Distributed Transmission Line Research Articles

Design of coplanar waveguide matching circuit for RF-CMOS front-end

For enhanced performance with smaller transceiver size at microwave frequencies, a design method is proposed in which the impedance matching network is included in the filter and integrated with the antenna. In this paper, a low noise amplifier (LNA) and a power amplifier (PA) are designed by the CMOS process. A method is presented in which the input and output impedances are matched on the chip by a matching circuit using distributed transmission lines. As the distributed transmission lines, coplanar waveguides (CPW) are used for realization of miniaturized design. First, the RF characteristics of the CPW meander line are evaluated by an electromagnetic field simulator and are compared with measured results. Next, an amplifier integrated with matching circuits is designed and its performance is predicted by a simulator. The targeted frequency of operation is 2.4 GHz for wireless LAN (IEEE802.11b). © 2005 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 88(7): 19–26, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.20161

ELO MODEL REDUCTION AND CASE STUDY OF EVENLY DISTRIBUTED RC INTERCONNECT

This paper presents state space closed forms and transfer function recursive algorithms for evenly distributed RC interconnect models and their even length-order (ELO) model reduction. The closed-forms have a computation complexity O(1). The characteristics of the ELO model simplification to its original model are revealed. It is shown that extremely high-order RC interconnects can be accurately approximated only by a tenth or higher order ELO model. The order may be reduced further when external ports are included and dominated. The results are useful to VLSI interconnect model reduction and design, and to control systems with a distributed transmission line.

Zinc-rich powder coatings characterisation in artificial sea water: EIS analysis of the galvanic action

Two zinc-rich powder coatings are applied onto phosphatised steel substrate and are studied using electrochemical impedance spectroscopy (EIS). Measurements are performed before (dry experiment) and during immersion in artificial sea water. Before immersion, EIS spectra show that percolation threshold is not attained for coating A, while coating B presents an effective percolation. In this latter case, and in order to account for the distribution of the zinc particles within the coating described as isolated, semi-isolated and percolant grains, a distributed transmission line model is proposed. When panels are immersed, the model is modified due to the electrolyte penetration through the coating, in particular with the introduction of an ionic resistance. However, it is shown that EIS spectra are not significantly modified when this ionic resistance is changed.

A compact band-pass filter using multi-element resonators

A compact, band-pass filter utilizing multi-element resonators, structured from sections of distributed transmission lines, is presented. A band-pass filter design procedure is established that emphasizes CAD techniques to characterize the individual resonators and to determine the resonator coupling values required for a specified pass-band response. Detailed band-pass filter design examples are illustrated and simulation results are employed to validate the design procedure. © 2003 Wiley Periodicals, Inc. Int J RF and Microwave CAE 13, 447–458, 2003.

Hyperreal transients on transfinite distributed transmission lines and cables

AbstractA prior work showed how non‐standard analysis could be used to derive hyperreal transients in transfinite electrical networks containing lumped inductors, capacitors, resistors and sources. In this work, hyperreal transients are derived for transfinite electrical networks whose parameters are distributed. In particular, explicit expressions are derived for hyperreal transients on uniform transmission lines and cables that ‘extend beyond infinity’ transfinitely. This requires a substantially altered technique as compared to the prior work. The present one uses a different kind of truncation procedure that reduces the transfinite line or cable to a conventionally infinite one and then expands the latter in steps to ‘fill out’ the transfinite line or cable. Copyright © 2003 John Wiley & Sons, Ltd.

Fast and accurate fault detection/location algorithms for double‐circuit/three‐terminal lines using phasor measurement units

This paper presents new PMU‐based fault detection/location algorithms for double‐circuit/three‐terminal transmission lines. The development of the algorithms is based on distributed transmission line models and synchronized positive sequence voltage and current phasors. The proposed fault detector is very sensitive, such that it can quickly identify faults. In particular, high impedance faults can be easily detected. A fault direction discriminator is also developed to distinguish between internal and external faults with respect to the protected zone. When an internal fault occurs, the discriminator starts the process of fault locating. The methods do not require fault type identification and their computational costs are very low since they do not require iterative operations. Moreover, the algorithms provide excellent performance for transposed and untransposed lines. The EMTP/ATP simulator was used to verify the performance of the methods. The simulation studies show that the algorithms can detect faults quickly, discriminate fault direction correctly, and provide a high degree of accuracy in fault location. The algorithms are independent of various fault and system conditions such as fault types, fault positions, fault path resistance, pre‐fault load flows, mutual coupling effect of lines, and line shunt capacitance.

