Lumped-constant Circuit Research Articles

Modeling and Design of Thin-Film π-Type Micro Thermoelectric Generator Using Vacuum/Insulator-Hybrid Isolation for Self-Powered Wearable Devices

Modeling and design of a thin-film $\pi $ -type micro thermoelectric generator ( $\mu $ TEG) using a new module structure, which is powered by body heat, are demonstrated for wearable device (WD) applications. The module has a vacuum/insulator-hybrid isolation structure enabling it to achieve high output power, whose interspace between the cold-side and convex-shape hot-side plates is isolated by an insulator for the thermopile integration region and by vacuum for its outside region. A lumped-constant circuit model and structure optimization algorithm for the $\mu $ TEG module using a single tradeoff parameter for the thermal and electrical resistances are developed so as to maximize the output power, based on a homeothermic system model of humans with the thermogenic action limit of humans. The developed model can accurately reproduce results analyzed by a distributed-constant circuit model. The optimum design of this $\mu $ TEG module can exhibit sufficiently high output power applicable to a power source of self-powered WDs.

Dissipation in microwave quantum circuits with hybrid nanowire Josephson elements

Recent experiments on hybrid Josephson junctions have made the argument a topical subject. However, a quantity which remains still unknown is the tunneling (or response) time, which is strictly connected to the role that dissipation plays in the dynamics of the complete system. A simple way for evaluating dissipation in microwave circuits, previously developed for describing the dynamics of conventional Josephson junctions, is now presented as suitable for application even to non-conventional junctions. The method is based on a stochastic model, as derived from the telegrapher's equation, and is particularly devoted to the case of junctions loaded by real transmission lines. When the load is constituted by lumped-constant circuits, a connection with the stochastic model is also maintained. The theoretical model demonstrated its ability to analyze both classically-allowed and forbidden processes, and has found a wide field of applicability, namely in all cases in which dissipative effects cannot be ignored.

Broadband lossy conductor wall processing using lumped constant circuit and recursive formulas on FDTD method

AbstractA practical conductor boundary processing method using the surface impedance boundary condition in the FDTD method is presented. In the present method, the surface impedance on the conductor is first replaced by an approximate equation. This approximation can easily suppress the approximation errors in the frequency range of interest in the analysis. Next, by means of inverse Laplace transform, the approximate equation is expressed in the time domain. In this way, the problem can be replaced by the excellent recursive operation previously proposed and a new update equation can be derived. Also, as a confirmation of the validity of the present conductor boundary processing method, an FDTD analysis is carried out for propagation of the TEM wave between the conductors and the results are compared with the theoretical values of the analysis model. As a result, remarkable agreement with the theoretical values is obtained over a broad frequency range. © 2006 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 89(6): 8–13, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.20172

Broadband lossy conductor wall processing using lumped constant circuit on FDTD method

AbstractA practical conductor boundary processing technique in the FDTD method based on the surface impedance boundary condition is proposed. The surface impedance of the conductor is approximated by the input impedance of a lumped element circuit. It is shown that this approximation is highly accurate in a broad bandwidth. The effectiveness of this method is numerically confirmed. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 87(6): 1–9, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.20068

Surge analysis of the tank of a gas-insulated line using lumped constant circuits

Surge voltages evaluated by a digital analysis method, for example, electromagnetic transients program (EMTP) and by an analog analysis method (transient network analyzer: TNA) are compared with experimental results on a scaled model of a gas insulated line. From the results, it is confirmed that the analog analysis method has a satisfactory accuracy and its computing speed is quite high. The error caused by the lumped element modeling of the gas insulated line is comparatively small, and the line is not necessary to be treated as a distributed parameter line. The lumped element model is advantageous to understand the mechanism of the transient characteristic of the induced transient voltage. A simple equivalent circuit of the gas insulated line is proposed and its accuracy is confirmed by a comparison with the calculated result obtained by an accurate line method. The transient overvoltages of the tank and across the insulated flange can be analytically calculated using the equivalent model.

Noise estimation system for board‐level electrical circuit–calculation of capacitance coefficient of multiconductor system by calcap

AbstractNetwork analysis with equivalent lumped constant circuits is effective for evaluating the noise generated on a circuit board considered as a total electronic circuit system. This paper considers the partial capacitance calculation program (CALCAP) that is used for expressing the pattern wiring in terms of equivalent lumped constant parameters within a loaded design system (NESSY) insensitive to the noise. In the CALCAP, three‐dimensional orientations of multiconductors on a substrate are considered and the formulations have been done with the image method and the integral equations. As a tool in a system, the CALCAP is designed for ease of parameter input and routine work, and for high‐speed execution. To this end, a nonuniform sampling algorithm is used. The capacitance of an isolated equipotential parallel plate has been computed and the dividing methods have been compared. The present method was found to be superior to others. The capacitance of parallel plates and strip lines have been computed using the present method. For the strip lines, appropriate measures have been obtained for: (1) the segmentation method; and (2) the length of the cell. Further, the capacitance has been measured and the cross‐talk experiment has been performed for a simple model of strip lines. The results of the capacitance calculation and those of the circuit simulation have been compared and found to be in good agreement.

