Broadband symmetric amplitude equalization directional coupler and coupling method

Abstract

The application provides a broadband symmetrical amplitude equalization directional coupler and a coupling method, relates to the technical field of microwave radio frequency passive devices, and comprises the following parts: a single-section coupling line located in an input through branch, the single-section coupling line being a double-layer metal biased wide-side coupling line; a symmetrical amplitude equalizer connected to a coupling port and an isolation port respectively; and an LC matching network connected to an input port and an output port respectively, so that the directional coupler suitable for 18-50GHz can be constructed, and strong coupling of the directional coupler is realized.

Description

Technical Field

[0001] This invention relates to microwave radio frequency passive device technology, and more particularly to a broadband symmetrical amplitude equalization directional coupler and coupling method. Background Technology

[0002] Directional couplers are a class of basic microwave passive devices used to distribute, combine, isolate, and sample power within a certain frequency band and ratio. They are widely used in balanced amplification, reflective phase shifting, matched amplification, signal sources, and transceiver systems. As the operating frequency of radio frequency systems continues to increase, the demand for ultra-wideband, low insertion loss, high directivity, and on-chip integrated directional couplers is growing. For applications with high frequencies and relatively large bandwidths, such as 18-50GHz, solutions based on low-frequency lumped networks are difficult to cover due to the excessively high frequency. The conventional approach is to cascade multiple 1 / 4 wavelength coupling lines to broaden the bandwidth by increasing the number of stages. However, multi-stage cascading has inherent contradictions: the more stages there are, the greater the insertion loss and the larger the chip area. Furthermore, the on-chip coupling lines are in a non-uniform medium, and the phase velocities of odd and even modes are inconsistent. Increasing the number of stages will worsen the isolation and directivity.

[0003] In existing technologies, the idea of ​​introducing an amplitude equalization circuit on the basis of a single-segment coupled line is proposed. That is, the center frequency of the single-segment coupled line is set at a higher frequency point, so that the coupling degree increases monotonically with frequency within the operating frequency band. Then, an amplitude equalizer is connected to the coupling port and the isolation port. The attenuation slope opposite to the coupling curve is used to compensate for the coupling degree, thereby obtaining a flat coupling degree and improving directivity in a wide frequency band. However, it is mainly verified in the 2-20GHz frequency band. When it is extended to the 18-50GHz higher frequency band, a new problem is encountered: the on-chip edge-coupled microstrip line is limited by the minimum line spacing, making it difficult to achieve the strong coupling required by the directional coupler.

[0004] Therefore, how to construct a directional coupler suitable for 18-50GHz and achieve strong coupling of the directional coupler has become an urgent problem to be solved. Summary of the Invention

[0005] This invention provides a broadband symmetrical amplitude equalization directional coupler and coupling method, which can construct a directional coupler suitable for 18-50GHz and achieve strong coupling of the directional coupler.

[0006] A first aspect of the present invention provides a broadband symmetrical amplitude equalization directional coupler, comprising:

[0007] A single-segment coupling line is located in the input direct branch, and the single-segment coupling line is a double-layer metal biased wide-side coupling line;

[0008] A symmetrical amplitude equalizer is connected to both the coupling port and the isolation port.

[0009] An LC matching network is connected to the input port and the output port respectively;

[0010] Obtain the high-end cutoff frequency of the preset operating frequency band, and set the center frequency of the single-segment coupling line as the high-end cutoff frequency.

[0011] Optionally, in one possible implementation of the first aspect, the single-segment coupling line located in the input through branch includes:

[0012] A multilayer metal structure was obtained based on the integrated passive device process;

[0013] The metal layers of the multi-layer metal structure are selected to determine the double-layer metal. The coupling line is placed on the double-layer metal to obtain a double-layer metal biased wide-side coupling line as a single-segment coupling line.

[0014] Optionally, in one possible implementation of the first aspect, obtaining the multilayer metal structure based on integrated passive device technology includes:

[0015] Obtain a substrate and electroplate gold on the bottom of the substrate to serve as a ground plane;

[0016] Based on a preset metal type, metal layers are sequentially deposited on the substrate, and a preset isolation medium is used to perform dielectric isolation between the metal layers to obtain a multi-layer metal layer, which includes a first metal layer, a second metal layer and a third metal layer.

[0017] A multilayer metal structure is obtained based on the substrate, the ground plane, and the multilayer metal layers.

[0018] Optionally, in one possible implementation of the first aspect, the step of selecting metal layers in the multilayer metal structure to determine a double-layer metal, placing the coupling line on the double-layer metal, and obtaining a double-layer metal biased wide-side coupling line as a single-segment coupling line includes:

[0019] The first metal layer and the second metal layer are selected as a double-layer metal;

[0020] Based on the longitudinal direction, two coupling lines are staggered and overlapped and placed in the first and second metal layers of the double-layer metal, respectively, to obtain a double-layer metal biased wide-side coupling line as a single-segment coupling line.

