Coupled Transmission Lines Research Articles

Analysis and Design of an 8.5-Gb/s/Link Multi-Drop Bus Using Energy-Equipartitioned Transmission Line Couplers

An 8.5-Gb/s/link non-contact multi-drop bus is presented. The signal reflections that limit the data rates of conventional multi-drop bus interfaces are dramatically reduced by using transmission line couplers at each signal branching point. As an energy-equipartitioned technique provides the same signal level to every port, wider receiver margin is achieved. The data rate is improved by 1.8 times compared to the most advanced multi-drop bus interface. The theoretical analysis and design techniques of energy-equipartitioned transmission line couplers are discussed in this paper. The design methodologies were verified through simulations performed by using a full-3D EM-simulator and experiments with FR4 test boards. Due to the low-cut characteristics of the couplers, the low-frequency components are cut off so that differentiated pulses arrive at the receiver input point. A receiver detects and recovers the received pulses by integrating them using hysteresis characteristics. The design techniques of the transceiver for the transmission line couplers are also discussed in this paper. The proposed methods were verified by using a test chip fabricated with a 90-nm CMOS process. Experiments with a prototype of an eight-drop multi-drop bus system confirmed at a data rate of 8.5-Gb/s/link. The measured timing margin at the far-end module was 0.49-UI at a BER of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-12</sup> . The power consumption of the transceiver was 75.6-mW at a supply voltage of 1.2-V.

Microwave Emission from Hybridized States in a Semiconductor Charge Qubit.

We explore the microwave radiation emitted from a biased double quantum dot due to the inelastic tunneling of single charges. Radiation is detected over a broad range of detuning configurations between the dot energy levels, with pronounced maxima occurring in resonance with a capacitively coupled transmission line resonator. The power emitted for forward and reverse resonant detuning is found to be in good agreement with a rate equation model, which considers the hybridization of the individual dot charge states.

Asymmetrical solitary waves in coupled nonlinear transmission lines

Asymmetrical solitary waves are characterized in symmetrical, capacitively coupled transmission lines, called coupled nonlinear transmission lines (NLTLs), which are periodically loaded with Schottky varactors, in order to amplify short electrical pulses. In this work, the transmission equations of coupled NLTLs are numerically solved, using two symmetrical Korteweg–de Vries (KdV) systems with linear dispersionless coupling, to show that the lines exhibit symmetry breaking in order to support asymmetrical solitary waves. In particular, two interacting solitary waves with different polarities are investigated. The KdV systems show that the polarities of the preceding and the subsequent waves in coupled NLTLs are interchanged through colliding interactions. The process is quantified in the framework of reduction theory, assuming small velocity differences and interaction strength between the two waves. In addition, results show that the leading wave gains amplitude via collision, which means that coupled NLTLs provide good platforms for amplifying short electrical pulses.

New Design Formulas for Asymmetric Coupled-Section Marchand Balun

Design formulas for the asymmetric coupled-section Marchand balun are derived. The characteristic impedance, port impedance and electrical length of asymmetrical coupled transmission lines across two layers comprise the design formulas for designing the Marchand balun. A Marchand balun is realized based on the deduced design formulas using two identical asymmetrical coupled transmission lines fabricated across two layers. The conventional approach for designing the Marchand balun exploits the coupling coefficients of coupled transmission lines, and then provides ranges for their characteristic impedances which may but lead to inaccurate design. More accurate design method is established using the design formulas derived without using the coupling coefficients of coupled transmission lines. One example to verify the derived design formulas is taken and fabricated, showing measurement results of bandwidth from 0.62 to 1.44 GHz with the return loss of more than 10 dB, where $S_{21}$ and $S_{31}$ show better than $-4~{\rm dB}$ . Over these frequencies the measurement results show the phase and amplitude imbalances of $\pm 2^{\circ}$ and 0.2 dB, respectively.

Beam-forming module for backhaul link in a Relay-aided 4G network

A novel beam-forming module based on Wilkinson power divider technology, including attenuators and phase shifter chips is designed, fabricated and evaluated to be incorporated in a Relay Station connecting it with the Base Station under a 4G network. The proposed module is a 1:8 port circuit, utilizing two substrates, providing approximately 700MHz bandwidth over 3.5GHz frequency band and less than −20dB transmission line coupling. Moreover an external control unit that feeds the beam-forming module with code-words that define the proper amplitude/phase of the excitation currents is established and described. The presented module is connected to a planar array and tested for two beam-forming scenarios, providing satisfactory radiation patterns.

