Low-pass filter circuit, low-pass filter and electronic equipment
By using multiple sets of cascade filter units and short-cut equivalent resonance circuits in low-pass filters, the problem of large size of low-pass filters in the prior art is solved, and high-frequency suppression is achieved in equipment with limited space The effect of the signal.
Patent Information
- Application Number
- CN202420608165.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-03-26
- Publication Date
- 2025-01-17
- Estimated Expiration
- 2034-03-26
AI Technical Summary
Existing low-pass filters require multi-capacitor inductor structure cascade when implementing high-frequency signal suppression, resulting in large equipment sizes and difficult to implement in cavity layouts with limited space.
Multiple sets of cascaded filter units are adopted, each group includes series subunits and parallel subunits. Through the electrical connection of series inductors and parallel capacitors, the equivalent resonance is achieved using short lines, reducing space occupation, and improving through the cascaded filter unit. Cutoff frequency.
It is implemented to install and use in the main transmission connection card slot with a narrow spatial structure, save space, and attenuation and suppression of high-frequency signals through the number of nodes of cascaded inductor capacitors.
Smart Images
Figure CN222366255U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of power electronics technology, and in particular to a low-pass filter circuit, a low-pass filter and an electronic device. Background Art
[0002] Low-pass filters are widely used in the field of radio frequency communication to allow only low-frequency signals below the cutoff frequency to pass through, and to block high-frequency signals above the cutoff frequency from passing through, so as to avoid interference between the unwanted high-frequency signals and other components of the module after passing through, thus affecting the normal operation of the system. Low-pass filters are composed of resistors and capacitors. Usually, in the field of radio frequency passive cavity filters, traditional low-pass filters are generally implemented by a candied haws string type, where the low-resistance section uses capacitors to pass high frequencies and block low frequencies, and the high-resistance section uses inductors to pass low frequencies and block high frequencies. The low-pass string is insulated from the cavity by a heat shrink tubing.
[0003] However, in current low-pass filters, in order to achieve high suppression of high-frequency signals, a relatively large number of capacitor and inductor structures need to be cascaded, and the total length is relatively long. In the cavity layout, a large space is required, which is not easy to implement. Utility Model Content
[0004] In order to solve the above technical problems, the embodiments of the present application provide a low-pass filtering circuit, a low-pass filter and an electronic device.
[0005] The utility model provides a technical solution:
[0006] In a first aspect, the utility model provides a low-pass filter circuit, which is applied to a low-pass filter, wherein the filter circuit comprises a plurality of groups of cascaded filter units;
[0007] Each group of the filter units includes a series sub-unit and a parallel sub-unit. When the filter units are cascaded, the series sub-units corresponding to the filter units are electrically connected in sequence.
[0008] The series subunit includes a first filter inductor, and the parallel subunit includes a second filter inductor and a filter capacitor, wherein the second filter inductor is electrically connected to the filter capacitor.
[0009] In one implementation, the first end of the first filter inductor serves as the first end of the series sub-unit, and the second end of the first filter inductor serves as the second end of the series sub-unit.
[0010] In one embodiment, the first end of the parallel subunit is electrically connected to the second end of the series subunit, the first end of the second filter inductor serves as the first end of the parallel subunit, and the second end of the filter capacitor serves as the second end of the parallel subunit.
[0011] In one embodiment, the second end of the second filter inductor is electrically connected to the first end of the filter capacitor.
[0012] In one embodiment, the parallel subunit is a short stub, and the second end of the parallel subunit serves as the free end of the short stub.
[0013] In one implementation, the number of the filtering units is at least 2.
[0014] In a second aspect, the utility model provides a low-pass filter, comprising a filter housing, an insulating layer, and a low-pass filter circuit as described in any one of the aforementioned embodiments.
[0015] In one embodiment, the low-pass filter further includes an insulator, and the insulator is used to fix the low-pass filter circuit on the filter housing.
