Passive band-stop filter

Abstract

Disclosed in the present application is a passive band-stop filter. The passive band-stop filter comprises a signal input module, a frequency adjustment portion, a signal attenuation portion and a signal output module, wherein the signal input module is used for connecting to a radio frequency signal; the frequency adjustment portion comprises three resonant filtering modules connected in series, and the three resonant filtering modules connected in series are electrically connected to the signal input module and are used for adjusting the frequency of the radio frequency signal; the signal attenuation portion comprises two resonant attenuation modules; a common node is formed between every two adjacent resonant filtering modules among the three resonant filtering modules connected in series, and a first end of each resonant attenuation module is electrically connected to the common node, and a second end thereof is grounded; and the signal output module is electrically connected to the three resonant filtering modules connected in series. In the passive band-stop filter provided in the present application, resonant attenuation modules are used for attenuating a clutter signal of a preset passband frequency in a radio frequency signal, and therefore steep stop-band suppression can be realized.

Description

Passive band-stop filters

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on December 20, 2023, with application number 202311763652.6 and invention name “Passive Band-Rejection Filter”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the technical field of passive band-stop filters, and in particular to a passive band-stop filter. Background Art

[0003] As electronic devices develop toward digitalization, multifunctionality, and miniaturization, and electronic systems move toward networking, high speed, and broadband, new electronic components will develop toward miniaturization, integration, and high frequency. Furthermore, electronic components, previously designed to adapt to device miniaturization and passively improve, are now actively meeting the performance requirements posed by the development of digital and microelectronics technologies, demonstrating a trend toward industrialization.

[0004] Band-stop filters, as an important circuit component in microwave communication systems, can be used to suppress unwanted high-frequency signals, thereby improving the performance of the communication system. With the continuous development of modern communication systems, not only are more miniaturized band-stop filters required, but also increasingly higher requirements are placed on the insertion loss, production cost, and stopband characteristics of band-stop filters.

[0005] Traditional band-stop filters generally adopt a planar structure, arranging capacitors, inductors and other reactive elements in a certain order to form a band-stop filter. This not only has low integration and large size, but also has large insertion loss and less than ideal performance, which cannot meet the requirements of RF circuits for miniaturization and high performance of devices.

[0006] Therefore, achieving miniaturized band-stop filters with excellent filtering characteristics has become a pressing issue in the industry. In recent decades, numerous researchers have conducted research on miniaturization of band-stop filters, and thanks to the development of low-temperature co-fired ceramic (LTCC) technology, this miniaturization has made significant progress. LTCC technology is an effective approach for miniaturizing passive components. LTCC band-stop filters offer the advantages of small size, light weight, high reliability, and consistent mass production.

[0007] However, the current micro-LTCC band-stop filter's stop-band suppression is not steep enough, and at 1575MHz, the out-of-band suppression is better than 18dB. Technical issues

[0008] One of the objectives of the embodiments of the present application is to provide a passive band-stop filter, aiming to solve the problem that the stop-band suppression of the current miniature LTCC band-stop filter is not steep enough. Technical Solutions

[0009] To solve the above technical problems, the technical solutions adopted in the embodiments of the present application are:

[0010] In a first aspect, a passive band-stop filter is provided, which includes: a signal input module, a frequency adjustment unit, a signal attenuation unit and a signal output module, wherein the signal input module is used to access the radio frequency signal; the frequency adjustment unit includes three resonance filter modules connected in series, and the three resonance filter modules connected in series are electrically connected to the signal input module, and are used to adjust the frequency of the radio frequency signal; the signal attenuation unit includes two resonance attenuation modules, and a common node is formed between two adjacent resonance filter modules in the three resonance filter modules connected in series, the first end of the resonance attenuation module is electrically connected to the common node, and the second end of the resonance attenuation module is grounded, and is used to attenuate the interference signal of the preset passband frequency in the radio frequency signal; the signal output module is electrically connected to the three resonance filter modules connected in series, and is used to output the processed radio frequency signal.

