages of broadband, low loss, compact structure, small size, and easy interconnection with other types of chips. Therefore, the present invention provides a coaxial lumped capacitor structure, and the design of a high-pass filter and a continuous duplexer. Summary of the invention

[0006] In order to solve the problems existing in the prior art, the present invention provides a coaxial lumped capacitor structure that can be used in high-pass filters and continuous duplexers. The coaxial lumped capacitor structure is designed based on additive manufacturing technology, aiming to achieve high-pass filters and broadband continuous duplexers with excellent electrical performance, easy integration with various active and passive devices, low manufacturing cost, and suitable for wide application.

[0007] In order to achieve the above-mentioned objectives, in a first aspect, the present invention provides a coaxial lumped capacitor structure, including a quasi-parallel plate capacitor structure, an upper conductor, a lower conductor and an outer conductor. The quasi-parallel plate capacitor structure, the upper conductor and the lower conductor together constitute an inner conductor, which is arranged in the outer conductor. The quasi-parallel plate capacitor structure adopts a metal-dielectric-metal stacked arrangement structure, and the upper conductor and the lower conductor are connected to the two ends of the quasi-parallel plate capacitor structure respectively.

[0008] Furthermore, based on the additive manufacturing process, it includes a five-layer structure, the parallel plate capacitor structure is located on the third layer, the outer conductor is located on the first to fifth layers, the third layer is divided into three layers, the dielectric in the parallel plate capacitor structure is located on the 3-2 layer, the metal is located on the 3-1 layer and the 3-3 layer, the upper conductor is located on the 3-3 layer, and the lower conductor is located on the 3-1 layer, and the area of ​​the parallel plate capacitor structure is proportional to the capacitance value.

[0009] Furthermore, there are multiple periodically arranged strip-structured dielectrics between the outer conductor and the inner conductor, located in the 3-2 layer, for supporting the suspended inner conductor. The dielectric in the parallel plate capacitor-like structure is the same as the dielectric in the strip-structure.

[0010] Furthermore, a dielectric is arranged in a lower layer of the upper conductor located at layer 3-3, and a dielectric is arranged in an upper layer of the lower conductor located at layer 3-1.

[0011] In a second aspect, the present invention provides a high-pass filter based on a coaxial lumped capacitor structure, comprising a first-order resonator, a second-order resonator, a third-order resonator, a fourth-order resonator and a fifth-order resonator connected in sequence; the first-order resonator, the third-order resonator and the fifth-order resonator all adopt the above-mentioned coaxial lumped capacitor structure to realize the series capacitor in the high-pass filter prototype, and the second-order resonator and the fourth-order resonator all adopt short-circuit stubs to replace the parallel inductor in the high-pass filter prototype.

[0012] Furthermore, the second-order resonator and the fourth-order resonator respectively include two identical short-circuit branches symmetrically arranged along the axis direction of the inner conductor, which is equivalent to connecting the two short-circuit branches in parallel and doubling the impedance value of the short-circuit branches.

[0013] Further, the width of the short-circuit branch of the second resonator is smaller than the width of the short-circuit branch of the fourth resonator, and the length of the short-circuit branch of the second resonator is smaller than the length of the short-circuit branch of the fourth resonator.

[0014] Furthermore, the overlapping length of the upper and lower metal layers in the parallel plate capacitor structure used in the first resonator, the overlapping length of the upper and lower metal layers in the parallel plate capacitor structure in the fifth resonator, and the overlapping length of the upper and lower metal layers in the parallel plate capacitor structure in the third resonator decreases successively.

[0015] In a third aspect, the present invention provides a continuous duplexer based on a coaxial lumped capacitor structure, comprising a low-frequency output transmission line segment, a high-frequency output transmission line segment, a common input transmission line segment, a low-pass filter and a high-pass filter; two ends of the common input transmission line segment are respectively connected to an input end of the low-pass filter and an input end of the high-pass filter, the low-frequency output transmission line segment is connected to an output end of the low-pass filter, and the high-frequency output transmission line segment is connected to an output end of the high-pass filter; The high-pass filter adopts the above-mentioned high-pass filter structure; The low-pass filter is based on a T-shaped SIR branch-loaded structure, including a first resonator to a fifth resonator connected in sequence, the first resonator, the third resonator and the fifth resonator use a high-impedance transmission line, and the second resonator and the fourth resonator use a branch-loaded structure instead of a low-impedance transmission line.

