6-18GHz amplitude equalizer

Abstract

The utility model relates to the technical field of amplitude equalizers, in particular to a 6-18GHz amplitude equalizer, which comprises a substrate and a metal layer arranged on the substrate. Wherein the metal layer comprises a signal input circuit, a first-stage absorption circuit, a first low-pass filter circuit, a second-stage absorption circuit, a second low-pass filter circuit, a third-stage absorption circuit, a third low-pass filter circuit, a fourth-stage absorption circuit, a low-pass filter microstrip line and a signal output circuit. According to the invention, the equalizer circuit is provided with multiple stages of absorption circuits to absorb signal energy of part of frequency in an input signal, an open-circuit resonance structure and a short-circuit resonance structure are alternately used in each stage of absorption circuit, and a complementary coupling structure is formed between the front and rear stages of absorption circuits. Meanwhile, a low-pass filter circuit is arranged for impedance and capacitance matching, and amplitude characteristic balance within the frequency band range of 6-18 GHz is achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of amplitude equalizers, in particular to a 6-18 GHz amplitude equalizer. Background Art

[0002] As an important component in microwave applications, power amplifiers are widely used in current radar systems, communication systems, and electronic countermeasures. After the power amplifier is cascaded in multiple stages, its amplitude will fluctuate greatly. In actual applications, the input of the power amplifier is generally constant. In order to ensure that the output power of the power amplifier can meet the requirements at the low gain point, the input power of the power amplifier will be relatively high. At this time, for the high gain point, there is a problem of too high input power, resulting in over-pushing of the power amplifier. Over-pushing power amplifiers will have problems such as gain compression, AM / PM conversion, and reliability. Existing ones all achieve amplitude balancing by adding an equalizer, and the equalizer needs to adopt different forms for different frequency bands. At present, for the 6-18GHz frequency band, the microstrip line is generally used. The length and width of the microstrip line in the microstrip equalizer are variable, and the resistor on it is a concentrated resistor, and its RF characteristics are unknown, which makes it difficult to debug the equalizer. Microstrip lines have characteristics that repeat with frequency multiples. For example, for a 6 GHz microstrip line, its length is λ, then it becomes 2λ at 12 GHz and 3λ at 18 GHz. There is periodicity within the frequency band, which makes it difficult to balance some amplitude characteristics. Utility Model Content

[0003] To this end, the present application provides a 6~18 GHz amplitude equalizer, which helps to solve the problem that the existing equalizer has periodicity in the 6~18 GHz frequency band, making it difficult to equalize the amplitude characteristics.

[0004] The utility model provides a 6-18 GHz amplitude equalizer, comprising: a substrate and a metal layer arranged on the substrate; wherein:

[0005] The metal layer includes a signal input circuit, a first-stage absorption circuit, a first low-pass filter circuit, a second-stage absorption circuit, a second low-pass filter circuit, a third-stage absorption circuit, a third low-pass filter circuit, a fourth-stage absorption circuit, a low-pass filter microstrip line and a signal output circuit;

[0006] The first-stage absorption circuit includes a first absorption resistor and a first open-circuit resonator connected in series, the input end of the first absorption resistor is connected to the signal input circuit, and the output end of the first absorption resistor is connected to the input end of the first low-pass filter circuit;

[0007] The second-stage absorption circuit comprises a second absorption resistor and a first short-circuit resonator connected in series, the input end of the second absorption resistor is connected to the output end of the first low-pass filter circuit, and the output end of the second absorption resistor is connected to the input end of the second low-pass filter circuit;

[0008] The third-stage absorption circuit comprises a third absorption resistor and a second open-circuit resonator connected in series, the input end of the third absorption resistor is connected to the output end of the second low-pass filter circuit, and the output end of the third absorption resistor is connected to the input end of the third low-pass filter circuit;

[0009] The fourth-stage absorption circuit includes a fourth absorption resistor and a second short-circuit resonator connected in series, the input end of the fourth absorption resistor is connected to the output end of the third low-pass filter circuit, and the output end of the fourth absorption resistor is connected to the input end of the low-pass filter microstrip line.