Ultrawideband fixed phase shifters based on coupled transmission lines with stubs

The synthesis problem is solved for fixed phase shifters with a new structure of the phase-shifting channel, which is formed by cascading several two-ports. Each two-port is section of distributed–coupled transmission lines with a short-circuited stub. An advantage of the proposed structure over existing analogues is shown.

An Efficient Analytical Method for Electromagnetic Field to Transmission Line Coupling Into a Rectangular Enclosure Excited by an Internal Source

A simple and efficient analytical method has been developed for predicting the electromagnetic field coupling with a lossless transmission line (TL) located in a rectangular enclosure. The metallic enclosure is excited by an internal electrical short dipole or monopole source. The electric fields generated inside the rectangular enclosure and excited by some simple sources are calculated by using the electric-type dyadic Green's function. Our approach combines, on one hand, a lumped-pi circuit model of TL and, on the other hand, the Agrawal coupling model. A simple equivalent circuit has been derived which can give prediction for the coupling between the cavity field and the TL. This method is computationally less intensive compared to other numerical methods to solve such a problem. The analytical results have been successfully compared over a wide frequency band with the finite-difference time domain and experimental results carried out in different combinations of source and line position.

FDTD technique based crosstalk analysis of bundled SWCNT interconnects

The equivalent electrical circuit model of a bundled single-walled carbon nanotube based distributed RLC interconnects is employed for the crosstalk analysis. The accurate time domain analysis and crosstalk effect in the VLSI interconnect has emerged as an essential design criteria. This paper presents a brief description of the numerical method based finite difference time domain (FDTD) technique that is intended for estimation of voltages and currents on coupled transmission lines. For the FDTD implementation, the stability of the proposed model is strictly restricted by the Courant condition. This method is used for the estimation of crosstalk induced propagation delay and peak voltage in lossy RLC interconnects. Both functional and dynamic crosstalk effects are analyzed in the coupled transmission line. The effect of line resistance on crosstalk induced delay, and peak voltage under dynamic and functional crosstalk is also evaluated. The FDTD analysis and the SPICE simulations are carried out at 32 nm technology node for the global interconnects. It is observed that the analytical results obtained using the FDTD technique are in good agreement with the SPICE simulation results. The crosstalk induced delay, propagation delay, and peak voltage obtained using the FDTD technique shows average errors of 4.9%, 3.4% and 0.46%, respectively, in comparison to SPICE.

Characterization of leapfrogging solitary waves in coupled nonlinear transmission lines

Leapfrogging solitary waves are characterized in two capacitively coupled transmission lines that are periodically loaded with Schottky varactors, called coupled nonlinear transmission lines (NLTLs). The coupling implies that a nonlinear solitary wave moving on one of the lines is bounded with the wave moving on the other line, which results in the periodic amplitude/phase oscillation called leapfrogging. In this study, we clarify how the leapfrogging frequency depends on the physical parameters of coupled NLTLs using a numerical model validated through measuring test lines and demonstrate the relaxation of leapfrogging. In addition, coupled Korteweg-de Vries equations are derived by applying the reductive perturbation method to the transmission equations of coupled NLTLs. Using perturbation theory based on the inverse scattering transform, a closed-form expression of leapfrogging frequency is obtained and the parameter values that simulate the properties well are examined. Engineering applications based on leapfrogging are finally discussed.

Impedance Perturbation Theory for Coupled Uniform Transmission Lines

Taking the impedance mismatch of transmission lines as a small quantity, a novel impedance perturbation theory based on the lumped transmission line model is established for both the single-ended and coupled transmission lines. The propagation constant, S-parameters, and T-parameters can be directly constructed from an impedance perturbation factor. As an application example, a detailed perturbation analysis is carried out for differential striplines, which provides insights in the S-parameter features and the splitting in the modal propagation constants. The corresponding numerical simulation indicates that the perturbation model captures and explains the most important features of the exact S-parameters. As another application example, the perturbation model is employed in the through-reflection-line deembedding formulas to evaluate the measurement accuracy and sensitivity. The trends obtained by this analysis is later confirmed by experimental results.