[0016] Furthermore, the cross section of the loading branch of the second-order resonator in the low-pass filter along the width direction of the coaxial line remains unchanged, and the cross section of the loading branch of the fourth-order resonator along the width direction of the coaxial line changes in two steps.

[0017] Compared with the prior art, the present invention has at least the following beneficial effects: the present invention innovatively realizes a lumped capacitor structure in a coaxial transmission line, solving the problem that a series capacitor structure cannot be realized in a transmission line filter using series-parallel open-circuit or short-circuit branches.

[0018] Secondly, based on the coaxial lumped capacitor structure designed by the present invention, the present invention realizes a high-pass filter in the coaxial transmission line, which has a high operating frequency, a wide operating bandwidth, and a low loss, and has the potential for large-scale application.

[0019] Finally, the present invention realizes a broadband continuous duplexer based on a coaxial transmission line, which has lower loss, better electrical performance, smaller size, and is easy to integrate with various active and passive devices. At the same time, the low-pass filter in the duplexer adopts a T-type SIR branch loading structure, and the open-circuit branches can insert transmission zeros in the stop band of the filter, so that the low-pass filter has better stop band suppression performance. In short, the broadband continuous duplexer designed by the present invention can be actually applied to a miniaturized ultra-wideband on-chip / coaxial test system and is an important component thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the prior art solutions, the drawings used in the embodiments or the prior art solutions are briefly introduced below. It should be noted that the drawings described below are only some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without creative work.

[0021] FIG. 1( a ) is a schematic cross-sectional view of a rectangular coaxial line based on a three-dimensional metal micromachining process according to an embodiment of the present invention, and FIG. 1( b ) is a schematic three-dimensional structure view of a rectangular coaxial line based on a three-dimensional metal micromachining process according to an embodiment of the present invention; FIG2 (a) is a schematic diagram of a three-dimensional structure of a coaxial lumped capacitor structure provided in an embodiment of the present invention, FIG2 (b) is a side view of an inner conductor of the coaxial lumped capacitor structure, and FIG2 (c) is a top view of an inner conductor of a coaxial lumped capacitor structure provided in an embodiment of the present invention; Figure 3 A comparison between the simulation results of a coaxial lumped capacitor structure provided by an embodiment of the present invention and the simulation results of an ideal capacitor; FIG4(a) is an overall schematic diagram of a high-pass filter based on a coaxial lumped capacitor structure provided in an embodiment of the present invention, FIG4(b) is a schematic diagram of the internal structure of a high-pass filter based on a coaxial lumped capacitor structure provided in an embodiment of the present invention, FIG4(c) is a cross-sectional view of a high-pass filter based on a coaxial lumped capacitor structure provided in an embodiment of the present invention, and FIG4(d) is a side cross-sectional view of a high-pass filter based on a coaxial lumped capacitor structure provided in an embodiment of the present invention; Figure 5 The simulation results of a high-pass filter based on a coaxial lumped capacitor structure provided by an embodiment of the present invention; FIG6(a) is an overall schematic diagram of a continuous duplexer based on a coaxial lumped capacitor structure provided in an embodiment of the present invention, FIG6(b) is a schematic diagram of the internal structure of a continuous duplexer based on a coaxial lumped capacitor structure provided in an embodiment of the present invention, and FIG6(c) is a side cross-sectional view of a continuous duplexer based on a coaxial lumped capacitor structure provided in an embodiment of the present invention; FIG7(a) shows the simulation results of the return loss of the common input port, the insertion loss of the low-frequency output port, and the insertion loss of the high-frequency output port of the continuous duplexer based on the coaxial lumped capacitor structure. FIG7(b) shows the simulation results of the return loss of the low-frequency output port and the high-frequency output port of the continuous duplexer based on the coaxial lumped capacitor structure, as well as the isolation between the low-frequency output port and the high-frequency output port. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions 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. 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.

