LC band-pass filter circuit and filter

Abstract

The utility model discloses an LC band-pass filter circuit and a filter, and belongs to the technical field of microwave filtering, the circuit comprises an input port, an output port, a first band-pass filter unit, a first attenuation suppression unit, a second attenuation suppression unit and a second band-pass filter unit; one end of the first attenuation suppression unit is connected with the input port, and the other end is grounded; the output end of the first band-pass filtering unit is connected with the input end of the second band-pass filtering unit; the output end of the second band-pass filtering unit is connected with the output port; and the second attenuation suppression unit is respectively connected with the input port, the input end and the output end of the first band-pass filtering unit and the input end of the second band-pass filtering unit. According to the utility model, a plurality of transmission zeros are introduced into each band-pass filtering unit, the plurality of transmission zeros are formed through the grounded attenuation suppression unit and the band-pass filtering units, and out-of-band suppression and insertion loss suppression are provided for signal filtering.

Description

Technical Field

[0001] This utility model relates to the field of microwave filtering technology, and in particular to an LC bandpass filter circuit and filter. Background Technology

[0002] In RF circuit design, LC bandpass filters play an irreplaceable role and have advantages in intermediate frequency circuits. As plate circuits are becoming smaller and the requirements for out-of-band rejection and insertion loss of bandpass filters are becoming more stringent, it is necessary to increase the order and transmission zeros to achieve high rejection performance.

[0003] Traditional LC filters are difficult to increase in the number of transmission zeros, and increasing the filter order increases insertion loss, which is often a contradiction. Traditional LC filters are difficult to achieve high near-end rejection attenuation, and usually require increasing the order and transmission zeros to change the out-of-band rejection attenuation. However, too many transmission zeros and orders will bring additional insertion loss and circuit complexity.

[0004] Therefore, there is an urgent need for an LC bandpass filter circuit and filter that can provide good out-of-band rejection and insertion loss suppression during signal filtering. Utility Model Content

[0005] Therefore, it is necessary to provide an LC bandpass filter circuit and filter that can provide good out-of-band rejection and insertion loss suppression during signal filtering.

[0006] To achieve the above objectives, on the one hand, this utility model provides an LC bandpass filter circuit, including: an input port, an output port, a first bandpass filter unit, a first attenuation suppression unit, a second attenuation suppression unit, and a second bandpass filter unit;

[0007] One end of the first attenuation suppression unit is connected to the input port, and the other end is grounded; the output end of the first bandpass filter unit is connected to the input end of the second bandpass filter unit; the output end of the second bandpass filter unit is connected to the output port; the second attenuation suppression unit is connected to the input port, the input end and the output end of the first bandpass filter unit, and the input end of the second bandpass filter unit, respectively.

[0008] The first bandpass filter unit and the second bandpass filter unit include multiple LC series resonant units that are grounded. Through the grounded first attenuation suppression unit and the second attenuation suppression unit, as well as the first bandpass filter unit and the second bandpass filter unit, multiple filtering transmission zeros are formed during the signal filtering process, providing out-of-band suppression and insertion loss suppression for signal filtering.

[0009] In one possible implementation, the first attenuation suppression unit includes a first inductor and a first capacitor;

[0010] One end of the first inductor is connected to the input port, and the other end is grounded;

[0011] One end of the first capacitor is connected to the input port, and the other end is grounded.

[0012] In one possible implementation, the LC series resonant unit includes an inductor and a capacitor connected in series, with one end of the plurality of LC series resonant units connected to the first bandpass filter unit and the second bandpass filter unit, and the other end grounded, thereby generating a bandpass transmission zero through the grounded plurality of LC series resonant units.

[0013] In one possible implementation, the first bandpass filter unit includes a first low-pass filter subunit and a first high-pass filter subunit;

[0014] The first low-pass filter subunit and the first high-pass filter subunit are connected in series.