[0016] In one embodiment, one end of the insulator is a first limiting structure, and the buckle of the first limiting structure is in contact with the low-pass filter circuit; the middle section of the insulator passes through the low-pass filter circuit and the insulating layer, and the other end of the insulator is a second limiting structure, and the buckle of the second limiting structure is in contact with the filter housing.
[0017] In a third aspect, the utility model provides an electronic device, comprising the low-pass filter as described in any one of the aforementioned implementations.
[0018] The beneficial effects of the low-pass filter circuit provided by the utility model are:
[0019] The low-pass filter circuit provided in the present application can be installed and used in a main transmission connection plate slot with a relatively narrow spatial structure, and can be flexibly embedded into the main transmission connection plate to form an integrated whole, thereby saving space. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the utility model and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying creative work.
[0021] Figure 1 A circuit diagram of a low-pass filter circuit provided by an embodiment of the present application is shown;
[0022] Figure 2 A schematic diagram of the structure of a low-pass filter circuit provided in an embodiment of the present application is shown;
[0023] Figure 3 A structural schematic diagram showing another perspective of a low-pass filter circuit provided in an embodiment of the present application;
[0024] Figure 4 A schematic structural diagram of an insulator provided in an embodiment of the present application is shown;
[0025] Figure 5 A structural schematic diagram of another implementation of a low-pass filter circuit provided in an embodiment of the present application is shown.
[0026] Reference numerals: 110 - first filter unit, 120 - second filter unit, 120 - short stub, 130 - insulator. DETAILED DESCRIPTION
[0027] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Generally, the components of the embodiments of the utility model described and shown in the drawings here can be arranged and designed in various different configurations.
[0028] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the present invention to be protected, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0029] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.
[0030] In the description of the present utility model, it should be understood that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the utility model product is conventionally placed when in use, or are the orientations or positional relationships conventionally understood by those skilled in the art. They are only for the convenience of describing the present utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present utility model.
[0031] Furthermore, the terms “first”, “second”, “third”, etc. are merely used for distinguishing descriptions and are not to be understood as indicating or implying relative importance.
[0032] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.
[0033] Example 1
[0034] Low-pass filter is a filtering method, the rule is that low-frequency signals can pass normally, while high-frequency signals exceeding the set threshold are blocked and weakened. However, the degree of blocking and weakening will vary according to different frequencies and different filtering purposes.
[0035] Low-pass filters are widely used in the field of radio frequency communication to allow only low-frequency signals below the cutoff frequency to pass through, and to block high-frequency signals above the cutoff frequency from passing through, so as to avoid interference between the unwanted high-frequency signals and other components of the module after passing through, thus affecting the normal operation of the system. Low-pass filters are composed of resistors and capacitors. Usually, in the field of radio frequency passive cavity filters, traditional low-pass filters are generally implemented by a candied haws string type, where the low-resistance section uses capacitors to pass high frequencies and block low frequencies, and the high-resistance section uses inductors to pass low frequencies and block high frequencies. The low-pass string is insulated from the cavity by a heat shrink tubing.
[0036] However, in current low-pass filters, in order to achieve high suppression of high-frequency signals, a relatively large number of capacitor and inductor structures need to be cascaded, and the total length is relatively long. In the cavity layout, a large space is required, which is not easy to implement.
[0037] Based on this, the utility model provides a low-pass filter circuit to overcome the defect in the prior art that the traditional low-pass filter structure cannot be used due to limited space layout.
[0038] The low-pass filter circuit provided by the utility model is applied to a low-pass filter, and the filter circuit comprises a plurality of groups of cascaded filter units;
[0039] Each group of the filter units includes a series sub-unit and a parallel sub-unit. When the filter units are cascaded, the series sub-units corresponding to the filter units are electrically connected in sequence; the series sub-unit includes a first filter inductor, and the parallel sub-unit includes a second filter inductor and a filter capacitor, and the second filter inductor is electrically connected to the filter capacitor.
