Miniaturized low-loss LTCC millimeter wave band-pass filter

Abstract

A miniaturized low-loss LTCC millimeter wave band-pass filter disclosed by the present invention comprises a ceramic body and an outer electrode, the outer electrode is embedded at the outer side of the ceramic body, and the ceramic body comprises an LTCC dielectric substrate and an inner electrode embedded in the LTCC dielectric substrate. The inner electrode comprises a top layer metal sheet, a source end, a load end, a first resonator, a second resonator, a third resonator, a bottom layer metal sheet and grounding stand columns, the source end and the load end are arranged in a symmetrical structure and located below the top layer metal sheet, and the two ends of the two grounding stand columns are connected with the top layer metal sheet and the bottom layer metal sheet respectively; the first resonator and the third resonator are arranged in a symmetrical structure and are respectively located below the source end and the load end, one end of the first resonator and one end of the third resonator are respectively connected with the two grounding columns, the second resonator is located above the bottom layer metal sheet, and the filter has a wide stop-band suppression effect in a millimeter wave band. And the signal transmission efficiency is effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of LTCC filters, and in particular to a miniaturized low-loss LTCC millimeter-wave bandpass filter. Background Art

[0002] With the rapid development of wireless communication technology, millimeter wave communication technology has become a key technology in the fields of mobile communication and low-orbit satellite communication due to its rich spectrum resources and high data transmission rate. As a key component of the communication system, filters have strict requirements in millimeter wave systems. High-reliability equipment requires millimeter wave filters to have high performance, small size, and light weight. Among them, small size and low loss are important indicators of millimeter wave filters.

[0003] In the millimeter wave frequency band, distributed microstrip filters are easier to miniaturize than other structures. However, the microstrip filters currently used in communication systems are designed based on PCB (Printed Circuit Board) technology. Filters designed based on single-layer PCB board technology will result in a larger circuit area because the microstrip lines can only be designed on the same plane.

[0004] The performance of microstrip filters needs to be achieved through mutual coupling between microstrip lines. Traditional filters designed based on single-layer PCB board technology need to adjust the degree of coupling by changing the distance between adjacent transmission lines, and the transmission lines with smaller spacing make processing more difficult. In addition, the cross-coupling technology of the filter can introduce more transmission zeros to improve the passband and out-of-band performance. However, traditional filters designed based on single-layer PCB board technology need to add additional circuits when realizing cross-coupling, which will increase the filter loss.

[0005] The filter designed based on the multilayer PCB process can place the band lines on different layers, and the stacking method can greatly reduce the size of the filter. According to "Yunbo Rao; Huizhen Jenny Qian; Jie Zhou; Yuandan Dong; Xun Luo, Miniaturized 28-GHz packaged bandpass filter with high selectivity and wide stopband using multilayer PCB technology. IEEE Microwave and Wireless Components Letters, 32 (2022) 664-667", a bandpass filter packaged by multilayer PCB technology is proposed, which is conducive to the miniaturization of the filter. However, the PCB board used in the filter has large dielectric loss, and additional metal gaskets need to be added when designing through holes, which increases the insertion loss of the filter and affects the transmission efficiency of the signal. In addition, there are additional through-hole metal gaskets on the front and back sides of the filter, which are easy to connect with the inner electrode resonator and have high requirements for processing technology. In addition, the minimum line width of the inner electrode of the filter is 0.05mm, which has high requirements for processing accuracy and limited applicable packaging processes. Therefore, how to design a bandpass filter in the millimeter wave frequency band that meets the requirements of miniaturization, has low loss characteristics, and is easy to process and implement remains a technical challenge. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention proposes a miniaturized low-loss LTCC millimeter-wave bandpass filter to solve the technical problems of the traditional bandpass filter chip being large in size, difficult to process and having large insertion loss.

