bluuebunny/crossref_metadata_2025_split huggingface dataset:
Generation of causal and semicausal 2‐D IIR structures from fir structures via state feedback
Authors: Lehner D. , Unbehauen R. 
Published: July 2007

AbstractA method is presented to realize a class of 2‐D IIR digital filters by extension of 2‐D FIR structures through feedback paths. Most features of the initial FIR structures remain unchanged (e.g. parallelism, number of delay elements). the approach described is applied to a class of 2‐D FIR filter structures owning several advantages. the method is generalized to semicausal filters.
The set of lagrange and routh formulations for non‐linear networks
Authors: Shragowitz Eugene , Gerlovin Emmanuel 
Published: July 2007

AbstractFormulations of systems of Lagrange and Routh equations for arbitrary non‐linear electrical circuits are given. the use of Routh equations for this purpose is new. It is proved that these formulations are equivalent to the complete system of Kirchhoff equations (instead of only a part of it as in prior works). the vector of generalized coordinates for the system of Lagrange equations consists of four subvectors (loop charges for fundamental loops, cut‐set fluxes for fundamental cut‐sets, branch fluxes for voltage and flux controlled elements and branch charges for current and charge controlled elements).For the defined set of Lagrange formulations, the uniqueness of a parametric representation is proved. the structure of the Lagrange (Hamilton, Routh) formulation set is then studied and it is proved that this set is an Abelian group. A duality of Lagrange triples for electrically and topologically dual circuits is established and it is proved that this relation between the sets of Lagrange triples is an isomorphism. It is also shown that the Brayton‐Moser equations and the anti‐Lagrangian equations similar to those of M. Milić and L. Novak represent partial cases of the formulated set.
A network model for the diffusion‐convection equation
Authors: Wong Chi Chung 
Published: July 2007

AbstractIn the past network models have been used frequently to simulate the Laplace's, wave and diffusion equations. In this paper the application of the network model is further extended to include the diffusion‐convection equation. the time‐dependent diffusion‐convection equation is first modelled by an RC electric network from which a set of ODEs is derived. Numerical experiments are then performed to compare the network model and the method of lines in solving the one‐dimensional linear diffusion‐convection equation and the Burgers' equation where highly non‐linear network components are required. It is shown that, for the former problem, the network method has improved accuracy for low Peclet numbers. At high Peclet numbers the behaviour of the network method resembles that of the method of lines (MOL) with upstream‐differencing. Spurious oscillations are absent. Computing time required to solve the network is slightly less than that for the MOL. For the Burgers' equation, the network method shows a substantial improvement over the MOL in terms of accuracy with no oscillations but requires longer computing time.
Computer‐aided design and optimization of control units for VLSI processors
Authors: de Micheli Giovanni 
Published: July 2007

AbstractThis review presents the models, methods and algorithms for synthesis and optimization of control units for VLSI processors. First, circuit structures used for control in the state‐of‐the‐art processors are described. the control synthesis methods are then presented as well as the algorithms for optimizing the control unit representation. Among these techniques, the symbolic design methodology is described that can be applied to optimize the silicon area taken by some particular structures of control units.
Waveform relaxation on parallel processors
Authors: Smart David W. , Trick Timothy N. 
Published: July 2007

AbstractWaveform relaxation algorithms for the simulation of digital MOS circuits exhibit natural parallelism which can be exploited on parallel processors. This paper addressed the question of how much the circuit simulation run‐time can be reduced by using this natural parallelism. the parallel waveform relaxation methods examined in this paper are based on the Gauss‐Seidel and Gauss‐Jacobi relaxation methods, and window‐level and time‐point level parallelization strategies. the different methods are evaluated using an actual multiprocessor implementation of the algorithms, and by using a program which estimates speed‐ups, neglecting overhead. the method giving the best performance is a function of the circuit being simulated and the number of processors used. When sufficiently many processors are available, the Gauss‐Jacobi method with time‐point pipelining offers the best speed‐up potential. Speed‐ups close to one order of magnitude should be possible using this method for 1000‐node for 32 processors.
Non‐reciprocal network synthesis using the generalized richards transformation
Authors: Unbehauen Rolf , Zimmer Gerhard 
Published: July 2007