[0010] Furthermore, the first absorption resistor, the second absorption resistor, the third absorption resistor and the fourth absorption resistor are all TaN thin film resistors.

[0011] Furthermore, the first low-pass filter circuit includes a first high-resistance microstrip line and a first capacitor matching microstrip line; the input end of the first high-resistance microstrip line is connected to the output end of the first absorption resistor, and the output end of the first high-resistance microstrip line is connected to the input end of the second absorption resistor through the first capacitor matching microstrip line.

[0012] Furthermore, the second low-pass filter circuit includes a second high-resistance microstrip line, a first impedance matching microstrip line and a second capacitance matching microstrip line; the input end of the second high-resistance microstrip line is connected to the output end of the second absorption resistor, the output end of the second high-resistance microstrip line is connected to the input end of the second capacitance matching microstrip line through the first impedance matching microstrip line, and the output end of the second capacitance matching microstrip line is connected to the input end of the third absorption resistor.

[0013] Furthermore, the third low-pass filter circuit includes a third high-resistance microstrip line, a second impedance matching microstrip line and a third capacitance matching microstrip line; the input end of the third high-resistance microstrip line is connected to the output end of the third absorption resistor, the output end of the third high-resistance microstrip line is connected to the input end of the third capacitance matching microstrip line through the second impedance matching microstrip line, and the output end of the third capacitance matching microstrip line is connected to the input end of the fourth absorption resistor.

[0014] Furthermore, the signal input circuit includes a signal input microstrip line and a pre-matching microstrip line, and the signal input microstrip line is connected to the input end of the first absorption resistor through the pre-matching microstrip line.

[0015] Furthermore, the substrate is an aluminum oxide substrate.

[0016] Furthermore, one end of the first short-circuit resonator is bonded to an edge of the substrate via conductive glue to form a short circuit; and one end of the second short-circuit resonator is bonded to an edge of the substrate via conductive glue to form a short circuit.

[0017] The beneficial effects of the utility model are embodied in:

[0018] In actual use, a 6~18GHz amplitude equalizer provided by the utility model is provided with a multi-stage absorption circuit in the equalizer circuit to absorb the signal energy of some frequencies in the input signal respectively, so as to reduce the input power. The utility model also respectively provides an open-circuit resonator and a short-circuit resonator in each stage of the absorption circuit to form a corresponding open-circuit resonance structure and a short-circuit resonance structure. By alternating the open-circuit resonance structure and the short-circuit resonance structure, a complementary coupling structure is formed between the front and rear two-stage absorption circuits, and the impedance and capacitance matching is performed in combination with the low-pass filter circuit between the adjacent two-stage absorption circuits, so as to achieve the amplitude characteristic balance within the 6~18GHz frequency band, and also realize a good port standing wave, solving the problem of the amplitude characteristic of the microstrip equalizer being repeated with the frequency multiple. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the planar structure of a 6~18GHz amplitude equalizer provided by the utility model;

[0020] Figure 2 It is a schematic diagram of simulation results of an amplitude equalizer in the utility model with an absorption resistor of 50Ω square resistance;

[0021] Figure 3 It is a schematic diagram of simulation results of an amplitude equalizer in the utility model with an absorption resistor of 45Ω square resistance;

[0022] Figure 4 It is a schematic diagram of simulation results of an amplitude equalizer in the utility model with an absorption resistor of 55Ω square resistance;

