CN114464973B - Reconfigurable filter attenuator based on continuously adjustable center frequency - Google Patents

Abstract

The invention provides a reconfigurable filter attenuator based on continuously adjustable center frequency, which comprises a substrate and a filter power dividing module constructed on the substrate; the filtering power dividing module comprises three microstrip resonators distributed in parallel at intervals, one end of each microstrip resonator is connected with a resonance adjusting unit for adjusting the resonance frequency of the microstrip resonator, and a coupling adjusting unit for adjusting the coupling state between the two adjacent microstrip resonators is connected between the two microstrip resonators; the microstrip resonator in the middle is connected with the first port through a port microstrip line, and the two microstrip resonators on two sides are connected with output microstrip lines respectively. The reconfigurable filter attenuator can realize the flexible reconfiguration of the center frequency while realizing the continuous adjustment of the pass band amplitude, thereby effectively enhancing the flexibility of the system.

Description

Reconfigurable filter attenuator based on continuously adjustable center frequency

technical field

The invention relates to a signal processing device in a wireless communication system, in particular to a reconfigurable filter attenuator based on a continuously adjustable center frequency.

Background technique

As a signal amplitude control device, the attenuator is widely used in various communication, radar and test systems. For example, in phased-array systems, attenuators are often used to adjust the amplitude ratio between signal paths to implement beamforming. As a frequency selection device, the band-pass filter is also an important part of the communication system. It is often used to select the operating frequency of the system and filter out clutter interference. The integrated design of the attenuator and the filter can effectively reduce the size of the system and reduce the cost of system production.

At present, a variety of feasible composite design schemes of filter attenuators have appeared in the prior art, including graphene loading design schemes and distributed digital switching design schemes. However, the existing filter attenuators usually only work at a fixed frequency, which is difficult to meet the multi-frequency and multi-mode performance requirements of modern communication systems and radar detection systems. Moreover, in the prior art that can realize the function of the filter attenuator, a variety of different device products are usually combined directly, which is not conducive to miniaturization and integration design.

Contents of the invention

The purpose of the present invention is to at least partly solve the above-mentioned problems in the prior art, and provide a novel reconfigurable filter attenuator with continuously adjustable center frequency, which can realize the flexibility of the center frequency while realizing the continuous adjustment of the passband amplitude. Refactoring to effectively enhance system flexibility.

The reconfigurable filter attenuator based on the continuously adjustable center frequency provided by the present invention includes a substrate and a filter power division module built on the substrate;

The filter power division module includes three microstrip resonators distributed in parallel intervals, one end of each microstrip resonator is connected to a resonance adjustment unit for adjusting the resonant frequency of the microstrip resonator, and two adjacent microstrip resonators A coupling adjustment unit for adjusting the coupling state between the two microstrip resonators is connected between the resonators;

Wherein, the microstrip resonator located in the middle is connected to the first port through a port microstrip line, and the two microstrip resonators located on both sides are respectively connected to output microstrip lines.

Preferably, each of the microstrip resonators includes a narrow microstrip line and a wide microstrip line, and the narrow microstrip line and the wide microstrip line are connected to form a step impedance resonator.

Preferably, each of the resonance adjustment units includes a first varactor diode and a first fixed capacitor, one end of the first fixed capacitor is connected to the end of the narrow microstrip line corresponding to the microstrip resonator, and the other end is connected to the first fixed capacitor. The cathode of one varactor is connected, and the anode of the first varactor is grounded.

Preferably, each of the coupling adjustment units includes two second varactor diodes, and the two second varactor diodes are connected in series in the width of two adjacent microstrip resonators in a back-to-back manner. between the microstrip lines.

Preferably, an impedance matching unit is connected between the narrow microstrip line of the microstrip resonator in the middle and the port microstrip line, and the wide microstrips of the two microstrip resonators on both sides An impedance matching unit is respectively connected between the line and the output microstrip line, and each impedance matching unit includes a third variable capacitance diode and a second fixed capacitor, and the anode of the third variable capacitance diode is connected to the corresponding narrow microstrip On the strip line, the cathode of the third variable capacitance diode is connected to the second fixed capacitor.