[0040] See also Figure 1, wherein the filter unit includes filter units such as the first filter unit 110, the second filter unit 120, etc., which are cascaded in sequence. Wherein, each group of filter units also includes series sub-units connected head to tail, and parallel branches of each filter unit, i.e., parallel sub-units. Exemplarily, each filter unit is composed of two inductors and one capacitor, the series sub-unit includes a first filter inductor, the parallel sub-unit includes a second filter inductor and a filter capacitor, the second filter inductor and the filter capacitor form a series resonance on the branch, and the parallel sub-unit is purely resistive. Taking the first filter unit 110 as an example, L1 is the first filter inductor, L2 is the second filter inductor, and C2 is the filter capacitor. In the second filter unit 120, L3 is the first filter inductor, L4 is the second filter inductor, and C2 is the filter capacitor. Wherein Z1...Zn respectively represent the impedance of the current branch, and n represents the number of filter units.
[0041] It should be noted that the number of cascaded filter units is at least 2, but not limited to Figure 1 The first filtering unit 110, the second filtering unit 120, etc. shown in the figure can also be provided with a plurality of filtering units according to actual filtering requirements, and the specific number depends on the suppression requirements for high-frequency signals.
[0042] In one embodiment, the first end of the first filter inductor serves as the first end of the series subunit, and the second end of the first filter inductor serves as the second end of the series subunit. In one embodiment, the first end of the parallel subunit is electrically connected to the second end of the series subunit, the first end of the second filter inductor serves as the first end of the parallel subunit, and the second end of the filter capacitor serves as the second end of the parallel subunit. In one embodiment, the second end of the second filter inductor is electrically connected to the first end of the filter capacitor. Exemplarily, the series subunit is a high impedance line.
[0043] See also Figure 2 In one implementation, the parallel subunit is a short stub 120 , and the second end of the parallel subunit serves as a free end of the short stub 120 .
[0044] The stub 120 is a transmission line or waveguide used for connection. The free end of the stub 120 is open circuit or (in the case of a waveguide) short circuit. Ignoring the loss of the transmission line, the input impedance of the stub 120 is purely reactive. The free ends of the stubs 120 are independent of each other.
[0045] The stub 120 may be used as a capacitor, an inductor, and a resonant circuit at radio frequencies. In this embodiment, the second filter inductor and the filter capacitor in the parallel subunit are equivalently obtained by the stub 120. The stub 120 can save space for the low-pass filter circuit and can be conveniently embedded in the cavity main transmission connecting plate structure.
[0046] In one embodiment, the number of the filter units is at least 2. The low-pass filter circuit provided in the present application can be obtained by cascading multiple filter units, and the more filter units there are, the higher the cut-off frequency.
[0047] The low-pass filter circuit provided by the present application can be installed and used in the main transmission connecting plate card slot with a relatively narrow spatial structure, and can be flexibly embedded in the main transmission connecting plate to form an integrated whole, thereby saving space. By changing the inductor L and the capacitor C and the parallel series resonant circuit, it is possible to allow low-frequency signals to pass through while preventing high-frequency signals from passing through, and the attenuation suppression of high-frequency signals can be achieved by the number of cascaded inductors and capacitors.
[0048] Example 2
[0049] The utility model provides a low-pass filter, which comprises a filter housing, an insulating layer and a low-pass filter circuit as described in any one of the above implementation modes.
[0050] The low-pass filter circuit provided in the present application occupies a small space and adopts a short-line 120 equivalent series resonant circuit, without the need to adopt a candied haws string structure. Therefore, the corresponding low-pass filter can also be designed as a strip-shaped sheet, which can be installed and used in the main transmission connecting sheet slot with a relatively narrow spatial structure.
[0051] See also Figure 2 and Figure 3 , Figure 2 is a front view of the low-pass filter circuit, Figure 3 is a cross-sectional view of the low-pass filter circuit. In one embodiment, the low-pass filter further comprises an insulator 130, and the insulator 130 is used to fix the low-pass filter circuit on the filter housing.
[0052] See also Figure 4 In one embodiment, one end of the insulator 130 is a first limiting structure, and the buckle of the first limiting structure is in contact with the low-pass filter circuit; the middle section of the insulator 130 passes through the low-pass filter circuit and the insulating layer, and the other end of the insulator 130 is a second limiting structure, and the buckle of the second limiting structure is in contact with the filter housing.