[0007] In order to solve the above technical problems, the technical solution of the present invention is:

[0008] A miniaturized low-loss LTCC millimeter-wave bandpass filter comprises a ceramic body and an external electrode, wherein the external electrode is embedded outside the ceramic body, the ceramic body comprises an LTCC ceramic dielectric matrix and an internal electrode embedded in the LTCC ceramic dielectric matrix, the internal electrode comprises a top metal sheet, a source end, a load end, a first resonator, a second resonator, a third resonator, a bottom metal sheet and a grounding column, the source end and the load end are symmetrically arranged and located below the top metal sheet, the source end and the load end are respectively connected to the external electrode through an input feed metal sheet and an output feed metal sheet, the two ends of the two grounding columns are respectively connected to the top metal sheet and the bottom metal sheet, the first resonator and the third resonator are symmetrically arranged and located below the source end and the load end, one end of the first resonator and the third resonator are respectively connected to two grounding columns, and the second resonator is located above the bottom metal sheet.

[0009] In the above technical solution, the first resonator and the third resonator are located below the source end and the load end, and are connected to the top metal sheet and the bottom metal sheet through metallized through holes without the need for additional gaskets. The two are mirror-symmetrical to form horizontal electrical coupling, and the first resonator forms a vertical electrical coupling with the load end.

[0010] The second resonator is located below the first resonator and the third resonator, and forms a vertical magnetic coupling with the first resonator and the third resonator.

[0011] Preferably, the first resonator and the third resonator are both quarter-wavelength stepped impedance resonators. The quarter-wavelength resonator can realize structural miniaturization due to its small size, and its resonance mode has only odd-order modes, thereby avoiding the excitation of the second harmonic.

[0012] Preferably, the second resonator is a half-wavelength stepped impedance resonator. The half-wavelength resonator and the quarter-wavelength resonator have different harmonic distributions, and the stopband suppression can be broadened by mutual suppression of harmonics.

[0013] Preferably, the dielectric constant of the LTCC ceramic dielectric matrix is ​​7.5 and the loss tangent is 0.002. The medium dielectric constant LTCC ceramic can reduce the size of the filter while ensuring low delay. The low loss tangent value can reduce the insertion loss of the filter.

[0014] Preferably, the external electrode includes an input electrode, an output electrode and a grounding electrode, the input electrode and the output electrode are symmetrically arranged on the left and right sides of the ceramic body, and the two grounding electrodes are symmetrically arranged on the front and back sides of the ceramic body, so that no additional grounding columns are required on the front and back sides.

[0015] Preferably, the source end is connected to the input electrode via an input feed metal sheet, and the load end is connected to the output electrode via an output feed metal sheet.

[0016] Preferably, the inner electrode further comprises a shielding unit symmetrically arranged on both sides of the source end and the load end.

[0017] In the above technical solution, the shielding unit is provided to shield the stray light, thereby improving the filtering effect of the filter.

[0018] Preferably, the shielding unit comprises a shielding column and three shielding metal layers, the top end of the shielding column is connected to the top metal sheet, the bottom end of the shielding column is connected to the bottom metal sheet, and the three shielding metal layers are installed on the shielding column from top to bottom.

[0019] In the above technical solution, the three shielding metal layers are symmetrically arranged on both sides of the feeding structure and the resonator, thereby forming a compact LTCC miniaturized filter structure.

[0020] Preferably, a grounding substrate is disposed on the bottom side of the LTCC ceramic dielectric substrate.

[0021] In the above technical solution, the grounding substrate is provided so as to be compatible with the PCB board and is more convenient to use.

[0022] Preferably, the outer electrode and the inner electrode are both made of silver.

[0023] The present invention has the following characteristics and beneficial effects:

[0024] The above technical solution is adopted, and the stepped impedance microstrip line is designed by a three-dimensional multilayer structure layout. Compared with the bandpass filter realized based on a single-layer PCB board, the area is small and the chip integration is improved. The coupled microstrip line resonator and the feeding structure are located in different structural layers, and the vertical coupling method is adopted to overcome the technical problem that the spacing between the coupled microstrip lines in the planar coupling method is small, which leads to high processing difficulty. More importantly, compared with the filter designed based on the multilayer PCB process, the millimeter wave filter designed based on the LTCC technology in this design has small dielectric loss of LTCC ceramic dielectric, and reduces additional through holes and does not require additional through hole metal gaskets when designing through holes, which will greatly reduce the insertion loss of the filter. At the same time, this design removes the extra through holes and metal gaskets on the edge, so that the terminal length of the input and output and resonator can be designed freely, and will not be connected to the metal sheet on the edge, which is easy to process. In terms of process, the requirements for the accuracy of the inner electrode line width are low, which is conducive to the application of the designed filter structure in different packaging processes. In addition, compared with the PCB process filter, the filter based on the LTCC process also has good temperature stability and mechanical reliability, enabling it to work stably in various environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0026] Figure 1 It is a schematic diagram of the outer surface structure of the LTCC millimeter wave bandpass filter of the present invention;