[0023] Attached Figure 1 Middle: 1-signal input microstrip line, 2-pre-matching microstrip line, 3-first absorption resistor, 4-first open-circuit resonator, 5-first high-impedance microstrip line, 6-first capacitor matching microstrip line, 7-second absorption resistor, 8-first short-circuit resonator, 9-second high-impedance microstrip line, 10-first impedance matching microstrip line, 11-second capacitor matching microstrip line, 12-third absorption resistor, 13-second open-circuit resonator, 14-third high-impedance microstrip line, 15-second impedance matching microstrip line, 16-third capacitor matching microstrip line, 17-fourth absorption resistor, 18-second short-circuit resonator, 19-low-pass filter microstrip line, 20-signal output microstrip line, 21-substrate. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0025] Example 1: Reference Figure 1 As shown, this embodiment provides a 6-18 GHz amplitude equalizer, including: a substrate 21 and a metal layer arranged on the substrate 21.

[0026] The metal layer includes a signal input circuit, a first-stage absorption circuit, a first low-pass filter circuit, a second-stage absorption circuit, a second low-pass filter circuit, a third-stage absorption circuit, a third low-pass filter circuit, a fourth-stage absorption circuit, a low-pass filter microstrip line 19 and a signal output circuit.

[0027] The first-stage absorption circuit includes a first absorption resistor 3 and a first open-circuit resonator 4 connected in series, the input end of the first absorption resistor 3 is connected to the signal input circuit, and the output end of the first absorption resistor 3 is connected to the input end of the first low-pass filter circuit.

[0028] Specifically, the first-stage absorption circuit of this embodiment is used to absorb part of the energy in the signal input circuit, reduce the power of the input signal, and balance the amplitude of the signal. The first-stage absorption circuit is also provided with a first open-circuit resonator 4 to form an open-circuit resonant structure. The first open-circuit resonator 4 is used to select which frequency signals are absorbed by the characteristics of the resonator. Because the resonator itself has a frequency selection function, its frequency selectivity means that at a specific frequency, the circuit responds most strongly to the signal of this frequency. This frequency is called the resonant frequency. Among them, the resonator is mainly composed of inductance and capacitance, and the values ​​of inductance and capacitance determine the frequency of the resonator.

[0029] The second-stage absorption circuit includes a second absorption resistor 7 and a first short-circuit resonator 8 connected in series, the input end of the second absorption resistor 7 is connected to the output end of the first low-pass filter circuit, and the output end of the second absorption resistor 7 is connected to the input end of the second low-pass filter circuit.

[0030] Specifically, in this embodiment, the second-stage absorption circuit is also used to absorb part of the energy of the signal and balance the amplitude characteristics of the signal. In terms of circuit structure, the second-stage absorption circuit includes a first short-circuit resonator 8, so that the second-stage absorption circuit and the first-stage absorption circuit form a complementary coupling structure, which can better balance the amplitude characteristics.

[0031] The third-stage absorption circuit includes a third absorption resistor 12 and a second open-circuit resonator 13 connected in series, wherein the input end of the third absorption resistor 12 is connected to the output end of the second low-pass filter circuit, and the output end of the third absorption resistor 12 is connected to the input end of the third low-pass filter circuit.

[0032] Among them, the third-stage absorption circuit of this embodiment is in the same form as the first-stage absorption circuit, except that the energy absorbed by the third-stage absorption circuit is different from the energy of the first-stage absorption circuit. In this embodiment, the resonant frequency of the second open-circuit resonator 13 in the third-stage absorption circuit is different from the frequency of the first open-circuit resonator 4, so that the energy absorbed by the third-stage absorption circuit is different from the energy of the first-stage absorption circuit. The specific resonant frequency can be selected according to the actual debugging requirements. The embodiment will not be repeated here.

[0033] The fourth-stage absorption circuit includes a fourth absorption resistor 17 and a second short-circuit resonator 18 connected in series, the input end of the fourth absorption resistor 17 is connected to the output end of the third low-pass filter circuit, and the output end of the fourth absorption resistor 17 is connected to the input end of the low-pass filter microstrip line 19.