[0023] Embodiment 1, as shown in FIG. 1( a ), the inner conductor of the rectangular coaxial line is located in the third layer, and the outer conductor is located in the first to fifth layers. The thickness of the first and fifth layers is H 1 =0.05mm, the thickness of the second, third and fourth layers is H 2 =0.1mm, where the inner conductor of the third layer is divided into three layers, with thickness from bottom to top. H 3-1 =0.025mm, H 3-2 =0.025mm, H 3-3 =0.05mm. The width between the inner walls of the outer conductor is W 1=0.4mm, the width of the outer conductor side wall is W 2 =0.15mm, the width of the inner conductor is W 3 =0.176mm. In addition, there are multiple periodically arranged strip-shaped dielectrics between the inner and outer conductors, located in the 3-2 layer, which are used to support the suspended coaxial inner conductor. Figure 1(b) shows the three-dimensional structure of the rectangular coaxial line. There are periodically distributed release holes on the outer conductor, with four release holes opened every 0.7mm to facilitate the subsequent washing of excess photoresist.

[0024] Embodiment 2 is a schematic diagram of the three-dimensional structure of a coaxial lumped capacitor structure, FIG2(b) is a side view of the inner conductor of the coaxial lumped capacitor structure provided by an embodiment of the present invention, and FIG2(c) is a top view of the inner conductor of the coaxial lumped capacitor structure provided by an embodiment of the present invention.

[0025] A coaxial lumped capacitor structure designed by the present invention includes a metal-dielectric-metal vertically arranged quasi-parallel plate capacitor structure 11, an upper conductor 12, a lower conductor 13 and an outer conductor 14, as shown in FIG2(a). FIG2(b) shows a side view of the inner conductor of the coaxial lumped capacitor structure, wherein the length of the overlapped portion of the upper and lower metal layers in the quasi-parallel plate capacitor structure 11 is L 1 =0.07mm, the lengths of the upper conductor 12 and the lower conductor 13 are both L 2 =0.07mm. The upper and lower metal layers in the quasi-parallel plate capacitor structure 11 are located at the 3-3 layer and the 3-1 layer, respectively, and the dielectric is located at the 3-2 layer. The upper conductor 12 and the lower conductor 13 are located at the 3-3 layer and the 3-1 layer, respectively. In addition to the dielectric in the quasi-parallel plate capacitor structure 11, the lower layer 3-2 of the upper conductor 12 is also arranged with a dielectric, which will generate parasitic capacitance and increase the realized capacitance value. Similarly, the upper layer 3-2 of the lower conductor 13 can also be arranged with a dielectric to further increase the realized capacitance value. Figure 2(c) is a top view of the inner conductor of the coaxial lumped capacitor structure. The width of the inner conductor of the quasi-parallel plate capacitor structure 11 is W 4 =0.176mm, and the width of the upper conductor 12 and the lower conductor 13 on both sides is W 5 =0.26mm, the inner conductor width of the parallel plate capacitor structure 11 is different from the width of the upper conductor 12 and the lower conductor 13 on both sides, which can increase discontinuity in the signal transmission path, introduce new parasitic inductance and parasitic capacitance to the structure, so that the capacitor structure can exhibit similar characteristics to an ideal capacitor in a wider frequency band.

[0026] Figure 3The simulation results of a coaxial lumped capacitor structure provided in an embodiment of the present invention are compared with the simulation results of an ideal capacitor, showing the return loss and insertion loss of the coaxial lumped capacitor structure, and compared with the return loss and insertion loss of the ideal capacitor. It can be seen that in the frequency range of about DC-300GHz, the performance of the designed capacitor structure is highly consistent with that of the ideal capacitor.

[0027] Embodiment 3, Figure 4 (a) is an overall schematic diagram of a high-pass filter based on a coaxial lumped capacitor structure provided in an embodiment of the present invention, Figure 4 (b) is a schematic diagram of the internal structure of a high-pass filter based on a coaxial lumped capacitor structure provided in an embodiment of the present invention, Figure 4 (c) is a cross-sectional view of a high-pass filter based on a coaxial lumped capacitor structure provided in an embodiment of the present invention, and Figure 4 (d) is a side cross-sectional view of a high-pass filter based on a coaxial lumped capacitor structure provided in an embodiment of the present invention.

