High-frequency Transmission Lines Research Articles

Effects of Non-Gaussian Surface Roughness on Conductor Loss in High-Frequency Transmission Lines

Effects of Non-Gaussian Surface Roughness on Conductor Loss in High-Frequency Transmission Lines

Low-Loss Si-Based Dielectrics for High Frequency Components of Superconducting Detectors

Silicon-based dielectric is crucial for many superconducting devices, including high-frequency transmission lines, filters, and resonators. Defects and contaminants in the amorphous dielectric and at the interfaces between the dielectric and metal layers can cause microwave losses and degrade device performance. Optimization of the dielectric fabrication, device structure, and surface morphology can help mitigate this problem. We present the fabrication of silicon oxide and nitride thin film dielectrics. We then characterized them using Scanning Electron Microscopy, Atomic Force Microscopy, and spectrophotometry techniques. The samples were synthesized using various deposition methods, including Plasma-Enhanced Chemical Vapor Deposition and magnetron sputtering. The film's morphology and structure were modified by adjusting the deposition pressure and gas flow. The resulting films were used in superconducting resonant systems consisting of planar inductors and capacitors. Measurements of the resonator properties, including their quality factor, were performed.

Research on 3D Optical Module Integrating Edge Coupler and TSV

3D integration photonic interposer is becoming popular in the field of co-packaging optics (CPO). In this paper, we integrate the edge coupler and through silicon via (TSV) into the silicon interposer. Different high-frequency transmission lines are designed, analyzed and simulated. The measured results and the simulation have a good correspondence. The high frequency transmission lines, which consist of 10 μm × 100 μm TSVs and two redistribution layer (RDL) lines of 100 μm on the top layer and one 100 μm RDL line on the bottom layer, shows perfect insertion loss less than 0.35 dB @67 GHz. In addition, the 56GBaud (112Gbps) eye diagram is tested and shows excellent transmission quality. Edge couplers are designed and fabricated by packaging process. The coupling loss of coupler is less than 1.7 dB/facet. The 3D optical package module based on the active optical interposer has also been realized and verified.

Crosstalk reduction using novel cross-shaped resonators with via fence in high-frequency transmission lines

PurposeThe purpose of this paper is to design a suitable guard trace to reduce the electromagentic interference between two closely spaced high frequency transmission lines. A novel cross-shaped resonator combined via fence is passed down to alleviate far-end and near-end crosstalk (NEXT) in tightly coupled high-speed transmission lines. The distance between the adjacent transmission lines is increased stepwise as a function of trace width.Design/methodology/approachA rectangular-shaped resonator via fence is connected by a guard trace has been proposed to overcome the coupling between the traces that is separated by 2 W. Similarly, by creating a cross-shaped resonator via fence connected by guard trace that reduces the spacing further by 1.5 W.FindingsA tightly coupled transmission line structure that needs separation by a designed unit cell structure. Further research needs to be conducted to improve the NEXT, far-end crosstalk (FEXT) and spacing between the transmission lines.Originality/valueThis study portrays a novel method that combines the resonators via fence with a minimum spacing between the tightly coupled transmission lines which reduce the NEXT and FEXT; thereby reducing the size of the routing area. The resultant test structures are characterized at high frequencies using time domain and frequency domain analysis. The following scattering parameters such as insertion loss, NEXT and FEXT of the proposed method are measured as 1.504 dB, >30 dB and >20 dB, respectively.

Coplanar waveguide superconducting microwave power divider: Design, preparation and experimental tests

Power divider is a useful device that divides the power of signal into different subpowers at a certain ratio. The superconducting power divider plays an important role in various superconducting quantum computing circuits and superconducting microwave photon detectors. Therefore, in this paper we investigate how to design and prepare a typical coplanar waveguide superconducting microwave power divider. The parameters are designed by using the odd-even mode method to analyze the transport features of a three-port microwave network. Specifically, the microwave transport properties of the device with a center frequency of 5 GHz and 3 dB power division ratio are simulated. Then, the designed aluminum coplanar waveguide superconducting power divider on silicon is prepared by micro-processing technology and experimentally tested at low temperature. It is shown that the measurement results are consistent with the design parameters. It is noted that the center frequency of the actually prepared power divider is measured to be about 5.25 GHz, which is slightly different from the result of the design and simulation. This difference is probably due to the following main reasons. Firstly, the limited precision of the micromachining process is caused by the fact that the fabricated quarter-wave impedance matching line is etched incompletely, leading the length of the impedance matching line to be shortened. As a consequence, the frequency of the prepared power divider is slightly higher. Secondly, the simulation software is not designed specially for superconducting device simulations, thereby yielding the design parameters slightly different from those of the fabricated superconducting devices. Additionally, a series of attenuations has been used in the experimental test system of the superconducting microwave power dividers for reducing the various noises. This causes the input test signal to weaken, thus the reflected signal turns significantly small. Therefore, none of the <i>S</i><sub>11</sub> parameters of the device can be effectively measured. Finally, neither of <i>S</i><sub>21</sub> and <i>S</i><sub>31</sub> parameters measured in the experiment is the predicted –3 dB, which is mainly due to the imperfections in the welding between SMA connectors and high-frequency transmission lines, and the spot welding between high-frequency transmission lines and power divider samples, and also due to the discontinuities of the high-frequency transmission line and the power divider and so on. All these factors can yield the tested insertion loss of the device. Hopefully, the method in this work can be extended to designing and preparing other passive superconducting microwave devices.