[0021] Optionally, in one possible implementation of the first aspect, the symmetrical amplitude equalizer is connected to both the coupling port and the isolation port, including:

[0022] By selecting resistors, inductors, and capacitors, multiple components are obtained.

[0023] A symmetrical amplitude equalizer is obtained by connecting components based on a bridge-T symmetrical topology.

[0024] Optionally, in one possible implementation of the first aspect, the selection of resistors, inductors, and capacitors to obtain multiple components includes:

[0025] Spiral inductors are selected as inductor components, and MIM capacitors are selected as capacitor components.

[0026] By selecting resistors based on preset resistance values, multiple resistor components can be obtained.

[0027] Multiple components are obtained based on the inductor, capacitor, and resistor components.

[0028] Optionally, in one possible implementation of the first aspect, the LC matching network is connected to both the input port and the output port, and includes:

[0029] Based on an LC matching network composed of series inductors and parallel capacitors;

[0030] Connect to the LC matching network according to the input port and output port respectively.

[0031] A coupling method for a broadband symmetric amplitude equalization directional coupler, characterized by comprising:

[0032] Obtain the high-end cutoff frequency of the preset operating frequency band, and set the center frequency of the single-segment coupling line as the high-end cutoff frequency;

[0033] The change in coupling degree of the single-segment coupling line with frequency within the operating frequency band is measured to determine the slope of the increase in coupling degree;

[0034] The flat coupling degree is obtained based on the rising slope and the symmetrical amplitude equalizer.

[0035] Optionally, in one possible implementation of the first aspect, obtaining the flat coupling degree based on the rising slope and the symmetrical amplitude equalizer includes:

[0036] The target attenuation slope of the symmetrical amplitude equalizer is determined based on the rising slope, wherein the target attenuation slope is equal in absolute value and opposite in sign to the rising slope;

[0037] The symmetrical amplitude equalizer is connected to the coupling port of the directional coupler, and the coupling degree of the coupling port is reverse-compensated to obtain a flat coupling degree.

[0038] Optionally, in one possible implementation of the first aspect, it also includes:

[0039] The directional coupler operates in the frequency band of 18 GHz to 50 GHz, and the coupling port has a coupling degree of 15 dB within the operating frequency band.

[0040] The beneficial effects of this invention are as follows:

[0041] 1. This invention can construct a directional coupler suitable for 18-50GHz, achieving strong coupling. Specifically, this invention employs a single-segment coupling line combined with an amplitude equalizer. The required coupling strength can be achieved using only a single offset wide-side coupling line, eliminating the need for additional winding wiring. The coupling flatness is within ±0.5dB. By setting the center frequency of the single-segment coupling line at the high end of the operating frequency band, the coupling degree within the 18GHz to 50GHz band exhibits a monotonically increasing trend with frequency. A symmetrical amplitude equalizer is then used for reverse compensation with an opposite attenuation slope. The combination of these two methods results in a flat coupling degree within the operating frequency band.

[0042] 2. This invention employs an offset wide-side coupling structure to avoid the line spacing limitations of on-chip edge coupling, achieving 15dB strong coupling in a single-segment structure. Specifically, the single-segment coupling line in this invention uses a double-layer metal offset wide-side coupling structure, where the two coupling lines are located in adjacent metal layers and partially overlap vertically. This structure achieves power distribution through strong electromagnetic coupling between the upper and lower layers, overcoming the limitation of minimum line spacing in on-chip edge coupling structures and achieving strong coupling.

[0043] 3. This invention simplifies design and layout by using a symmetrical amplitude equalizer, improving port symmetry and matching performance. Specifically, the two amplitude equalizers connected to the coupling port and the isolation port employ identical symmetrical bridge T-type topology. Compared to the asymmetrical bridge T-type equalizers in the prior art, the symmetrical configuration of this invention ensures that the component configurations of the two branches are completely identical, simplifying circuit design and layout while improving port symmetry and matching performance. Functionally, the two symmetrical amplitude equalizers are connected to the coupling port and the isolation port respectively. The equalizer connected to the coupling port applies frequency-selective attenuation to the coupled signal, with its attenuation slope opposite to the rising slope of the coupling, thus making the coupling at the equalizer output end tend to be flat within the operating frequency band. The identical equalizer connected to the isolation port is used to absorb leakage signals, improving isolation and directivity. Attached Figure Description

[0044] Figure 1 A schematic diagram of a broadband symmetrical amplitude equalization directional coupler provided by the present invention;

[0045] Figure 2 This is a schematic diagram of an integrated passive device process stack provided by the present invention;

[0046] Figure 3 This is a schematic diagram of the structure of a symmetrical amplitude equalizer provided by the present invention. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] The terms "first," "second," "third," "fourth," etc. (if present) in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein.

[0049] It should be understood that in the various embodiments of the present invention, the sequence number of each process does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0050] It should be understood that in this invention, "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or device.