[0028] As shown in Fig. 4(a) and Fig. 4(b), the high-pass filter includes five orders of resonators connected in sequence. The first-order resonator 21, the third-order resonator 23 and the fifth-order resonator 25 all use a coaxial lumped capacitor structure to realize the series capacitor in the high-pass filter prototype. The second-order resonator 22 and the fourth-order resonator 24 both use short-circuit branches to replace the parallel inductance in the high-pass filter prototype. The short-circuit branches used by the second-order resonator 22 and the fourth-order resonator 24 are processed in parallel, that is, the second-order resonator 22 and the fourth-order resonator 24 respectively include two identical short-circuit branches arranged symmetrically along the axis direction of the inner conductor, doubling the impedance value of the short-circuit branches, reducing the inner conductor width of the short-circuit branches, and reducing the possibility of short circuit caused by the small distance between the inner conductor and the outer conductor during the processing. At the same time, it also enhances the support strength of the entire high-pass filter structure. Fig. 4(c) is a cross-sectional view of the high-pass filter. The width of one of the short-circuit branches of the second-order resonator 22 is W 6 =0.089mm, length L 3 =0.798mm, the two short-circuit branches of the second-order resonator 22 have the same size; the width of one of the short-circuit branches of the fourth-order resonator 24 is W 7 =0.124mm, length L 4 =0.865mm, and the two short-circuit branches of the fourth-order resonator 24 have the same size. The first-order resonator 21 of the high-pass filter is connected to the external input coaxial line, and the fifth-order resonator 25 is connected to the external output coaxial line. The inner conductor width of the input coaxial line and the output coaxial line is W 8=0.176mm, the impedance is 50 ohms. Figure 4(d) is a side view of the inner conductor of the high-pass filter, the overlapping length of the upper and lower metal layers in the parallel plate capacitor structure 11 used in the first-order resonator 21 L 5 =0.367mm, the overlapping length of the upper and lower metal layers in the parallel plate capacitor structure 11 in the third-order resonator 23 L 6 =0.161mm, the overlapping length of the upper and lower metal layers in the parallel plate capacitor structure 11 in the fifth-order resonator 25 L 7 =0.36mm.

[0029] Figure 5 The simulation results of a high-pass filter based on a coaxial lumped capacitor structure provided in an embodiment of the present invention include return loss and insertion loss. It can be seen that the return loss is greater than 20dB in the frequency range of 40GHz to 110GHz, and the insertion loss is between 0.74dB and 1.4dB, which has good performance.

[0030] Embodiment 4, Figure 6 (a) is an overall schematic diagram of a continuous duplexer based on a coaxial lumped capacitor structure provided in an embodiment of the present invention, Figure 6 (b) is a schematic diagram of the internal structure of a continuous duplexer based on a coaxial lumped capacitor structure provided in an embodiment of the present invention, and Figure 6 (c) is a side sectional view of a continuous duplexer based on a coaxial lumped capacitor structure provided in an embodiment of the present invention.

