Unified Circuit Research Articles

A unified circuit model for static and dynamic analyses of semiconductor optical amplifiers and laser diodes

Semiconductor optical amplifiers (SOAs) and laser diodes (LDs) are important components for optical systems. The structure and principle of SOAs and LDs are similar. In this paper, we have proposed a unified equivalent circuit model, which includes time delay circuit and different boundary conditions, for the simulations of traveling wave (TW) SOAs, Fabry–Perot (FP) SOAs and LDs. The effect of amplified spontaneous emission on FP-SOAs is also taken into account. Using this circuit model, our simulation results are in good agreement with published results for SOAs. This model has also been applied to analyze the static and dynamic behavior in LDs. A good agreement between our simulated results and the theoretical calculations is observed for LDs.

Unifying approach to left-handed material design

We show that equivalent circuits offer a qualitative and even quantitative simple explanation for the behavior of various types of left-handed (or negative-index) metamaterials. This allows us to optimize design features and parameters while avoiding trial and error simulations or fabrications. In particular, we apply this unifying circuit approach in accounting for the features and in optimizing the structure employing parallel metallic bars on the two sides of a dielectric film.

High-efficiency linear RF Amplifier - a unified circuit approach to achieving compactness and low distortion

The realization of a highly efficient linearized amplifier has emerged as a paramount issue in the design of advanced mobile handsets. In this paper, a new RF amplifier linearization scheme using a compensating transistor combination is proposed. The devised approach ably utilizes all terminals of an additional transistor that offers a unified pre-post-distortion and cubic distortion characteristic for performance improvement. Meticulous modeling along with a power-dependent Volterra series is performed to identify contributions on each mechanism under various power levels. An experimental four-tone test reveals a maximum 28-dB reduction for the intermodulation distortion at 1.95 GHz, which outperforms typical pre-distortions of 5-10 dB. A single-ended two-stage amplifier module demonstrates a state-of-the-art power efficiency of 55% with 27-dB transducer gain at 24-dBm output power. Meanwhile, the adjacent channel power ratio (ACPR/sub 1/) is maintained with good margins of -35dBc for a four-channel wideband code-division multiple-access signal under all output dynamics. Graceful degradations on modulation bandwidths, tone spacing, bias, and gain variations are also discussed, showing superb performance with virtually no dedicated retuning circuit parameters for multicarrier applications. By combining a bias control along with the proposed linearization technique, the average efficiency (12%) is 3/spl times/ higher than that of the fixed bias (3.94%), demonstrating the potential utility on further prolonging battery lifetime in practical scenarios.

Dielectric Properties and Phase Transition in the PbSe + PbSeO3 Composite Material

Electrochemical cells in the form of pressed pellets and polycrystalline films prepared from the PbSe + PbSeO3 two-phase composite are investigated by impedance spectroscopy. The dispersion analysis of the frequencies of the real and imaginary parts of the complex impedance made it possible to reveal a unified equivalent electric circuit for these cells and to calculate its parameters. The optical (ehf) and static (elf) permittivities of the PbSe and PbSeO3 phases are determined. The permittivities ehf = 20–45 and elf = 200–280 obtained for the PbSe phase are in reasonable agreement with the data available in the literature. The temperature dependences of the ac and dc resistances indicate that the PbSe + PbSeO3 composite undergoes a phase transition at a temperature Tc ≅ 363 K.

Identification of a new function model for the AC-impedance of thermally evaporated undoped selenium films using the Eigen-coordinates method

The experimental AC-impedance data of undoped amorphous and polycrystalline selenium films were taken at T=300K in the frequency range 100 Hz–10 kHz in the dark and under band-gap illumination. The data were analyzed using the Eigen-coordinates method in conjunction with a ‘separation’ procedure without prior use of equivalent circuits. A unified circuit model with generalized impedances was recognized to parameterize well the observed AC-impedance behavior. The features of this electrical model were linked to the fractality of the heterogeneous structural regions in these selenium specimens via one or two recap elements, each represented by a complex impedance of fractional power-law frequency behavior. These recap elements reflect the electric properties of scale-invariant circuits of self-affine normal (ideal) resistor–capacitor (RC) cells of the Cauer/Forster type.