AbstractA generalization of the Richards transformation is presented and its properties are derived. the new transformation is appropriate for the canonic synthesis of non‐reciprocal network sections based on the transformation of an impedance, and it is shown that under certain constraints a transformerless realization is possible. the generalized Richards transformation can also be applied to the synthesis of network sections without degree reduction of the impedance to be transformed. This kind of application is important for the realization of transfer functions. A dual transformation for an admittance is established. Finally, it is shown how to use the generalized Richards transformation for the synthesis of transfer functions by doubly terminated lossless two‐ports.
Measuring volterra kernels (II)
Authors: Chua Leo N. O. , Liao Youlin 
Published: July 2007

AbstractAccurate measurement of Volterra kernels is an essential step in the modelling of weakly non‐linear physical systems via the block box approach, and in model validation. This paper is a sequel to an earlier paper,1 where practical methods for measuring Volterra kernels were presented along with a quick method for measuring the second‐order Volterra kernels. This paper extends that quick method for measuring higher‐order frequency‐domain Volterra kernels of weakly non‐linear systems. We further developed the quick method to measure directly the points of the Volterra kernels which are located along one or more axes in the frequency domain, thus making our method complete and more accurate than that presented in Reference 1. We illustrate our method by actually measuring a weakly non‐linear circuit whose Volterra kernels can be accurately calculated. the experimentally measured and the theoretically predicted results agree remarkably well.
Impasse points. Part I: Numerical aspects
Authors: Chua Ieon O. , Deng An‐Chang 
Published: July 2007

AbstractImpasse point is an important phenomenon found in many non‐linear circuits and systems. Among other things, the presence of an impasse point Q implies that the circuit model is defective and must be remodelled by augmenting it with parasitic inductances and/or capacitances at appropriate locations in order to predict the bifurcation from slow to rapid motions (jump phenomenon) widely observed in practice. the presence of an impasse point Q also implies that a numerical simulation of the associated system of implicit differential‐algebraic equations would give rise to an extraneous and random small‐amplitude oscillation in the vicinity of Q. the wave‐form associated with this ‘fake’ oscillatory phenomenon depends on the error‐controlled mechanism of the integration routine and can be detected using the results from this paper.Impasse points in high‐order circuits (n > 2) need not be isolated. In fact, they often form an impasse set made of impasse curves, impasse surfaces, impasse manifolds, etc. In order to detect the impasse set associated with the implicit differential‐algebraic system.An analytical characterization of an impasse point (X0,y0) is derived and proved to be equivalent to that of solving for the limit‐points of an associated static bifurcation problem.Interpreting this as the parametric equation of a space curve in the y‐space, an impasse point (X0,y0) is simply a ‘turning point’ of this curve.
Impasse points. Part II: Analytical aspects
Authors: Chua Leon O. , Deng An‐Chang 
Published: July 2007

AbstractAn impasse point of the implicit differential‐algebraic system

equation image
.Has been characterized in Part I of this paper as a limit point of an induced solution curve

equation image
In this paper we use the Liapunov‐Schmidt procedure to derive an analytical test for identifying impasse points. We also invoke the transversality theory from differential topology to show that almost all singular points (Xo, yo) of S, which occur when the Jacobian matrix

equation image

is singular, are in fact impasse points.
A new general method to model signal timing of E/D NMOS logic
Authors: Wu Chung‐Yu , Lin Yen‐Tai 
Published: July 2007