[0031] The duplexer includes a low-frequency output transmission line segment 31, a high-frequency output transmission line segment 32, a common input transmission line segment 33, a low-pass filter 34 and a high-pass filter 35, wherein the common input transmission line segment 33 is perpendicular to the length direction of the coaxial line. The two ends of the common input transmission line segment 33 are respectively connected to the input end of the low-pass filter 34 and the input end of the high-pass filter 35, the low-frequency output transmission line segment 31 is connected to the output end of the low-pass filter 34, and the high-frequency output transmission line segment 32 is connected to the output end of the high-pass filter 35. The high-pass filter 35 is a high-pass filter structure of the above embodiment. The low-pass filter 34 is improved in the form of a traditional high-low impedance filter, and adopts a structure based on T-shaped SIR branch loading, including a first-order resonator to a fifth-order resonator connected in sequence, the first-order resonator, the third-order resonator and the fifth-order resonator still use a high-impedance transmission line, and the second-order resonator and the fourth-order resonator use a T-type ladder impedance loading branch structure to replace the low-impedance transmission line, and multiple transmission zeros can be inserted to improve the stopband suppression level. The cross section of the loading branch of the second-order resonator along the width direction of the coaxial line remains unchanged, and the cross section of the loading branch of the fourth-order resonator along the width direction of the coaxial line changes in two steps. The second-order resonator can introduce a transmission zero at 80GHz, and the fourth-order resonator can introduce a transmission zero at 130GHz, thereby improving the steep drop characteristics of the low-pass filter response curve. The impedance of the low-frequency output transmission line segment 31, the high-frequency output transmission line segment 32 and the common input transmission line segment 33 are all 50 ohms. The end of the common input transmission line segment 33 has a triangular guide angle, so that it can better transition with the low-pass filter 34 and the high-pass filter 35, reducing the reflection at the end of the common input transmission line segment 33. The low-pass filter 34 and the high-pass filter 35 are complementary filters when designed, so the duplexer can achieve ultra-wideband frequency continuous splicing.

[0032] FIG. 7( a ) shows the return loss of a common input port of a continuous duplexer based on a coaxial lumped capacitor structure provided by an embodiment of the present invention. S 33 ), insertion loss of low frequency output port ( S 13 ) and the insertion loss of the high frequency output port ( S 23 ), FIG7(b) shows the return losses of the low-frequency output port and the high-frequency output port of a continuous duplexer based on a coaxial lumped capacitor structure provided by an embodiment of the present invention, which are respectively S 11 and S 22 , and isolation between the low-frequency output port and the high-frequency output port ( S 12), it can be seen that the duplexer has two spectrally continuous channels, the low-frequency output signal range is DC-68GHz, and the high-frequency output signal range is 68-110GHz. In the DC-110GHz frequency band, the return loss of the common input port of the duplexer is better than 18dB, and the insertion loss of the low-frequency output port and the high-frequency output port cross at 68GHz, and the amplitude of the crossing point is about 3dB.

[0033] In summary, the present invention provides a coaxial lumped capacitor structure, which includes a quasi-parallel plate capacitor structure, an upper conductor, a lower conductor and an outer conductor. The quasi-parallel plate capacitor structure, the upper conductor and the lower conductor together constitute an inner conductor, which is arranged in the outer conductor. The quasi-parallel plate capacitor structure adopts a metal-dielectric-metal stacking arrangement structure; the upper conductor and the lower conductor are connected to the quasi-parallel plate capacitor structure at both ends. The capacitance value can be adjusted by changing the area of ​​the quasi-parallel plate capacitor structure; it is easy to integrate with various active and passive devices based on the additive manufacturing technology design. The present invention also provides a high-pass filter and a continuous duplexer based on the coaxial lumped capacitor structure, which solves the problem that the series capacitor structure cannot be realized in the filter in the form of a coaxial transmission line with open or short-circuited branches in series and parallel, and can be applied to wide-band probes and wide-band vector network analyzers.

[0034] The above is a description of a coaxial lumped capacitor structure provided by the present invention and its application in a high-pass filter and a duplexer. For those skilled in the art, according to the idea of ​​the embodiments of the present invention, there may be changes in the specific implementation and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A coaxial lumped capacitor structure, characterized in that: The invention comprises a quasi-parallel plate capacitor structure (11), an upper conductor (12), a lower conductor (13) and an outer conductor (14); the quasi-parallel plate capacitor structure (11), the upper conductor (12) and the lower conductor (13) together form an inner conductor which is arranged in the outer conductor (14); the quasi-parallel plate capacitor structure (11) adopts a metal-dielectric-metal stacking arrangement structure; and the two ends of the quasi-parallel plate capacitor structure (11) are respectively connected to the upper conductor (12) and the lower conductor (13).

