Broadband feed-through filter

Abstract

The invention discloses a broadband feed-through filter, and belongs to the technical field of filters, the broadband feed-through filter comprises a shell (1), a central conductor (2), a magnetic ring (3), a chip resistor (4), an integrated feed-through capacitor (5), a cavity-shaped bonding pad (6), a dielectric ring (7), an inductor (8), a limiting dielectric (9) and the like, the inductor (8) is a winding inductor, and the integrated feed-through capacitor (5) comprises a feed-through capacitor (51), a limiting hole (52), a ceramic bonding pad (53) and limiting ceramic (54); the blocking effect of the filter on low-frequency-band signals is obviously enhanced, the suppression degree of 20 dB within the frequency range of 100 kHz to 40 GHz can be achieved, the low-frequency band of filtered signals is obviously widened, the problem of deviation of a center conductor is solved, and the reliability and consistency of products are improved; moreover, the number of filter elements is effectively reduced, the production process is simplified, and the process consistency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of filters, and in particular to a broadband feed-through filter. Background Art

[0002] Feedthrough filter is a filter device used to suppress the interference of high-frequency harmonics on signals, power lines, etc. It is mainly used for signals, data lines, DC power lines, microwaves, and other high-frequency filtering applications.

[0003] Feed-through filters can be divided into C-type, LC-type, π-type, T-type, and double-T-type filters according to the circuit distribution of their inductance and capacitance. Its components generally include a center conductor, a through-hole capacitor, a grounding shell 10, a ferrite core 11, a resistor, etc. Fig.11 As shown, the current production and assembly method is mainly to assemble and weld the components in sequence, and finally seal them with resin. At present, the broadband feed-through filter using this structure can achieve a suppression degree of 20dB at 5MHz, but can only achieve a suppression degree of 5dB at 100kHz, as disclosed in the document "Principle and Design of Anti-RFI Feed-through Filter" DOI:10.19594 / j.cnki.09.19701.2021.04.013, at f=100kHz, the suppression degree IL>5dB, at f=5MHz, the suppression degree IL>20dB; at f=50MHz, the suppression degree IL>60dB); it can be seen that the low-frequency filtering performance of the broadband feed-through filter is limited. At the same time, the existing feed-through filter molding process requires multiple welding, the process is complicated, there is a possibility of mis-installation and missing assembly of components in the production process, and the welding process is easy to damage the capacitor and resistor, which is not conducive to the consistency and reliability of product performance parameters. Summary of the invention

[0004] The object of the present invention is to provide a broadband feed-through filter to solve the above problems.

[0005] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is as follows: a broadband feed-through filter, comprising a shell, a center conductor, a magnetic ring, a chip resistor, an integrated feed-through capacitor, a cavity-shaped pad, a dielectric ring, an inductor and a limiting medium, wherein the center conductor sequentially passes through the magnetic ring and the integrated feed-through capacitor at one end of the shell and is inserted into one end of the shell, the center conductor passes through the limiting medium (but not through the inductor) at one end of the shell, the magnetic ring, the chip resistor, the integrated feed-through capacitor, the dielectric ring, the inductor and the limiting medium are arranged sequentially from left to right in the shell, and the chip resistor is connected to the feed-through capacitor by welding; the inductor is a winding inductor.

[0006] In view of the above problems, the inventors of this application have found through analysis that the current feed-through filters often use single-turn inductors introduced by straight-through center conductors, which have a small inductance, thus limiting the low-frequency filtering performance of broadband feed-through filters. This application effectively increases the inductance of the feed-through filter through a wound inductor, significantly enhancing the blocking effect of the filter on low-frequency signals, and can easily achieve a suppression degree of 20dB in the frequency range of 100kHz to 40GHz, significantly widening the low-frequency band of the filtered signal.

[0007] As a preferred technical solution, the integrated feedthrough capacitor includes a feedthrough capacitor, a limiting hole is arranged in the middle of the feedthrough capacitor, a ceramic pad is arranged at the upper end of the feedthrough capacitor, and a limiting ceramic is arranged at the lower end.

[0008] As a further preferred technical solution, the aperture of the limiting hole is the same as the outer diameter of the central conductor; and the ceramic pad is provided with an inner annular pad and an outer annular pad.