Wideband CTL cell to measure operating range of UHF RFID

A wideband coupled transmission line (CTL) cell to measure the operating range of an UHF RFID (ORUR) is presented. Also, an ORUR test system is proposed to increase the isolation to more than 55 dB. It is shown that the ORUR measured by this proposed cell agrees well with the measured data using a fully anechoic chamber.

In brief

PAGE 380 A high efficiency, directive and linearly polarised slotted waveguide antenna array, realised with wire electrical discharge machining, has been presented by researchers in France. The antenna will be useful when applications based on rectangular waveguides are considered or when substrates need to be avoided. PAGE 403 Researchers in Korea and the US have presented a wideband coupled transmission line cell to measure the operating range of UHF RFID (ORUR). The authors have also proposed an ORUR test system to increase the isolation to more than 55 dB, and it is shown that the ORUR measured by the proposed cell agrees well with the measured data using a fully anechoic chamber. Avoiding substrates can be important in antenna applications PAGE 379 The first successful integration of a surface acoustic wave resonator on a titanium alloy (TC4 alloy) substrate has been presented by researchers in China. The AlN films were directly deposited on the TC4 metal substrate without the use of adhesives so the resonator could be used as an integrated strain sensor for structured health monitoring. RFID operating range can be measured using transmission line cells PAGE 397 A high efficient mm-scale spatial power combining structure has been proposed by researchers in China. High phase and amplitude consistency, as well as isolation between the output ports, are the key factors for the high efficiency of such structures allowing them to improve power output of mm-wave circuits. Aluminium Nitride films can be deposited on titanium substrates without adhesives PAGE 401 Researchers in the UK have reported the first waveguide filter with slots on broad side walls. Such a filter structure addresses the problem of joining, and so is useful in the design of terahertz or polymer-based waveguide filters that normally operate at a relatively low power level. Amplitude and phase consistency improve the efficiency of mm-wave power dividers Terahertz systems operate at low power levels so require specialist filters

Design and Analysis of an Ultra–Wideband Band–Notched Band–Pass Filter

Abstract In this paper it is intended to design an ultra-wideband band-pass filter, using new models of coupled transmission lines. In this paper, by providing a new model of resonators, the bandwidth of band-pass filters (which are one of the most crucial elements in communication systems) will be moderately increased, while their size and volume decreases. In addition to the increase in bandwidth in these filters, due to the increasing usage of new satellite communication systems, the frequency response of these filters will be developed to utilize notch in the pass band, and an ultra-wideband band-pass filter with notch will be designed and analyzed.

결합 전송선로 이론을 이용한 적층 세라믹 커패시터의 임피던스 특성 예측

결합 전송선로 이론을 이용한 적층 세라믹 커패시터의 임피던스 특성 예측

Right/Left-Handed Transmission Lines Based on Coupled Transmission Line Sections and Their Application Towards Bandpass Filters

Novel metamaterial structures featuring left-handed (LH) and composite right/left-handed (CRLH) character are presented. The proposed unit cells utilize sections of coupled transmission lines. It is shown that by taking advantage of the coupling between transmission lines an additional degree of freedom is achieved, and therefore, the design process of artificial transmission lines is more flexible. The general behavior of each of the proposed circuits is presented and analyzed. Moreover, the design equations are formulated and the design process of each unit cell is described. The usefulness and validity of the proposed unit cells are illustrated and verified by the design and measurements of compact artificial transmission line sections utilizing the presented structures. Moreover, possible applications are discussed.

New differential-mode-source cable bundle crosstalk model based on multiconductor transmission lines theory