[0034] Specifically, the form of the fourth-stage absorption circuit in the embodiment of the present invention is the same as that of the second-stage absorption circuit, and the specific absorbed energy is also determined by the resonant frequencies of the first short-circuit resonator 8 and the second short-circuit resonator 18 .

[0035] Furthermore, in one embodiment, the first absorption resistor 3, the second absorption resistor 7, the third absorption resistor 12 and the fourth absorption resistor 17 of this embodiment are all thin film resistors in the form of TaN (tantalum nitride). Among them, the thin film resistor is a resistor made by evaporating a certain resistivity material on the surface of an insulating material by a method similar to evaporation. This embodiment uses a thin film resistor in the form of TaN (tantalum nitride) as an absorption resistor, which has the characteristics of a high melting point (3090°C), a small resistance temperature coefficient and high stability. When preparing the resistor, a sputtering process can be used.

[0036] In some embodiments, reference Figure 2 , Figure 3 , Figure 4 As shown in the simulation result diagram of the amplitude equalizer, this embodiment provides the simulation results of the amplitude equalizer when the square resistance of the absorption resistor is 45Ω, 50Ω and 55Ω. By comparison, it can be found that the simulation effect of the amplitude equalizer designed in this embodiment is the best when the square resistance of the absorption resistor is 50Ω. Therefore, when the square resistance of the first absorption resistor 3, the second absorption resistor 7, the third absorption resistor 12 and the fourth absorption resistor 17 of this embodiment are all set to 50Ω, it is the best embodiment of the utility model.

[0037] Specifically, in addition to the expected components (such as resistors, capacitors, and inductors) in the circuit, the additional effects caused by physical structure, material properties, or manufacturing processes are called parasitic parameters. Parasitic parameters include parasitic capacitance, parasitic resistance, parasitic inductance, etc. They can affect the circuit's frequency response, signal integrity, power consumption, delay, and other performances, and have a significant impact on the performance of the circuit. Therefore, in this embodiment, a first low-pass filter circuit, a second low-pass filter circuit, a third low-pass filter circuit, and a low-pass filter microstrip line 19 are also provided in the circuit of the amplitude equalizer to eliminate the parasitic parameters in the circuit.

[0038] Furthermore, in one embodiment, the first low-pass filter circuit of this embodiment includes a first high-resistance microstrip line 5 and a first capacitor matching microstrip line 6; the input end of the first high-resistance microstrip line 5 is connected to the output end of the first absorption resistor 3, and the output end of the first high-resistance microstrip line 5 is connected to the input end of the second absorption resistor 7 through the first capacitor matching microstrip line 6.

[0039] Specifically, the first low-pass filter circuit of this embodiment is used to eliminate impedance mutation and parasitic capacitance matching of the signal processed by the first-stage absorption circuit. The high characteristic impedance of the first high-resistance microstrip line 5 can reduce the load effect on the signal output end, and combine with the first capacitor matching microstrip line 6 to eliminate the impedance mutation and parasitic parameters such as parasitic capacitance and parasitic resistance between the first-stage absorption circuit and the second-stage absorption circuit.

[0040] Furthermore, in one embodiment, the second low-pass filter circuit of this embodiment includes a second high-resistance microstrip line 9, a first impedance matching microstrip line 10 and a second capacitance matching microstrip line 11; the input end of the second high-resistance microstrip line 9 is connected to the output end of the second absorption resistor 7, the output end of the second high-resistance microstrip line 9 is connected to the input end of the second capacitance matching microstrip line 11 through the first impedance matching microstrip line 10, and the output end of the second capacitance matching microstrip line 11 is connected to the input end of the third absorption resistor 12.

[0041] Furthermore, the third low-pass filter circuit includes a third high-resistance microstrip line 14, a second impedance matching microstrip line 15 and a third capacitor matching microstrip line 16; the input end of the third high-resistance microstrip line 14 is connected to the output end of the third absorption resistor 12, the output end of the third high-resistance microstrip line 14 is connected to the input end of the third capacitor matching microstrip line 16 through the second impedance matching microstrip line 15, and the output end of the third capacitor matching microstrip line 16 is connected to the input end of the fourth absorption resistor 17.