[0015] In one possible implementation, the plurality of bandpass transmission zeros include a first transmission zero and a second transmission zero; the plurality of LC series resonant units include a first LC resonant subunit and a second LC resonant subunit; the first low-pass filter subunit includes a second inductor, a third inductor, a first LC resonant subunit, and a second LC resonant subunit;

[0016] The second and third inductors are connected in series;

[0017] One end of the first LC resonator unit is connected to the second inductor, and the other end is grounded to form the first transmission zero.

[0018] One end of the second LC resonator unit is connected to the third inductor, and the other end is grounded to form a second transmission zero.

[0019] In one possible implementation, the plurality of bandpass transmission zeros further includes a third transmission zero and a fourth transmission zero; the plurality of LC series resonant units further includes a third LC resonant subunit and a fourth LC resonant subunit; the first high-pass filter subunit includes a second capacitor and a third capacitor;

[0020] The second capacitor and the third capacitor are connected in series;

[0021] One end of the third LC resonator unit is connected to the second capacitor, and the other end is grounded to form the third transmission zero.

[0022] One end of the fourth LC resonator unit is connected to the third capacitor, and the other end is grounded to form the fourth transmission zero.

[0023] In one possible implementation, the second attenuation suppression unit includes a fifth capacitor and a sixth capacitor;

[0024] One end of the fifth capacitor is connected to the input port, and the other end is connected to the input of the first bandpass filter unit.

[0025] One end of the sixth capacitor is connected to the output of the first bandpass filter unit, and the other end is grounded.

[0026] In one possible implementation, the second bandpass filter unit includes a second low-pass filter subunit and a second high-pass filter subunit;

[0027] The second low-pass filter subunit and the second high-pass filter subunit are connected in series.

[0028] In one possible implementation, the plurality of bandpass transmission zeros further includes a fifth transmission zero and a sixth transmission zero; the plurality of LC series resonant units further includes a fifth LC resonator unit and a sixth LC resonator unit;

[0029] The second low-pass filter subunit includes a fourth inductor and a fifth LC resonant subunit;

[0030] The second high-pass filter subunit includes a fourth capacitor and a sixth LC resonant subunit;

[0031] The fourth inductor and the fourth capacitor are connected in series;

[0032] One end of the fifth LC resonator unit is connected to the fourth inductor, and the other end is grounded to form the fifth transmission zero.

[0033] One end of the sixth LC resonator unit is connected to the fourth capacitor, and the other end is grounded to form the sixth transmission zero.

[0034] Secondly, this utility model also provides a filter, including the LC bandpass filter circuit described above.

[0035] The beneficial effects of this invention are as follows: By setting an input port, an output port, a first bandpass filter unit, a first attenuation suppression unit, a second attenuation suppression unit, and a second bandpass filter unit; one end of the first attenuation suppression unit is connected to the input port, and the other end is grounded; the output end of the first bandpass filter unit is connected to the input end of the second bandpass filter unit; the output end of the second bandpass filter unit is connected to the output port; the second attenuation suppression unit is connected to the input port, the input end and output end of the first bandpass filter unit, and the input end of the second bandpass filter unit respectively; the first and second bandpass filter units include multiple grounded LC series resonant units. Through the grounded first and second attenuation suppression units and the first and second bandpass filter units, multiple filtering transmission zeros are formed during the signal filtering process, providing out-of-band suppression and insertion loss suppression for signal filtering. This invention, by introducing multiple bandpass transmission zeros in the bandpass filter unit, combined with the grounded attenuation suppression unit and the bandpass filter unit, forms multiple filtering transmission zeros, providing out-of-band suppression and insertion loss suppression for signal filtering. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0037] Figure 1 This is a schematic diagram of an embodiment of the LC bandpass filter circuit provided by this utility model. Detailed Implementation

[0038] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the scope of protection of the present utility model.

[0039] In the description of the embodiments of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0040] The terms "first," "second," etc., used in the embodiments of this utility model are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a technical feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature.