[0011] In one embodiment, the three resonant filter modules connected in series are respectively a first resonant filter module, a second resonant filter module, and a third resonant filter module. The first end of the first resonant filter module is electrically connected to the signal input module, the second end of the first resonant filter module is electrically connected to the first end of the second resonant filter module, the second end of the second resonant filter module is electrically connected to the first end of the third resonant filter module, and the second end of the third resonant filter module is electrically connected to the signal output module.

[0012] In one embodiment, a first common node is formed between the first resonant filter module and the second resonant filter module, and a second common node is formed between the second resonant filter module and the third resonant filter module; the two resonant attenuation modules are respectively the first resonant attenuation module and the second resonant attenuation module, the first end of the first resonant attenuation module is electrically connected to the first common node, the first end of the second resonant attenuation module is electrically connected to the second common node, and the second ends of the first resonant attenuation module and the second resonant attenuation module are both grounded.

[0013] In one embodiment, the first resonant filter module includes a first inductor and a first capacitor, the first inductor and the first capacitor are connected to resonate in parallel, the second resonant filter module includes a second inductor and a second capacitor, the second inductor and the second capacitor are connected to resonate in parallel, and the third resonant filter module includes a third inductor and a third capacitor, the third inductor and the third capacitor are connected to resonate in parallel.

[0014] In one embodiment, the first resonance attenuation module includes a fourth capacitor and a fourth inductor, which resonate in series. The second resonance attenuation module includes a fifth capacitor and a fifth inductor, which resonate in series.

[0015] In one embodiment, the passive band-stop filter further includes a substrate, the frequency adjustment unit and the signal attenuation unit are both arranged in the substrate, the first resonant filtering module and the third resonant filtering module are mirror-symmetrical along the center of the substrate, and the first resonant attenuation module and the second resonant attenuation module are mirror-symmetrical along the center of the substrate.

[0016] In one embodiment, the first inductor, the second inductor, the third inductor, the fourth inductor, and the fifth inductor are all rectangular spiral coils extending along the thickness direction of the substrate.

[0017] In one embodiment, the first capacitor, the second capacitor, and the third capacitor are VIC capacitors; and the fourth capacitor and the fifth capacitor are planar MIN capacitors.

[0018] In one embodiment, the fourth inductor and the fifth inductor each include a plurality of rectangular inductor layers, which are spaced apart along the thickness direction of the substrate. Adjacent rectangular inductor layers are electrically connected via conductive columns, and the spacing between adjacent rectangular inductor layers is 0.13 mm.

[0019] In one embodiment, the substrate is a low-loss low-temperature co-fired ceramic dielectric with a relative dielectric constant of 5.0±0.3 and a dielectric loss tanα≤0.003. Beneficial effects

[0020] The beneficial effect of the passive band-stop filter provided by the embodiment of the present application is that: the passive band-stop filter provided by the present application electrically connects the first ends of the two resonant attenuation modules to the common node formed between two adjacent resonant filter modules in the three series-connected resonant filter modules, and grounds the second ends of the resonant attenuation modules, so that the passive band-stop filter provided by the present application can attenuate the clutter signal of the preset passband frequency in the radio frequency signal through the resonant attenuation module, and adjust the frequency of the radio frequency signal through the three series-connected resonant filter modules. At the same time, since the passive band-stop filter provided by the present application uses the resonant attenuation module to attenuate the clutter signal of the preset passband frequency in the radio frequency signal, it can achieve steep stopband suppression. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or exemplary technical descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0022] FIG1 is a circuit diagram of a passive band-stop filter according to an embodiment of the present application;

[0023] FIG2 is an external view of a passive band-stop filter provided in an embodiment of the present application;

[0024] FIG3 is a schematic structural diagram of a passive band-stop filter provided in an embodiment of the present application;

[0025] FIG4 is a schematic structural diagram of a passive band-stop filter from another perspective provided by an embodiment of the present application;

[0026] FIG5 is a graph showing the insertion loss and return loss of the passive band-stop filter according to an embodiment of the present application. Modes for Carrying Out the Invention

[0027] In order to make the purpose, technical solutions and advantages of this application more clearly understood, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit this application.