[0051] It should be understood that in this invention, "multiple" refers to two or more. "And / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "Contains A, B, and C", "Contains A, B, and C" means that all three A, B, and C are contained; "Contains A, B, or C" means that one of A, B, and C is contained; "Contains A, B, and / or C" means that any one, two, or three of A, B, and C are contained.

[0052] It should be understood that in this invention, "B corresponding to A", "B corresponding to A", "A and B correspond", or "B and A correspond" means that B is associated with A, and B can be determined based on A. Determining B based on A does not mean determining B solely based on A; B can also be determined based on A and / or other information. Matching A and B is defined as a similarity between A and B that is greater than or equal to a preset threshold.

[0053] Depending on the context, "if" as used here can be interpreted as "when," "when," "in response to determination," or "in response to detection."

[0054] The technical solution of the present invention will be described in detail below with reference to specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0055] like Figure 1 As shown, the present invention provides a structural schematic diagram of a broadband symmetrical amplitude equalization directional coupler, which includes:

[0056] S1, a single-segment coupling line, is located in the input direct branch. The single-segment coupling line is a double-layer metal biased wide-side coupling line.

[0057] It should be noted that in the ultra-wideband high-frequency band of 18GHz to 50GHz, conventional on-chip edge-coupled microstrip lines are limited by the design rules of the minimum line spacing in semiconductor processes, making it difficult to achieve the strong 15dB coupling required by directional couplers. This is because the coupling strength of edge-coupled lines increases as the line spacing decreases. However, in the high-frequency band, the line spacing required to achieve 15dB coupling is already less than the minimum value allowed by the process. While cascading multiple coupling lines can broaden the operating bandwidth by increasing the number of stages, increasing the number of stages will bring multiple problems such as increased insertion loss, a doubling of chip area, and a decrease in isolation and directivity due to the inconsistent phase velocities of odd and even modes in non-uniform media. Therefore, in order to achieve the required strong coupling in a single-segment structure while avoiding the performance degradation caused by multi-segment cascading, a double-layer metal biased wide-edge coupling structure can be used as the implementation method of a single-segment coupling line. By utilizing the strong interlayer electromagnetic coupling effect between the upper and lower metal layers, sufficient coupling can be obtained without shortening the line spacing, thereby simplifying the structure, saving chip area, and ensuring coupling performance in the ultra-wideband range.

[0058] It is understandable that the input direct-through branch refers to the main signal transmission path from the input port to the direct-through output port in a directional coupler. The bias wide-side coupling refers to a transmission line structure in which two coupling lines are respectively laid on two adjacent metal layers, and partially overlap and partially misalign in the vertical projection direction, achieving power coupling through the interaction of the electric and magnetic fields between the layers. The single-segment coupling line refers to setting a coupling transmission line segment between the input port and the direct-through output port, rather than a multi-segment cascaded structure.

[0059] In some embodiments, the specific implementation of step S1 includes:

[0060] S11 is a multi-layer metal structure obtained based on the integrated passive device process.

[0061] It should be noted that the realization of the biased wide-side coupling structure requires the process conditions of multiple metal layers and interlayer dielectric isolation. That is, the two coupling lines must be placed on different metal layers and interact with each other through interlayer electromagnetic fields. At the same time, dielectric layers are needed between the metal layers to provide electrical isolation to prevent short circuits, and the interlayer distance is controlled to adjust the coupling strength. Therefore, in order to provide a physical basis for the biased wide-side coupling line and the subsequent spiral inductor, MIM capacitor and LC matching network, multilayer metal structures can be fabricated based on integrated passive device technology.

[0062] It is understandable that the integrated passive device process refers to the process technology of integrating passive components such as inductors, capacitors, resistors and transmission lines on semiconductor or dielectric substrates using multilayer metal and dielectric processes. The multilayer metal structure is a device structure with multiple metal layers.

[0063] In some embodiments, the specific implementation of step S11 includes:

[0064] S111, Obtain the substrate and electroplate the bottom of the substrate with gold as a ground plane.

[0065] It should be noted that radio frequency microwave devices require a stable reference ground plane to provide a signal return path and a common ground reference potential during operation. At the same time, for microstrip line transmission structures, the bottom ground plane and the top layer signal line together constitute the necessary boundary conditions for electromagnetic field distribution. That is, the characteristic impedance and electromagnetic field mode of the signal line directly depend on the existence of the ground plane and its distance from the signal line. If a complete bottom ground plane is lacking, signal return failure will lead to increased electromagnetic radiation, significant parasitic effects, and unnecessary coupling between ports. Therefore, in order to provide a common ground reference, electromagnetic boundary, and signal loop for the subsequent multilayer metal structure, a ground plane can be fabricated at the bottom of the substrate.

[0066] It is understandable that a GaAs semiconductor substrate is obtained, which serves as the base material for the entire device. This substrate has high resistivity to reduce high-frequency losses. Then, an electroplating gold process can be used to deposit a layer of metal gold on the back side, i.e., the bottom, of the substrate. This gold layer uniformly covers the entire bottom of the substrate, and after electroplating, a continuous ground plane is formed.