[0041] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the present invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0042] Before describing the embodiments, the relevant terms are defined as follows:

[0043] A transmission zero is the frequency at which the filter's transfer function equals zero. At this frequency, signal energy cannot pass through the filter, thus completely blocking the signal. From an energy perspective, the transmission zero is the frequency at which power is totally reflected back to the signal source.

[0044] A bandpass filter is a filter that allows signals within a specific frequency range to pass through while suppressing signals below and above that frequency range.

[0045] This invention provides an LC bandpass filter circuit and filter, which will be described below.

[0046] In some embodiments of this utility model, such as Figure 1 As shown, Figure 1 A schematic diagram of an embodiment of the LC bandpass filter circuit provided by this utility model includes: an input port 10, an output port 50, a first bandpass filter unit 30, a first attenuation suppression unit 20, a second attenuation suppression unit (not shown in the figure), and a second bandpass filter unit 40.

[0047] One end of the first attenuation suppression unit 20 is connected to the input port 10, and the other end is grounded; the output end of the first bandpass filter unit 30 is connected to the input end of the second bandpass filter unit 40; the output end of the second bandpass filter unit 40 is connected to the output port 50; the second attenuation suppression unit is connected to the input port 10, the input end and the output end of the first bandpass filter unit 30, and the input end of the second bandpass filter unit 40, respectively.

[0048] The first bandpass filter unit 30 and the second bandpass filter unit 40 include multiple LC series resonant units that are grounded. Through the grounded first attenuation suppression unit 20 and the second attenuation suppression unit, as well as the first bandpass filter unit 30 and the second bandpass filter unit 40, multiple filtering transmission zeros are formed during the signal filtering process, providing out-of-band suppression and insertion loss suppression for signal filtering.

[0049] It should be noted that this embodiment is an improvement on the elliptic filter circuit. An elliptic filter is a filter with equal ripple characteristics in both the passband and stopband. Compared with other types of filters, elliptic filters have the smallest passband and stopband ripple under the same order condition, and can obtain a narrower transition bandwidth. First, the center frequency, bandwidth, passband ripple, and stopband attenuation parameters in the bandpass filter circuit are determined. An appropriate elliptic filter circuit order is selected. The higher the order, the better the filtering performance, but the higher the design and implementation complexity. Therefore, it is necessary to select an appropriate order. Through the elliptic function, the parameters of each elliptic filter circuit, and the allowable specific frequency range, the parameters of each component in the low-pass and high-pass filter circuits are set. The low-pass and high-pass filter circuits are cascaded to form a bandpass filter unit. The various filter components are isolated by a grounded series LC circuit. The constructed filter circuit is simulated and tested using test equipment such as a network analyzer or spectrum analyzer. Based on the test results, the parameters of each component in the circuit are adjusted and optimized to improve the filter performance.

[0050] Specifically, the first attenuation unit forms the first transmission zero by grounding, improving the attenuation characteristics of the transmission zeros formed on both sides of the passband. In this embodiment, appropriate parameters are calculated and set for the components in the first attenuation unit. Through simulation testing, the attenuation of the left and right sides of the passband can be increased by 10dB. The first bandpass filter unit performs the first filtering and screening of the input signal, allowing signals within a specific frequency range to pass. The second attenuation suppression unit isolates the first bandpass filter unit from the second bandpass filter unit, improving the attenuation of the transmission zeros formed on both sides of the passband. At the same time, the capacitor connected to the input port serves as a component of the second attenuation suppression unit. In the first and second bandpass filter units, combined with high-pass filter components, out-of-band rejection is further enhanced. The second bandpass filter unit further filters the signal to ensure that only signals within the required frequency range can pass through. In the first and second bandpass filter units, multiple grounded series LC circuits are set to form multiple transmission zeros. Transmission zeros are generated in the stopband of the filter, thereby further improving the stopband attenuation performance of the filter. The first and second bandpass filter units connected in series, combined with the grounded series LC circuits, minimize transmission loss, improve transmission zero characteristics, and increase the attenuation amplitude of the left and right passband rejection.