[0027] Figure 2 is an equivalent circuit diagram of the LTCC millimeter wave bandpass filter of the present invention;

[0028] Figure 3 It is a three-dimensional schematic diagram of a miniaturized low-loss LTCC millimeter-wave bandpass filter structure provided by the present invention;

[0029] Figure 4 It is a schematic top view of the source and load ends of the present invention;

[0030] Figure 5 is a schematic top view of the resonator 1 and the resonator 3 of the present invention;

[0031] Figure 6 is a schematic top view of a resonator 2 of the present invention;

[0032] Figure 7 1 is a diagram of the S11 simulation result of the LTCC millimeter-wave bandpass filter of the present invention;

[0033] Figure 8 1 is a diagram of the S21 simulation result of the LTCC millimeter-wave bandpass filter of the present invention;

[0034] Fig. 9 It is a three-dimensional schematic diagram of the structure of the LTCC millimeter wave bandpass filter loaded with a PCB test board of the present invention;

[0035] Fig.10 is a three-dimensional schematic diagram of a multi-layer PCB test board of the present invention;

[0036] Fig.11 This is a S11 simulation result diagram of the LTCC millimeter wave bandpass filter loaded with a PCB test board of the present invention;

[0037] Fig.12 It is a diagram of the S21 simulation results of the LTCC millimeter-wave bandpass filter loaded with a PCB test board according to the present invention.

[0038] In the figure, 1-ceramic body, 2-input electrode, 3-output electrode, 4-ground electrode;

[0039] 101-LTCC ceramic dielectric substrate, 102-top metal sheet, 103-input feed metal sheet, 104-output feed metal sheet, 105-source end, 106-load end, 107-first resonator, 108-third resonator, 109-second resonator, 110-bottom metal sheet, 111-ground substrate, 112-shielding column, 113-ground column. DETAILED DESCRIPTION

[0040] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0041] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings.

[0042] On the contrary, the present invention covers any substitution, modification, equivalent method and scheme made on the essence and scope of the present invention as defined by the claims. Further, in order to make the public have a better understanding of the present invention, some specific details are described in detail in the detailed description of the present invention below. Those skilled in the art can fully understand the present invention without the description of these details.

[0043] In order to solve the technical problems of large chip size, high processing difficulty and large insertion loss of traditional bandpass filters, an embodiment of the present application provides a miniaturized low-loss LTCC (Low Temperature Co-fired Ceramic) millimeter-wave bandpass filter.

[0044] The miniaturized low-loss LTCC millimeter-wave bandpass filter provided in the embodiment of the present application can be applied to 5G millimeter-wave communication systems and low-orbit communication satellite systems. Specifically, it can cover the n257 frequency band (26.5GHz-29.5GHz) and n258 band (24.25GHz-27.5GHz) of FR2.

[0045] like Figure 1 , Figure 3 , Fig. 9 and Fig.10 As shown, the present invention provides a miniaturized low-loss LTCC millimeter-wave bandpass filter, including an outer surface electrode, a multilayer LTCC filter structure and a PCB test substrate.

[0046] like Figure 4 , Figure 5 , Figure 6As shown in FIG. 1 , the filter mainly includes a source-load transmission line, two bent grounded quarter-wavelength step impedance resonators, and a bent half-wavelength step impedance resonator. The resonator bending, vertical multi-layer stacking of LTCC design, and the relatively large dielectric constant of LTCC ceramic materials enable a compact structure and easy integration.

[0047] like Figure 7 , Figure 8 , Fig.11 , Fig.12 As shown, the LTCC millimeter wave filter has extremely low insertion loss and high out-of-band suppression capability in the millimeter wave frequency band. The resonant frequency, bandwidth, zero point and spurious position can be flexibly adjusted to achieve filtering performance in different application scenarios.

[0048] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments, but the embodiments of the present invention are not limited thereto.

