bluuebunny/crossref_metadata_2025_split huggingface dataset:
Realization of tunable RC‐active oscillators using grounded capacitors and voltage amplifiers
Authors: Bhattacharyya B. B. , Sundaramurthy M. , Swamy M. N. S. 
Published: July 2007

AbstractA systematic procedure is given to generate a set of tunable RC oscillators, each using two finite gain voltage controlled voltage sources, three resistors and two grounded capacitors. These realizations are shown to be minimal with respect to passive and active elements under the constraint that (one end of) all the capacitors remain grounded. The set consists of four oscillators and is shown to be complete, that is, no additional oscillator circuit can be generated under the given assumptions. A simple approach is then introduced for testing the structures for latch up behaviour. This approach also suggests a way of redesigning the oscillator circuits to render them free of latch up problems, if they exist. Experimental results are found to be in good agreement with the theory.
An analogue filter synthesis package based upon vector space operations
Authors: Marshall T. G. , Liu F. C. 
Published: July 2007

AbstractA complete APL analogue filter synthesis package is described which includes provisions for avoiding ill‐conditioning when polynomials with clustered roots are considered. The solution to the numerical problem that is employed in this package is the introduction of a change in representation in a linear manner by a change of basis. This is accomplished by the reformulation of the polynomial problem as a vector space problem. This results in a set of vector space synthesis algorithms which are conveniently implemented in APL. The conventional polynomial operations of filter synthesis such as polynomial division, zero shifting, and removal of a known factor lead to interesting and challenging vector space algorithms. These algorithms and their APL implementations are discussed. An advantage of this approach for APL implementations is that complex arithmetic can be avoided by selecting an appropriate basis for the vector space.
The design of low noise digital filters with controlled dynamic range
Authors: Bonsaver E. , Szczupak J. , Mitra S. K. 
Published: July 2007

AbstractA novel digital filter structure, that allows proper positioning of the zeros of the noise transfer functions to reduce the output roundoff noise, is introduced. Relations between zero locations, roundoff noise and dynamic range are derived and are then utilized in an heuristic optimization method for synthesizing a low noise scaled digital filter structure. Illustrative examples supporting the proposed approach are included.
Formulation of equations in terms of scalar functions for lumped non‐linear networks
Authors: Milič Mirko M. , Novak Ladislav A. 
Published: July 2007

AbstractA general method is presented of formulating the Lagrangian and anti‐Lagrangian equations for networks consisting of non‐linear RLCM (M = memristor) multiports with hybrid representation.The formulation is obtained with no restriction on the network topology. An explicit procedure is given to construct the scalar functions needed. This procedure is based on the concept of L and H functions introduced. The Brayton‐Moser equations in a generalized form can be directly obtained from the anti‐Lagrangian equations. From these equations, new equations of Brayton‐Moser type can also be derived.The invariance property of Lagrangian and anti‐Lagrangian equations under a transformation of variables is also discussed.
Experimental noise effects on transfer function—phase evaluations via Hilbert transforms: Application to optical fibres
Authors: Bassi Paolo , Zoboli Maurizio 
Published: July 2007

AbstractThe effect of measurement noise on the phase of a linear network‐transfer‐function, computed as the Hilbert transform of the modulus, is investigated experimentally. As a typical example, the case of an optical fibre is dealt with. It is shown that, when noise is present, theoretically equivalent methods of performing this transform lead to results affected by uncertainties strongly depending on the chosen algorithm.
Initial vertex partitioning and testing isomorphism of graphs and digraphs
Authors: Bhat Kabekode V. S. , Rahnavard M. H. 
Published: July 2007

AbstractIn this paper, we present a new method for initial vertex partitioning of graphs (digraphs) using the notion of a vertex label that includes several parameters of the graph for each vertex of the graph (digraph). Our method provides a more refined initial vertex partitioning for graphs (digraphs) than any of the known methods in O(nE) time for a graph withnvertices andEedges. Several examples are given as illustrations of the method. A computational comparison of our method with the Schmidt‐Druffel algorithm is presented. The method can be coupled with any existing good back‐tracking method for testing isomorphism of graphs and digraphs.
Principles of complex wave digital filters
Authors: Fettweis Alfred 
Published: July 2007

AbstractThe theory of real wave digital filters (WDFs) is extended to complex WDFs. A fundamental requirement turns out to be that of one‐realness, a complex impedance in the reference filter being called one‐real if it is real for Ψ = 1, where Ψ is the equivalent complex frequency. The only new components then required are complex multipliers with unimodular coefficients, but the adaptors are just as in the real case. The stability properties known for real WDFs can, in this way, also be extended.
Optimal selection of IC fabrication parameters
Authors: Karmokolias C. , Portnoy W. M. , Saeks R. E. 
Published: July 2007