[0042] Among them, the second low-pass filter circuit and the third low-pass filter circuit of this embodiment are of the same form, and both use high-resistance microstrip lines, impedance matching microstrip lines and capacitance matching microstrip lines to match and eliminate parasitic capacitance and impedance mutations in the circuit, thereby reducing the impact of parasitic parameters on the circuit.

[0043] Furthermore, in one embodiment, the signal input circuit of this embodiment includes a signal input microstrip line 1 and a pre-matching microstrip line 2, wherein the signal input microstrip line 1 is connected to the input end of the first absorption resistor 3 through the pre-matching microstrip line 2. The function of the pre-matching microstrip line 2 is to pre-match the power of the input signal to ensure the stability and reliability of the signal input power, reduce power loss, and reduce the distortion of the amplitude equalizer.

[0044] Furthermore, in one embodiment, the substrate 21 of this embodiment is an aluminum oxide substrate, which has good insulation properties and can effectively isolate the circuit to avoid failures caused by leakage and other problems.

[0045] Furthermore, in one embodiment, one end of the first short-circuit resonator 8 of this embodiment is bonded to the edge of the substrate 21 through conductive glue to form a grounded short circuit, and at the same time, one end of the second short-circuit resonator 18 is bonded to the edge of the substrate 21 through conductive glue to form a grounded short circuit.

[0046] Furthermore, the signal output circuit of the present embodiment is implemented in the form of a microstrip line, specifically a signal output microstrip line 20 .

[0047] This embodiment absorbs the signal energy of some frequencies in the input signal separately by setting a multi-stage absorption circuit in the equalizer circuit to reduce the input power. The utility model also sets an open-circuit resonator and a short-circuit resonator in the absorption circuit respectively to form a corresponding open-circuit resonance structure and a short-circuit resonance structure. By alternating the open-circuit resonance structure and the short-circuit resonance structure, a complementary coupling structure is formed between the front and rear absorption circuits, and the impedance and capacitance matching is performed in combination with the low-pass filter circuit between the adjacent two-stage absorption circuits, so as to achieve the amplitude characteristic balance within the frequency band of 6~18GHz, and also achieve good port standing wave, solving the problem of the amplitude characteristic of the microstrip equalizer repeating with the frequency multiple.

[0048] Embodiment 2: To facilitate understanding of the structure and function of the amplitude equalizer of this embodiment, this embodiment describes the working principle of the amplitude equalizer in conjunction with the amplitude equalization processing process of the signal. Figure 1In the circuit structure of the amplitude equalizer shown, the signal is input from the left to the signal input microstrip line 1, which is a standard 50Ω microstrip line. After pre-matching through the pre-matching microstrip line 2, it enters the first-stage absorption circuit, which is composed of a first absorption resistor 3 in the form of a planar TaN and a first open-circuit resonator 4. The function of the first absorption resistor 3 is to absorb part of the energy on the microstrip line. The first open-circuit resonator 4 of this embodiment is implemented by a microstrip line, so the first open-circuit resonator 4 is designed as an open-circuit microstrip line resonator, and its function is to select which frequency signals are absorbed, and they will form an absorber in the form of a notch. Since the absorber can only absorb part of the energy, it does not match the 50Ω standard microstrip line, so a section of high-resistance microstrip line and the second absorption resistor 7 are required to form a low-pass filter circuit to further match the impedance. In the matching, it is considered that there is a certain parasitic capacitance between the pre-matching microstrip line 2 and the first high-resistance microstrip line 5, so the first capacitance matching microstrip line 6 is added to the low-pass filter circuit for further capacitance matching to obtain the first low-pass filter circuit.