[0028] It should be noted that when a component is referred to as being "fixed on" or "disposed on" another component, it may be directly on the other component or indirectly on the other component. When a component is referred to as being "connected to" another component, it may be directly or indirectly connected to the other component. The terms "upper", "lower", "left", "right", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of 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. Therefore, they cannot be understood as limitations on this application. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to the specific circumstances. The terms "first" and "second" are only used for the purpose of convenience of description and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features. "Multiple" means two or more, unless otherwise clearly and specifically defined.

[0029] In order to illustrate the technical solution provided by this application, a detailed description is given below with reference to specific drawings and embodiments.

[0030] Referring to Figures 1 to 5, according to one aspect of the present application, an embodiment of the present application provides a passive band-stop filter, which includes: a signal input module P1, a frequency adjustment unit, a signal attenuation unit and a signal output module P2, wherein the signal input module P1 is used to access the radio frequency signal; the frequency adjustment unit includes three resonance filter modules connected in series, and the three resonance filter modules connected in series are electrically connected to the signal input module P1, for adjusting the frequency of the radio frequency signal; the signal attenuation unit includes two resonance attenuation modules, and a common node is formed between two adjacent resonance filter modules in the three resonance filter modules connected in series, the first end of the resonance attenuation module is electrically connected to the common node, and the second end of the resonance attenuation module is grounded, for attenuating the interference signal of the preset passband frequency in the radio frequency signal; the signal output module P2 is electrically connected to the three resonance filter modules connected in series, for outputting the processed radio frequency signal. The passive band-stop filter provided in this embodiment electrically connects the first ends of the two resonant attenuation modules to the common node formed between two adjacent resonant filter modules in the three series-connected resonant filter modules, and grounds the second ends of the resonant attenuation modules. This enables the passive band-stop filter provided in this embodiment to attenuate the clutter signal of a preset passband frequency in the radio frequency signal through the resonant attenuation module, and adjust the frequency of the radio frequency signal through the three series-connected resonant filter modules. At the same time, since the passive band-stop filter provided in this embodiment uses the resonant attenuation module to attenuate the clutter signal of a preset passband frequency in the radio frequency signal, it can achieve steep stopband suppression.

[0031] In a specific embodiment, compared with the band-stop filter in the prior art having an out-of-band suppression better than 18 dB at 1575 MHz, the center frequency of the passive band-stop filter provided in this embodiment is 1330 MHz, the stopband bandwidth of the passive band-stop filter is 1280 MHz to 1380 MHz, and the stopband suppression is better than 42 dB.

[0032] In a specific embodiment, the three series-connected resonant filter modules in this embodiment are respectively a first resonant filter module, a second resonant filter module, and a third resonant filter module. The first end of the first resonant filter module is electrically connected to the signal input module P1, the second end of the first resonant filter module is electrically connected to the first end of the second resonant filter module, the second end of the second resonant filter module is electrically connected to the first end of the third resonant filter module, and the second end of the third resonant filter module is electrically connected to the signal output module P2. By electrically connecting the first end of the first resonant filter module provided in this embodiment to the signal input module P1, the second end of the first resonant filter module is electrically connected to the first end of the second resonant filter module, the second end of the second resonant filter module is electrically connected to the first end of the third resonant filter module, and the second end of the third resonant filter module is electrically connected to the signal output module P2, the passive band-stop filter provided in this embodiment can adjust the frequency of the RF signal through the first resonant filter module, the second resonant filter module, and the third resonant filter module.

[0033] In a specific embodiment, a first common node is formed between the first resonant filter module and the second resonant filter module, and a second common node is formed between the second resonant filter module and the third resonant filter module; the two resonant attenuation modules are respectively a first resonant attenuation module and a second resonant attenuation module, the first end of the first resonant attenuation module is electrically connected to the first common node, the first end of the second resonant attenuation module is electrically connected to the second common node, and the second ends of the first resonant attenuation module and the second resonant attenuation module are both grounded. By electrically connecting the first end of the first resonant attenuation module provided in this embodiment to the first common node, the first end of the second resonant attenuation module is electrically connected to the second common node, and grounding the second ends of the first resonant attenuation module and the second resonant attenuation module, the passive band-stop filter provided in this embodiment can filter the interference signal of the preset passband frequency in the radio frequency signal through the first resonant attenuation module and the second resonant attenuation module.