As preferably, the narrow microstrip line of the microstrip resonator in the middle is close to the narrow microstrip line of the microstrip resonator on one side thereof, so that in the energized state, the microstrip resonator in the middle and the microstrip resonator on the one side Magnetic coupling can be formed between the microstrip resonators; the narrow microstrip line of the microstrip resonator in the middle is far away from the narrow microstrip line of the microstrip resonator on the other side, so that in the energized state, the microstrip in the middle Magnetic coupling cannot transfer energy between the strip resonator and the microstrip resonator on this other side.

Preferably, in each of the resonance adjustment units, a bias circuit is loaded between the first varactor diode and the first fixed capacitor; in each of the coupling adjustment units, two of the second varactors A bias circuit is loaded between the capacitor diodes; in each of the impedance matching units, a bias circuit is loaded between the third variable capacitance diode and the second fixed capacitor.

Preferably, the wide microstrip line of each microstrip resonator is connected with a grounding resistor.

Preferably, it also includes a broadband balun module with a broadband phase shifting unit and a Wilkinson power divider, the broadband phase shifting unit has a first transmission path and a second transmission path, and the first transmission path and the second transmission path Both ends of the Wilkinson power divider are respectively connected between the output end of the Wilkinson power divider and the output microstrip line, and the input end of the Wilkinson power divider is connected to the second port.

Preferably, the first transmission path includes a coupled transmission line with an electrical length of 180°, and an open line with an electrical length of 45° and an open line with an electrical length of 45° are vertically loaded on both ends of the coupled transmission line. The grounding short-circuit line; the second transmission path includes a bent transmission line with an electrical length of 180° and an impedance equal to the port impedance of the Wilkinson power divider.

Technical effect of the present invention is at least reflected in:

In some embodiments, the reconfigurable filter attenuator provided by the present invention adopts a filter power divider with a new structure design, and by adjusting the output phase and power distribution ratio of the filter power divider, good bandpass filter performance can be formed At the same time, the continuous and flexible adjustment of the amplitude in the passband is realized, which effectively reduces the system volume and reduces the system cost.

In some embodiments, the continuous adjustment of the working frequency can be realized by introducing a reconstruction element into the filter power divider, so that the device can support various working frequency requirements, and the system flexibility is effectively enhanced.

In other embodiments, the reconfigurable filter attenuator provided by the present invention adopts a cascaded design structure of filter power splitter and broadband balun, which can better realize the filter attenuation function with continuously adjustable center frequency , compared with existing filter attenuators, it has multiple performance advantages such as multi-functional integration and device miniaturization.

Description of drawings:

FIG. 1 is a schematic structural diagram of a reconfigurable filter attenuator according to an embodiment of the present application;

FIG. 2 is a schematic structural diagram of a reconfigurable filter attenuator according to another embodiment of the present application;

FIG. 3 is a diagram showing the dimension parameters of the reconfigurable filter attenuator in the embodiment of the present application;

FIG. 4 is a physical diagram of a reconfigurable filter attenuator according to an embodiment of the present application;

Fig. 5 is the S-parameter test result diagram of the central frequency of the reconfigurable filter attenuator of the embodiment of the present application being 1.01 GHz;

FIG. 6 is a diagram of the S-parameter test results of the central frequency of the reconfigurable filter attenuator of the embodiment of the present application being 1.09 GHz;

FIG. 7 is a graph of S-parameter test results of the reconfigurable filter attenuator of the embodiment of the present application with a center frequency of 1.19 GHz.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

See also shown in Fig. 1-7, the specific embodiment that the present invention provides is as follows:

Referring to FIG. 1, as an embodiment, a reconfigurable filter attenuator based on a continuously adjustable center frequency includes a substrate 1 and a filter power division module built on the substrate 1;

The filter power division module includes three microstrip resonators (2, 3, 4) distributed in parallel at intervals, and one end of each microstrip resonator is connected with a resonance adjustment unit for adjusting the resonant frequency of the microstrip resonator. A coupling adjustment unit for adjusting the coupling state between the two microstrip resonators is connected between the two adjacent microstrip resonators;

Wherein, the microstrip resonator located in the middle is connected to the first port (port 1) through the port microstrip line 5, and the two microstrip resonators located on both sides are respectively connected with output microstrip lines (6, 7 ).

It can be understood that, in the filter power division module of this embodiment, the continuous adjustment of the operating frequency can be realized by introducing the reconfiguration element, so that the device can support various operating frequency requirements, and the system flexibility is effectively enhanced. Specifically, the continuous adjustment and control of the working frequency can be realized through the resonance adjustment unit; in addition, the coupling state between the resonators can be adjusted through the coupling adjustment unit, and the microstrip resonator located in the middle to the two sides of the resonator can be realized. Power distribution ratio of a microstrip resonator. Furthermore, through the output phase and power distribution ratio of the filter power division module, while forming good band-pass filtering performance, continuous and flexible adjustment of the amplitude in the pass band can be realized, effectively reducing the system volume and system cost.