Conducted EMI Investigation of a SiC-Based Multiplexing Converter for EV/PHEV

This paper investigates the conducted electromagnetic interference (EMI) characteristics of an on-board multiplexing converter that utilizes paralleled silicon carbide (SiC) devices to achieve high efficiency and high-power density for the application in electric vehicles (EVs) and plug-in hybrid electric vehicles (PHEVs). The multiplexing converter can operate as a three-phase interleaved DC/DC converter with a peak output power of 60 kW or an integrated two-stage non-isolated on-board charger (OBC) with an output power of 6.6 kW. The novelty of this paper is that it reveals that in the DC/DC mode the series resonance between the input negative lead parasitic inductance and the high frequency transmission line effects of the input power inductor will increase the conducted EMI levels, which can be mitigated by optimizing the winding methods of the power inductor or by adding a small capacitor, and reveals that in the non-isolated OBC mode the shielded cable on the battery-side will increase the grid-side EMI in the low frequency ranges, which can be suppressed by integrated installation of EMI filters without affecting the system power density. Firstly, parasitic parameters of the components of the multiplexing converter, such as the power inductors, the SiC MOSFETs and the shielded cables, are extracted and validated with impedance measurements, and the corresponding equivalent circuit models are established. Then, the conducted EMI simulation models of the multiplexing converter in different working modes are established. The influence of different interference sources and different parasitic parameters on the system EMI characteristics are analyzed, and the effective EMI suppression measures are given without affecting the system power density. Finally, the conducted EMI characteristics of the multiplexing converter and the effectiveness of the proposed EMI suppression measures are tested and verified through experiments.

Computation of the resonance frequencies of the transmission line resonators used in MRI

Stripline high frequency resonators or transmission line resonators (TLRs) manufactured as concentric RF coils at the opposite sides of a dielectric sheet serve as wireless self-resonant transmitters-receivers in MRI. Owing to their high quality factor relative to traditional RF coils composed of bulk inductor and capacitors, frequency selectivity of TLRs is high, making them promising elements for single-nucleus MRI. However, the computation of their resonance frequencies is cumbersome, and numerous mathematical mistakes and typos in publications lead to incorrect results. The present publication is the first to summarize the corrected formulas for computations and presents comparison of such computations to real measurements.

Radio Frequency Transmission: Improving Radio Frequency Transmission Properties of Graphene via Carrier Concentration Control toward High Frequency Transmission Line Applications (Adv. Funct. Mater. 18/2019)

Radio Frequency Transmission: Improving Radio Frequency Transmission Properties of Graphene via Carrier Concentration Control toward High Frequency Transmission Line Applications (Adv. Funct. Mater. 18/2019)

Development of a Mobile Application for Teaching Transmission Line Theory

<p>The teaching of transmission line theory in electrical engineering courses must be tailored to an audience which is increasingly reluctant to adhere to abstract disciplines. In our opinion, the best solution to make transmission line courses more attractive is to offer practical applications and intensively use of mathematical computer-aided teaching tools to overcome, at the beginning, the difficulties linked to the theory. Indeed, transmission line theory comes alive when the travelling waves are animated on a screen (smartphone, tablets, laptop, etc.). Fundamental concepts such as “progressive wave”, “reflected wave” and “load matching” could be easily demonstrated in the classroom or at home. Transmission line simulations are applied to problems using connections to shunt, open, matched and unmatched loads, and show how the signal waveforms arise from one end to another. The proposed Android-based animations are used with a sinusoidal generator to illustrate the evolution to the sinusoidal steady state and allow learners to easily handle the corresponding Smith chart. Students are encouraged to run those applications at home as a computational laboratory to verify their solutions to homework problems. <br />This article introduces simple Android-based virtual tools for the investigation and visualization in real time of waves traveling along a terminated finite-length transmission line, without and with faults between the source and the load. The package can be used as an educational tool in various lectures or homework to aid teaching high frequency electronics and transmission lines theory.</p>

