High-speed data transmission slip ring based on artificial surface plasmon and design method thereof

Abstract

The application relates to the technical field of non-contact data transmission slip rings, and particularly discloses a high-speed data transmission slip ring based on artificial surface plasmons and a design method thereof. The slip ring adopts opposite differential microstrip line layers arranged on an inner ring and an outer ring as an anode plate and a cathode plate for electric field wireless transmission, and a structure of a symmetric T-shaped groove is periodically loaded on the differential microstrip line to stimulate an artificial surface plasmon transmission mode. Through structural optimization and parameter optimization design of the differential microstrip line layer, energy loss of a signal transmission slip ring in a CT scanning device during high-speed data transmission is reduced; the size of the signal transmission slip ring is reduced; and the data transmission rate, anti-interference ability and conformability of the signal transmission slip ring are improved.

Description

Technical Field

[0001] This invention relates to the field of non-contact data transmission slip ring technology, and in particular to a high-speed data transmission slip ring based on artificial surface plasmons and its design method. Background Technology

[0002] In the field of modern medical imaging, computed tomography (CT) technology, with its high-resolution three-dimensional imaging capabilities, has become an indispensable tool in clinical diagnosis. However, with the continuous advancement of CT technology, its data generation rate has increased exponentially, reaching several Gbps or even tens of Gbps. This poses new challenges to the transmission capacity, reliability, and anti-interference capabilities of data channels. Specifically, during high-speed data acquisition, CT scanning equipment requires higher transmission rates to ensure real-time image reconstruction, while simultaneously guaranteeing high reliability of data transmission to avoid diagnostic errors due to data loss or mistakes.

[0003] Traditional mechanical contact slip rings only support data transmission rates of tens of Mbps and suffer from wear issues. Therefore, modern CT equipment employs non-contact data transmission technology, effectively reducing system failure rates and improving equipment stability and lifespan. Capacitive coupling technology is an effective non-contact high-speed data transmission technology suitable for CT slip rings. It transmits signals through an electric field without physical contact, supports Gbps-level data transmission, and features small size, light weight, and low cost. A typical capacitively coupled signal is a high-speed serial differential signal.

[0004] In capacitively coupled data transmission, the following adverse factors exist: (1) High-frequency attenuation: Due to the capacitive reactance characteristics of the coupling capacitor (usually 1-10pF), the high-frequency components are significantly attenuated, resulting in signal rise time degradation and signal waveform distortion; (2) Common-mode noise sensitivity: Parasitic electricity between the coupling electrode and ground can easily introduce common-mode interference; (3) Impedance mismatch: When directly connecting the optical module circuit, the impedance of the receiving end (50-100 ohms) does not match the impedance of the coupling path, thereby causing signal reflection; (4) Inter-symbol interference: The previous chip interferes with the current chip.

[0005] Due to the above factors, the received signal by capacitive coupling exhibits weak strength, frequency-selective fading, and waveform distortion. The receiver cannot effectively and reliably recover the data, and the bit error rate (BER) is usually higher than 1e-6, which cannot meet the requirements of medical image transmission (BER<1e-12). Summary of the Invention

[0006] This invention provides a high-speed data transmission slip ring based on artificial surface plasmons and its design method, which solves the technical problem that capacitively coupled signals in the prior art are weak, distorted, and easily interfered with.

[0007] To address the above technical problems, this invention provides a high-speed data transmission slip ring based on artificial surface plasmons, comprising an inner ring and an outer ring coaxially arranged. The inner ring includes, from the inside out, an inner grounding ring, an inner dielectric base ring, and an inner differential microstrip line layer. The outer ring includes, from the outside in, an outer grounding ring, an outer dielectric base ring, and an outer differential microstrip line layer. The inner differential microstrip line layer and the outer differential microstrip line layer serve as the transmitting and receiving plates for wireless data transmission via an electric field. The parameters of both satisfy the following requirements: they can obtain the dispersion characteristics of surface plasmons in the optical frequency band and can support artificial surface plasmon modes.

[0008] Preferably, the differential microstrip circuit layer includes an inner first conductor ring and an inner second conductor ring that are symmetrically arranged and serve as positive and negative plates for each other; the inner first conductor ring has a plurality of outward-facing first T-shaped grooves uniformly formed along the radial direction, and the short side of the first T-shaped groove is located on the side close to the inner first conductor ring and the inner second conductor ring.

[0009] Preferably, the outer differential microstrip circuit layer is coaxially opposite to the inner differential microstrip circuit layer. The outer differential microstrip circuit layer includes an outer first conductor ring and an outer second conductor ring that are symmetrically arranged and serve as positive and negative electrodes. The outer first conductor ring has a plurality of outward-facing second T-shaped grooves evenly formed along the radial direction. The short sides of the second T-shaped grooves are located on the adjacent sides of the outer first conductor ring and the outer second conductor ring.