As shown in Figure 1, as a preferred implementation, each of the microstrip resonators includes a narrow microstrip line and a wide microstrip line, and the narrow microstrip line and the wide microstrip line are connected to form a step impedance resonator. Specifically, for the convenience of description, the microstrip resonator located in the middle is called the first resonator 2, the microstrip resonator located below is called the second resonator 3, and the microstrip resonator located above is called the third resonator device 4; the first resonator 2 is composed of narrow microstrip line 201 and wide microstrip line 202, the second resonator 3 is composed of narrow microstrip line 301 and wide microstrip line 302, and the third resonator 4 is composed of narrow microstrip line The microstrip line 401 and the wide microstrip line 402 are connected, and the microstrip lines of the three resonators are parallel to each other.

As a preferred implementation manner, each of the resonance adjustment units includes a first varactor diode and a first fixed capacitor, one end of the first fixed capacitor is connected to the end of the narrow microstrip line corresponding to the microstrip resonator, The other end is connected to the cathode of the first varactor diode, and the anode of the first varactor diode is grounded. Specifically, as shown in FIG. 1 , the end of the narrow microstrip line 201 of the first resonator 2 is connected in sequence with a first fixed capacitor C4 and a first varactor diode CV4, and at the end of the narrow microstrip line of the second resonator 3 The end of 301 is connected with the first fixed capacitor C5 and the first varactor diode CV5 in sequence, and the end of the narrow microstrip line 401 of the third resonator 4 is connected with the first fixed capacitor C6 and the first varactor diode CV6 in sequence.

Further preferably, in each of the resonance adjustment units, a bias circuit is loaded between the first varactor diode and the first fixed capacitor. Specifically, between the first varactor diode CV4 and the first fixed capacitor C4, between the first varactor diode CV5 and the first fixed capacitor C5, between the first varactor diode CV6 and the first fixed capacitor C6, load There is a bias circuit; the bias circuit is used to adjust the capacitance value of the corresponding first varactor diode (CV4, CV5, CV6), and realize the frequency control of the filter power division module by adjusting the capacitance value, so as to realize the continuous frequency of the central frequency adjust. Optionally, in the bias circuit, the bias voltage is connected between a resistor and loaded between the first varactor diode and the first fixed capacitor.

As a preferred implementation manner, each of the coupling adjustment units includes two second varactor diodes, and the two second varactor diodes are connected in series between two adjacent microstrips in a cathode back-to-back manner. between the wide microstrip lines of the resonator. Specifically, as shown in FIG. 1, a second varactor diode CV7 connected in series in a cathode back-to-back manner is connected between the wide microstrip line 202 of the first resonator 2 and the wide microstrip line 302 of the second resonator 3. and CV8, the second varactor diodes CV9 and CV10 connected in series in a cathode back-to-back manner are connected between the wide microstrip line 202 of the first resonator 2 and the wide microstrip line 402 of the third resonator 4 .

Further preferably, in each of the coupling adjustment units, a bias circuit is loaded between the two second varactor diodes. Specifically, a bias circuit is respectively loaded between the second varactor diodes CV7 and CV8 and between the second varactor diodes CV9 and CV10, through which the second varactor diodes (CV7, CV8 , CV9, CV10) capacitance value adjustment, thereby respectively realizing the adjustment of the coupling state between the first resonator 2 and the second resonator 3 and the coupling state between the first resonator 2 and the third resonator 4, and then Adjustment of the power distribution ratio from the first resonator 2 to the second resonator 3 and the third resonator 4 is achieved.