[0034] 1 to 4 , in a specific embodiment, the first resonant filter module in this embodiment includes a first inductor L1 and a first capacitor C1, the first inductor L1 and the first capacitor C1 being in parallel resonance, the second resonant filter module includes a second inductor L2 and a second capacitor C2, the second inductor L2 and the second capacitor C2 being in parallel resonance, and the third resonant filter module includes a third inductor L3 and a third capacitor C3, the third inductor L3 and the third capacitor C3 being in parallel resonance. By configuring the first resonant filter module provided in this embodiment to include the first inductor L1 and the first capacitor C1, and configuring the first inductor L1 and the first capacitor C1 to be in parallel resonance, configuring the second resonant filter module to include the second inductor L2 and the second capacitor C2, and configuring the second inductor L2 and the second capacitor C2 to be in parallel resonance, and configuring the third resonant filter module to include the third inductor L3 and the third capacitor C3, and configuring the third inductor L3 and the third capacitor C3 to be in parallel resonance, the passive band-stop filter provided in this embodiment can effectively adjust the frequency of the RF signal through the first resonant filter module, the second resonant filter module, and the third resonant filter module.

[0035] In an optional embodiment, the frequency adjustment unit provided in this embodiment includes a first conduction band S1, a second conduction band S2, a third conduction band S3 and a fourth conduction band S4, the first end of the first conduction band S1 is connected to the signal input module P1, the second end of the first conduction band S1 is electrically connected to the first end of the first capacitor C1 and the first end of the first inductor L1, the first end of the second conduction band S2 is electrically connected to the first capacitor C1 and the second end of the first inductor L1, the second end of the second conduction band S2 is electrically connected to the first end of the second capacitor C2 and the second inductor L2, the first end of the third conduction band S3 is electrically connected to the second end of the second capacitor C2 and the second inductor L2, the second end of the third conduction band S3 is electrically connected to the first end of the third capacitor C3 and the third inductor L3, the first end of the fourth conduction band S4 is electrically connected to the second end of the third capacitor C3 and the third inductor L3, and the second end of the fourth conduction band S4 is electrically connected to the signal output. By electrically connecting the first end of the first capacitor C1 and the first inductor L1 to the second end of the first conductive strip S1, and electrically connecting the second end of the first capacitor C1 and the first inductor L1 to the first end of the second conductive strip S2, the first capacitor C1 and the first inductor L1 can be made to resonate in parallel. By electrically connecting the first end of the second capacitor C2 and the second inductor L2 to the second end of the second conductive strip S2, and electrically connecting the second end of the second capacitor C2 and the second inductor L2 to the first end of the third conductive strip S3, the second capacitor C2 and the second inductor L2 can be made to resonate in parallel. By electrically connecting the first end of the third capacitor C3 and the third inductor L3 to the second end of the third conductive strip S3, and electrically connecting the second end of the third capacitor C3 and the third inductor L3 to the first end of the fourth conductive strip S4, the third capacitor C3 and the third inductor L3 can be made to resonate in parallel.

[0036] 1 to 4 , in a specific embodiment, the first resonant attenuation module in this embodiment includes a fourth capacitor C4 and a fourth inductor L4, which resonate in series with the fourth inductor L4, and the second resonant attenuation module includes a fifth capacitor C5 and a fifth inductor L5, which resonate in series with the fifth inductor L5. By configuring the first resonant attenuation module provided in this embodiment to include the fourth capacitor C4 and the fourth inductor L4, and configuring the fourth capacitor C4 and the fourth inductor L4 to resonate in series, and configuring the second resonant attenuation module to include the fifth capacitor C5 and the fifth inductor L5, and configuring the fifth capacitor C5 and the fifth inductor L5 to resonate in series, the passive band-stop filter provided in this embodiment can generate a zero in the stopband, thereby achieving steep stopband suppression.

