A wideband amplitude equalizer based on high-precision MIM capacitor

Abstract

This invention relates to the field of microwave circuit technology and discloses a broadband amplitude equalizer based on high-precision MIM capacitors. The equalizer includes a substrate, multiple metal thin films, multiple oxide films, multiple thin-film resistors, and metal vias, forming a structure with multiple MIM capacitors and resonant branches. By adjusting the length and width of each metal film and the value of the thin-film resistors, the equalizer can operate at the required level of equalization within the operating frequency range. The equalizer of this invention utilizes thin-film technology, enabling miniaturization. Furthermore, the use of MIM capacitors allows for more precise implementation of smaller capacitance values, resulting in lower high-frequency parasitic parameters and effectively meeting broadband requirements.

Description

Technical Field

[0001] This invention relates to the field of microwave circuit design technology, and more specifically, to a broadband amplitude equalizer based on high-precision MIM (metal-insulator-metal) capacitors. Background Technology

[0002] Currently available waveguide or coaxial equalizers are heavy, bulky, and have poor integration. While GaAs MMIC equalizer chips on the market can be made in small sizes, they have limited power handling capabilities, and because they are off-the-shelf products, their equalization accuracy usually cannot accurately meet actual usage requirements. Summary of the Invention

[0003] Technical Objective: To address the aforementioned technical problems, this invention proposes a broadband amplitude equalizer based on high-precision MIM capacitors. It employs high-precision MIM capacitors and thin-film resistors, using a ceramic substrate as the substrate. By utilizing thin-film technology, miniaturization can be achieved. Due to the use of MIM capacitors, smaller capacitance values ​​can be achieved more precisely. Furthermore, because MIM capacitors have low high-frequency parasitic parameters, they can well meet broadband requirements.

[0004] Technical solution: To achieve the above technical objectives, the present invention adopts the following technical solution:

[0005] A broadband amplitude equalizer based on high-precision MIM capacitors, characterized in that it comprises:

[0006] Substrate, serving as a substrate;

[0007] The multi-segment metal thin film includes a first metal thin film, a second metal thin film, a third metal thin film, a fourth metal thin film, a fifth metal thin film, and a sixth metal thin film;

[0008] Multiple oxide plates, including a first oxide, a second oxide, and a third oxide;

[0009] Multiple thin-film resistors, including a first thin-film resistor, a second thin-film resistor, and a third thin-film resistor;

[0010] In this configuration, the first metal film, the second metal film, the third metal film, and the fourth metal film are arranged on the same straight line. The first oxide connects the first metal film and the second metal film to form a first MIM capacitor. The second oxide connects the second metal film and the third metal film to form a second MIM capacitor. The third oxide connects the third metal film and the fourth metal film to form a third MIM capacitor. The end of the first metal film furthest from the first oxide serves as the input or output terminal of the equalizer, and the end of the fourth metal film furthest from the third oxide serves as the output or input terminal of the equalizer.

[0011] The second thin-film resistor and the second MIM capacitor are connected in parallel to form the first resonant branch;

[0012] The first thin-film resistor is connected to the first oxide film and the sixth metal film respectively. The other end of the sixth metal film has a first metal via. The first thin-film resistor, the sixth metal film, and the first metal via constitute the second resonant branch.

[0013] The third thin-film resistor is connected to the third oxide film and the fifth metal film respectively. The other end of the fifth metal film has a second metal via. The third thin-film resistor, the fifth metal film and the second metal via form the third resonant branch.

[0014] Preferably, the substrate is made of ceramic with a dielectric constant of 9.8;

[0015] The thickness of each metal thin film ranges from 2 to 4 times the skin depth, and from 4 to 8 times the skin depth at a frequency of 2 GHz. ,

[0016] Each oxide layer serves as the insulating dielectric between the metal electrodes of the capacitor, using Si. or The thickness ranges from 0.05 to 1. .

[0017] Preferably, the first metal film, the second metal film, the third metal film, and the fourth metal film, together with the substrate, form a transmission line with an impedance of 50 ohms. .

[0018] Beneficial effects: Due to the adoption of the above technical solution, the present invention has the following beneficial effects:

[0019] This invention uses MIM capacitors with a ceramic substrate as the substrate and utilizes thin-film technology to achieve miniaturization. At the same time, due to the use of MIM capacitors, smaller capacitance values ​​can be achieved more precisely, and their high-frequency parasitic parameters are small, which significantly reduces parasitic capacitance and can meet broadband requirements. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the equalizer structure of the present invention;

[0021] Figure 2 This is a schematic diagram of a MIM capacitor structure;

[0022] Figure 3 Here is the equivalent circuit diagram of the MIM capacitor;

[0023] Figure 4 These are simulation curves of equalization performance for equalizers ranging from 1 to 21 GHz.