[0051] This embodiment includes an input port 10, an output port 50, a first bandpass filter unit 30, a first attenuation suppression unit 20, a second attenuation suppression unit, and a second bandpass filter unit 40. One end of the first attenuation suppression unit 20 is connected to the input port 10, and the other end is grounded. The output end of the first bandpass filter unit 30 is connected to the input end of the second bandpass filter unit 40. The output end of the second bandpass filter unit 40 is connected to the output port 50. The second attenuation suppression unit is connected to the input port 10, the input end and the output end of the first bandpass filter unit 30, and the input end of the second bandpass filter unit 40, respectively. The first bandpass filter unit 30 and the second bandpass filter unit 40 include multiple grounded LC series resonant units. Through the grounded first attenuation suppression unit 20 and the second attenuation suppression unit, as well as the first bandpass filter unit 30 and the second bandpass filter unit 40, multiple filtering transmission zeros are formed during the signal filtering process, providing out-of-band suppression and insertion loss suppression for signal filtering.

[0052] This invention forms multiple filtering transmission zeros by introducing multiple bandpass transmission zeros into the bandpass filter unit, combined with the grounded attenuation suppression unit and the bandpass filter unit, thereby providing out-of-band suppression and insertion loss suppression for signal filtering.

[0053] In some embodiments of this utility model, the first attenuation suppression unit 20 includes a first inductor L1 and a first capacitor C1;

[0054] One end of the first inductor L1 is connected to the input port 10, and the other end is grounded;

[0055] One end of the first capacitor C1 is connected to the input port 10, and the other end is grounded.

[0056] Specifically, appropriate inductors and capacitors are selected based on parameters such as required bandwidth, center frequency, and out-of-band rejection. By adjusting the parameter values ​​of the inductors and capacitors, the desired frequency response characteristics of the filter can be achieved. Grounding the inductor allows it to form a more stable electrical connection with other components in the circuit, reducing electromagnetic interference and noise. Grounding the capacitor improves its stability, allowing for better absorption and release of electrical energy, thereby improving the frequency response and transmission zero characteristics of the filter. Setting grounded inductors and capacitors at the input port of the bandpass filter circuit forms an LC resonant circuit, providing frequency selectivity for the circuit. Through multiple experiments and tests, the values ​​of the inductors and capacitors are precisely adjusted to find the optimal combination, accurately controlling the passband and stopband characteristics of the filter, improving the transmission zero attenuation characteristics on both sides of the passband, and enhancing the filter's performance.

[0057] This embodiment uses a grounded inductor and capacitor to form an LC resonant circuit, which improves the transmission zero-point attenuation characteristics formed on both sides of the passband and enhances the filter's performance.

[0058] In some embodiments of this utility model, the LC series resonant unit includes an inductor and a capacitor connected in series. One end of the plurality of LC series resonant units is connected to the first bandpass filter unit and the second bandpass filter unit, and the other end is grounded. The bandpass transmission zero is generated through the grounded plurality of LC series resonant units.

[0059] Specifically, by setting multiple grounded LC series resonant units on the bandpass filter, the grounded LC series resonant units generate a resonance effect at a specific frequency, thereby introducing transmission zeros into the transmission characteristics of the filter. When the frequency of the input signal is equal to the resonant frequency, the resonant unit will absorb most of the signal energy, resulting in a reduction in the amplitude of the input signal and forming transmission zeros. Through multiple grounded series LC resonant units, multiple transmission zeros can be introduced on both sides of the passband. These transmission zeros can further improve the frequency selectivity and stopband rejection capability of the filter.

[0060] This embodiment improves the filter's performance by introducing multiple transmission zeros on both sides of the passband through multiple grounded series LC resonant units.

[0061] In some embodiments of this utility model, the first bandpass filter unit 30 includes a first low-pass filter subunit 31 and a first high-pass filter subunit 32;

[0062] The first low-pass filter subunit 31 and the first high-pass filter subunit 32 are connected in series.