Improving Radio Frequency Transmission Properties of Graphene via Carrier Concentration Control toward High Frequency Transmission Line Applications

AbstractGraphene has been gradually studied as a high‐frequency transmission line material owing to high carrier mobility with frequency independence up to a few THz. However, the graphene‐based transmission lines have poor conductivity due to their low carrier concentration. Here, it is observed that the radio frequency (RF) transmission performance could be severely hampered by the defect‐induced scattering, even though the carrier concentration is increased. As a possible solution, the deposition of the amorphous carbon on the graphene is studied in the high‐frequency region up to 110 GHz. The DC resistance is reduced by as much as 60%, and the RF transmission property is also enhanced by 3 dB. Also, the amorphous carbon covered graphene shows stable performance under a harsh environment. These results prove that the carrier concentration control is an effective and a facile method to improve the transmission performance of graphene. It opens up the possibilities of using graphene as interconnects in the ultrahigh‐frequency region.

EMC Board Design Utilizing High-Frequency Transmission Line Characteristics of Wiring Patterns

EMC Board Design Utilizing High-Frequency Transmission Line Characteristics of Wiring Patterns

Transparent and flexible high frequency transmission lines based on composite structure comprising silver nanowires and polyvinyl butyral

Percolated networks of silver nanowires (AgNWs) have attracted intensive attention because of their remarkable mechanical stability, along with their excellent optical and electrical performance for the fabrication of flexible transparent electrodes. Most prior research has mainly focused on fabricating transparent electrodes that can be used in optoelectronic devices such as touch sensors, light emitting diodes, and photovoltaics. However, fabrication of transparent and flexible transmission lines designed to conduct alternating current of high frequency has not been reported so far. Herein, we developed highly transparent, mechanically stable transmission line by employing inverted layer processing (ILP) in order to embed the AgNWs just below the surface of a free-standing transparent polymer. For this, we synthesized polyvinyl butyral (PVB), which can be prepared from polyvinyl alcohol by reaction with butyraldehyde, for AgNW support. AgNWs deposited on a preliminary substrate (glass) were plasmonically sintered to significantly enhance their conductivity, and then transferred to the surface of the cured PVB film by the ILP. Measurements and simulation of specially designed coplanar waveguide circuits comprising AgNWs and PVB revealed that the fabricated electrode can simultaneously provide impressive transmission performance as well as excellent mechanical flexibility and transparency. An interesting finding was that the transmission characteristics and mechanical stability are in a trade-off relationship, which needs to be carefully considered in the design and selection of materials for the flexible transmission lines.

A Proposal for a High-Voltage Transmission Line Directional Coupler

Directional couplers are devices generally used in high-frequency transmission lines and waveguides that respond to forward and reverse traveling waves separately. Hence they can be used to either measure standing-wave ratio in the steady state or to determine the direction of a propagating transient wave. Here, a design is proposed for a directional coupler to be used on multimode high-voltage transmission lines. Its performance is analyzed and several suggestions are made to improve its design.

Extraction of High-Frequency Phase-to-Phase Coupling in AC Machine Using Mixed-Mode Network Parameters

This paper proposes a method that extracts the phase-to-phase coupling of the three-phase stator winding of an ac motor for high-frequency characterization. Under the assumption of a symmetric structure, the multiport network parameters are obtained by the conversion of two-port mixed-mode network parameters. The proposed method simplifies the calculation to extract the impedance parameters of the three-phase winding structure without the full six-port measurement. Using the extracted parameters, we can construct a T-equivalent circuit and the corresponding transmission line model of a phase line, where the phase-to-phase coupling is distinguished from the self-coupling terms. Through the constructed equivalent circuit, the effect of the phase-to-phase coupling is clearly observed by comparing the high-frequency transmission line parameters. To verify the proposed method, the calculated input impedance is compared with the measured data.