Unified equivalent-circuit model of planar discontinuities suitable for field theory-based CAD and optimization of M(H)MIC's

Unified dynamic equivalent-circuit model for characterizing planar unbounded discontinuities is reported for use in the field-theory-based computer-aided design and optimization of high-frequency integrated circuits and structures such as monolithic and hybrid microwave integrated circuits (M(H)MIC's). The proposal of the circuit model is stemmed from a new scheme called the short-open calibration (SOC) technique. This SOC technique is directly accommodated in a full-wave method-of-moments (MoM) algorithm. The developed MoM algorithm is applied to the modeling of unbounded planar discontinuities that can be segmented into two distinct sections: static model of feed lines and dynamic model of circuit discontinuity. In this paper, the MoM, is formulated in such a way that the port voltages and currents are explicitly represented through relevant network matrices. The SOC technique is used to remove or separate unwanted parasitics brought by the approximation of the impressed voltage source and also the problem of resulting consistency between the two-dimensional and three-dimensional simulations. Results for a class of planar circuit discontinuities are very well compared with measurements and also available publications. Generalized end-to-end coupling structure having offset and unequal input/output lines (to name a specific example) is studied to indicate the parametric and dispersion effects on its equivalent capacitance and radiation conductance. Advantageous features of the proposed unified circuit model suggests its practical usefulness and high accuracy in the design and optimization of a wide range of M(H)MIC's and planar antennas.

STUDY OF FAULT ANALYSIS USING TWO VECTOR SYSTEM SYMMETRICAL COMPONENTS

ABSTRACT This paper studies the application of two vector system symmetrical components to two-wires-ground network analysis. Normally, there exist both symmetrical and asymmetrical parts in the network, so that analytical calculation for load case, especially for fault case, using 3 — Ø symmetrical components will be very complicated. Features of network analysis using two vector system symmetrical components are fully considered. By means of sequence circuit coupling, symmetrical and asymmetrical parts are mutually interconnected so as to form an unified sequence circuit. Then according to boundary conditions for specified case (load or fault) complex sequence network is established for analysis. Transform relations of currents and voltages are developed and sequence parameers are derived. Complex sequence networks for various faults are given.

Space vector control of a unified compensator for nonactive power

The paper presents an application of space vector control for compensators for nonactive power (fundamental reactive power, higher harmonics, unbalance, slow variation of active power, load levelling). The new method is based on analysis of the load current space vector in rotating coordinates. The paper also proposes a new, unified power circuit for a nonactive power compensator.

Time-domain macromodels for VLSI interconnect analysis

This paper presents a method of obtaining time-domain macromodels of VLSI interconnection networks for circuit simulation. The goal of this work is to include interconnect parasitics in a circuit simulation as efficiently as possible, without significantly compromising accuracy. Stability issues and enhancements to incorporate transmission line interconnects are also discussed. A unified circuit simulation framework, incorporating different classes of interconnects and based on the proposed macromodels, is described. The simplicity and generality of the macromodels is demonstrated through examples employing RC- and RLC-interconnects.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Spiral Vector Theory of Electric Circuit.

Conventional electric circuit theories make use of two different expressions of state variables. Phasor or vector expression is used for steady state analysis and real value expression is used for transient state analysis. Due to the different expressions steady state and transient state solutions are not compatible and it causes inconvenience and awkwardness in analysis and computer simulation. The spiral vector method proposed in this paper, which makes use of exponential time function for expressing state variables, can treat electric circuit analysis in an unified way and opens up a new area of the unified circuit theory. The spiral vector method is a very powerful tool for analysis and control of AC machines also.1)-4)

A unified circuit model for bipolar transistors including quasi-saturation effects

This paper describes a compact model for bipolar transistors which includes quasi-saturation effects. The assumptions used in the formulation of this model are clearly stated and justified, and a step by step derivation of the model equations is presented. These equations model both de and charge storage effects. Parameter extraction techniques are qualitatively described and the compact model is evaluated using detailed physical simulations of a high voltage bipolar transistor. In addition, simulations employing this model are compared with measurements and are found to be in excellent agreement.

Unified power-supply circuit for the SVD-120A mercury-quartz lamp for its use as a radiation source in photometric instruments

Unified power-supply circuit for the SVD-120A mercury-quartz lamp for its use as a radiation source in photometric instruments

Book Review: Unified Circuit Theory in Electronics and Engineering Analysis

Book Review: Unified Circuit Theory in Electronics and Engineering Analysis

Book Review: Unified Circuit Theory in Electronics and Engineering Analysis

Book Review: Unified Circuit Theory in Electronics and Engineering Analysis