[0009] As a preferred technical solution, the shell is made of metal conductor material.

[0010] As a preferred technical solution, a through hole is provided on the side surface of the central conductor.

[0011] As a preferred technical solution, a limiting ring is provided on the limiting medium.

[0012] Compared with the prior art, the advantages of the present invention are: (1) The present invention effectively increases the inductance of the feed-through filter through the winding inductor, so that the blocking effect of the filter on low-frequency signals is significantly enhanced, and can easily achieve a suppression degree of 20dB in the frequency range of 100kHz to 40GHz, thereby further widening the low-frequency band of the filtered signal; (2) The present invention solves the problem of center conductor deviation by setting a limiting medium at an appropriate position, thereby improving product reliability and consistency; (3) The present invention effectively reduces the number of filter components by integrating the through-hole capacitor, the resistor pad, and the center conductor tray, which is conducive to simplifying the production process and improving the consistency of the process; (4) The present invention is applicable to low-frequency and high-frequency application scenarios of filters. By replacing component models, the filter performance can be highly adjustable. That is, by enhancing the inductance of the inductor and the capacitance of the integrated feedthrough capacitor, the signal suppression degree of the filter can be effectively increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The feed-through filter of the embodiment of the present invention is an outline diagram; Figure 2An exploded diagram of the internal structure of a feed-through filter according to an embodiment of the present invention; Figure 3 is a cross-sectional view of a feed-through filter after assembly according to an embodiment of the present invention; Figure 4 for Figure 3 Structural diagram of the middle shell; Figure 5 for Figure 3 The structural diagram of the central conductor in; Figure 6 for Figure 3 The structural diagram of the integrated feedthrough capacitor; Figure 7 for Figure 6 A cross-sectional view of Figure 8 for Figure 3 Structural diagram of the cavity-shaped pad; Fig. 9 for Figure 3 Structural diagram of the inductor in the circuit; Fig.10 for Figure 3 Structural diagram of the middle limit ring; Fig.11 It is a structural diagram of a feed-through filter in the prior art; Fig.12 It is a simulation diagram of the broadband feed-through filter according to an embodiment of the present invention.

[0014] In the figure: 1. outer shell; 2. center conductor; 21. through hole; 3. magnetic ring; 4. chip resistor; 5. integrated through-hole capacitor; 51. through-hole capacitor; 52. limiting hole; 53. ceramic pad; 531. inner ring pad; 532. inner ring pad; 54. limiting ceramic; 6. cavity pad; 7. dielectric ring; 8. inductor; 9. limiting dielectric; 91. limiting ring; 10. grounded shell; 11. ferrite core. DETAILED DESCRIPTION

[0015] The present invention will be further described below in conjunction with the accompanying drawings.

[0016] Example:

[0017] A broadband feedthrough filter, see Figure 1 , Figure 2 and Figure 3, comprising a shell 1, a center conductor 2, a magnetic ring 3, a chip resistor 4, an integrated through-hole capacitor 5, a cavity-shaped pad 6, a dielectric ring 7, an inductor 8 and a limiting medium 9, wherein the center conductors 2 are two, one of which passes through the magnetic ring 3 and the integrated through-hole capacitor 5 in sequence at one end of the shell 1 and is inserted into one end of the shell 1, and the other center conductor 2 passes through the limiting medium 9 at the other end of the shell 1, and the magnetic ring 3, the chip resistor 4, the integrated through-hole capacitor 5, the dielectric ring 7, the inductor 8 and the limiting medium 9 are arranged in sequence from left to right in the shell 1; the inductor 8 is a winding inductor; In this embodiment, The housing 1 is made of a metal conductor material such as brass. Figure 4 As shown, it plays the role of fixing other components and grounding to export high-frequency noise, and at the same time eliminates the coupling capacitance formed by the input and output leads of the single-turn inductor; The central conductor 2 is made of metal such as brass and has a structure as follows: Figure 5 As shown, a through hole 21 is provided on its side for leading out the welding wire, and the central conductor 2 plays the role of transmitting signals. The two central conductors 2 are connected by wires at the ends of the filter to transmit electrical signals; The magnetic ring 3 and the central conductor 2 form a single-turn inductor, and together with the inductor 8, they play a high impedance role for high-frequency signals, wherein the large inductance of the winding inductor also plays a filtering role for low-frequency signals; The chip resistor 4 keeps the internal circuit with a high DC resistance to ground; The structure of the integrated feedthrough capacitor 5 is as follows Figure 6 and Figure 7 As shown, it includes a through-hole capacitor 51, a limiting hole 52 is arranged in the middle of the through-hole capacitor 51, a ceramic pad 53 is arranged at the upper end of the through-hole capacitor 51, and a limiting ceramic 54 is arranged at the lower end; the aperture of the limiting hole 52 is the same as the outer diameter of the center conductor 2, and is used to limit the position of the center conductor 2, and is slightly larger than the aperture of the limiting ceramic 54, so as to limit the axial position of the center conductor 2; the ceramic pad 53 is provided with an inner annular pad 531 and an outer annular pad 532; In addition to playing the role of capacitor, the integrated through-hole capacitor 5 also integrates welding pads (i.e., inner annular welding pad 531 and outer annular welding pad 532) and limiting ceramic 51 for limiting the position of the central conductor. The inner annular welding pad 531 and the outer annular welding pad 532 of the ceramic welding pad 53 can be welded to the chip resistor 4. The presence of ceramic is used to buffer the deformation of the resistor and capacitor caused by temperature rise. This integrated design can effectively simplify the design and production of the filter; The structure of the cavity pad 6 is as follows Figure 8 As shown, it is used to fix the integrated through-hole capacitor 5, the chip resistor 4 and the magnetic ring 3, and at the same time isolate the destructive effect of the deformation of the shell 1 on the internal components; The structure of the inductor 8 is as follows Fig. 9 As shown, it is made by winding a wire around a magnetic core; The structure of the limiting medium 9 is as follows Fig.10 As shown, a limiting ring 91 which is slightly smaller than the outer diameter of the center conductor 2 and is used to fix the position of the center conductor 2 prevents the center conductor 2 from axial displacement, and a notch thereon leaves a channel for the potting resin.

[0018] The simulation diagram of the broadband feed-through filter of this embodiment is shown in FIG. Fig.12 As shown, from Fig.12 It can be seen that at a frequency of 100kHz, the suppression has reached 36dB, and the suppression gradually increases at higher frequencies.

[0019] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A broadband feed-through filter, characterized in that: The invention comprises a shell (1), a central conductor (2), a magnetic ring (3), a chip resistor (4), an integrated through-hole capacitor (5), a cavity-shaped pad (6), a dielectric ring (7), an inductor (8) and a limiting medium (9), wherein the central conductor (2) passes through the magnetic ring (3) and the integrated through-hole capacitor (5) in sequence at one end of the shell (1) and is inserted into one end of the shell (1), and the central conductor (2) passes through the limiting medium (9) at the other end of the shell (1); the magnetic ring (3), the chip resistor (4), the integrated through-hole capacitor (5), the dielectric ring (7), the inductor (8) and the limiting medium (9) are arranged in sequence from left to right in the shell (1); and the inductor (8) is a winding inductor.

2. A broadband feed-through filter according to claim 1, characterized in that: The integrated through-hole capacitor (5) comprises a through-hole capacitor (51), a limiting hole (52) is arranged in the middle of the through-hole capacitor (51), a ceramic pad (53) is arranged at the upper end of the through-hole capacitor (51), and a limiting ceramic (54) is arranged at the lower end.

3. A broadband feed-through filter according to claim 2, characterized in that: The aperture of the limiting hole (52) is the same as the outer diameter of the central conductor (2); and the ceramic pad (53) is provided with an inner annular pad and an outer annular pad.

4. The broadband feed-through filter according to claim 1, characterized in that: The shell (1) is made of a metal conductor material.

5. The broadband feed-through filter according to claim 1, characterized in that: A through hole (21) is provided on the side surface of the central conductor (2).

6. The broadband feed-through filter according to claim 1, characterized in that: A limiting ring (91) is provided on the limiting medium (9).

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