[0049] Specifically, Figure 1 and Figure 2 As shown, it includes a ceramic body 1 and an external electrode, and the external electrode is embedded in the outside of the ceramic body, wherein the external electrode includes an input electrode 2, an output electrode 3 and a grounding electrode 4, and the input electrode 2 and the output electrode 3 are symmetrically arranged on the left and right sides of the ceramic body 1, and the two grounding electrodes 4 are symmetrically arranged on the front and back sides of the ceramic body 1.

[0050] In this embodiment, the overall external dimensions are 2.0 mm×1.2 mm×0.66 mm, a ceramic with a dielectric constant of 7.5 and a loss tangent of 0.002 is used as the green ceramic tape material, and metallic silver is used as the conductor material. The thickness of a single layer of green ceramic tape can be 72 um, and the thickness of the metal conductor can be 10 um.

[0051] In a further configuration of this embodiment, the ceramic body 1 includes a LTCC ceramic dielectric matrix 101 and an internal electrode embedded in the LTCC ceramic dielectric matrix 101, and the internal electrode includes a top metal sheet 102, a source terminal 105, a load terminal 106, a first resonator 107, a third resonator 108, a second resonator 109, a bottom metal sheet 110 and a grounding column 113.

[0052] The source terminal 105 and the load terminal 106 are symmetrically arranged and located below the top metal sheet 102. The source terminal 105 and the load terminal 106 are respectively connected to the external electrodes through the input feed metal sheet 103 and the output feed metal sheet 104. The source terminal 105 is connected to the input electrode 2 through the input feed metal sheet 103, and the load terminal 106 is connected to the output electrode 3 through the output feed metal sheet 104, thereby forming a horizontal cross coupling.

[0053] In this embodiment, Figure 4 As shown, the source end and the load end are formed by a bent metal microstrip line and a bent metal microstrip line on the other side of the symmetry center to form a source-load coupling, and a transmission zero point is introduced on the left and right sides of the passband.

[0054] In this embodiment, the structure of the source end and the load end is the same, and the structure is U-shaped after bending, wherein the widths of the metal microstrip lines on both sides after bending are W1=0.07mm and W2=0.08mm respectively; the heights of the metal microstrip lines on both sides are L1=0.46mm and L3=0.52mm, and the height of the metal microstrip line in the middle bending part is L2=0.11mm. The distance between the metal microstrip lines on both sides is S1=0.15mm, and the distance between the source end and the load end is S2=0.155mm.

[0055] The two ends of the two grounding pillars 113 are respectively connected to the top metal sheet 102 and the bottom metal sheet 110, the first resonator 107 and the third resonator 108 are symmetrically arranged and are respectively located below the source end 105 and the load end 106, one end of the first resonator 107 and the third resonator 108 are respectively connected to the two grounding pillars 113, and the second resonator 109 is located above the bottom metal sheet 110. The first resonator 107 and the third resonator 108 are both quarter-wavelength stepped impedance resonators, and the second resonator 109 is a half-wavelength stepped impedance resonator.

[0056] It can be understood that the first resonator and the third resonator are located below the source end and the load end, and are connected to the top metal sheet and the bottom metal sheet through metallized through holes, so there is no need to add additional gaskets. The two are mirror-symmetrical to form horizontal direct coupling.

[0057] The second resonator is located below the first resonator and the third resonator, and forms a vertical direct coupling with the first resonator and the third resonator.

[0058] Specifically, Figure 5 As shown, in this embodiment, a quarter-wavelength first resonator 107 with one end grounded and a mirror-symmetrical third resonator 108 form a horizontal direct coupling.

[0059] In this embodiment, the first resonator and the third resonator have the same structure and are bent into a U-shaped structure, wherein the widths of the metal microstrip lines on both sides after bending are W3=0.09mm and W4=0.12mm respectively; the heights of the metal microstrip lines on both sides are L4=0.64mm and L6=0.34mm, and the height of the metal microstrip line in the middle bending part is L4=0.64mm. The distance between the metal microstrip lines on both sides is S3=0.0085mm, and the distance between the first resonator and the third resonator is S4=0.16mm.