[0010] Preferably, the design parameters of the inner differential microstrip circuit layer include: the width w of the inner first conductor ring and the inner second conductor ring, the length i and width j of the short side of the first T-shaped groove, the length p and width q of the long side of the first T-shaped groove, the distance d between the inner first conductor ring and the inner second conductor ring, and the distance l between the long sides of two adjacent first T-shaped grooves on the inner first conductor ring; the design parameters of the outer differential microstrip circuit layer are consistent with the design parameters of the inner differential microstrip circuit layer.

[0011] Preferably, the parameter design target of the differential microstrip line layer is: Nyquist frequency f nyquist =2.5GHz, target differential impedance Z diff =100Ω, insertion loss I at 2.5GHz L <0.5dB, far-end crosstalk F EXT <-40dB; the base ring material of the differential microstrip circuit layer is Rogers 4350B, with a minimum processable linewidth of 0.1mm and a dielectric constant ε. r =3.48, base ring thickness h=0.254 mm, copper thickness t=0.035 mm.

[0012] Preferably, w, i, j, p, q, d, and l are all selected within their respective initial scan ranges; the initial scan range of l is the center value of l. center The fluctuation range of l is ±15%, and the center value of l is l. center Based on the speed of light c and the effective dielectric constant ε eff f nyquist The effective dielectric constant ε is estimated using an empirical formula. eff The estimation is based on microstrip line theory; the initial scan range of p and i is the center value of p and i. center i center The fluctuation range of ±10%, the center value of p and i center i center Satisfy: p center ≈(0.4~0.45)*l center i center ≈(0.3~0.35)*l center The initial scan range of w and d is the center value of w and d. center d center The fluctuation range is ±15%, and the center value of w and d is w. center d center Using professional impedance calculation software or approximate formulas based on Z diff h, ε r t is calculated; the initial scan range of j and q is 0.15mm~0.20mm.

[0013] Preferably, w=0.41mm, d=0.63mm, i=12.2mm, j=0.18mm, p=16.1mm, q=0.18mm, and l=40.5mm.

[0014] This invention also provides a design method for a high-speed data transmission slip ring based on artificial surface plasmons, the key of which includes the following steps:

[0015] The first step is to determine an initial scan range for each parameter based on the dominant influence, empirical formulas and process constraints of the differential microstrip circuit layer.

[0016] The second step is to use simulation software to gradually select the optimal parameter combination that can simultaneously meet all performance indicators within the determined initial parameter scanning range.

[0017] Furthermore, the first step specifically includes the following steps:

[0018] Clearly define fixed design objectives, unchanging input conditions, and process constraints;

[0019] The center value of l is calculated using an empirical formula, and the initial scan range is determined based on this center value.

[0020] The center values ​​of p and i are determined based on the empirical proportional relationship with the period l, and the corresponding initial scan range is determined based on their center values.

[0021] The center values ​​of w and d are calculated using a microstrip line calculator, and the corresponding initial scan range is determined based on these center values.

[0022] Set j and q to a range close to the minimum machining size;

[0023] The second step includes the following steps:

[0024] Feasible (p,i) combinations are selected through dispersion analysis to form a list. A ;

[0025] Impedance optimization is performed as a list. A For each (p,i), pair it with the optimal (w,d) to form a list. B ;

[0026] Filter the list by global performance verification. B The optimal combination of (p,i,w,d);

[0027] Arbitrarily determine a set of (j,q) values ​​within the range of j and q;

[0028] Given the current values ​​(p,i,w,d,j,q), scan l and observe the values ​​of S11 and S21.

[0029] Choose the option that optimizes S21 and S11 and f. a The l value that still meets the standard is used to obtain the final optimal combination of parameters (p,i,w,d,j,q,l).

[0030] The present invention also provides a medical CT scanning device, the key of which is that its rotating part and fixed part use the inner ring and the outer ring of the high-speed data transmission slip ring based on artificial surface plasmons for data transmission. The parameters of the high-speed data transmission slip ring are designed using the design method of the high-speed data transmission slip ring based on artificial surface plasmons.