AbstractA new general modelling method for E/D NMOS logic is proposed and applied to the case of inverters. In this model, non‐linear device currents in the large‐signal equivalent circuit are reformulated by the curve‐fitting technique. Then output voltage wave‐forms are analytically solved region by region from the equivalent circuit. From the derived formulae, the rise/fall time and delay time can be calculated. Wide‐range comparisons with SPICE simulation results were performed to verify the accuracy and the general applicability of the developed model. Two examples are given to demonstrate the applications of the developed timing model to timing analysis. It is shown that the model has a good accuracy for E/D inverters with a wide range of beta ratios, gate sizes, capacitive loads, input voltage wave‐forms and device parameters. Moreover, the required CPU time and memory are small. These make the proposed modelling method an interesting approach to model E/D NMOS gates for CAD applications.
Limitations and complexity of digital hardware simulators used for large‐scale analogue circuit and system dynamics
Authors: Roska Tamás 
Published: July 2007

AbstractLarge‐scale electronic circuits and systems are considered with increasing complexity measured in terms of the number of circuit or system elements. the dynamics will be calculated by a digital prototype hardware simulator exploiting parallelism, pipelining and look‐up table techniques to realize minimum solution time. Our ‘canonical’ conceptual prototype digital simulator (PDS) is given and its parts are analysed in detail, including a minimal memory realization of a multivariable non‐linear mapping (look‐up table). It is shown that if the increase of the complexity of the simulator does not exceed the increase of the complexity of the circuit or system to be simulated, then the simulation complexity (measured in terms of the accumulated time of basic calculation steps) will not decrease, but instead will increase. Hence there is an inherent limitation in the digital simulation of analogue operators. This result suggests at the same time that the digital method of data and signal processing has some inherent limitations, a striking example of overcoming it being the neural circuit. the speeding up of the digital hardware due to the scaling down of feature sizes in integrated circuits and the reduction of the time step due to the increase in system size are also taken into account.
A transformation method for the solution of power switching circuits based on network topological concepts
Authors: Milias‐Argitis J. , Zacharias Th. 
Published: July 2007

AbstractIn this paper, a general and systematic method for the analysis of varying topology power semiconductor circuits is presented. the changes of the conduction state of the semiconductor switching devices are handled by successive modifications of the tree of the circuit graph. These tree modifications are systematically reflected on a square transformation tensor. On the basis of well known network topological concepts, this generalized transformation tensor can be constructed in a relatively simple way. This tensor constitutes a flexible and powerful tool to assemble automatically the necessary on‐switch current and off‐switch voltage equations required for any conduction pattern. These manipulations are accomplished with a step‐by‐step modification procedure of the equations describing the circuit in the most previous conduction state. the basic steps of an algorithm suitable for the practical implementation of the analysis of any power switching network on a digital computer are described, and an example is used to demonstrate the effectiveness of the proposed method.
Development of a symmetrically stabilized four‐phase oscillator and some implications
Authors: Kaplan B. Z. , Yardeni D. 
Published: July 2007

AbstractThis paper treats the development of a non‐linearly stabilized oscillator model which generates four sine waves in quadrature. This system is dealt with in spite of the fact that quadrature signals can be generated by a simple two‐phase oscillator. the latter generates only two of the signals needed in a four‐phase system. the rest of the phases signals could nevertheless be obtained by inventing the originally existing signals. It appears, however, that for certain applications the generation of all four signals in a completely cyclic and symmetrical manner (the one described here) is preferable. It is envisaged that one such application is related to recent methods of actively feeding phased array antennas, where each element in the array is connected to an appropriate oscillator phase stage.Most of the paper deals with the development of an appropriate generator model. the non‐linear oscillator dynamics is treated comprehensively. the peculiar behaviour associated with the limit cycle dynamics and with other manifestations of the system dynamics is investigated. It appears from the detailed simulation work that there exist regions of initial conditions where the system solutions are expected to be relatively sensitive to initial conditions. As a result, it is believed that the system with certain additions may reveal chaotic dynamic behaviour. the realization of the system in electronic hardware is also discussed.
The convergence of a PLL with variable parameters
Authors: Wullch Dov , Bar Moshe 
Published: July 2007