[0037] In an optional embodiment, the passive band-stop filter of this embodiment further includes a substrate, the frequency adjustment unit and the signal attenuation unit are both disposed within the substrate, the first resonant filter module and the third resonant filter module are mirror-symmetrical about the center of the substrate, and the first resonant attenuation module and the second resonant attenuation module are mirror-symmetrical about the center of the substrate. By arranging the first resonant filter module and the third resonant filter module provided in this embodiment to be mirror-symmetrical about the center of the substrate, and arranging the first resonant attenuation module and the second resonant attenuation module to be mirror-symmetrical about the center of the substrate, the design and processing difficulty of the passive band-stop filter provided in this embodiment can be effectively reduced.

[0038] In a specific embodiment, the first capacitor C1 and the third capacitor C3 provided in this embodiment are mirror-symmetrical along the center of the substrate, the first inductor L1 and the third inductor L3 are mirror-symmetrical along the center of the substrate, the fourth capacitor C4 and the fifth capacitor C5 are mirror-symmetrical along the center of the substrate, and the fourth inductor L4 and the fifth inductor L5 are mirror-symmetrical along the center of the substrate.

[0039] In an optional embodiment, the first conductive strip S1 and the fourth conductive strip S4 provided in this embodiment are mirror-symmetrical along the center of the substrate, and the second conductive strip S2 and the third conductive strip S3 are mirror-symmetrical along the center of the substrate.

[0040] In an optional embodiment, the substrate provided in this embodiment is in the shape of a rectangular parallelepiped, and the first capacitor C1 and the third capacitor C3 provided in this embodiment are mirror-symmetrical along the center line of the length direction of the substrate, the first inductor L1 and the third inductor L3 are mirror-symmetrical along the center line of the length direction of the substrate, the fourth capacitor C4 and the fifth capacitor C5 are mirror-symmetrical along the center line of the length direction of the substrate, the fourth inductor L4 and the fifth inductor L5 are mirror-symmetrical along the center line of the length direction of the substrate, the first conduction strip S1 and the fourth conduction strip S4 are mirror-symmetrical along the center line of the length direction of the substrate, and the second conduction strip S2 and the third conduction strip S3 are mirror-symmetrical along the center line of the length direction of the substrate.

[0041] In a specific embodiment, the first inductor L1, the second inductor L2, the third inductor L3, the fourth inductor L4, and the fifth inductor L5 are all rectangular spiral coils extending along the thickness direction of the substrate. By configuring the first inductor L1, the second inductor L2, the third inductor L3, the fourth inductor L4, and the fifth inductor L5 provided in this embodiment as rectangular spiral coils extending along the thickness direction of the substrate, the space occupied by the first inductor L1, the second inductor L2, the third inductor L3, the fourth inductor L4, and the fifth inductor L5 in the cross-section of the substrate in the thickness direction can be effectively reduced, thereby enabling the substrate to have a smaller length and width, thereby effectively reducing the volume of the passive band-stop filter provided in this embodiment.

[0042] In a specific embodiment, the first capacitor C1, the second capacitor C2, and the third capacitor C3 of this embodiment are VIC capacitors; the fourth capacitor C4 and the fifth capacitor C5 are both planar MIN (metal-dielectric-metal) capacitors. By configuring the first capacitor C1, the second capacitor C2, and the third capacitor C3 provided in this embodiment as VIC (vertically interdigitated) capacitors, the space occupied by the first capacitor C1, the second capacitor C2, and the third capacitor C3 in the cross-section along the thickness direction of the substrate can be effectively reduced, thereby enabling the substrate to have smaller length and width dimensions, thereby effectively reducing the volume of the passive band-stop filter provided in this embodiment.

[0043] In an optional embodiment, the signal attenuation unit provided in this embodiment further includes a planar metal plate C0, which is disposed in a substrate. The fourth capacitor C4 provided in this embodiment includes a first metal plate, and the fifth capacitor C5 includes a second metal plate. The positions of the first metal plate and the second metal plate correspond to the positions of the planar metal plate C0. The first metal plate and the second metal plate are both disposed parallel to the planar metal plate C0, and the first metal plate and the second metal plate can form a planar MIN capacitor with the planar metal plate C0.