[0053] Also, see Figure 5The structural layout of the present application is relatively flexible, and multiple alternatives are possible. The short stub 120 of the parallel branch can be placed downward, upward, or partially upward and partially downward. The insulator 130 for fixing the short stub 120 can be in various shapes, such as a screw-like structure with a barbed stopper, or an insulator 130 that is symmetrical on both sides but has a barbed stopper in the middle, and the stopper structure is fixed on the short stub 120.
[0054] The low-pass filter provided by the present application can be installed and used in the main transmission connecting plate card slot with a relatively narrow spatial structure, and can be flexibly embedded in the main transmission connecting plate to form an integrated whole, thereby saving space. By changing the inductance L and the capacitance C and the parallel series resonant circuit, it is possible to allow low-frequency signals to pass through and prevent high-frequency signals from passing through, and the attenuation suppression of high-frequency signals can be achieved by the number of cascaded inductors and capacitors.
[0055] Example 3
[0056] The utility model provides an electronic device, wherein the electronic device comprises the low-pass filter as described in any one of the above-mentioned implementation modes.
[0057] The electronic device provided by the present application includes a low-pass filter. The low-pass filter can be designed as a strip-shaped sheet structure, which can be installed and used in the main transmission connecting sheet card slot with a relatively narrow spatial structure, and can be flexibly embedded in the main transmission connecting sheet to form an integrated whole, thereby saving space. By changing the inductance L and the capacitance C and the parallel series resonant circuit, it is possible to allow low-frequency signals to pass through and prevent high-frequency signals from passing through, and the attenuation suppression of high-frequency signals can be achieved by the number of cascaded inductors and capacitors.
[0058] The above description is only the preferred embodiment of the utility model, and is not intended to limit the utility model. For those skilled in the art, the utility model can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.
Claims
1. A low-pass filter circuit, characterized in that: Applied to a low-pass filter, the filter circuit comprises a plurality of groups of cascaded filter units; Each group of the filter units includes a series sub-unit and a parallel sub-unit. When the filter units are cascaded, the series sub-units corresponding to the filter units are electrically connected in sequence. The series subunit includes a first filter inductor, and the parallel subunit includes a second filter inductor and a filter capacitor, wherein the second filter inductor is electrically connected to the filter capacitor.
2. The low-pass filter circuit according to claim 1, characterized in that: The first end of the first filter inductor serves as the first end of the series sub-unit, and the second end of the first filter inductor serves as the second end of the series sub-unit.
3. The low-pass filter circuit according to claim 2, characterized in that: The first end of the parallel subunit is electrically connected to the second end of the series subunit, the first end of the second filter inductor serves as the first end of the parallel subunit, and the second end of the filter capacitor serves as the second end of the parallel subunit.
4. The low-pass filter circuit according to claim 3, characterized in that: The second end of the second filter inductor is electrically connected to the first end of the filter capacitor.
5. The low-pass filter circuit according to claim 3, characterized in that: The parallel subunit is a short stub, and the second end of the parallel subunit serves as the free end of the short stub.
6. The low-pass filter circuit according to claim 1, characterized in that: The number of the filtering units is at least 2.
7. A low-pass filter, characterized in that: The low-pass filter comprises a filter housing, an insulating layer and the low-pass filter circuit according to any one of claims 1 to 6.
8. The low-pass filter according to claim 7, characterized in that The low-pass filter further comprises an insulator, and the insulator is used to fix the low-pass filter circuit on the filter housing.
9. The low-pass filter according to claim 8, characterized in that One end of the insulator is a first limiting structure, and the buckle of the first limiting structure is in contact with the low-pass filter circuit; the middle section of the insulator passes through the low-pass filter circuit and the insulating layer, and the other end of the insulator is a second limiting structure, and the buckle of the second limiting structure is in contact with the filter housing.
10. An electronic device, characterized in that: The electronic device comprises the low-pass filter as claimed in any one of claims 7 to 9.