[0031] This invention provides a high-speed data transmission slip ring based on artificial surface plasmon polaritons (SSPP) and its design method, aiming to solve the problems of severe high-frequency signal attenuation, waveform distortion, poor anti-interference capability, and high bit error rate in existing capacitively coupled slip rings. The slip ring employs opposing differential microstrip line layers on the inner and outer rings as the transmitting and receiving electrodes for wireless electric field transmission, and periodically loads symmetrical T-shaped grooves on the differential microstrip lines to excite the artificial surface plasmon polariton (SSPP) transmission mode. Through optimized design of the transmitting and receiving electrodes, the energy loss of the signal transmission slip ring in CT scanning equipment during high-speed data transmission is reduced; the size of the signal transmission slip ring is decreased; and the data transmission rate, anti-interference capability, and conformal capability of the signal transmission slip ring are improved. The design method first determines the initial scanning range of each geometric parameter based on physical meaning and empirical formulas, and then accurately selects the optimal parameter combination through multi-level simulation steps such as dispersion analysis, impedance optimization, and global performance verification. This scheme enables the slip ring to operate stably at a rate of 5Gbps with a bit error rate of less than 1×10⁻⁶. -12 With an insertion loss of less than 0.5dB, it also has the advantages of small size, strong anti-interference ability and good conformal capability, making it particularly suitable for equipment such as medical CT that have extremely high requirements for data transmission rate and reliability. Attached Figure Description

[0032] Figure 1 This is a cross-sectional view of a high-speed data transmission slip ring based on artificial surface plasmons provided in an embodiment of the present invention;

[0033] Figure 2 This is a structural diagram of the internal differential microstrip circuit layer provided in an embodiment of the present invention;

[0034] Figure 3 This is provided by the embodiments of the present invention. Figure 1 Structural equivalent diagram;

[0035] Figure 4 This is provided by the embodiments of the present invention. Figure 3 The circuit equivalent diagram;

[0036] Figure 5 This is a parameter definition diagram of the internal differential microstrip circuit layer provided in an embodiment of the present invention;

[0037] Figure 6 This is a flowchart of the design method for a high-speed data transmission slip ring provided in an embodiment of the present invention. Detailed Implementation

[0038] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. The embodiments are given for illustrative purposes only and should not be construed as limiting the present invention. The accompanying drawings are for reference and illustration only and do not constitute a limitation on the scope of patent protection of the present invention, because many changes can be made to the present invention without departing from the spirit and scope of the present invention.

[0039] This invention first provides a high-speed data transmission slip ring based on artificial surface plasmons, the cross-sectional view of which is shown below. Figure 1 As shown, the system includes an inner ring 1 and an outer ring 2 arranged coaxially. The inner ring 1 includes an inner grounding ring 11, an inner dielectric base ring 12, and an inner differential microstrip line layer 13, arranged from the inside out. The outer ring 2 includes an outer grounding ring 21, an outer dielectric base ring 22, and an outer differential microstrip line layer 23, arranged from the outside in. The inner differential microstrip line layer 13 and the outer differential microstrip line layer 23 serve as the transmitting and receiving electrodes for wireless data transmission via an electric field. Data is transmitted through the electric field formed between the transmitting and receiving electrodes. Depending on specific needs, the transmitting electrode and the receiving electrode of the inner differential microstrip line layer 13 and the receiving electrode are determined. To address the problems of weak, distorted, and easily interfered capacitively coupled signals in the prior art, the parameters of the inner differential microstrip line layer 13 and the outer differential microstrip line layer 23 satisfy the following requirements: they can obtain the dispersion characteristics of surface plasmon polaritons in the optical frequency band and can support artificial surface plasmon polariton (SSPP) modes. To achieve this condition, the present invention has carried out special structural and parameter designs for the inner differential microstrip line layer 13 and the outer differential microstrip line layer 23.

[0040] like Figure 1 As shown, the inner differential microstrip circuit layer 13 includes an inner first conductor ring 131 and an inner second conductor ring 132 that are symmetrically arranged vertically and serve as positive and negative plates to each other; the outer differential microstrip circuit layer 23 is coaxially arranged opposite to the inner differential microstrip circuit layer 13, and the outer differential microstrip circuit layer 23 includes an outer first conductor ring 231 and an outer second conductor ring 232 that are symmetrically arranged vertically and serve as positive and negative plates to each other. Figure 2 The diagram shows a partial structure of the inner first conductor ring 131 and the inner second conductor ring 132. It can be seen that multiple outward-facing first T-shaped grooves 3 are uniformly formed along the radial direction on the inner first conductor ring 131 and the inner second conductor ring 132, with the short sides of the first T-shaped grooves 3 located on the adjacent sides of the inner first conductor ring 131 and the inner second conductor ring 132. Similarly, multiple outward-facing second T-shaped grooves are uniformly formed along the radial direction on the outer first conductor ring 231, with the short sides of the second T-shaped grooves located on the adjacent sides of the outer first conductor ring 231 and the outer second conductor ring 232.