[0024] Figure 5These are simulation curves of return loss for equalizers from 1 to 21 GHz.

[0025] 1-Substrate, 2-First metal thin film, 3-First oxide, 4-First thin film resistor, 6-Second metal thin film, 9-Third metal thin film, 7-Second thin film resistor, 8-Second oxide, 11-Fourth metal thin film, 10-Third oxide, 13-Fifth metal thin film, 12-Third thin film resistor, 5-Sixth metal thin film, 14-First metal via, 15-Second metal via. Detailed Implementation

[0026] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings. The working principle of the amplitude equalizer is well known to those skilled in the art and will not be elaborated here.

[0027] Example 1

[0028] Please refer to Figure 1 This is a schematic diagram of a broadband amplitude equalizer based on a high-precision MIM (metal-insulator-metal) capacitor proposed in this invention. It includes a substrate 1, a first metal thin film 2, a first oxide 3, a first thin film resistor 4, a second metal thin film 6, a third metal thin film 9, a second thin film resistor 7, a second oxide 8, a fourth metal thin film 11, a third oxide 10, a fifth metal thin film 13, a third thin film resistor 12, and a sixth metal thin film 5.

[0029] The first metal film 2, the first oxide 3, and the second metal film 6 form the first MIM capacitor; the second metal film 6, the second oxide 8, and the third metal film 9 form the second MIM capacitor; and the third metal film 9, the third oxide 10, and the fourth metal film 11 form the third MIM capacitor.

[0030] The first metal film 2, the second metal film 6, the third metal film 9, and the fourth metal film 11 together with the substrate form a transmission line with an impedance of 50Ω.

[0031] The end of the first metal film 2 furthest from the first oxide 3 serves as the input or output terminal of the equalizer, and the end of the fifth metal film 13 furthest from the third oxide 10 serves as the output or input terminal of the equalizer. The other end of the second metal film 6 is simultaneously connected to one end of the second thin-film resistor 7 and the second oxide 8. The other ends of the second thin-film resistor 7 and the second oxide 8 are connected side-by-side to the third metal film 9. The second thin-film resistor 7 and the second MIM capacitor form the first RLC resonant branch, connected in parallel between the first MIM capacitor and the third MIM capacitor.

[0032] The other end of the second metal film 6 is connected to one end of the first film resistor 4. The other end of the first film resistor 4 is connected to the second metal film 6. The first film resistor 4, the second metal film 6, and the first metal via 14 constitute the second RLC resonant branch. The second RLC resonant branch is grounded through the first metal via 14.

[0033] One end of the third metal film 9 is connected to one end of the third film resistor 12. The other end of the third film resistor 12 is connected to one end of the fifth metal film 13. The other end of the fifth metal film 13 is grounded through the second metal via 15. The first film resistor 4, the third film resistor 12, the fifth metal film 13, and the second metal via 15 form the third RLC resonant branch.

[0034] The lengths of the second metal film 6 and the fifth metal film 13 are one-quarter of the wavelength of the broadband amplitude equalizer.

[0035] By adjusting the length and width of each metal film, as well as the values ​​of the thin-film resistors and MIM capacitors, the circuit can be made to resonate at a specified frequency. The resonant frequency does not attenuate; attenuation occurs at other frequencies deviating from the resonant frequency. The attenuation is altered by adjusting the values ​​of thin-film resistors 4 and 12. Through these adjustments, the equalizer can be made to operate with the desired level of equalization within its operating frequency range.

[0036] Please refer to Figure 2 This is a schematic diagram of a MIM capacitor structure. The MIM capacitor includes a substrate, a first metal thin-film electrode, a second metal thin-film electrode, and an oxide layer disposed between the two metal thin-film electrodes. Two segments of metal thin films of equal thickness are disposed on the substrate as the first metal thin-film electrodes, separated by an oxide layer. The second metal thin-film electrode is located above the first metal thin-film electrodes. One end of the second metal thin-film electrode is connected to one segment of the first metal thin-film electrode and is separated from the other segment by an oxide layer. That is, there are both connection and overlap areas between the second metal thin-film electrode and the first metal thin-film electrode on the substrate. The thickness of the metal thin film should be 2 to 4 times the skin depth (approximately 4 to 8 times the skin depth at 2 GHz). Oxides are commonly used as insulating dielectrics between the metal electrodes of capacitors. or Its thickness is 0.05 to 1 mm. MIM capacitors have high capacitance density and low parasitic parameters due to their thinner insulating oxide layer. Furthermore, they are produced using thin-film technology, resulting in high precision.