AbstractA phase‐locked loop with variable parameters is considered. In such a system it is possible to obtain a short convergence time together with a small bandwidth. It is supposed that the PLL's parameters cannot be switched and there is a restriction on the velocity of the parameter variation.An optimal strategy of parameter variation is obtained which gives an improvement in convergence time by a factor of about 30 in comparision to fixed parameter and small‐bandwidth PLLs.
A global delay model for domino cmos circuits with application to transistor sizing
Authors: Kang S. M. , Chen H. Y. 
Published: July 2007

AbstractDomino CMOS circuits have played important roles in the design of high‐speed VLSI chips such as 32‐bit microprocessors and their family chips. Many researchers have worked on the characterization of the delay time and optimal design of domino CMOS circuits using circuit simulators as the main CAD tools. This paper presents a global analytical delay model for an important class of domino CMOS circuits wherein a multitude of n‐channel transistors form a series connection. the new model is shown to predict the delay time from the precharging clock edge to the 0.5 VDD output level with less than 10% error as compared to that from SPICE simulation over the entire design space. the delay model has been applied efficiently to the design automation of domino CMOS circuits modules.
Criteria for the existence of impulse responses and kernel representations for linear maps
Authors: Ball David , Sandberg Irwin W. 
Published: July 2007

AbstractResults are given that establish, for the first time, necessary and sufficient conditions for the existence of impulse responses and kernel representations for linear not‐necessarily‐time‐invariant systems described by input‐output operator equations.These results concern systems whose inputs and outputs are real‐valued functions on the real line R, the half‐line 10, ∞) or R″′. They deal with causal as well as non‐causal maps and considerably extend related previous results which concern causal maps defined on functions on the half‐line.
Curve‐search algorithm for DC analysis of non‐linear electronic circuits
Authors: Petrenko A. I. , Omer‐Imerely A. R. 
Published: July 2007

AbstractThe solution of the original DC analysis problem is reformulated as a search for a certain point in functional space which belongs to the curve in the same space. the generalized matrix equation of the hyperplane normal to this curve is easily derived and a new iterative algorithm is presented. Some critical situations arising in non‐linear circuit simulation and the behaviour of the new approach in these cases are considered. Six application examples are given.
A new biquadratic topology for mosfet‐C filters using non‐balanced structures
Authors: Liberatore A. , Manetti S. , Piccirilli M. C. 
Published: July 2007

AbstractA new topology for the realization of MOSFET‐C integrated biquadratic filters is proposed which uses an MOS differentiator with non‐balanced structures. an interesting characteristic of the new topology is the possibility of realizing lowpass, bandpass and highpass filters with a one‐to‐one relationship between the biquadratic parameters and the circuit elements. This characteristic allows the implementation of programmable switchable filters.
Bounds on solutions of non‐linear resistive networks
Authors: Cel J. 
Published: July 2007

AbstractTwo methods for finding bounds on the solutions of some classes of resistive circuits containing non‐linear no‐gain resistors are presented. the magnitude of a voltage or current is shown to be bounded by its magnitudes appearing after replacement of all non‐linear devices by subcircuits consisting only of open‐ and short‐circuit elements. Examples of transistor circuits taken for comparison from the existing literature illustrate how the theorems work in practice.
Analysis of white and f−α noise in oscillators
Authors: Kaertner Franz X. 
Published: July 2007

AbstractIn this paper the general correlation spectrum of an oscillator with white and f‐αa noise sources is derived from the Langevin equations describing the deterministic and stochastic behaviour of an oscillator by perturbation methods. the treatment of f‐α noise and the influence of the finite measuring time on the noise spectra are included in a time domain calculation. the theory is applied to a Van der Pol oscillator exhibiting parametric sideband amplification and to a realized oscillator demonstrating the applicability of the theory to technically relevant circuits.
Fractal pattern of second‐order non‐linear digital filters: A new symbolic analysis
Authors: Chua L. O. , Lin T. 
Published: July 2007