[0044] As shown in Figure 4, to reduce the high-frequency insertion loss of the passive band-stop filter provided in this embodiment, the fourth inductor L4 and the fifth inductor L5 in this embodiment each include multiple rectangular inductor layers. The multiple rectangular inductor layers are spaced apart along the thickness direction of the substrate, and adjacent rectangular inductor layers are electrically connected by conductive pillars. The spacing between adjacent rectangular inductor layers is 0.13 mm. By setting the spacing between adjacent rectangular inductor layers provided in this embodiment to 0.13 mm, the coupling between the inductors themselves can be effectively reduced, the Q value of the inductors can be improved, and thus the high-frequency insertion loss of the filter can be effectively reduced, resulting in the passive band-stop filter provided in this embodiment having a wider high-frequency passband range.

[0045] In an optional embodiment, the first inductor L1 , the second inductor L2 , and the third inductor L3 provided in this embodiment are all four-layer spiral inductor structures.

[0046] In an optional embodiment, the fourth inductor L4 and the fifth inductor L5 provided in this embodiment are both seven-layer spiral inductor structures.

[0047] In an optional embodiment, the passive band-stop filter provided in this embodiment also includes a first grounding module GND1 and a second grounding module GND2. The first grounding module GND1 and the second grounding module GND2 provided in this embodiment are both arranged on the substrate, and the flat metal plate C0 is connected to the first grounding module GND1 and the second grounding module GND2 to achieve grounding of the first resonance attenuation module and the second resonance attenuation module.

[0048] In a specific embodiment, the left cutoff frequency of the passive band-stop filter provided in this embodiment can be adjusted by changing the sizes of the first inductor L1, the second inductor L2, the third inductor L3, the fourth capacitor C4, and the fifth capacitor C5.

[0049] In a specific embodiment, the right cutoff frequency of the passive band-stop filter provided in this embodiment can be adjusted by changing the sizes of the first capacitor C1, the second capacitor C2, the third capacitor C3, the fourth inductor L4, and the fifth inductor L5.

[0050] In an optional embodiment, the frequency adjustment part and the signal attenuation part provided in this embodiment form the inner electrode of the passive band-stop filter; the signal input module P1, the signal output module P2, the first grounding module GND1 and the second grounding module GND2 form the end electrodes of the passive band-stop filter.

[0051] In an optional embodiment, the material of the inner electrode provided in this embodiment is silver.

[0052] In an optional embodiment, the terminal electrode provided in this embodiment is composed of a three-layer structure, which is a silver layer, a nickel layer and a tin layer in order from the middle of the substrate to the outside of the substrate.

[0053] In an optional embodiment, the passive band-stop filter provided in this embodiment is formed by LTCC (low temperature co-fired ceramic) technology, has a volume of 4.8mm*4.2mm*1.5mm, and has a filter order of 5.

[0054] As shown in Figure 5, in a specific embodiment, the passive band-stop filter provided in this embodiment has a center frequency of 1330 MHz, a stopband bandwidth of 1280 MHz to 1580 MHz, and steep stopband rejection of better than 42 dB. The passband ranges are: DC to 1080 MHz and 1580 MHz to 3500 MHz. The passband insertion loss is low, with in-band insertion loss less than 1.8 dB and in-band return loss better than 16 dB. This filter has the advantages of low passband loss, high out-of-band rejection, and low cost, meeting the requirements of downstream electronic equipment for miniaturization, high performance, and low cost.

[0055] In summary, the passive band-stop filter provided by this embodiment has at least the following beneficial technical effects: the passive band-stop filter provided by this embodiment electrically connects the first ends of the two resonant attenuation modules to the common node formed between two adjacent resonant filter modules in the three series-connected resonant filter modules, and grounds the second end of the resonant attenuation module, so that the passive band-stop filter provided by this embodiment can attenuate the interference signal of the preset passband frequency in the radio frequency signal through the resonant attenuation module, and adjust the frequency of the radio frequency signal through the three series-connected resonant filter modules. At the same time, since the passive band-stop filter provided by this embodiment uses the resonant attenuation module to attenuate the interference signal of the preset passband frequency in the radio frequency signal, it can achieve steep stopband suppression.