[0063] Specifically, the high-pass filter unit is used to remove low-frequency components from the signal, retaining only the high-frequency part. It allows signals with frequencies higher than a preset high-pass threshold to pass through, while signals with frequencies lower than the high-pass threshold are attenuated or blocked. Conversely, the low-pass filter unit removes high-frequency components from the signal, retaining only the low-frequency part. It allows signals with frequencies lower than a preset low-pass threshold to pass through, while signals with frequencies higher than the low-pass threshold are attenuated or blocked. By connecting the high-pass filter unit and the low-pass filter unit in series and adjusting their cutoff frequencies, only signals located between these two cutoff frequencies can pass through.

[0064] In some embodiments of this utility model, the multiple bandpass transmission zeros include a first transmission zero P1 and a second transmission zero P2; the multiple LC series resonant units include a first LC resonant subunit 311 and a second LC resonant subunit 312; the first low-pass filter subunit 31 includes a second inductor L2, a third inductor L3, a first LC resonant subunit 311, and a second LC resonant subunit 312.

[0065] The second inductor L2 and the third inductor L3 are connected in series;

[0066] One end of the first LC resonator unit 311 is connected to the second inductor L2, and the other end is grounded, which is used to form the first transmission zero point P1;

[0067] One end of the second LC resonator unit 312 is connected to the third inductor L3, and the other end is grounded, which is used to form the second transmission zero point P2.

[0068] Specifically, inductors have the characteristic of blocking AC while passing DC, and the higher the AC frequency, the less likely it is to pass through. Therefore, the second inductor L2 and the third inductor L3 connected in series will impede high-frequency signals. The two inductors are connected in series, and a series LC circuit grounded is connected between each inductor, thus forming a multi-stage low-pass filter structure. Each additional stage of the filter further increases the attenuation of high-frequency signals while retaining low-frequency signals to form a low-pass filter subunit.

[0069] This embodiment forms a multi-stage low-pass filter by connecting two inductors in series and two grounded series LC circuits in the middle of each inductor. This low-pass filter circuit has a simple structure, good stability, and high reliability.

[0070] In some embodiments of this utility model, the multiple bandpass transmission zeros further include a third transmission zero P3 and a fourth transmission zero P4; the multiple LC series resonant units further include a third LC resonant subunit 321 and a fourth LC resonant subunit 322; the first high-pass filter subunit 32 includes a second capacitor C2 and a third capacitor C3;

[0071] The second capacitor C2 and the third capacitor C3 are connected in series;

[0072] One end of the third LC resonator unit 321 is connected to the second capacitor C2, and the other end is grounded, which is used to form the third transmission zero point P3;

[0073] One end of the fourth LC resonator unit 322 is connected to the third capacitor C3, and the other end is grounded to form the fourth transmission zero P4.

[0074] Specifically, the series-connected second capacitor C2 and third capacitor C3 impede high-frequency signals because capacitors have a greater impedance to high-frequency signals than to low-frequency signals. When the signal passes through the first high-pass filter subunit 32, it first encounters the third LC resonant subunit 321, which attenuates or reflects the signal to varying degrees depending on its frequency. Then, the signal passes through the second capacitor C2, undergoing high-frequency attenuation, then encounters the fourth LC resonant subunit 322, further encounters the third LC resonant subunit 321, and finally passes through the third capacitor C3, undergoing further high-frequency attenuation. The entire circuit forms a filter with a specific frequency response.

[0075] This embodiment forms a multi-stage high-pass filter by connecting two capacitors in series, and connecting two grounded series LC circuits in the middle of each capacitor to form an effective high-pass filter structure. This high-pass filter circuit has a simple structure, good stability, and high reliability.