As a preferred embodiment, as shown in FIG. 1, between the narrow microstrip line 201 of the first resonator 2 and the port microstrip line 5, between the wide microstrip line 301 of the second resonator 3 and the first output An impedance matching unit is respectively connected between the striplines 6 and between the wide microstrip line 401 of the third resonator 4 and the second output microstrip line 7; each impedance matching unit includes a third varactor diode and a second A fixed capacitor, the anode of the third varactor diode is connected to the corresponding narrow microstrip line, and the cathode of the third varactor diode is connected to the second fixed capacitor. Specifically, as shown in FIG. 1, a third variable capacitance diode CV1 and a second fixed capacitor C1 are sequentially connected to the narrow microstrip line 201 near its end, and the anode of the third variable capacitance diode CV1 is connected to the narrow microstrip line 201. On the stripline 201, its cathode is connected to the second fixed capacitor C1, and the second fixed capacitor C1 is connected to one end of the port microstrip line; on the narrow microstrip line 301 near its end, the third varactor diode CV2 and The second fixed capacitor C2, the anode of the third varactor diode CV2 is connected to the narrow microstrip line 301, and its cathode is connected to the second fixed capacitor C2, and the second fixed capacitor C2 is connected to one end of the first output microstrip line 6; The position close to the end of the microstrip line 401 is connected to the third variable capacitance diode CV3 and the second fixed capacitor C3 in sequence, the anode of the third variable capacitance diode CV3 is connected to the narrow microstrip line 401, and its cathode is connected to the second fixed capacitor C3. Capacitor C3, the second fixed capacitor C3 is connected to one end of the second output microstrip line 7 .

Further preferably, in each of the impedance matching units, a bias circuit is loaded between the third varactor diode and the second fixed capacitor. Specifically, between the third varactor diode CV1 and the second fixed capacitor C1, between the third varactor diode CV2 and the second fixed capacitor C2, between the third varactor diode CV3 and the second fixed capacitor C3 are respectively loaded with a bias circuit. It can be understood that, in this embodiment, the capacitance value corresponding to the third varactor diode (CV1, CV2, CV3) can be adjusted through the loaded bias circuit, so as to adjust the external quality factor of the filter power division module for external Coupling matching, that is, controlling the impedance matching of the input/output port of the filter power division module; in addition, the setting of the second fixed capacitor (C1, C2, C3) is used to isolate the adverse effect of the DC bias voltage of the third varactor diode on the external device .

As a preferred embodiment, referring to Fig. 1, the narrow microstrip line 201 of the first resonator 2 and the narrow microstrip line 301 of the second resonator 3 are close to each other, so that in the electrified state, the first resonance A magnetic coupling can be formed between the resonator 2 and the second resonator 3 to realize energy transfer between the first resonator 2 and the second resonator 3; the narrow microstrip line 201 of the first resonator 2 and the third resonator The narrow microstrip lines 401 of 4 are far away from each other, so that in the energized state, magnetic coupling cannot be formed between the first resonator 2 and the third resonator 4 to transfer energy. It should be noted that, in this embodiment, since the high impedance parts (i.e., narrow microstrip lines) of the first resonator 2 and the second resonator 3 are relatively close, it is easy to transfer energy from the first resonator through magnetic coupling. 2 to the second resonator 3, and the second varactor diodes CV7 and CV8 loaded between the first resonator 2 and the second resonator 3 can also transfer energy from the first resonator 2 to the The second resonator 3 , therefore, an electromagnetic hybrid coupling form can be generated between the first resonator 2 and the second resonator 3 . Energy cannot be transferred between the first resonator 2 and the third resonator 4 through magnetic coupling, therefore, the coupling type between the first resonator 2 and the third resonator 4 is pure electrical coupling. To sum up, in the scheme of this embodiment, by adjusting the capacitance value of the second varactor diode, the power distribution ratios from the first resonator 2 to the second resonator 3 and the third resonator 4 can be respectively realized; at the same time, by Switching the coupling type between the first resonator 2 and the second resonator 3 can make the two output signals of the filter power division module in the same-phase or anti-phase state, that is, power division or balun mode.

As a preferred implementation manner, the wide microstrip line of each microstrip resonator is connected with a grounding resistor. Specifically, a grounding resistor is connected to the wide microstrip line 202, the wide microstrip line 302, and the wide microstrip line 402 respectively, and the other end of the grounding resistor is grounded, that is, each microstrip resonator is connected to a DC through the grounding resistor. For grounding, preferably, the grounding resistor adopts a 100KΩ chip resistor.

As a preferred implementation, the reconfigurable filter attenuator based on the continuously adjustable center frequency of this embodiment also includes a broadband balun module, and the broadband balun module includes cascaded broadband phase shifting units and Wilkinson Power divider 12, the broadband phase shifting unit has a first transmission path and a second transmission path, the two ends of the first transmission path and the second transmission path are respectively connected to the output end of the Wilkinson power divider and the Between the aforementioned output microstrip lines (6, 7), the input end line 15 of the Wilkinson power divider 12 is connected to the second port (port 2).