印刷配線技術による高周波伝送線路の実現

印刷配線技術による高周波伝送線路の実現

Inkjet-printing deposition of silver electro-conductive layers on textile substrates at low sintering temperature by using an aqueous silver ions-containing ink for textronic applications

The main problem in preparing stable and printable inks for the inkjet printing of textile substrates is in overcoming their roughness and high sintering temperature. In this study, the modified Tollens’ process for the preparation of a suitable water-soluble ink containing silver for the inkjet printing of textile substrates as a tool for textronic applications was adopted. The choice of this type of ink ensured inkjet printability of textile surfaces with simultaneous sintering at low temperature not exceeding 90°C. The surface resistance of the inkjet-printed silver layers on all the textile fabrics studied steadily decreased with the number of silver layers deposited. In the case of 8 prints on synthetic textiles made of polyacrylonitrile, polypropylene, polyester and basalt fibres the surface resistance in the range 0.155–0.235Ω/sq. was achieved. For some textile substrates made of natural fibres and their blends with synthetic fibres, to achieve the proper conductivity an interlayer of acrylic copolymer containing resin was applied. The surface resistance for the same number of prints was in the range of 0.389–0.622Ω/sq. The study confirmed the usefulness of ink applied in printing silver electrodes and their resistance to bending, washing and dry-cleaning processes. On the basis of these findings, some potential applications in textronic systems, e.g., capacitors, textile heating actuators, textile patch antennas, and high-frequency transmission lines were proposed.

ICD lead failure detection in chronic soaked leads.

Abrasion-induced insulation breach is a common failure mode of silicone-body, transvenous, implantable cardioverter defibrillator leads. It is caused either by external compression or internal motion of conducting cables. The present method of monitoring lead integrity measures low frequency conductor impedance. It cannot detect insulation failures until both the silicone lead body and inner fluoropolymer insulation have been breached completely, exposing conductors directly to blood or tissue. Even then the resistance changes are usually swamped by the baseline values. Thus the first clinical presentation may be either failure to deliver a life-saving shock or painful, inappropriate shocks in normal rhythm. We have previously presented a method for identifying early lead failure based on high frequency transmission line impedance measurements. That work used fresh leads in a liquid simulation bath; we have now demonstrated similar effects in leads soaked for 32 days and hence with saline-saturated silicone lead bodies.

Chip-Level Optical Interconnects Using Polymer Waveguide Integrated With Laser/PD on Silicon

In this letter, we demonstrate a chip-level high-speed optical interconnect, where the optical transmitter/receiver, the polymer waveguides, and the silicon-trench 45° microreflectors are integrated on a single silicon platform. The silicon platform with a silicon trench can provide independent photonic and electrical layers, respectively, for high-speed and low-speed (except high-frequency transmission lines) data transmissions. In order to demonstrate the technical capability of chip-level optical interconnects, the vertical-cavity surface-emitting laser (VCSEL)/photodetector (PD) and the driver/amplifier IC as well as the polymer waveguides combined with the 45° microreflectors are integrated on the electrical and photonic layers of the silicon platform, respectively. The total optical transmission (VCSEL-to-waveguide-to-PD via two 45° microreflectors) is −4.7 dB. The high-speed transmission experiment shows the clear eye opening up to 20-Gbit/s data rate. The bit error rate better than $10^{\mathrm {\mathbf {-12}}}$ for the proposed architecture is also successfully demonstrated. It reveals such chip-level optical interconnects based on the proposed silicon platform with the polymer waveguides is suitable for high-speed data transmission.

Nano-Second Pulse Programming of Resistive RAM Devices and Its Benefits

ReRAM devices have shown interesting results through traditional current v. voltage characterization involving the use of complex voltage sources with current compliance. While these results may be used to roughly estimate and display functionality, they do not allow for accurate estimate of switching time, injected power, small programmers and therefore interest to the industry. Given today’s constraints in terms of power and real estate, it is appealing to transition towards simpler pulse amplitude/width modulation strategies. We present a TiN/SiOx/TiN device which relies on intrinsic switching and is successfully programmed by means of nano-second pulses. This leads to a better understanding of the switching mechanism, non-redundant power injection, accurate power consumption estimates and the possibility of compact and efficient programming circuits. Issues involving high frequency transmission lines were taken into account. Dynamically changing impedance in the device under test leads to a need for careful consideration of pulse magnitude.

Chip-Level 1 $\times$ 2 Optical Interconnects Using Polymer Vertical Splitter on Silicon Substrate

The chip-level 1 × 2 optical interconnects using the polymer vertical splitter developed on a silicon substrate are demonstrated. The 1 × 2 vertical-splitting configuration is realized using a polymer waveguide terminated at three silicon 45 ° reflectors. The high-frequency transmission lines combined with the indium solder bumps are developed to flip-chip assemble a vertical-cavity surface-emitting laser chip at the input port and two photodetector chips at two output ports. Total transmission loss of -3.26 dB with a splitting ratio of 1 : 1 for the proposed splitter is experimentally obtained. A 10-Gbit/s data transmission with bit error rates better than 10-12 for two output ports is achieved. It reveals that such chip-level 1 × 2 optical interconnects using the polymer vertical splitter are suitable for high-speed data transmission with multiple output ports.