[0049] After being processed by the first low-pass filter circuit, the signal enters the second-stage balancing structure composed of the second absorption resistor 7 and the first short-circuit resonator 8, that is, the second-stage absorption circuit. The first short-circuit resonator 8 also adopts a microstrip line structure, but the first short-circuit resonator 8 is different from the first open-circuit resonator 4 in that the first short-circuit resonator 8 adopts a short-circuit to ground form. Since it is difficult to perform metallized vias on the alumina substrate 21, the grounding of this level of microstrip line is formed by bonding the first short-circuit resonator 8 to the edge of the substrate 21 using conductive glue. The first short-circuit resonator 8 is designed as a short-circuit type microstrip line resonator, resulting in the opposite performance of the first open-circuit resonator 4 during resonance, forming a complementary coupling structure in the circuit. The mismatch introduced by the first short-circuit resonator 8 is also matched by the second low-pass filter circuit composed of the second high-resistance microstrip line 9, the first impedance matching microstrip line 10, and the second capacitance matching microstrip line 11, and the parasitic parameters in the middle are offset by the first impedance matching microstrip line 10.

[0050] The third-level balancing structure formed by the third absorption resistor 12 and the second open-circuit resonator 13, i.e., the third-level absorption circuit, is implemented by the second open-circuit resonator 13 using a microstrip line. The second open-circuit resonator 13 is designed as an open-circuit resonant structure, and its form is the same as that of the first open-circuit resonator 4, except that its length is different, so the resonant frequency is different, and the resistance value of the resistor is different, and the absorbed energy is also different. The mismatch caused by the second open-circuit resonator 13 is matched by the third low-pass filter circuit composed of the third high-resistance microstrip line 14, the second impedance matching microstrip line 15, and the third capacitance matching microstrip line 16, and the impedance mutation caused by the intermediate parasitic parameters is absorbed by the second impedance matching microstrip line 15.

[0051] The fourth absorption resistor 17 and the second short-circuit resonator 18 form a fourth-level balancing structure, i.e., a fourth-level absorption circuit. The second short-circuit resonator 18 is also implemented by a microstrip line and is designed as a short-circuit resonator. It absorbs part of the energy, and the mismatch generated is matched by a low-pass filter microstrip line 19 and a third capacitor matching microstrip line 16, etc., and finally outputs the signal to the signal output microstrip line 20.

[0052] The first absorption resistor 3, the second absorption resistor 7, the third absorption resistor 12, and the fourth absorption resistor 17 in the circuit structure of the entire amplitude equalizer are all TaN thin film resistors with a square resistance of 50Ω. However, in actual processing, the square resistance has an error of ±10%, so the influence of the square resistance on the effect of the entire structure also needs to be considered.

[0053] Therefore, in some embodiments, the substrate 21 may be an aluminum oxide substrate with a thickness of 0.254 mm, and the machining accuracy of the metal layer is about ±5 um, so the influence of the metal error on the result can be ignored.

[0054] In this embodiment, since the metal layer is mainly realized by thin film technology, the side view, bottom view, front view and other structural views of the amplitude equalizer structure are not very helpful for understanding the concept of this embodiment, so this embodiment does not provide the above structural views.

[0055] This embodiment adopts an alternating structure of open-circuit microstrip lines and short-circuit microstrip lines, with a matching unit of low-pass filtering in the middle, which can achieve better impedance matching within the bandwidth. Since the open circuit and the short circuit show different characteristics, the characteristics of the two are complementary to achieve better amplitude characteristic suppression, which can eliminate the octave parasitic passband problem existing in the existing microstrip line amplitude equalizer. At the same time, since the substrate is aluminum oxide, it has good conductive properties, so the amplitude equalizer of this embodiment can withstand greater power than the general thick film resistive equalizer.

[0056] In the description of the embodiments of the present invention, specific features, structures, materials or characteristics may be combined in a suitable manner in any one or more embodiments or examples.