[0056] The above are merely optional embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included within the scope of the claims of the present application.

Claims

1. A passive band-stop filter, characterized in that: The passive band-stop filter comprises: A signal input module, wherein the signal input module is used to access a radio frequency signal; A frequency adjustment unit, the frequency adjustment unit comprising three series-connected resonant filter modules, the three series-connected resonant filter modules are electrically connected to the signal input module, and are used to adjust the frequency of the radio frequency signal; A signal attenuation unit, the signal attenuation unit comprising two resonance attenuation modules, a common node is formed between two adjacent resonance filter modules of the three series-connected resonance filter modules, a first end of the resonance attenuation module is electrically connected to the common node, and a second end of the resonance attenuation module is grounded, for attenuating a clutter signal of a preset passband frequency in the radio frequency signal; A signal output module, the signal output module is electrically connected to the three series-connected resonant filter modules, and is used to output the processed radio frequency signal.

2. The passive band-stop filter according to claim 1, characterized in that: The three series-connected resonant filter modules are respectively a first resonant filter module, a second resonant filter module and a third resonant filter module, wherein a first end of the first resonant filter module is electrically connected to the signal input module, a second end of the first resonant filter module is electrically connected to a first end of the second resonant filter module, a second end of the second resonant filter module is electrically connected to a first end of the third resonant filter module, and a second end of the third resonant filter module is electrically connected to the signal output module.

3. The passive band-stop filter according to claim 2, characterized in that: A first common node is formed between the first resonance filter module and the second resonance filter module, and a second common node is formed between the second resonance filter module and the third resonance filter module; The two resonance attenuation modules are respectively a first resonance attenuation module and a second resonance attenuation module. The first end of the first resonance attenuation module is electrically connected to the first common node, the first end of the second resonance attenuation module is electrically connected to the second common node, and the second ends of the first resonance attenuation module and the second resonance attenuation module are both grounded.

4. The passive band-stop filter according to claim 3, characterized in that: The first resonant filter module includes a first inductor and a first capacitor, the first inductor and the first capacitor are connected in parallel to resonate, the second resonant filter module includes a second inductor and a second capacitor, the second inductor and the second capacitor are connected in parallel to resonate, and the third resonant filter module includes a third inductor and a third capacitor, the third inductor and the third capacitor are connected in parallel to resonate.

5. The passive band-stop filter according to claim 4, characterized in that: The first resonance attenuation module includes a fourth capacitor and a fourth inductor, and the fourth capacitor and the fourth inductor are connected in series to resonate. The second resonance attenuation module includes a fifth capacitor and a fifth inductor, and the fifth capacitor and the fifth inductor are connected in series to resonate.

6. The passive band-stop filter according to claim 5, characterized in that: The passive band-stop filter also includes a substrate, the frequency adjustment unit and the signal attenuation unit are both arranged in the substrate, the first resonance filter module and the third resonance filter module are mirror-symmetrical along the center of the substrate, and the first resonance attenuation module and the second resonance attenuation module are mirror-symmetrical along the center of the substrate.

7. The passive band-stop filter according to any one of claims 4 to 6, characterized in that: The first inductor, the second inductor, the third inductor, the fourth inductor and the fifth inductor are all rectangular spiral coils extending along the thickness direction of the substrate.

8. The passive band-stop filter according to any one of claims 4 to 6, characterized in that: The first capacitor, the second capacitor and the third capacitor are VIC capacitors; The fourth capacitor and the fifth capacitor are both planar MIN capacitors.

9. The passive band-stop filter according to claim 7, characterized in that: The fourth inductor and the fifth inductor both include a plurality of rectangular inductor layers, which are spaced apart along the thickness direction of the substrate, and two adjacent rectangular inductor layers are electrically connected via conductive columns, and the spacing between two adjacent rectangular inductor layers is 0.13 mm.

10. The passive band-stop filter according to claim 6, characterized in that: The substrate is a low-loss, low-temperature co-fired ceramic medium with a relative dielectric constant of 5.0±0.3 and a dielectric loss tanα≤0.003.

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