[0076] In some embodiments of this utility model, the second attenuation suppression unit includes a fifth capacitor C5 and a sixth capacitor C6;

[0077] One end of the fifth capacitor C5 is connected to the input port 10, and the other end is connected to the input terminal of the first bandpass filter unit 30;

[0078] One end of the sixth capacitor C6 is connected to the output terminal of the first bandpass filter unit 30, and the other end is grounded.

[0079] Specifically, by connecting the fifth capacitor C5 in series with the first bandpass filter unit 30, the performance of the filter is further enhanced by utilizing the frequency response characteristics of the capacitor and the frequency selection function of the bandpass filter circuit. By interleaving the capacitor and inductor in series, the transmission zero-point characteristics are improved, and the attenuation amplitude of the left and right bandpass suppression is increased, providing better out-of-band suppression in the first bandpass filter unit 30.

[0080] Furthermore, a grounded sixth capacitor C6 is placed between the first bandpass filter unit 30 and the second bandpass filter unit 40 to isolate the first bandpass filter unit 30 and the second bandpass filter unit 40, thereby improving the attenuation of the transmission zeros formed on both sides of the passband and reducing signal transmission loss.

[0081] This embodiment provides excellent out-of-band rejection for the filter circuit by setting a capacitor connected in series with the pass filter unit and a capacitor grounded, thereby improving the attenuation of the left and right passband rejection and reducing transmission loss.

[0082] In some embodiments of this utility model, the second bandpass filter unit 40 includes a second low-pass filter subunit 41 and a second high-pass filter subunit 42;

[0083] The second low-pass filter subunit 41 and the second high-pass filter subunit 42 are connected in series.

[0084] This embodiment uses a simple second bandpass filter unit 40 to filter the output signal of the first bandpass filter unit 30 again, which can more effectively select and transmit signals within a specific frequency range, more effectively suppress out-of-band interference, and improve the performance of the filter circuit.

[0085] In some embodiments of this utility model, the multiple bandpass transmission zeros further include a fifth transmission zero P5 and a sixth transmission zero P6; the multiple LC series resonant units further include a fifth LC resonator unit 411 and a sixth LC resonator unit 421;

[0086] The second low-pass filter subunit 41 includes a fourth inductor L4 and a fifth LC resonant subunit 411;

[0087] The second high-pass filter subunit 42 includes a fourth capacitor C4 and a sixth LC resonant subunit 421;

[0088] The fourth inductor L4 and the fourth capacitor C4 are connected in series;

[0089] One end of the fifth LC resonator unit 411 is connected to the fourth inductor L4, and the other end is grounded to form the fifth transmission zero point P5.

[0090] One end of the sixth LC resonator unit 421 is connected to the fourth capacitor C4, and the other end is grounded to form the sixth transmission zero P6.

[0091] Specifically, connecting inductor L4 and capacitor in series, and connecting grounded series LC resonant units at their output terminals respectively, forms a simple filter circuit. This can be seen as a combination of two interacting LC resonant circuits, with each resonant circuit performing frequency selection and filtering on its input signal.

[0092] Based on the above-described LC bandpass filter circuit, this utility model embodiment also provides a corresponding filter that can realize the technical solution described in the above-described LC bandpass filter circuit embodiment, which will not be repeated here.

[0093] The LC bandpass filter circuit provided by this utility model has been described in detail above. Specific examples have been used to illustrate the principle and implementation of this utility model. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​this utility model. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​this utility model. Therefore, the content of this specification should not be construed as a limitation of this utility model.

Claims

1. An LC bandpass filter circuit, characterized by, The application relates to a signal filter. The signal filter comprises an input port, an output port, a first band-pass filter unit, a first attenuation suppression unit, a second attenuation suppression unit and a second band-pass filter unit. One end of the first attenuation suppression unit is connected with the input port, and the other end is grounded; the output end of the first band-pass filter unit is connected with the input end of the second band-pass filter unit; and the output end of the second band-pass filter unit is connected with the output port. The second attenuation suppression unit is connected with the input port, the input end and the output end of the first band-pass filter unit and the input end of the second band-pass filter unit respectively. The first band-pass filter unit and the second band-pass filter unit comprise a plurality of LC series resonance units grounded, and a plurality of filter transmission zero points are formed in the signal filtering process through the first attenuation suppression unit and the second attenuation suppression unit grounded and the first band-pass filter unit and the second band-pass filter unit, so that the signal filtering is provided with out-of-band suppression and insertion loss suppression.