[0041] Figure 1 The slip ring structure shown can be equivalent to: Figure 3As shown, where T + T - Representing the positive and negative electrodes respectively, R + R - These represent the positive and negative receiving plates (made of metal). The dielectric base ring is made of a non-metallic material (such as polytetrafluoroethylene). The four plates are arranged facing each other, forming a resonant capacitance and parasitic capacitance between them. The corresponding equivalent circuit is shown below. Figure 4 As shown, where C c1 C represents the resonant capacitance between the transmitting positive plate and the receiving positive plate. c2 C represents the resonant capacitance between the transmitting negative plate and the receiving negative plate. r1 C represents the parasitic capacitance between the positive transmitting plate and the negative receiving plate. r2 This represents the parasitic capacitance between the transmitting negative plate and the receiving positive plate. The equivalent capacitance formed between the four plates allows data to be transmitted from the transmitting side to the receiving side, completing contactless high-speed data transmission.

[0042] The design parameters of the external differential microstrip circuit layer 23 are consistent with the design parameters of the internal differential microstrip circuit layer 13. Taking the internal differential microstrip circuit layer 13 as an example... Figure 5 This is a parameter annotation diagram for layer 13 of the differential microstrip circuit. (See diagram for example.) Figure 5 As shown, the width of the inner first conductor ring 131 and the inner second conductor ring 132 is w (referred to as line width), the length and width of the short side of the first T-shaped groove 3 are i and j respectively, the length and width of the long side of the first T-shaped groove 3 are p and q respectively, the distance between the inner first conductor ring 131 and the inner second conductor ring 132 is d, and the distance between the long sides of two adjacent first T-shaped grooves 3 on any conductor ring is l.

[0043] In SSPP mode, transmission slip rings have the following advantages compared to traditional microstrip lines:

[0044] 1. Loss and equalization: The subwavelength slot of SSPP "locks" the electric field near the metal surface, shortens the conductor path and weakens the dielectric exposure, and reduces the conductor and dielectric losses simultaneously; as a result, the insertion loss is only 0.41dB at the 2.5GHz Nyquist frequency, and the entire line can meet BER<1e-12 without forward equalization.

[0045] 2. Crosstalk and wiring density: The strong field constraint brings -46dB of far-end crosstalk. The center distance between adjacent differential pairs can be reduced to 1mm, which is still better than the performance of microstrip at 2mm pitch. The line width + spacing is reduced from 0.6mm to 0.25mm, which reduces the wiring area per unit length by 70%.

[0046] 3. Conformal capability: At a bending radius of 5mm, the S21 (insertion loss) drift of SSPP differential lines is less than 0.05dB, and the impedance drift is less than 2Ω; microstrip lines, on the other hand, exhibit significant radiation and impedance mismatch, requiring additional shielding or thicker dielectric, which increases thickness and cost.

[0047] In summary, in practical scenarios with 2.5Gbps×2 differential channels, SSPP breaks the traditional microstrip differential's "power consumption-area-signal integrity" triangle constraint in one go with its comprehensive advantages of smaller size, lower loss, lower crosstalk, no need for equalization, and flexibility. It is one of the optimal solutions for current 5Gbps total throughput board-level interconnects.

[0048] like Figure 6 As shown in the flowchart, the parameters of the differential microstrip line layer 13 are designed using the following steps:

[0049] Step 1: Based on the dominant influence of each parameter, empirical formulas, and process constraints, determine a reasonable and efficient initial scan range for each parameter to avoid blind searching;

[0050] Step 2: Using simulation software, within a defined initial parameter scanning range, gradually select the optimal parameter combination that can simultaneously meet all performance indicators.

[0051] The dominant influences of each parameter are as follows: l affects the operating frequency band, p and i affect the asymptotic frequency, w affects the characteristic impedance, d affects the differential impedance, and j and q affect manufacturability. Since the dominant influences of each parameter are inconsistent, the initial scan range of the design parameters follows the order of decreasing dominant influence: l→p, i→w, d→j, q. Before defining the initial scan range of the design parameters, it is necessary to determine the design objectives, constant input conditions, and process constraints. Specifically, the first step includes the following steps:

[0052] 1. Clearly define fixed design objectives, unchanging input conditions, and process constraints.

[0053] The design goal is to achieve the Nyquist frequency f. nyquist =2.5GHz (corresponding to 5Gbps), target differential impedance Z diff =100Ω, insertion loss I at 2.5GHz L <0.5dB, far-end crosstalk F EXT <-40dB.

[0054] The constant input conditions include: the base ring material is Rogers 4350B, and its dielectric constant ε r=3.48, base ring thickness h=0.254mm, copper thickness t=0.035mm. These are the input conditions for the design, and all subsequent steps are based on these fixed conditions. 1oz (ounce / square foot, 0.035mm) copper thickness is the most common and economical choice in the PCB manufacturing industry. The default supply specification for most commercial high-frequency boards (such as Rogers, Isola) is 1oz copper foil. Setting the copper thickness to 1oz ensures manufacturability and cost control in the design.