[0067] Among them, substrate refers to the base material that supports the structure of integrated circuits or passive devices, such as GaAs material, which has high electron mobility and semi-insulating properties, making it suitable for the manufacture of high-frequency radio frequency devices. Electroplating gold is a process of depositing a gold layer on the surface of the substrate through electrolysis. Ground plane refers to the complete metal layer formed at the bottom of the substrate.

[0068] S112, based on a preset metal type, metal layers are sequentially laid on the substrate, and a preset isolation medium is used to perform dielectric isolation between the metal layers to obtain a multilayer metal layer, wherein the multilayer metal layer includes a first metal layer, a second metal layer and a third metal layer.

[0069] It should be noted that the bias wide-side coupling structure requires the two coupling lines to be placed on different metal layers. In order to provide sufficient metal layer resources for the bias wide-side coupling lines and the passive components in the subsequent equalizer, multiple layers of metal can be laid in sequence and isolation media can be used for interlayer isolation.

[0070] Understandably, according to the preset process flow of GaAs IPD technology, various metal layers are sequentially deposited on a substrate that has already undergone bottom gold plating. Specifically, for example... Figure 2 As shown, a first dielectric material is first deposited on the substrate surface. Then, a first metal layer M1 is formed by sputtering or electroplating and patterned by photolithography to define the circuit pattern of the layer. Subsequently, a preset isolation dielectric layer, such as thin-film polyimide (PI) and thin-film silicon nitride (SiN), is coated on M1 to achieve electrical isolation between M1 and the next metal layer. Next, a second metal layer M2 is deposited on the dielectric layer and patterned. Then, an isolation dielectric layer is coated again, and a third metal layer M3 is deposited and patterned. Through the above layer-by-layer deposition and isolation steps, a three-layer metal structure containing the first metal layer M1, the second metal layer M2, and the third metal layer M3 is finally obtained. The thickness of each metal layer, the dielectric constant and thickness of the dielectric layer are precisely controlled by IPD process parameters to ensure that subsequent components such as coupling lines, inductors and capacitors have predictable electrical performance.

[0071] Among them, the preset metal type refers to the material composition of each metal layer determined in advance according to the IPD process specification, such as gold, copper, etc. The thickness of each metal layer can be the same or different according to the design requirements. The preset isolation medium refers to the insulating material used to fill the gap between adjacent metal layers, such as thin film polyimide and thin film silicon nitride.

[0072] S113, a multilayer metal structure is obtained based on the substrate, the ground plane, and the multilayer metal layers.

[0073] It is understandable that a multilayer metal structure includes a substrate, a ground plane, and multiple metal layers.

[0074] S12, Select the metal layers of the multi-layer metal structure, determine the double-layer metal, place the coupling line on the double-layer metal, and obtain the double-layer metal biased wide-side coupling line as a single-segment coupling line.

[0075] It should be noted that after obtaining the multi-layer metal structure, it is necessary to select a suitable metal layer to support the bias wide-side coupling line. Since the bias wide-side coupling structure requires the two coupling lines to be located on different metal layers in order to achieve electromagnetic coupling between layers, the metal layers of the multi-layer metal structure can be selected to determine the double-layer metal, and the two coupling lines can be arranged on the selected two metal layers to form the bias wide-side coupling structure, thereby obtaining a single-segment coupling line.

[0076] Among them, double-layer metal refers to two adjacent metal layers selected from a multi-layer metal structure to support two coupling lines respectively.

[0077] In some embodiments, the specific implementation of step S12 includes:

[0078] S121, Select the first metal layer and the second metal layer as a double metal layer.

[0079] It is understandable that adjacent first and second metal layers can be selected as the double metal layer.

[0080] In this structure, the first metal layer and the second metal layer are the two metal layers closest to the substrate in the multilayer metal structure.

[0081] It is easy to understand that in a multilayer metal structure, any two adjacent metal layers can be selected as a double metal layer to facilitate the subsequent placement of coupling lines.

[0082] S122, based on the longitudinal direction, two coupling lines are staggered and overlapped and placed in the first metal layer and the second metal layer of the double-layer metal respectively, to obtain a double-layer metal biased wide-side coupling line as a single-segment coupling line.

[0083] It should be noted that after determining the double-layer metal bearing the coupling line, the two coupling lines need to be laid on these two layers of metal respectively. Offset wide-side coupling obtains a wider working bandwidth and a flatter coupling response while retaining strong interlayer coupling by staggering and overlapping the two lines. At the same time, it reduces the sensitivity to process alignment accuracy. Therefore, in order to achieve sufficient coupling strength and wide-band flatness in a single-segment structure, the two coupling lines can be laid out in a longitudinally staggered and overlapping manner.