2. The coaxial lumped capacitor structure according to claim 1, characterized in that: Based on the additive manufacturing process, the structure comprises five layers, the parallel plate capacitor structure (11) is located in the third layer, the outer conductor is located in the first to fifth layers, the third layer is divided into three layers, the dielectric in the parallel plate capacitor structure (11) is located in the 3-2 layer, the metal is located in the 3-1 layer and the 3-3 layer, the upper conductor (12) is located in the 3-3 layer, and the lower conductor (13) is located in the 3-1 layer. The area of ​​the parallel plate capacitor structure (11) is proportional to the capacitance value.

3. The coaxial lumped capacitor structure according to claim 2, characterized in that: There are multiple periodically arranged strip-shaped dielectrics between the outer conductor (14) and the inner conductor, located in the 3-2 layer, and used to support the suspended inner conductor. The dielectric in the parallel plate capacitor-like structure (11) is the same as the dielectric in the strip-shaped structure.

4. The coaxial lumped capacitor structure according to claim 2, characterized in that: A dielectric is arranged in a lower layer of the upper conductor (12) located at the 3-3 layer, and a dielectric is arranged in an upper layer of the lower conductor (13) located at the 3-1 layer.

5. A high-pass filter based on a coaxial lumped capacitor structure, characterized in that: The invention comprises a first-order resonator (21), a second-order resonator (22), a third-order resonator (23), a fourth-order resonator (24) and a fifth-order resonator (25) which are connected in sequence; the first-order resonator (21), the third-order resonator (23) and the fifth-order resonator (25) all adopt the coaxial lumped capacitor structure described in any one of claims 1 to 5, the second-order resonator (22) and the fourth-order resonator (24) all adopt short-circuit branches to replace parallel inductors, and the second-order resonator (22) and the fourth-order resonator (24) adopt short-circuit branches in parallel.

6. The high-pass filter based on the coaxial lumped capacitor structure according to claim 5, characterized in that: The second-order resonator (22) and the fourth-order resonator (24) respectively include two identical short-circuit branches symmetrically arranged along the axis direction of the inner conductor, doubling the impedance value of the short-circuit branches.

7. The high-pass filter based on the coaxial lumped capacitor structure according to claim 5, characterized in that: The width of the short-circuit branch of the second resonator (22) is smaller than the width of the short-circuit branch of the fourth resonator (27), and the length of the short-circuit branch of the second resonator (22) is smaller than the length of the short-circuit branch of the fourth resonator (27).

8. The high-pass filter based on the coaxial lumped capacitor structure according to claim 5, characterized in that: The overlapping length of the upper and lower metal layers in the quasi-parallel plate capacitor structure (11) used in the first resonator (21), the overlapping length of the upper and lower metal layers in the quasi-parallel plate capacitor structure (11) in the fifth resonator (25), and the overlapping length of the upper and lower metal layers in the quasi-parallel plate capacitor structure (11) in the third resonator (23) decrease in sequence.

9. A continuous duplexer based on a coaxial lumped capacitor structure, characterized in that: It comprises a low-frequency output transmission line segment (31), a high-frequency output transmission line segment (32), a common input transmission line segment (33), a low-pass filter (34) and a high-pass filter (35); two ends of the common input transmission line segment (33) are respectively connected to the input end of the low-pass filter (34) and the input end of the high-pass filter (35); the low-frequency output transmission line segment (31) is connected to the output end of the low-pass filter (34); and the high-frequency output transmission line segment (32) is connected to the output end of the high-pass filter (35); The high-pass filter (32) adopts the high-pass filter structure described in any one of claims 5 to 8; The low-pass filter (31) is based on a T-shaped SIR branch loading structure, comprising a first resonator to a fifth resonator connected in sequence, wherein the first resonator, the third resonator and the fifth resonator use a high-impedance transmission line, and the second resonator and the fourth resonator use a branch loading structure instead of a low-impedance transmission line.

10. The continuous duplexer based on the coaxial lumped capacitor structure according to claim 9, characterized in that: The cross section of the loading branch of the second-order resonator in the low-pass filter (34) along the width direction of the coaxial line remains unchanged, and the cross section of the loading branch of the fourth-order resonator along the width direction of the coaxial line changes in two steps.

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