[0055] Process constraints: The minimum processable line width / spacing is set to 0.1mm.

[0056] 2. Calculate the center value of l using an empirical formula and determine the initial scan range based on this center value.

[0057] The center value of l center The following empirical formula is used for estimation:

[0058] ,

[0059] Where c represents the speed of light, ε eff To determine the effective dielectric constant, it needs to be estimated first. Assuming an initial microstrip linewidth w0 = 0.4 mm, then ε... eff Estimated by the following formula:

[0060] ,

[0061] This formula originates from microstrip line theory, ε eff It is between 1 and ε r The values ​​between and describe the equivalent distribution of the electric field in the medium and air.

[0062] Finally, regarding l center A fluctuation range of ±15% is given as the initial scan range of l to cover the estimation error.

[0063] 3. Determine the center values ​​of p and i based on the empirical proportional relationship with the period l, and determine the corresponding initial scan range based on their center values.

[0064] The central value of p center Set to: p center ≈(0.4~0.45)*l center p is similar to the length of a harmonic oscillator; the larger p is, the higher the resonant frequency (asymptotic frequency f). a The lower the value.

[0065] The center value of i center Set to: i center ≈(0.3~0.35)*l center i affects the coupling capacitance; the larger i is, the larger the capacitance, which in turn reduces f.a .

[0066] Finally, a scan range of ±10% is given around the center values ​​of p and i as the initial scan range for p and i. Our goal is to find the value of f by scanning. a Slightly higher than f nyquist (e.g., a combination of 2.8-3.2GHz).

[0067] 4. Use a microstrip line calculator to calculate the center values ​​of w and d, and determine the corresponding initial scan range based on these center values.

[0068] The differential impedance is mainly determined by ω and d. Increasing ω decreases the impedance; increasing d increases the impedance. We use professional impedance calculation software (such as ADS, Polar SI9000) or approximate formulas, inputting Z... diff =100Ω, h, ε r , t, to obtain the center value w of w and d center and d center .

[0069] Taking Polar SI9000 as an example, the central value w center and d center The operation steps are as follows:

[0070] ① Choose the correct model:

[0071] In the model selection area, select the "Diffential Microstrip" model.

[0072] Ensure the selected model reflects the "Embedded" or "Coated" state (i.e., whether the cable is covered by solder mask). For inner layer signals, a model without solder mask is typically chosen.

[0073] ② Input known parameters:

[0074] H1: Dielectric thickness (Height), i.e., base ring thickness h = 0.254 mm.

[0075] Er1: Dielectric constant of the medium. Input ε r =3.48.

[0076] W1: Top Width. This is one of the targets to be calculated; leave it blank or set an initial value.

[0077] S1: Spacing. This is another target to be calculated; leave it blank or set an initial value.

[0078] T1: Conductor Thickness. Input copper thickness t = 0.035 mm.

[0079] C1: Solder mask thickness, typically very thin (approximately 0.01mm). This needs to be specified if the signal is on the surface and covered by solder mask. For inner layers or surface layers not covered by solder mask, it can be set to 0.

[0080] Er2: Dielectric constant of the green oil layer, usually set to 4.2. This item is invalid if C1=0.

[0081] ③ Set the target and calculate it in reverse:

[0082] In the Impedance Required field, enter 100 and select the unit Ohms (Ω).

[0083] Then, choose one of the following methods:

[0084] Method A (Reverse Line Width Calculation): Specify a reasonable spacing S1 (e.g., 0.6 mm), then click the Solve Width button. The software will automatically calculate the required line width W1 (i.e., w). center ), further based on w center and d center The correlation is calculated to determine d. center .

[0085] Method B (Reverse Spacing Calculation): Specify a reasonable line width W1 (e.g., 0.4mm), and then click the "Solve Spacing" button. The software will automatically calculate the required spacing S1 (i.e., d). center ), further based on w center and d center The correlation was calculated to determine w. center .

[0086] ④ Obtain the center value:

[0087] Through the above operations, a precise pair of (w) can be directly obtained. center ,d center ).

[0088] In this embodiment, for Rogers 4350B (h=0.254mm), SI900 calculates: w center ≈0.41mm, d center ≈0.63mm.

[0089] w can also be calculated using approximation formulas. center d center Specifically, it includes:

[0090] ① Calculate the single-ended impedance Z0

[0091] For a given linewidth w, its single-ended characteristic impedance (Ω) can be estimated using the following formula:

[0092] ,

[0093] ② Calculate the differential impedance Z diff

[0094] After obtaining the single-ended impedance Z0, the differential impedance can be approximated as:

[0095] ,

[0096] ③ Solve iteratively using the above formula

[0097] The process is as follows:

[0098] Let's first assume a value for w (e.g., 0.4 mm);

[0099] Substitute it into the single-ended impedance formula to calculate Z0;

[0100] Then, substitute Z0 and an assumed d value (e.g., 0.6 mm) into the differential impedance formula to calculate Z. diff ;

[0101] The calculated Z diff Compared to the target value of 100Ω;

[0102] Based on the comparison results, adjust the values ​​of w or d, and then repeat the aforementioned steps until Z is reached. diff Approaching 100Ω infinitely, output the final w or d as w. center and d center .