Three dimensional perspective plotting and fitting of immittance data

Three dimensional perspective plotting of impedance or admittance data illustrates directly the interdependencies between the three variables: real part, imaginary part, and frequency. In addition, the three planar projections included show the associated three relationships between any two of these variables. We illustrate the usefulnes and versatility of such plotting for synthetic data derived from given equivalent circuits and for data obtained from measurements on lumped-constant circuits and on ionic conductors. The utility of nonlinear complex least squares data fitting is demostrated by a 3-D plot which compares both the original data and calculated “data” obtained from the fitting results.

Miniaturization of wide-band VHF filters by using spiral resonators

The miniaturization of a wide-band VHF filter composed of distributed resonators has been studied. The miniaturized filter was realized with spiral resonant lines and lumped capacitors. The filter was designed using a prototype filter circuit composed of only series-resonant lumped-constant circuits. Each resonant circuit is transformed to another resonant circuit consisting of a spiral resonant line and two capacitors. One capacitor is connected to each end of the spiral resonant line. With this technique, the line length becomes very short, e.g., one-twentieth wavelength, in comparison with the line length in conventional resonant lines of one-half or one-quarter wavelength. A filter which has a 160-185 MHz passband and a volume of 3 × 4 × 10 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> was realized with 10 spiral resonators. The filter exhibits superior characteristics with very little volume.

Equivalent circuit of coaxial (APC-7)-to-microstrip transition

A simple distributed and lumped-constant circuit model is presented for a coaxial (APC-7)-to-microstrip transition, commonly used to measure microwave integrated circuits. The model, which also includes a resistance, was experimentally verified by an automatic network analyser (a.n.a.) in the S, C and X bands. For the critical v.s.w.r. parameter, agreement was found to be within a percentage fraction and the transmission coefficient |S21| was in accordance with the a.n.a. accuracy.

Modified travelling-wave techniques to solve electrical transients on lumped and distributed constant circuits. Refraction-coefficient method

The paper describes a newly developed travelling-wave technique, the ‘refraction-coefficient method’, to solve electrical transients on complicated lumped constant circuits connected to distributed lines. Travelling waves on distributed constants are calculated with the ordinary refraction coefficients, and travelling waves on lumped constants are dealt with by the modified refraction coefficients of the new method. The new method makes it possible to solve complicated lumped constant circuits, which have been regarded as almost impossible to handle by the travelling-wave technique. Typical applications are shown for overvoltages due to a lightning stroke on a line connected to a complicated lumped constant circuit, and for switching surges due to energisation of a line, followed by a line fault and de-energisation. As is illustrated by the applications, the computation time needed by the new technique is considerably less than that required by the existing methods, and the accuracy is also very high.

Direct-Coupled-Resonator Filters

A new analysis is given of direct-coupled-resonator filters that results in excellent response at much greater bandwidths than has previously been possible. The method relies on the fact that the coupling elements can be made into perfect impedance inverters, or "quarter-wave" transformers, by the addition of negative elements in lumped-constant circuits, or of short negative lengths of line in waveguide and transmission-line circuits. Specific design formulas are given for filters constructed of lumped-constant elements, waveguide, and strip or other TEM transmission line, and for pass band response functions of the maximally flat and Tchebycheff types. The formulas include a simple frequency transformation that corrects for the frequency sensitivity of the coupling reactances, and thereby greatly improves the design accuracy for both lumpedconstant and microwave types when the bandwidth is more than a few per cent. Exact response curves computed from typical filter designs are compared to the prototype-function response curves, and it is shown that the design formulas give good results with bandwidths of at least 20 per cent in guide wavelength in the case of waveguide filters, or 20 per cent in frequency for TEM-mode transmission-line and lumped-constant filters.

Directional Channel-Separation Filters

A class of frequency-selective networks is described that combines the properties of a coupler and a conventional filter. These networks, which will be called directional filters, are particularly suited for combining or separating signals of different frequencies in communication systems, for multiplexing several equipments connected to a single antenna, etc. A signal entering one arm of the network will be transferred with essentially zero loss to a second arm over a desired channel of frequencies, while at other frequencies the signal will emerge with little loss from a third arm. Over the entire frequency range the fourth arm is isolated and the first arm is nonreflecting. Many new types of filters have been found and are described in this paper. Several of these are particularly easy to design and build in strip or coaxial line, while others lead to compact, economical structures in waveguide. Several lumped-constant circuits are also given. Design information and experimental data are included in this paper.

Resistor-Transmission-Line Circuits

Necessary and sufficient conditions are derived for a function to be the driving-point impedance of a physically realizable network consisting (essentially) of lumped resistors and lossless transmission lines. The circuits so developed are thoroughly practical for pure reactances and in many other special cases, but, in general, ideal transformers are sometimes required. A rigorous correspondence between lumped-constant circuits and line-resistor circuits is established. This correspondence immediately extends the usefulness of a wealth of theorems and techniques.