A PFN Marx generator based on high-voltage transmission lines

A novel, high-voltage Marx generator based on distributed transmission lines is described. The generator is capable of producing a nominally rectangular output voltage pulse of up to 200 kV into an open-circuit load. The voltage-pulse duration and risetime are 100 and 30 ns respectively. The generator is 50 cm in diameter and 50 cm in height, and is comprised of five voltage-multiplying stages with each stage made from 25 m of 50 , 40 kV dc co-axial transmission-line cable. The transmission-line cable for each stage is configured as two parallel pulse-forming lines with a resultant output impedance per stage of 25 . For five stages the output impedance is therefore 125 . The generator construction is described and the performance is evaluated in terms of the risetime, erection time, jitter in the erection time and output-voltage efficiency.

Electrical material data for railway track transmission line parameter studies

Identification of the equivalent distributed transmission line parameters of rail track by electromagnetic field methodology requires the numerical values of the electrical material properties of the track components. The authors describe modelling to determine the electrical conductivity, permeability and permittivity of the rails, sleepers, ballast and ground as functions of frequency, current and the environmentally influenced moisture content. Appropriate verification procedures are described based on published reference data and practical measurements. The paper concludes by presenting reference track component material data for use in numerical models.

Single-cycle waveforms and non-periodic waves in dispersive media (exactly solvable models)

Exactly solvable models for impulse time domain electromagnetics of dispersive media are developed to describe the interaction of ultrashort (single-cycle) transients with certain classes of insulators and conductors. Transient-excited fields are described analytically by means on new, exact, non-periodic and non-stationary solutions to Maxwell's equations, obtained directly in the time domain without using Fourier-expansion or time-space separation methods. Such non-separable solutions form the mathematical basis of non-periodic waves optics. Extensions to spherical and MHD single-cycle transients, shock-excited distributed transmission lines, and some inhomogeneous and nonlinear media are presented. A flexible technique for modeling real transients by Laguerre functions is developed which enables the shape and duration dependence of the refraction and reflection features of single-cycle waveforms to be presented explicitly.

Simulink simulation of transmission lines

MATLAB can manipulate and invert large matrices and can be used in many numerical applications. MATLAB's capabilities can be extended with a recent addition called Simulink, a program which is normally used in the analysis and synthesis of modern control systems. Simulink, now incorporated into MATLAB, can also be used to analyze distributed transmission lines. Hence, it can be directly used in the analysis and design of microwave, electric power, and VLSI networks. In addition to demonstrating its wider applicability, we include several examples that are normally described in books or papers directed to the study of pulse propagation along transmission lines.

Comments on "An equivalent transformation for the mixed lumped lossless two-port and distributed transmission line"

Stimulated by previous articles by the authors of the above paper [see ibid., vol. 42, p. 272-82, 1994] Finkler and Unbehauen have done related research. In doing so, they have found additional results and synthesis applications. These are communicated here briefly. >

ELECTROMAGNETIC FIELDS IN TRACTION SYSTEMS: MODELLING AND APPLICATIONS

A two‐dimensional electromagnetic field model of a railway track and traction line is used to determine the equivalent track distributed transmission line parameters in the frequency range DC to 30kHz. The model is solved using the finite‐element method to find the minimum energy condition for two conditions: current excitation to obtain the resistance and inductance, and voltage excitation for the conductance and capacitance. The results have been confirmed using practical test data, and their application is illustrated in a time‐domain circuit simulation to model interference between power and signalling currents in a 750V DC electric railway.

An equivalent transformation for the mixed lumped lossless two-port and distributed transmission line

It is shown that the circuit consisting of a cascade connection of a lumped type D section and a distributed transmission line is transformed to an equivalent circuit consisting of a cascade connection of a class of a nonuniform transmission line and a lumped type D section. Previously obtained equivalent transformations, i.e., Brune, type C, type A and type B sections, are included in the type D section transformation presented in this paper. The type D section is reduced into the Brune section and both type A and B sections are obtained as a degenerate case of the Brune section. Procedures for obtaining these transformations are given and a general theorem concerned with a mixed lumped lossless two-port and distributed transmission line transformation is established. By using these equivalent transformations, a new analytical method for nonuniform transmission lines is derived without having to solve the telegraph equations. >

Multilevel optimization of high speed VLSI interconnect networks by decomposition