[0103] Based on the processing capabilities, around the central value w center and d center A scan range of ±15% is given as the initial scan range for w and d.

[0104] 5. Set j and q to a range close to the minimum machining dimension.

[0105] The values ​​j and q have relatively little impact on performance, mainly affecting the concentration of the field and the feasibility of processing. Typically, they are first fixed at a single value for primary optimization, and then fine-tuned at the end. A small range based on the process is directly set, such as 0.15mm~0.20mm.

[0106] After determining the parameter range, values ​​within that range generally meet our design goals. However, to achieve optimal performance, we need to determine a set of optimal parameters. Specifically, the second step includes the following steps:

[0107] 1. Screening feasible (p,i) combinations through dispersion analysis

[0108] Specifically, it includes:

[0109] 11) Establish a single-period element eigenmode model in HFSS / CST and apply periodic boundary conditions;

[0110] 12) Fix l, w, d, j, q as their intermediate values;

[0111] 13) Perform a two-dimensional parameter scan on p and i;

[0112] 14) Extract each dispersion curve and read its asymptotic frequency f. a ;

[0113] 15) Filter out all that satisfy f a Combinations of (p,i) greater than 2.8GHz are listed in List. A .

[0114] 2. Optimize the impedance into a list. A For each (p,i), the optimal pairing is (w,d).

[0115] Specifically, it includes:

[0116] 21) From List A Choose one (p, i) combination from the given list;

[0117] 22) Establish a 3-period difference pair model and set port excitation;

[0118] 23) Perform a two-dimensional parameter scan on w and d;

[0119] 24) Simulate and evaluate the S-parameters to find the (w,d) combination that makes S11 < -15dB@2.5GHz and the differential impedance closest to 100Ω;

[0120] 25) Record this (p,i,w,d) combination and its performance;

[0121] 26) For List A Repeat steps 21) to 25) for all combinations to form a list. B (Sorted by S11 performance).

[0122] 3. Filter the list by global performance verification. B The optimal (p,i,w,d) combination

[0123] Specifically, it includes:

[0124] 31) From List B Select the top 3 combinations.

[0125] 32) Establish a complete model with multiple cycles (e.g., 10 cycles) for each group;

[0126] 33) Perform full-wave S-parameter simulation;

[0127] 34) Evaluation of key performance indicators: S21 > -0.5dB, FEXT < -40dB, S11 < -20dB @ 2.5GHz;

[0128] 35) Select the best combination that satisfies all the indicators at the same time.

[0129] 4. Perform tolerance and robustness analysis on the selected optimal combination.

[0130] Monte Carlo analysis was performed on the finally selected optimal combination, and a tolerance analysis report was output to prove the stability and reliability of the design under manufacturing tolerances. Key parameters such as w, p, and i were set to vary randomly within ±5%, and multiple simulations were run to statistically analyze the distribution of performance indicators (such as S21 and S11).

[0131] 5. Perform final verification of (p,i,w,d) using time-domain eye diagrams.

[0132] A time-domain transient simulation was performed on a model with optimal parameters (p,i,w,d). A 5Gbps PRBS-31 bitstream was input, and an eye diagram was output at the receiver. The eye height was verified to be >80mV, the eye width >0.3UI, and the BER <1×10⁻⁶. -12 .

[0133] 6. Randomly determine a set of (j,q) values ​​within the range of j and q;

[0134] 7. Given the current values ​​(p,i,w,d,j,q), scan l;

[0135] 8. Observe the values ​​of S11 and S21.

[0136] The change in l will slightly affect the impedance, and it is necessary to ensure that S11 remains below -20dB. Also, find the l value at 2.5GH that maximizes S21 (minimizes loss).

[0137] 9. Choose the option that best enables S21@2.5GHz (minimum insertion loss) and optimizes S11 and f. a The l value still meets the standard.

[0138] The propagation constant of the SSPP mode is determined by l, p, and i together. An optimal l can resonate best with the existing p and i, making energy transfer most efficient and thus minimizing losses.

[0139] After obtaining the first set of optimal parameters, a multi-cycle complete transmission line model is established, and simulation is performed to verify whether the insertion loss, return loss, far-end crosstalk, and common-mode rejection ratio meet the target. If they do not meet the target, the process is repeated in the previous steps where adjustments can be made to obtain a new combination of parameters and then the verification is repeated until the performance requirements are met.