As a further preferred implementation, referring to Fig. 2, the first transmission path includes a coupled transmission line 8 with an electrical length of 180°, and a pair of electrical lengths 8 is vertically loaded on both ends of the coupled transmission line 8. 45° open line (901, 1001) and a grounded short line (902, 1002) with an electrical length of 45°; the second transmission path includes an electrical length of 180° and an impedance of the Wilkinson power division tor port impedance of the bent transmission line 11. Specifically, in the first transmission path, one end of the coupling transmission line 8 is vertically loaded with the first loading line 9 formed by connecting the first open line 901 and the first ground short line 902, and the other end of the coupling transmission line 8 One end is vertically loaded with a second loading line 10 connected by a second open line 1001 and a second grounding short line 1002, one side of the first loading line 9 is vertically connected to the first output microstrip line 6, and the second loading line 10 One side of the vertically connected to the first output microstrip line 13 of the Wilkinson power divider 12; in the second transmission path, one end of the bent transmission line 11 is connected to the second output microstrip line 7, bent The other end of the transmission line 11 is connected to the second output end microstrip line 14 of the Wilkinson power divider 12; between the first output end microstrip line 13 and the second output end microstrip line 14 of the Wilkinson power divider 12 Connect with an isolation resistor for better isolation.

It is worth noting that, in some embodiments provided above, the reconfigurable filter attenuator adopts a design structure in which the filter power division module and the broadband balun module are cascaded, which can better realize the continuously adjustable center frequency The filter attenuation function, compared with the existing filter attenuator, has multiple performance advantages such as multi-functional integration and device miniaturization. Among them, the broadband phase shifting unit in the broadband balun module can adjust the phase slope by adjusting the impedance of the coupled transmission line and the loaded open line and the ground short line. Compared with the delay line used in the traditional phase shifter, the present invention implements The broadband phase shift unit provided in the example has the advantage of larger bandwidth.

In order to further illustrate the technical effect of the reconfigurable filter attenuator based on the continuously adjustable center frequency provided by the embodiment of the present application, a specific description will be given below in combination with test results.

Referring to FIG. 4 , it shows the physical diagram of the reconfigurable filter attenuator used as a test. The circuit structure of the physical diagram in FIG. 4 is the same as that shown in FIG. 2 . Refer to FIG. 3 for specific dimension parameters. Specifically, the substrate adopts Rogers 6010, the thickness of the substrate is 25mil, and the varactor diodes (CV1, CV2, CV3, CV4, CV5, CV6, CV7, CV8, CV9, CV10) select the MA46H202 type varactor diode of MACOM Company; the fixed capacitance ( C1, C2, C3, C4, C5, C6) use fixed-value chip capacitors with package type 0402; the involved resistors use chip resistors with package model 0402, except for isolation resistors with 100Ω, the resistance values of other resistors are the same 100KΩ. The optimal circuit size parameters obtained after simulation optimization design are: L ₁ = 18mm, L ₂ = 6mm, L ₃ = 6.14mm, L ₄ = 13.73mm, L ₅ = 27.6mm, W ₁ = 1mm, W ₂ = 4mm , W ₃ =0.57mm, W ₄ =0.32mm, W ₅ =0.16mm, S ₁ =1.2mm, S ₂ =2mm, d ₁ =1.38mm, d ₂ =0.68mm.

Figure 5, Figure 6 and Figure 7 are the S-parameter test results of the tested reconfigurable filter attenuators with center frequencies of 1.01GHz, 1.09GHz and 1.19GHz, respectively, where the solid line (Solid) is the actual measurement (Meas) The dashed line (Dased) is the simulation (Sim) curve; it can be seen from the test results that by adjusting the bias state of each varactor diode in the circuit, different center frequencies and different passband amplitude curves at the same center frequency can be obtained , it can be further seen that the reconfigurable filter attenuator provided by the embodiment of the present application realizes the continuous adjustment of the center frequency in the range of 1.01GHz-1.19GHz, and realizes excellent reconfigurable bandpass filter performance, while the passband The insertion loss can be continuously adjusted within the range of 3.3dB-21.5dB. Therefore, the above results verify that the reconfigurable filter attenuator of the embodiment of the present application can form a good band-pass filtering performance while realizing flexible adjustment of the pass-band amplitude, and at the same time, its center frequency can also be continuously adjusted within a certain range .