The traditional cable bundle crosstalk model is established based on an intra-system common mode source, without considering the crosstalk of cable bundles stimulated by a differential-mode source between different systems. To solve the physical problem of crosstalk between independent circuit cable bundles which is stimulated by a differential-mode source, in this article we propose a new differential-mode source cable bundle crosstalk calculation method based on the multiconductor transmission line theory. According to the mechanism of the differential-mode-stimulated transmission line coupling, using this method we obtain a new three-conductor transmission line parasitic parameter circuit model and mathematic matrix model through using the transmission line propagating transverse electro magnetic mode. We deduce the parasitic parameter calculation formula by an image method and Neumann formula, and then obtain the new cable bundle crosstalk chain parameter array equations in frequency domain. By using the top and end boundary conditions of the new differential-mode cable bundle crosstalk model, we finally work out the crosstalk voltage in frequency domain. In this article, we take the crosstalk between differential-mode parallel double culprit cables and the victim cable from other independent circuit for example. By simulating the crosstalk voltage of victim cable in different position arrangements, we obtain the crosstalk physical law between cable bundles under the differential-mode source condition, that is, the crosstalk of the victim cable located between differential-mode circuits is much larger than that situated outside the differential-mode circuit. We can also verify that this model can be used to calculate the crosstalk caused by differential-mode source at different frequencies. In this article, we analytically calculate the crosstalk problems caused by differential-mode source cable bundles for the first time, which provides theoretical basis for solving some practical electromagnetic compatibility problems such as the bundling of a large quantity of wires and the predicting of cable bundle crosstalk. Therefore it perfects the application of multiconductor transmission line model to cable bundle crosstalk problem, and has strong guiding significance.

Broadband Input Block of Radio Receiver for Software-Defined Radio Devices

Abstract In the paper a cost-effective input block of the SDR receiver for 0.9 — 2.4 GHz frequency band built of capacitive-tuned selective amplifier and broadband Vivaldi antenna is presented. The applied selective amplifier consists of three identical sections of tunable filters and two stages of monolithic broadband amplifiers. The single filter section proposed by the authors, due to its ability to absorb parasitic inductances of varicap diodes, simplifies usage of encapsulated varicap diodes in design of tunable in broad band selective filters dedicated to input stages of the receivers. Moreover, proposed filter section has small variation of in-band insertion loss in comparison to varicap-tuned filters built of coupled transmission lines which are commonly applied in input blocks of the microwave receivers. The described selective amplifier could be easily integrated on a single substrate with the Vivaldi antenna which is a cost effective way of fabrication of the tunable in broad band input block of a receiver that has desired gain, selectivity and directivity of the antenna.

Adaptive distance relay setting for parallel transmission network connecting wind farms and UPFC

Abstract The paper presents an adaptive distance relay setting for parallel transmission network connecting wind farms. The ideal trip characteristics of distance relay is greatly affected in presence of mutual coupling of parallel transmission lines as the apparent impedance is significantly affected. Similarly, the reach setting of the relay for the lines connecting wind farms is significantly affected as the relay end voltage fluctuates continuously. Thus, the proposed study focuses on developing adaptive relay setting for parallel transmission network including wide variations in operating conditions of wind farms and effect of mutual coupling, together. Further, the performance of the proposed adaptive relay setting for parallel lines including Unified Power Flow Controller (UPFC) indicates the potential ability of the proposed analytical approach in handling distance relaying in transmission system.

Mesh analysis for extracting the S-parameters of lumped element RF and microwave circuits

This paper demonstrates the applicability of basic mesh current circuit analysis techniques, usually learned in the first year of engineering studies, to lumped element RF circuits, which are usually taught with more sophisticated analysis techniques. As an example, the S-parameters of the 90° lumped element hybrid coupler is derived using the traditional mesh current analysis, and compared to that of the distributed micro-strip response. The distributed transmission line coupler is transformed into equivalent lumped element PI sections, and then combined for the resulting lumped element coupler. Mesh current analysis is then utilized to demonstrate the equivalence between the lumped element coupler and the micro-strip coupler as well as the ability to easily simulate the effects of finite inductor Q on the circuit's performance.

Accurate time-domain modeling of multi-finger pHEMT transistor based on transmission line theory

In this paper, a fully distributed modeling of double gate InGaAs pHEMT as a 5-line active coupled transmission line is described. In order to apply the transmission line theory, a proper equivalent lumped circuit model is allocated for the differential length of the double gate quintuple line transistor and the active multi-conductor transmission line equations are obtained. The passive element values are extracted through numerical analysis and conversion of the single gate active small signal model to the double gate one is performed by an introduced scaling method. These equations are solved by the finite difference time domain technique. The simulation results are compared with the results of conventional slice modeling which are in agreement at low frequencies but show differences, at high frequencies.