[0140] Finally, process tolerance analysis is performed: tolerance analysis is conducted on key dimensional parameters, and after confirming that the performance drift is within the allowable range, the final design parameters are output.

[0141] The advantages of this parameter design method are:

[0142] 1. The effective scanning range of each parameter can be quickly determined based on physical meaning and empirical formulas. This avoids wasting time in the invalid parameter space, reduces the search range by several orders of magnitude, and makes it possible to find the global optimum within a limited number of simulations;

[0143] 2. A hierarchical optimization strategy is adopted, strictly adhering to the physical principles affecting performance:

[0144] First layer (p,i): First, determine the operating mode (SSPP) and operating frequency band (f) through dispersion analysis. a This is the foundation of high performance.

[0145] The second layer (w,d): Based on the correct mode, optimize impedance matching to ensure effective signal energy injection.

[0146] The third layer (l,j,q): final fine-tuning to minimize insertion loss and meet process requirements.

[0147] This process ensures that the final solution can simultaneously meet multiple demanding requirements such as high speed, low loss, low crosstalk, and high impedance matching, breaking the dilemma of "high speed, small size, and low power consumption" that is difficult to achieve simultaneously in traditional designs.

[0148] 3. Process tolerance analysis (Monte Carlo analysis) is an essential final step. It predicts and verifies the performance stability of the product under manufacturing tolerances during the design phase, greatly improving the engineering practical value of the design and the success rate of industrialization.

[0149] The following is a specific example.

[0150] After completing the first step, the following initial scanning range was determined through calculation and estimation: l=32~40mm, p=13~16mm, i=10~12mm, w=0.38~0.46mm, d=0.58~0.66mm, j=q=0.15~0.20mm.

[0151] After completing the second step, the final optimal parameter combination is obtained:

[0152] w=0.41mm, d=0.63mm, i=12.2mm, j=0.18mm, p=16.1mm, q=0.18mm, l=40.5mm.

[0153] This invention also provides a medical CT scanning device in which a high-speed data transmission slip ring based on artificial surface plasmons is used for data transmission between the rotating part and the fixed part. The parameters of the high-speed data transmission slip ring are designed using a design method based on artificial surface plasmons for high-speed data transmission slip rings.

[0154] In summary, the high-speed data transmission slip ring based on artificial surface plasmons and its design method provided in this invention aim to solve the problems of severe high-frequency signal attenuation, waveform distortion, poor anti-interference capability, and high bit error rate in existing capacitively coupled slip rings. This slip ring employs opposing differential microstrip line layers on the inner and outer rings as the transmitting and receiving electrodes for wireless electric field transmission, and periodically loads symmetrical T-shaped grooves on the differential microstrip lines to excite the artificial surface plasmon (SSPP) transmission mode. Through optimized design of the transmitting and receiving electrodes, the energy loss of the signal transmission slip ring in CT scanning equipment during high-speed data transmission is reduced; the size of the signal transmission slip ring is decreased; and the data transmission rate, anti-interference capability, and conformal capability of the signal transmission slip ring are improved. The design method first determines the initial scanning range of each geometric parameter based on physical meaning and empirical formulas, and then accurately selects the optimal parameter combination through multi-level simulation steps such as dispersion analysis, impedance optimization, and global performance verification. This scheme enables the slip ring to operate stably at a rate of 5Gbps with a bit error rate of less than 1×10⁻⁶. -12 With an insertion loss of less than 0.5dB, it also has the advantages of small size, strong anti-interference ability and good conformal capability, making it particularly suitable for equipment such as medical CT that have extremely high requirements for data transmission rate and reliability.