In the description of the embodiments of the present invention, specific features, structures or characteristics may be combined in any one or more embodiments or examples in an appropriate manner.

In the description of the embodiments of the present invention, it should be understood that "-" and "~" indicate the same range of two numerical values, and the range includes the endpoint. For example: "A-B" means greater than or equal to A, and less than or equal to the range of B. "A to B" means a range that is greater than or equal to A and less than or equal to B.

In the description of the embodiments of the present invention, the term "and/or" herein is only an association relationship describing associated objects, which means that there may be three relationships, for example, A and/or B, which can mean: exist alone A, A and B exist at the same time, and B exists alone. In addition, the character "/" in this article generally indicates that the contextual objects are an "or" relationship.

Although the embodiments of the present invention have been shown and described, those skilled in the art can understand that various changes, modifications and substitutions can be made to these embodiments without departing from the principle and spirit of the present invention. and modifications, the scope of the invention is defined by the appended claims and their equivalents.

Claims (2)

1. A reconfigurable filter attenuator based on a continuously adjustable center frequency, characterized in that it includes a substrate and a filter power division module built on the substrate; The filter power division module includes three microstrip resonators distributed in parallel intervals, one end of each microstrip resonator is connected to a resonance adjustment unit for adjusting the resonant frequency of the microstrip resonator, and two adjacent microstrip resonators A coupling adjustment unit for adjusting the coupling state between the two microstrip resonators is connected between the resonators; Wherein, the microstrip resonator located in the middle is connected to the first port through a port microstrip line, and the two microstrip resonators located on both sides are respectively connected with output microstrip lines; Each of the microstrip resonators includes a narrow microstrip line and a wide microstrip line, and the narrow microstrip line and the wide microstrip line are connected to form a step impedance resonator; Each of the resonance adjustment units includes a first varactor diode and a first fixed capacitor, one end of the first fixed capacitor is connected to the end of the narrow microstrip line corresponding to the microstrip resonator, and the other end is connected to the first varactor diode The cathode connection of the first varactor diode is grounded; Each of the coupling adjustment units includes two second varactor diodes, and the two second varactor diodes are connected in series between the wide microstrip lines of two adjacent microstrip resonators in a cathode back-to-back manner between; An impedance matching unit is connected between the narrow microstrip line of the microstrip resonator in the middle and the port microstrip line, and the wide microstrip lines of the two microstrip resonators on both sides are connected to the An impedance matching unit is respectively connected between the output microstrip lines, each impedance matching unit includes a third varactor diode and a second fixed capacitor, and the anode of the third varactor diode is connected to the corresponding narrow microstrip line, The cathode of the third varactor diode is connected to the second fixed capacitor; The narrow microstrip line of the microstrip resonator in the middle is close to the narrow microstrip line of the microstrip resonator on one side, so that in the energized state, the microstrip resonator in the middle and the microstrip resonator on the side Magnetic coupling can be formed between; the narrow microstrip line of the microstrip resonator in the middle is far away from the narrow microstrip line of the microstrip resonator on the other side, so that in the energized state, the microstrip resonator in the middle and the The microstrip resonators on the other side cannot transfer energy through magnetic coupling; In each of the resonance adjustment units, a bias circuit is loaded between the first varactor diode and the first fixed capacitor; in each of the coupling adjustment units, a bias circuit is loaded between the two second varactor diodes A bias circuit is loaded; in each of the impedance matching units, a bias circuit is loaded between the third varactor diode and the second fixed capacitor; Each wide microstrip line of the microstrip resonator is connected with a grounding resistor; It also includes a broadband balun module with a broadband phase shifting unit and a Wilkinson power divider, the broadband phase shifting unit has a first transmission path and a second transmission path, and the two ends of the first transmission path and the second transmission path are respectively connected between the output terminal of the Wilkinson power divider and the output microstrip line, and the input terminal of the Wilkinson power divider is connected to the second port. 2. The reconfigurable filter attenuator according to claim 1, wherein the first transmission path comprises a coupling transmission line with an electrical length of 180°, and an electrical connection is vertically loaded at both ends of the coupling transmission line. An open line with a length of 45° and a grounded short-circuit line with an electrical length of 45°; the second transmission path includes a bent transmission line with an electrical length of 180° and an impedance equal to the port impedance of the Wilkinson power divider.

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