AbstractThis paper studies the three‐valued symbolic dynamics associated with the second‐order non‐linear digital filter which has been shown to be a chaotic system recently. A new necessary and sufficient condition is given for a periodic sequence to be an admissible one. the condition is further used to prove that four types of periodic sequences cannot be admissible.
Realization of complex digital filters based on the LBC two‐pair extraction procedure
Authors: Acha José I. , Torres Francisco 
Published: July 2007

AbstractThe synthesis of real digital filters based on the lossless bounded real (LBR) two‐pair extraction procedure is extended to the complex domain. the only component then required is a first‐order reciprocal lossless bounded complex (LBC) two‐pair. This two‐pair permits the synthesis of any bounded complex (BC) or lossless bounded complex (LBC) digital transfer function. Lastly, a unitary implementation in terms of Givens (planar) rotation modules is given for the proposed two‐pair.
Measuring volterra kernels III: How to estimate the highest significant order
Authors: Chua Leon O. , Liao Youlin 
Published: July 2007

AbstractEfficient methods were previously given for measuring the frequency‐domain transfer functions, namely Volterra kernels of weakly non‐linear systems. the success of these methods depends crucially on the assumption that the highest significant order of the system under test is known. Practical algorithms for determining the highest significant order of non‐linear systems are presented in this paper. Our algorithm can be used not only to validate the measurement results obtained by the methods presented earlier but is also capable of determining whether a Volterra series representation actually exists for the system under test.
On the design of 1D IIR digital filters with coefficients of finite word length
Authors: Papamarkos N. , Vachtsevanos G. 
Published: July 2007

AbstractThis paper presents new linear programming techniques for the design of optimal 1D IIR digital filters. the first method is based on a linear minimax criterion and leads to a linear programming approximation problem whose optimal solution is attained by a new fast algorithm. Next, the linear minimax approximation problem is extended and formulated as two linear integer programming problems which permit the design of 1D IIR digital filters with coefficients of finite word length. the first of these methods is formulated as a 0‐1 integer linear programming problem and its optimal solution is attained rapidly by a new algorithm. This method appears to be suitable for the design of high‐order digital filters. the second method is more general and is formulated as a mixed integer linear programming problem. to solve the design problem efficiently, a new integer tree search algorithm is introduced. the feasibility of the proposed algorithms is illustrated with detailed solutions or numerical examples.
Time‐varying analogue constrained notch filter
Authors: Wulich Dov 
Published: July 2007

AbstractThe idea of discrete constrained notch filters is well known and widely described in the literature. Time‐invariant as well as time‐varying filters are considered. Because of the discrete nature of such filters, their application is limited to sampled signals, usually obtained as samples of low‐frequency signals. the aim of this paper is to give some ideas on how to synthesize a time‐varying analogue constrained notch filter which can be used directly for continuous signals.
Multilevel and non‐ideal quantization in ∑ δ modulation
Authors: Feely Orla , Chua Leon O. 
Published: July 2007

AbstractOversampled sigma‐delta analogue‐to‐digital conversion has been the focus of much research attention in recent years. Converters based on this principle have been found to be particularly suited to integrated circuit implementation owing to their simple structure and robustness to circuit imperfection. the analysis of the sigma‐delta system is complicated by the presence of a discontinuous non‐linear element, with the result that until very recently few rigorous studies of such converters had appeared in the literature.In this paper we study the operation of the single‐loop sigma‐delta modulator, consisting of a quantizer and a discrete‐time integrator in a feedback loop, with constant input. Our analysis uses the tools of non‐linear dynamics to derive rigorous descriptions of system behaviour. In particular we focus on the effects of the discontinuous nonlinear element‐the quantizer. In the most basic case the quantizer has two levels. We study the effect of quantizer offsets in conjunction with leaky integration on the behaviour of this system. We then study the effect on system operation of increasing the number of quantization levels and explain in quantitative terms the structure of the resultant input versus average output characteristic.