[0084] Understandably, two coupling lines are drawn on the selected first metal layer M1 and second metal layer M2. In the longitudinal direction, i.e., the signal transmission direction, the positions of the two coupling lines are designed to partially overlap and partially misalign. That is, when viewed from the vertical projection direction, the overlapping area of ​​the two coupling lines only covers a portion of their length, rather than being completely aligned. Specifically, when viewed from a top-down perspective, the two coupling lines extend longitudinally, and their projections in the longitudinal direction have overlapping segments, but their respective ends extend in opposite directions with non-overlapping segments. Adjusting the amount of misalignment, i.e., the length ratio of the overlapping segments, can adjust the interlayer coupling strength.

[0085] Among them, the smaller the misalignment, the more overlap there is and the stronger the coupling; the larger the misalignment, the less overlap there is and the weaker the coupling. For example, when the target coupling is 15dB, the specific misalignment is determined by electromagnetic simulation optimization based on the target coupling of 15dB and the thickness of the medium between M1 and M2 layers, so that the two coupling lines can obtain the required target coupling strength under the misalignment. The double-layer metal structure with two misaligned overlapping coupling lines is used as a single coupling line and connected between the input port and the through port for power distribution of the directional coupler.

[0086] The longitudinal direction refers to the direction in which the signal is transmitted in the coupling line, that is, the length direction of the coupling line. The staggered overlap refers to the arrangement of two coupling lines located in different metal layers that partially overlap and partially stagger in the vertical projection direction.

[0087] S2, symmetrical amplitude equalizer, is connected to the coupling port and the isolation port respectively.

[0088] It should be noted that because the center frequency of the single-segment coupling line is set at the high end of the operating frequency band, the coupling degree increases monotonically with frequency throughout the 18GHz to 50GHz band. That is, the coupling degree is low in the low-frequency band and high in the high-frequency band. If the output signal of the coupling port is directly used for subsequent circuits, this frequency-varying coupling degree fluctuation will lead to problems such as decreased power monitoring accuracy and uneven system link gain, which will seriously affect the overall performance of the RF system. At the same time, the isolation port of the directional coupler also needs to maintain good isolation in the broadband to ensure the directivity index. The worse the directivity, the stronger the signal leaked from the input port to the isolation port, which will interfere with the accuracy of power sampling and signal monitoring. Therefore, in order to reverse the coupling degree curve of the single-segment coupling line as the frequency increases to obtain a flat broadband coupling output, and at the same time improve the isolation degree and overall directivity of the isolation port, symmetrical amplitude equalizers with identical structures can be connected to the coupling port and the isolation port respectively.

[0089] Among them, the coupling port is the port in the directional coupler used to output the coupled signal, the isolation port is the port that theoretically has no signal output and is used to characterize the reverse isolation capability of the directional coupler, and the symmetrical amplitude equalizer refers to the amplitude equalizer that connects components according to a symmetrical topology.

[0090] In some embodiments, the specific implementation of step S2 includes:

[0091] S21, select resistors, inductors and capacitors to obtain multiple components.

[0092] It should be noted that the implementation of an amplitude equalizer requires three basic passive components: resistors, inductors, and capacitors. Since the selection of different component types and parameters directly determines the key performance indicators of the equalizer, such as attenuation slope, operating bandwidth, and port impedance, in order to select suitable components for ultra-wideband operation from 18GHz to 50GHz, the components and parameters of resistors, inductors, and capacitors can be selected and their parameters determined separately to obtain all the components required to build a symmetrical amplitude equalizer.

[0093] In some embodiments, the specific implementation of step S21 includes:

[0094] S211, a spiral inductor is selected as the inductor component, and a MIM capacitor is selected as the capacitor component.

[0095] Among them, a spiral inductor refers to an inductor element implemented on a chip in the form of a planar spiral trace. Its inductance value is determined by geometric parameters such as the number of spiral turns, line width, line spacing, and outer diameter. A MIM capacitor refers to a capacitor element implemented with a stacked structure of metal layer, insulating dielectric layer, and metal layer. Its capacitance value is determined by the overlapping area of ​​the upper and lower plates and the thickness and dielectric constant of the dielectric layer.

[0096] It is worth mentioning that interdigitated capacitors, as an alternative, can achieve the function of capacitors, but they have greater parasitic effects in the millimeter-wave frequency band and are not as stable as MIM capacitors, so they are not the preferred choice.

[0097] For example, the spiral inductor adopts a planar spiral structure with 3.5 turns, a line width of 10μm, and an inner diameter of 30μm, with an inductance value of 0.5nH to 2nH. The MIM capacitor is formed by sandwiching a silicon nitride dielectric layer between a second metal layer and a third metal layer, with a capacitance value of 0.1pF to 0.5pF.

[0098] S212: Select resistors according to preset resistance values ​​to obtain multiple resistor components.

[0099] It should be noted that the resistors in the amplitude equalizer are used to provide frequency-independent basic attenuation and determine the impedance characteristics of the equalizer. In a bridge T-type equalizer topology, the value of the resistor directly affects the attenuation slope, center frequency, and port matching status of the equalizer. If the resistor value deviates from the design target, the attenuation characteristics of the equalizer will not be able to accurately match the rising slope of the coupling line, ultimately affecting the coupling flatness. At the same time, an improper resistor value can also cause port mismatch and worsen the return loss. Therefore, in order to obtain an amplitude equalizer that meets the design target, it is necessary to accurately select the corresponding resistor components from the resistor options provided by the process according to the preset resistor values.