A multilevel optimization technique is developed for large-scale and hierarchical optimization of high-speed VLSI interconnects modeled by distributed transmission lines. Mathematical programming decomposition is combined with network tearing where the overall network is optimized by a set of parallel suboptimizations. The technique takes advantage of VLSI interconnects in the hierarchy of IC, multichip modules (MCM) and printed circuit board (PCB), and is faster than standard optimization. The convergence property of the technique is derived through Gauss-Seidel relaxation analysis and optimality conditions for the multiple suboptimizations.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Crosstalk effects between metal and polysilicon lines in CMOS integrated circuits

In this work the problem of crosstalk between a metal and a polysilicon line is considered. The polysilicon line is modeled as an RC distributed transmission line, and the metal fine is considered as a single node capacitively coupled to the polysilicon line. The voltage response in the polysilicon line to a step transition in the metal line is calculated, and the influence of geometrical aspects, resistance of polysilicon, and evolution of waveform with distance from the driver's end of the poly line are investigated.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A pseudothree-dimensional finite element analysis of nonuniform multiconductor transmission lines in the quasi-static and high-frequency regimes

A two-dimensional finite element analysis is used with a distributed transmission line model to analyze general nonuniform microwave transmission structures in the quasistatic and high-frequency regimes. An automated meshing scheme is employed to reduce the solution of the three-dimensional problem to one of solving a small number of two-dimensional lines. The distributed transmission line model is briefly outlined, and the quasi-static and full-wave finite element approaches are described. Results validating the approach and showing its versatility are presented and are compared to well-established models. A discussion of the tradeoffs between the full-wave and quasi-static approaches is also presented.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A novel technique for the analysis of dielectric height variations in microstrip circuits

This paper presents a technique based on the full-wave, two-dimensional spectral domain method and the distributed transmission line approach to analyze structures with a combination of conductor width and dielectric height variations. The technique is applied to a regular taper and the results are compared with existing models. A matched taper transition is then designed based on simultaneous variation of the conductor width and dielectric height such that their ratio is kept constant. The analysis of such tapers is carried out and compared to measured data. It is shown that significant reduction in the return loss can be achieved with such transitions over fairly wide, tunable frequency ranges.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Position detection of multiple light beams using phase detection

Earlier work on lateral-effect position-sensitive detectors (PSD) has used an amplitude detection signal-processing scheme to determine the position of the centroid of the incident light beam on the PSD surface. In this work we introduce a phase detection method of position measurement which is based on detecting the phase difference between the sinusoidal currents flowing through the metal electrodes. A distributed transmission line model for the PSD and a one-pole model for the transimpedance preamplifier are used in the analysis of the sensor. Experimental results are presented and are found to be in close agreement with simulation results. It is seen that the spatial resolution is proportional to the modulation frequency. With a light modulation frequency of 50 kHz and the introduction of frequency multiplication (/spl times/8) after the transimpedance preamplifier, a spatial resolution of 2 /spl mu/m is demonstrated. For application in multi-degree-of-freedom position sensors, we demonstrate the simultaneous detection of centroids of multiple light beams using frequency division multiplexing. Application of the phase method of position detection to a two dimensional PSD shows a maximum deviation from linearity of 1% over the working range of the PSD. >

Rail track distributed transmission line impedance and admittance: theoretical modeling and experimental results

Frequency-dependent distributed transmission line self and mutual impedances and admittances for a single-track, power-rail electrified railway are obtained by experiment and modeling. Impedance results obtained by numerical calculation from an electromagnetic minimum energy field solution using the finite-element method are compared with analytic impedance models based on the Carson-Pollaczek equations for a stratified, weakly conducting ground and with practical experimental measurements made on a short length of rail track. The running rail self conductances and the power rail to running rail mutual capacitances are also evaluated by the finite-element method and compared with experimental measurements. A physical interpretation of the results is given in terms of conductive and induced ground currents caused by finite ground conductivity and relative permittivity. >

Simulation of arbitrary transmission line networks with nonlinear terminations

The transient response of a high-speed digital circuit is determined by the interaction of a lossy distributed transmission line network and lumped nonlinear circuits. A robust and accurate method for the analysis of such a system is reported, and its implementation in an analog circuit simulator is discussed. The method uses a convolution technique and a time-domain impulse response to perform a transient simulation of a transmission line network. The time-domain impulse response is derived using a Fourier transform of modified frequency-domain scattering parameters. Implementation of the technique is verified by comparison with measured results.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>