[0060] like Figure 6 As shown, in this embodiment, the second resonator 109 is in the shape of a half-wavelength bent SIR with open ends. The coupling between the first resonator 107, the third resonator 108 and the second resonator 109 can generate a transmission zero on the left side of the passband, and the coupling between the source end and the load end can generate a transmission zero on the left and right sides of the passband, respectively. A total of two transmission zeros are introduced on the left side of the passband, and one transmission zero is introduced on the right side. The grounded quarter-wavelength SIR resonator and the half-wavelength SIR resonator have different harmonic distributions, and the stopband suppression can be widened by mutual suppression of harmonics.

[0061] In this embodiment, the second resonator 109 is in a W-shaped structure, and each bending portion is bent 90 degrees to form a shape similar to a rectangular wave. The widths of the metal microstrip lines on both sides after bending are W5=0.13mm, W6=0.12mm, and W7=0.13mm respectively; the heights of the metal microstrip lines are L7=0.14mm, L8=0.26mm, L9=0.17mm, L10=0.40mm, and L11=0.11mm respectively; and the distances between adjacent metal microstrip lines are S5=0.08mm and S6=0.085mm respectively.

[0062] Furthermore, the inner electrode also includes a shielding unit symmetrically arranged on both sides of the source end 105 and the load end 106. The shielding unit includes a shielding column 112 and three shielding metal layers, the top end of the shielding column 112 is connected to the top metal sheet 102, the bottom end of the shielding column is connected to the bottom metal sheet 110, and the three shielding metal layers are installed on the shielding column 112 from top to bottom.

[0063] Specifically, the three-layer metal gasket shielding metal layer is respectively parallel to the source end and the load end of the first layer, the first resonator and the third resonator of the second layer, and the second resonator of the third layer, wherein the shielding pillars are arranged in two rows, upper and lower, wherein the top ends of the first row of shielding pillars are connected to the top metal sheet, the bottom ends of the first row of shielding pillars are connected to the second shielding metal layer, the top ends of the second row of shielding pillars are connected to the second shielding metal layer, and the bottom ends of the second row of shielding pillars are connected to the bottom metal sheet, which are used to connect the upper and lower grounding layers, and also to avoid secondary harmonics caused by cavity resonance.

[0064] pass Figure 7 and Figure 8 It can be seen from the simulation results that this embodiment provides a miniaturized low-loss LTCC millimeter-wave bandpass filter, the passband can cover the 24.25-29.5GHz frequency band, the minimum insertion loss in the passband is 0.71dB, the maximum insertion loss is 1.8dB, and extremely low insertion loss is achieved in the millimeter wave band.

[0065] In a further configuration of this embodiment, a grounding substrate 111 is disposed on the bottom side of the LTCC ceramic dielectric substrate 101. The configuration of the grounding substrate 111 facilitates external connection to a PCB board.

[0066] Finally, in order to further illustrate the performance of a miniaturized low-loss LTCC millimeter-wave bandpass filter provided by this embodiment, as shown in FIG. Fig. 9 As shown, a three-dimensional schematic diagram of the LTCC millimeter wave bandpass filter structure loaded with a multi-layer PCB test board of the present invention.

[0067] Specifically, Fig.10 As shown in the figure, the multilayer PCB test board includes three layers of metal copper, one metal ground and three layers of PCB dielectric layers, a grounded coplanar waveguide (GCPW) transmission line and a grounding through hole in the middle. The metal layer and the transmission line are made of copper, which has good conductivity, low cost and is not easy to oxidize, and the thickness is 0.035mm; the materials of PCB dielectric layer 1 and PCB dielectric layer 3 are Rogers RO3003, which has good high-frequency characteristics, a thickness of 0.127mm, a dielectric constant of 3.0, and a loss tangent of 0.0013. The material of PCB dielectric layer 2 is FR4, with a thickness of 0.537mm, a dielectric constant of 4.4, and a loss tangent of 0.02. The grounding through hole is located directly below the LTCC filter and is arranged in an X shape to suppress the second harmonic generated by the cavity resonance. The radius of the through holes on both sides of the CPWG and the grounding through hole in the middle is 0.3mm. The characteristic impedance of the two GCPW transmission lines is 50 ohms, and the width of the middle transmission line is 0.24 mm.