[0100] Understandably, based on the target resistance value determined by circuit simulation, a resistor that meets the resistance requirement is searched and selected from the thin-film resistor layer options provided by the process. If the available resistance value of a single resistor cannot exactly meet the target value, multiple resistors can be selected in series or in parallel to achieve the target resistance value. After selection, multiple resistor components that meet the design requirements are obtained, so that they can be combined with spiral inductors and MIM capacitors to form a symmetrical amplitude equalizer.

[0101] The preset resistance value refers to the target resistance value of each resistor element determined based on the simulation optimization of the equalizer circuit.

[0102] S213, multiple components are obtained based on the inductor, capacitor and resistor components.

[0103] It is understandable that the components include inductors, capacitors, and resistors.

[0104] S22, based on the bridge T symmetrical topology, the components are connected to obtain a symmetrical amplitude equalizer.

[0105] It should be noted that, as Figure 3 As shown, after obtaining all the components required to build the equalizer, these components need to be connected according to a specific circuit topology to form an amplitude equalizer network with the required frequency selective attenuation characteristics. In the figure, L1 and L2 are inductors, C1 and C2 are capacitors, and R1, R2, and R3 are resistors. At the same time, in order to ensure that the two equalizers connected to the coupling port and the isolation port have exactly the same performance and achieve symmetrical configuration of the two branches, two equalizers need to be built with exactly the same topology and component parameters to ensure port symmetry and matching consistency. Therefore, the selected components are connected according to a bridge T-type symmetrical topology to form symmetrical amplitude equalizers connected to the coupling port and the isolation port respectively.

[0106] Among them, the bridge T-symmetric topology is a bridge T-type topology, which is a common equalizer circuit structure. Its feature is that by combining resistor and reactance branches, it can achieve amplitude-frequency characteristics where the attenuation changes monotonically with frequency over a wide frequency band. It also has a simple structure and is easy to integrate on-chip.

[0107] S3, an LC matching network, is connected to the input port and the output port respectively.

[0108] It should be noted that in a single-segment coupled-line scheme, when the port impedance is mismatched, a portion of the incident signal will be reflected back to the signal source, leading to deterioration of return loss and reduced transmission efficiency. At the same time, the reflected wave will also cause standing waves and additional phase distortion in the system, affecting the performance of the entire RF front-end. Multi-segment cascaded schemes can improve port matching by adjusting the impedance of each segment segment by segment, but at the cost of complex structure and increased area. The single-segment coupled-line scheme lacks this degree of freedom of multi-level adjustment. Therefore, port matching often becomes a performance bottleneck in the broadband. Therefore, in order to improve the return loss of the input port and the through port without increasing the complexity of the coupled line, LC matching networks can be connected to the input port and the output port respectively, so as to compensate the port impedance in the broadband by introducing additional reactive components.

[0109] Among them, the LC matching network refers to a two-port impedance transformation network composed of an inductor L and a capacitor C, which is used to match the port impedance to the system characteristic impedance, such as 50Ω, thereby reducing signal reflection and improving return loss. The topology of series inductor and parallel capacitor is one of the basic forms of LC matching network, which achieves broadband impedance compensation through the complementary changes of inductive reactance of inductor and capacitive reactance of capacitor at frequency.

[0110] In some embodiments, the specific implementation of step S3 includes:

[0111] S31 is based on an LC matching network formed by a series inductor and a parallel capacitor.

[0112] Among them, series inductor and parallel capacitor is a basic form of L-type matching network. The signal reaches the load end after passing through the series inductor, and the capacitor is connected in parallel to ground after the series inductor, thus forming a low-pass or band-pass impedance transformation structure.

[0113] Understandably, one end of the series inductor is connected to the input port, and the other end is connected to the input end of the single-segment coupled line. One end of the parallel capacitor is connected to the node between the inductor and the coupled line, and the other end is grounded. The LC matching network of the through port is arranged in the same way between the output end of the coupled line and the through port. By reasonably selecting the component values ​​of the series inductor and the parallel capacitor, the LC matching network can compensate and adjust the input impedance of the port in the ultra-wideband range of 18GHz to 50GHz, so that each port can obtain a good matching state in the target frequency band. Simulation verification shows that after introducing the LC matching network, the return loss of the input port, through port and coupled port is better than 14dB in the operating frequency band, achieving good port matching performance.

[0114] S32, connect to the LC matching network according to the input port and output port respectively.

[0115] It should be noted that both the input and output ports of the single-segment coupled-line structure suffer from high return loss in the ultra-wideband range. Both ports require matching improvement. If only the LC matching network is connected to the input port and not the through port, although the reflection at the input end is improved, the reflected signal from the through port will still be transmitted in the reverse direction along the coupled line, affecting the output stability and isolation of the coupled port. Therefore, in order to ensure a balanced improvement in the matching performance of each major port of the directional coupler and avoid the imbalance caused by single-end matching, the LC matching network can be connected to both the input and output ports respectively.