2. The LC bandpass filter circuit of claim 1, wherein, The first attenuation suppression unit comprises a first inductor and a first capacitor. One end of the first inductor is connected with the input port, and the other end is grounded. One end of the first capacitor is connected with the input port, and the other end is grounded.

3. The LC bandpass filter circuit of claim 1, wherein, The LC series resonance unit comprises a series-connected inductor and capacitor, one end of the plurality of LC series resonance units is connected with the first band-pass filter unit and the second band-pass filter unit, and the other end is grounded, so that the filter transmission zero points are generated through the plurality of LC series resonance units grounded.

4. The LC bandpass filter circuit of claim 1, wherein, The first band-pass filter unit comprises a first low-pass filter subunit and a first high-pass filter subunit. The first low-pass filter subunit and the first high-pass filter subunit are connected in series.

5. The LC bandpass filter circuit of claim 4, wherein, The plurality of filter transmission zero points comprise a first transmission zero point and a second transmission zero point; the plurality of LC series resonance units comprise a first LC resonance subunit and a second LC resonance subunit; and the first low-pass filter subunit comprises a second inductor, a third inductor, the first LC resonance subunit and the second LC resonance subunit. The second inductor and the third inductor are connected in series. One end of the first LC resonance subunit is connected with the second inductor, and the other end is grounded, so as to form the first transmission zero point. One end of the second LC resonance subunit is connected with the third inductor, and the other end is grounded, so as to form the second transmission zero point.

6. The LC bandpass filter circuit of claim 5, wherein, The plurality of filter transmission zero points further comprise a third transmission zero point and a fourth transmission zero point; the plurality of LC series resonance units further comprise a third LC resonance subunit and a fourth LC resonance subunit; and the first high-pass filter subunit comprises a second capacitor and a third capacitor. The second capacitor and the third capacitor are connected in series. One end of the third LC resonance subunit is connected with the second capacitor, and the other end is grounded, so as to form the third transmission zero point. One end of the fourth LC resonance subunit is connected with the third capacitor, and the other end is grounded, so as to form the fourth transmission zero point.

7. The LC bandpass filter circuit of claim 1, wherein, The second attenuation suppression unit comprises a fifth capacitor and a sixth capacitor. One end of the fifth capacitor is connected with the input port, and the other end is connected with the input end of the first band-pass filter unit. One end of the sixth capacitor is connected with the output end of the first band-pass filter unit, and the other end is grounded.

8. The LC bandpass filter circuit of claim 1, wherein, The second band-pass filter unit comprises a second low-pass filter subunit and a second high-pass filter subunit; The second low-pass filter subunit and the second high-pass filter subunit are connected in series.

9. The LC bandpass filter circuit of claim 8, wherein, The plurality of filter transmission zeros further comprises a fifth transmission zero and a sixth transmission zero; and the plurality of LC series resonance units further comprises a fifth LC resonance subunit and a sixth LC resonance subunit. The second low-pass filter subunit comprises a fourth inductor and a fifth LC resonance subunit; The second high-pass filter subunit comprises a fourth capacitor and a sixth LC resonance subunit; The fourth inductor and the fourth capacitor are connected in series; One end of the fifth LC resonance subunit is connected to the fourth inductor, and the other end is grounded, for forming a fifth transmission zero; One end of the sixth LC resonance subunit is connected to the fourth capacitor, and the other end is grounded, for forming a sixth transmission zero.

10. A filter, characterized by, An LC band-pass filter circuit comprising any one of claims 1 to 9.

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