[0057] In the description of the embodiments of the present utility model, the term "and / or" is used herein to describe the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0058] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A 6~18GHz amplitude equalizer, characterized in that: include: A substrate and a metal layer disposed on the substrate; wherein, The metal layer includes a signal input circuit, a first-stage absorption circuit, a first low-pass filter circuit, a second-stage absorption circuit, a second low-pass filter circuit, a third-stage absorption circuit, a third low-pass filter circuit, a fourth-stage absorption circuit, a low-pass filter microstrip line and a signal output circuit; The first-stage absorption circuit includes a first absorption resistor and a first open-circuit resonator connected in series, the input end of the first absorption resistor is connected to the signal input circuit, and the output end of the first absorption resistor is connected to the input end of the first low-pass filter circuit; The second-stage absorption circuit comprises a second absorption resistor and a first short-circuit resonator connected in series, the input end of the second absorption resistor is connected to the output end of the first low-pass filter circuit, and the output end of the second absorption resistor is connected to the input end of the second low-pass filter circuit; The third-stage absorption circuit comprises a third absorption resistor and a second open-circuit resonator connected in series, the input end of the third absorption resistor is connected to the output end of the second low-pass filter circuit, and the output end of the third absorption resistor is connected to the input end of the third low-pass filter circuit; The fourth-stage absorption circuit includes a fourth absorption resistor and a second short-circuit resonator connected in series, the input end of the fourth absorption resistor is connected to the output end of the third low-pass filter circuit, and the output end of the fourth absorption resistor is connected to the input end of the low-pass filter microstrip line.

2. The 6-18 GHz amplitude equalizer according to claim 1, characterized in that: The first absorption resistor, the second absorption resistor, the third absorption resistor and the fourth absorption resistor are all TaN thin film resistors.

3. The 6-18 GHz amplitude equalizer according to claim 1, characterized in that: The first low-pass filter circuit includes a first high-resistance microstrip line and a first capacitor matching microstrip line; the input end of the first high-resistance microstrip line is connected to the output end of the first absorption resistor, and the output end of the first high-resistance microstrip line is connected to the input end of the second absorption resistor through the first capacitor matching microstrip line.

4. The 6-18 GHz amplitude equalizer according to claim 1, characterized in that: The second low-pass filter circuit includes a second high-resistance microstrip line, a first impedance matching microstrip line and a second capacitance matching microstrip line; the input end of the second high-resistance microstrip line is connected to the output end of the second absorption resistor, the output end of the second high-resistance microstrip line is connected to the input end of the second capacitance matching microstrip line through the first impedance matching microstrip line, and the output end of the second capacitance matching microstrip line is connected to the input end of the third absorption resistor.

5. The 6-18 GHz amplitude equalizer according to claim 1, characterized in that: The third low-pass filter circuit includes a third high-resistance microstrip line, a second impedance matching microstrip line and a third capacitance matching microstrip line; the input end of the third high-resistance microstrip line is connected to the output end of the third absorption resistor, the output end of the third high-resistance microstrip line is connected to the input end of the third capacitance matching microstrip line through the second impedance matching microstrip line, and the output end of the third capacitance matching microstrip line is connected to the input end of the fourth absorption resistor.

6. The 6-18 GHz amplitude equalizer according to claim 1, characterized in that: The signal input circuit includes a signal input microstrip line and a pre-matching microstrip line, and the signal input microstrip line is connected to the input end of the first absorption resistor through the pre-matching microstrip line.

7. The 6-18 GHz amplitude equalizer according to claim 1, characterized in that: The substrate is an aluminum oxide substrate.

8. The 6-18 GHz amplitude equalizer according to claim 1, characterized in that: One end of the first short-circuit resonator is bonded to the edge of the substrate through conductive glue to form a short circuit; one end of the second short-circuit resonator is bonded to the edge of the substrate through conductive glue to form a short circuit.

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