[0116] S4, obtain the high-end cutoff frequency of the preset operating frequency band, and set the center frequency of the single-segment coupling line to the high-end cutoff frequency.

[0117] It should be noted that in the constructed single-segment offset wide-side coupled line structure, the trend of coupling degree with frequency depends on the relative position of the center frequency of the coupled line and the operating frequency band. Specifically, if the center frequency of the coupled line is set in the middle of the operating frequency band, the coupling degree increases with frequency in the frequency band below the center frequency, while the coupling degree decreases with frequency in the frequency band above the center frequency. The coupling degree change in the entire operating frequency band exhibits a non-linear or non-monotonic trend. This non-monotonic coupling degree change law cannot be effectively compensated by a simple monotonic attenuation equalizer. If the center frequency is set at the low end of the operating frequency band, most of the operating frequency band is located at the falling edge of the coupled line response curve, which also cannot form a simple compensation match with the equalizer. Therefore, in order to make the coupling degree of the single-segment coupled line exhibit a monotonic change law in the operating frequency band, so as to facilitate the subsequent symmetrical amplitude equalizer to accurately compensate with a reverse attenuation slope, the center frequency of the single-segment coupled line can be set at the high end of the operating frequency band.

[0118] Understandably, the operating frequency band is the preset operating frequency band of the directional coupler, such as 18GHz to 50GHz, the high-end cutoff frequency is the highest frequency point in the preset operating frequency band, such as 50GHz, and the center frequency refers to the frequency point corresponding to the maximum coupling degree of the coupling line.

[0119] In some embodiments, the coupling method corresponding to the directional coupler includes:

[0120] A1. Measure the change in coupling degree of the single-segment coupling line with frequency within the operating frequency band, and determine the slope of the increase in coupling degree.

[0121] It is understandable that the rising slope refers to the rate of change of the coupling degree with frequency monotonically increasing under the condition that the center frequency of a single coupled line is set at the high end of the operating frequency band.

[0122] For example, obtain the coupling degree 1 corresponding to frequency A and the coupling degree 2 corresponding to frequency B, and then calculate the rising slope as (coupling degree 2 - coupling degree 1) / (frequency B - frequency A).

[0123] A2, based on the rising slope and symmetrical amplitude equalizer, obtains the flat coupling degree.

[0124] It should be noted that the change in coupling degree with increasing frequency leads to inconsistent coupling output power at different frequency points. For example, the coupling power is lower in the low-frequency band and higher in the high-frequency band, which seriously affects the signal monitoring accuracy and link gain flatness of the system in broadband applications. However, the symmetrical amplitude equalizer has a frequency-varying attenuation characteristic, with a smaller attenuation in the low-frequency band and a larger attenuation in the high-frequency band. This attenuation can complement the rising slope of the coupling line. Therefore, in order to flatten the coupling degree curve by utilizing the frequency response characteristics of the symmetrical amplitude equalizer, which are opposite to those of the single-segment coupling line, the symmetrical amplitude equalizer can be used to compensate for the rising slope of the coupling line, ultimately obtaining a flat coupling degree within the operating frequency band.

[0125] Among them, flat coupling refers to maintaining the fluctuation range of coupling degree with frequency change within the target range within the preset working frequency band. For example, the target flatness is about ±0.5dB. Reverse compensation refers to superimposing the equalizer and the coupling line with opposite slopes to make the combined response of the two tend to be flat. The opposite slope means that as the coupling degree of the coupling line increases with frequency, the attenuation of the equalizer also increases with frequency. The two have opposite effects on the output signal and can therefore cancel each other out.

[0126] In some embodiments, the specific implementation of step A2 includes:

[0127] A21, determine the target attenuation slope of the symmetrical amplitude equalizer based on the rising slope, wherein the target attenuation slope is equal in absolute value to the rising slope but opposite in sign.

[0128] Understandably, the target attenuation slope is the attenuation slope of a symmetrical amplitude equalizer that counteracts the rising slope by compensating for the coupling degree of the reverse.

[0129] A22, connect the symmetrical amplitude equalizer to the coupling port of the directional coupler, and perform reverse compensation on the coupling degree of the coupling port to obtain a flat coupling degree.

[0130] Understandably, the obtained coupling slope is the design target value, which is used as the reference data for setting the attenuation slope of the symmetrical amplitude equalizer. Specifically, the parameters of the constructed bridge T-type symmetrical amplitude equalizer are adjusted using electromagnetic simulation software such as Keysight ADS. This involves adjusting the resistance of the series resistor, the inductance of the spiral inductor, and the capacitance of the MIM capacitor in the equalizer, so that the slope of the equalizer's attenuation with frequency is equal in absolute value and opposite in direction to the slope of the coupling. When the output signal of the coupling port enters the symmetrical amplitude equalizer, the low-frequency component experiences less attenuation and the high-frequency component experiences greater attenuation, thereby correcting the original low-frequency weak and high-frequency strong coupling distribution of the coupling line into a uniform flat distribution across the entire frequency band.