[0155] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A design method for a high-speed data transmission slip ring based on artificial surface plasmons, characterized in that, The high-speed data transmission slip ring includes an inner ring (1) and an outer ring (2) arranged coaxially. The inner ring (1) includes an inner grounding ring (11), an inner dielectric base ring (12), and an inner differential microstrip line layer (13) from the inside to the outside. The outer ring (2) includes an outer grounding ring (21), an outer dielectric base ring (22), and an outer differential microstrip line layer (23) from the outside to the inside. The inner differential microstrip line layer (13) and the outer differential microstrip line layer (23) are each other's transmitting and receiving plates for wireless data transmission through electric fields. The parameters of the two satisfy the following: they can obtain the dispersion characteristics of surface plasmons in the optical frequency band and can support artificial surface plasmon modes. The inner differential microstrip circuit layer (13) includes an inner first conductor ring (131) and an inner second conductor ring (132) that are symmetrically arranged and serve as positive and negative plates for each other. Multiple first T-shaped grooves (3) with outward openings are uniformly formed on the inner first conductor ring (131) and the inner second conductor ring (132) along the radial direction. The short side of the first T-shaped groove (3) is located on the side close to the inner first conductor ring (131) and the inner second conductor ring (132). The outer differential microstrip circuit layer (23) is coaxially arranged opposite to the inner differential microstrip circuit layer (13). The design parameters of the differential microstrip line layer (13) include the widths of the first conductor ring (131) and the second conductor ring (132). w The length of the short side of the first T-shaped groove (3) i ,width j The length of the long side of the first T-shaped groove (3) p ,width q The distance between the first inner conductor ring (131) and the second inner conductor ring (132) d The distance between the long sides of two adjacent first T-shaped grooves (3) on the first conductor ring (131) l The design parameters of the outer differential microstrip line layer (23) are consistent with the design parameters of the inner differential microstrip line layer (13). The design methodology includes the following steps: First step: Based on the dominant influence, empirical formula and process constraints of each parameter of the differential microstrip circuit layer (13), determine an initial scan range for each parameter; The second step is to use simulation software to gradually select the optimal parameter combination that can simultaneously meet all performance indicators within the determined initial parameter scanning range. The second step includes the following steps: Screening for feasible methods using dispersion analysis p , i Combine to form a list List A ; Impedance optimization to a list List A Each of the ( p , i ) Pairing Optimal ( w , d ), forming a list List B ; Filter the list by global performance verification List B The best ( p , i , w , d )combination; exist j and q Randomly select a group within the range ( j , q )value; In the current ( p , i , w , d , j , q Under the value, scan l Observe the values ​​of S11 and S21; Choose the option that optimizes S21 and S11. f a Still meets the standard l The value is used to obtain the final optimal combination of parameters. p , i , w , d , j , q , l ).

2. The design method of a high-speed data transmission slip ring based on artificial surface plasmons according to claim 1, characterized in that: The external differential microstrip line layer (23) includes an outer first conductor ring (231) and an outer second conductor ring (232) that are symmetrical and serve as positive and negative plates to each other. The outer first conductor ring (231) has a plurality of outward-facing second T-shaped grooves evenly distributed along the radial direction. The short side of the second T-shaped groove is located on the side close to the outer first conductor ring (231) and the outer second conductor ring (232).

3. The design method for a high-speed data transmission slip ring based on artificial surface plasmons according to claim 1, characterized in that, The first step specifically includes the following steps: Clearly define fixed design objectives, unchanging input conditions, and process constraints; Calculate using empirical formulas l The center value is used to determine the initial scan range; According to the cycle l Determining the empirical proportion p and i The center value is used to determine the corresponding initial scan range; Using a microstrip line calculator to calculate w and d The center value is used to determine the corresponding initial scan range; Will j and q Set to a range close to the minimum machining size.

4. The design method of a high-speed data transmission slip ring based on artificial surface plasmons according to claim 1, characterized in that: The parameter design target for the differential microstrip line layer (13) is: Nyquist frequency. f nyquist =2.5GHz, target differential impedance Z diff =100Ω, insertion loss at 2.5GHz I L <0.5dB, far-end crosstalk F EXT <-40dB; The base ring material of the differential microstrip circuit layer (13) is Rogers 4350B, with a minimum processable linewidth of 0.1mm and a dielectric constant of <-40dB. ε r =3.48, base ring thickness h =0.254 mm, copper thickness t =0.035mm.

5. The design method for a high-speed data transmission slip ring based on artificial surface plasmons according to claim 4, characterized in that: w , i , j , p , q , d , l Each was selected within its respective initial scan range; l The initial scan range is l central value l center The fluctuation range is ±15%. l central value l center According to the speed of light c Effective dielectric constant ε eff , f nyquist The effective dielectric constant is estimated using empirical formulas. ε eff Estimation is based on microstrip line theory; p and i The initial scan range is p and i central value p center , i center The fluctuation range is ±10%. p and i central value p center , i center satisfy: p center =[0.4 l center 0.45 l center ], i center =[0.3 l center 0.35 l center ]; w and d The initial scan range is w and d central value w center , d center The fluctuation range is ±15%. w and d central value w center , d center Using professional impedance calculation software or approximate formulas based on Z diff , h , ε r , t Perform calculations; j and q The initial scanning range is 0.15mm~0.20mm.

6. The design method for a high-speed data transmission slip ring based on artificial surface plasmons according to claim 5, characterized in that: w =0.41mm, d =0.63mm, i =12.2mm, j =0.18mm, p =16.1mm, q =0.18mm, l =40.5mm。 7. A medical CT scanning device, characterized in that, Its rotating part and fixed part use the inner ring (1) and the outer ring (2) in the design method of high-speed data transmission slip ring based on artificial surface plasmons as described in any one of claims 1-6 to transmit data.

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