[0068] The simulation results are as follows Fig.11 and Fig.12 As shown in the figure, the passband of the filter of the present invention can cover 26.5GHz-29.5GHz, the insertion loss in the bandwidth is as low as 0.69dB at the minimum and 1.16dB at the maximum, the lower stopband suppression is lower than -21dB, and the upper stopband suppression is lower than -17dB in the range of 31.98GHz-60GHz. In the millimeter wave frequency band, the signal in the band is transmitted with extremely low loss, and at the same time, it has a good suppression effect outside the band, which effectively improves the transmission efficiency of the signal.

[0069] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions and variations of these embodiments including components are made without departing from the principles and spirit of the present invention, and still fall within the scope of protection of the present invention.

Claims

1. A miniaturized low-loss LTCC millimeter-wave bandpass filter, characterized in that: The invention comprises a ceramic body (1) and an external electrode, wherein the external electrode is embedded in the outside of the ceramic body, the ceramic body (1) comprises a LTCC ceramic dielectric matrix (101) and an internal electrode embedded in the LTCC ceramic dielectric matrix (101), the internal electrode comprises a top metal sheet (102), a source end (105), a load end (106), a first resonator (107), a third resonator (108), a second resonator (109), a bottom metal sheet (110) and a grounding column (113), the source end (105) and the load end (106) are arranged in a symmetrical structure and are located below the top metal sheet (102), the source end (105) and the load end (106) are arranged in a symmetrical structure and are located below the top metal sheet (102), the source end (10 5) and the load end (106) are connected to the external electrode through the input feeding metal sheet (103) and the output feeding metal sheet (104), respectively; the two ends of the two grounding pillars (113) are connected to the top metal sheet (102) and the bottom metal sheet (110), respectively; the first resonator (107) and the third resonator (108) are arranged in a symmetrical structure and are respectively located below the source end (105) and the load end (106); one end of the first resonator (107) and the third resonator (108) are respectively connected to the two grounding pillars (113); and the second resonator (109) is located above the bottom metal sheet (110).

2. A miniaturized low-loss LTCC millimeter-wave bandpass filter according to claim 1, characterized in that: The first resonator (107) and the third resonator (108) are both quarter-wavelength stepped impedance resonators.

3. A miniaturized low-loss LTCC millimeter-wave bandpass filter according to claim 1, characterized in that: The second resonator (109) is a half-wavelength stepped impedance resonator.

4. A miniaturized low-loss LTCC millimeter-wave bandpass filter according to claim 1, characterized in that: The LTCC ceramic dielectric matrix (101) has a dielectric constant of 7.5 and a loss tangent of 0.

002.

5. A miniaturized low-loss LTCC millimeter-wave bandpass filter according to claim 1, characterized in that: The external electrodes include an input electrode (2), an output electrode (3) and a grounding electrode (4); the input electrode (2) and the output electrode (3) are symmetrically arranged on the left and right sides of the ceramic body (1); and the two grounding electrodes (4) are symmetrically arranged on the front and back sides of the ceramic body (1).

6. A miniaturized low-loss LTCC millimeter-wave bandpass filter according to claim 5, characterized in that: The source end (105) is connected to the input electrode (2) via an input feed metal sheet (103), and the load end (106) is connected to the output electrode (3) via an output feed metal sheet (104).

7. A miniaturized low-loss LTCC millimeter-wave bandpass filter according to claim 1, characterized in that: The inner electrode further comprises a shielding unit which is symmetrically arranged on both sides of the source end (105) and the load end (106).

8. A miniaturized low-loss LTCC millimeter-wave bandpass filter according to claim 7, characterized in that: The shielding unit comprises a plurality of shielding columns (112) and three shielding metal layers, the top end of the shielding column (112) is connected to the top metal sheet (102), the bottom end of the shielding column (112) is connected to the bottom metal sheet (110), and the three shielding metal layers are installed on the shielding column (112) from top to bottom.

9. A miniaturized low-loss LTCC millimeter-wave bandpass filter according to claim 1, characterized in that: A grounding substrate (111) is provided on the bottom side of the LTCC ceramic dielectric substrate (101).

10. The miniaturized low-loss LTCC millimeter-wave bandpass filter according to claim 1, characterized in that: The outer electrode and the inner electrode are both made of silver.

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