[0131] For example, when the coupling of the coupled line increases by about 3dB from low frequency to high frequency within the range of 18GHz to 50GHz, and the amplitude equalizer provides an incremental attenuation of about 3dB from low frequency to high frequency within the same frequency band, the coupling is maintained within the range of 15dB±0.5dB across the entire frequency band after the two are combined, achieving flat coupling.

[0132] The attenuation slope refers to the rate at which the attenuation of the amplitude equalizer changes with frequency.

[0133] In some embodiments, it also includes:

[0134] The directional coupler operates in the frequency band of 18 GHz to 50 GHz, and the coupling port has a coupling degree of 15 dB within the operating frequency band.

[0135] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A broadband symmetrical amplitude equalization directional coupler, characterized in that, include: A single-segment coupling line is located in the input direct branch, and the single-segment coupling line is a double-layer metal biased wide-side coupling line; A symmetrical amplitude equalizer is connected to both the coupling port and the isolation port. An LC matching network is connected to the input port and the output port respectively; Obtain the high-end cutoff frequency of the preset operating frequency band, and set the center frequency of the single-segment coupling line as the high-end cutoff frequency.

2. The broadband symmetrical amplitude equalization directional coupler according to claim 1, characterized in that, The single-segment coupling line located in the input direct branch includes: A multilayer metal structure was obtained based on the integrated passive device process; The metal layers of the multi-layer metal structure are selected to determine the double-layer metal. The coupling line is placed on the double-layer metal to obtain a double-layer metal biased wide-side coupling line as a single-segment coupling line.

3. The broadband symmetrical amplitude equalization directional coupler according to claim 2, characterized in that, The multilayer metal structure obtained based on integrated passive device technology includes: Obtain a substrate and electroplate gold on the bottom of the substrate to serve as a ground plane; Based on a preset metal type, metal layers are sequentially deposited on the substrate, and a preset isolation medium is used to perform dielectric isolation between the metal layers to obtain a multi-layer metal layer, which includes a first metal layer, a second metal layer and a third metal layer. A multilayer metal structure is obtained based on the substrate, the ground plane, and the multilayer metal layers.

4. The broadband symmetrical amplitude equalization directional coupler according to claim 3, characterized in that, The step of selecting metal layers in the multi-layer metal structure to determine a double-layer metal, and placing the coupling line on the double-layer metal to obtain a double-layer metal biased wide-side coupling line as a single-segment coupling line includes: The first metal layer and the second metal layer are selected as a double-layer metal; Based on the longitudinal direction, two coupling lines are staggered and overlapped and placed in the first and second metal layers of the double-layer metal, respectively, to obtain a double-layer metal biased wide-side coupling line as a single-segment coupling line.

5. The broadband symmetrical amplitude equalization directional coupler according to claim 1, characterized in that, The symmetrical amplitude equalizer is connected to both the coupling port and the isolation port, and includes: By selecting resistors, inductors, and capacitors, multiple components are obtained. A symmetrical amplitude equalizer is obtained by connecting components based on a bridge-T symmetrical topology.

6. The broadband symmetrical amplitude equalization directional coupler according to claim 5, characterized in that, The selection of resistors, inductors, and capacitors yields multiple components, including: Spiral inductors are selected as inductor components, and MIM capacitors are selected as capacitor components. By selecting resistors based on preset resistance values, multiple resistor components can be obtained. Multiple components are obtained based on the inductor, capacitor, and resistor components.

7. The broadband symmetrical amplitude equalization directional coupler according to claim 1, characterized in that, The LC matching network is connected to the input port and the output port respectively, and includes: Based on an LC matching network composed of series inductors and parallel capacitors; Connect to the LC matching network according to the input port and output port respectively.

8. A coupling method using a broadband symmetrical amplitude equalization directional coupler as described in any one of claims 1 to 7, characterized in that, include: The change in coupling degree of the single-segment coupling line with frequency within the operating frequency band is measured to determine the slope of the increase in coupling degree; The flat coupling degree is obtained based on the rising slope and the symmetrical amplitude equalizer.

9. The coupling method according to claim 8, characterized in that, The method of obtaining flat coupling based on the rising slope and symmetrical amplitude equalizer includes: The target attenuation slope of the symmetrical amplitude equalizer is determined based on the rising slope, wherein the target attenuation slope is equal in absolute value and opposite in sign to the rising slope; The symmetrical amplitude equalizer is connected to the coupling port of the directional coupler, and the coupling degree of the coupling port is reverse-compensated to obtain a flat coupling degree.

10. The coupling method according to claim 9, characterized in that, Also includes: The directional coupler operates in the frequency band of 18 GHz to 50 GHz, and the coupling port has a coupling degree of 15 dB within the operating frequency band.

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