[0037] Please refer to Figure 3 ,for Figure 2The equivalent circuit of a medium-sized MIM capacitor includes a sub-resistor R, a sub-inductance L, a sub-capacitor C, a sub-conductance G, a first capacitor C1, and a second capacitor C2. Sub-capacitor C and sub-conductance G are connected in parallel and then in series with sub-resistor R and sub-inductance L, forming a series structure. This series structure, together with the first capacitor C1 and the second capacitor C2, forms a parallel-series-parallel structure. The calculation formula is as follows (dimension in μm):

[0038] C= (pF)

[0039] (Ω)

[0040] (S)

[0041] L=

[0042] (pF)

[0043] in, The width of the metal film in the MIM capacitor. This is the length of the overlapping region between the two metal thin films in a MIM capacitor. This represents the thickness of the metal film in the MIM capacitor. denoted as ρ, where ρ is the thickness of the oxide in the MIM capacitor, and h is the thickness of the substrate dielectric.

[0044] Let be the dielectric constant of the oxide thin film. Width The effective dielectric constant of the microstrip line, is the dielectric constant of the dielectric substrate;

[0045] Surface resistance (Ω / unit area). It is a constant. , This is the characteristic impedance of the microstrip line.

[0046] This invention takes a 1GHz~21GHz broadband amplitude equalizer as an example to introduce the design of each part. The design is also effective for broadband amplitude equalizers in other frequency bands. In Ansys' HFSS software, a 3D model of the amplitude equalizer is created and high-frequency electromagnetic field simulation is performed. By adjusting the width and length of the metal film layers of each MIM capacitor (i.e., adjusting the capacitance of the MIM capacitors, the width and length of the thin-film resistors, and the width and length of other metal film layers), the insertion loss and return loss at the input and output terminals of the amplitude equalizer are optimized, resulting in the final simulation results. Figure 4 These are simulation curves of equalization performance from an equalizer ranging from 1 to 21 GHz. Figure 5The output shows the simulated return loss curves for an equalizer ranging from 1 to 21 GHz. The equalizer of this invention is not limited to the three-stage structure shown herein; it can be implemented using a multi-stage structure. The equalizer provided in this embodiment of the invention can employ... It should be noted that T-shaped and other structures are also within the scope of protection of this invention.

[0047] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the above embodiments do not limit the present invention in any way, and all technical solutions obtained by equivalent substitution or equivalent transformation fall within the protection scope of the present invention.

Claims

1. A wideband amplitude equalizer based on high-precision MIM capacitors, characterized by, include: Substrate (1), serving as a substrate; The multi-segment metal thin film includes a first metal thin film (2), a second metal thin film (6), a third metal thin film (9), a fourth metal thin film (11), a fifth metal thin film (13), and a sixth metal thin film (5). Multiple oxide sheets, including a first oxide (3), a second oxide (8), and a third oxide (10); Multiple thin-film resistors, including a first thin-film resistor (4), a second thin-film resistor (7), and a third thin-film resistor (12). The first metal film (2), the second metal film (6), the third metal film (9), and the fourth metal film (11) are arranged on the same straight line. The first oxide (3) connects the first metal film (2) and the second metal film (6) to form the first MIM capacitor. The second oxide (8) connects the second metal film (6) and the third metal film (9) to form the second MIM capacitor. The third oxide (10) connects the third metal film (9) and the fourth metal film (11) to form the third MIM capacitor. The end of the first metal film (2) away from the first oxide (3) serves as the input or output end of the equalizer. The end of the fourth metal film (11) away from the third oxide (10) serves as the output or input end of the equalizer. The second thin-film resistor (7) is connected in parallel with the second MIM capacitor to form the first resonant branch; The first thin film resistor (4) is connected to the first oxide (3) and the sixth metal thin film (5) respectively. The other end of the sixth metal thin film (5) is provided with a first metal via (14). The first thin film resistor (4), the sixth metal thin film (5) and the first metal via (14) constitute the second resonant branch. The third thin film resistor (12) is connected to the third oxide (10) and the fifth metal thin film (13) respectively. The other end of the fifth metal thin film (13) is provided with a second metal via (15). The third thin film resistor (12), the fifth metal thin film (13) and the second metal via (15) form the third resonant branch.

2. The wideband amplitude equalizer based on high-precision MIM capacitor according to claim 1, characterized in that: The substrate (1) is made of ceramic with a dielectric constant of 9.8; The thickness of each metal thin film ranges from 2 to 4 times the skin depth, and from 4 to 8 times the skin depth at a frequency of 2 GHz. , Each oxide sheet serves as the insulating medium between the metal electrodes of the capacitor. or The thickness ranges from 0.05 to 1. .

3. The wideband amplitude equalizer based on high-precision MIM capacitor of claim 1, characterized in that: The first metal thin film (2), the second metal thin film (6), the third metal thin film (9), and the fourth metal thin film (11) together with the substrate form a transmission line with an impedance of 50 ohms. .

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