AbstractA procedure is described in which the output characteristics of an integrated circuit are optimized with respect to a set of variable fabrication parameters. A simple RC coupled audio amplifier is used as an example. The gain–bandwidth product is obtained as a function of oxidation and diffusion times and temperatures, and the optimization is performed by way of a line search using these variables as the parameters of the optimization. The values established for the process parameters are consistent with those employed for conventional fabrication, and desired changes in performance can be obtained, in general, by a straightforward readjustment of the values of the process variables. Although limited by certain assumptions and a relatively primitive circuit, the results demonstrate the validity of the procedure.
Necessary and sufficient conditions for absolute stability of linear n‐ports
Authors: Zeheb Ezra , Walach Eugene 
Published: July 2007

AbstractA set of necessary and sufficient conditions is stated and proved for the absolute stability (under any passive terminations), in the ‘bibo’ sense, of a linear n‐port characterized by its open‐circuit impedance matrix. A more explicit set of such conditions is derived for the special case n = 3. In the process of deriving this set of conditions, some results and theorems concerning finding the zero sets of two and three parameter functions, are stated and proved. Also derived is a set of necessary and sufficient conditions for the absolute stability of two‐ports characterized by the scattering parameters. Such sets have already been derived previously, but the present set is considerably simpler.
A possibility of filling the gap between local and global passivity of non‐linear networks and some of its consequences
Authors: Roska Tamás 
Published: July 2007

AbstractIn the qualitative theory of non‐linear networks the non‐linear n‐ports are generally considered either locally passive or globally passive even eventually globally passive (the most restrictive or the least restrictive properties respectively). Moreover the reciprocity condition in many cases (e.g. complete stability) restricts the area of applications. In the area of economics and other fields, basically motivated by Sandberg's results, the role of the off‐diagonally monotone and antitone mappings is crucial.In this paper, based on the above facts and results, it is shown that partly similar classes of mappings could have a role in non‐linear network theory. More precisely, the off‐diagonally locally active (passive) n‐ports, defined in the paper, could represent an important new class of n‐ports.As an application of the features of this new class of n‐ports two Theorems are given showing conditions under which in case of a network consisting of off‐diagonally locally active n‐ports the DC solution can be uniquely calculated using the standard iterative methods and an autonomous network is asymptotically stable in a given domain. Hence, this paper partially overcomes the so called ‘curse of non‐reciprocity’.
A comparative study of multiple amplifier active RC biquadratic sections
Authors: Padukone Pradeep R. , Ghausi Mohammed S. 
Published: July 2007

AbstractBiquadratic sections play an important role in the design of high order active filters. This paper compares a number of popular multiple amplifier active RC biquads on the basis of their sensitivities as well as ω0 and Q enhancement effects due to finite amplifier gain–bandwidth products (GB). For sensitivity comparison, statistical sensitivity measures, which take into account the tolerances of various passive and active elements, are used. Simple expressions for gain, phase and transfer function sensitivities are derived for the case of uncorrelated element variations. Graphic illustrations of the effects of increasing ω0 and Q on the sensitivity measures are presented. In addition, root‐loci, which show the effects of GB on the network poles are included. To further facilitate the comparison, graphs demonstrating changes in ω0 and Q due to GB are also presented.
The generation of arbitrary‐phase polynomials by recurrence formulae
Authors: Henk Tamás 
Published: July 2007

AbstractA filter‐design oriented theory is presented for polynomials with prescribed phase properties. The phase function is specified by its values and/or higher derivative values at a set of given frequencies. The polynomials are generated by recurrence formulae whose coefficients are calculated by a recursive algorithm. Formulae are presented to calculate the higher derivatives of some composite functions of the phase which are utilized in the process of flat phase approximations.
Sensitivity minimization in signal‐flow graphs
Authors: Tan M. Ali , Acar Cevdet 
Published: July 2007

AbstractIn this work, the sensitivity minimization is studied for the signal‐flow graph of the state equations realizing a general biquadratic transfer function. The sensitivity measures are defined for the poles, the pole Q and the pole frequency. The formulae are derived for their evaluations. Branch transmittances minimizing each of these measures are found. Finally, it is shown that there exists a very simple relation between the measures. The results obtained in this study can be used in active filter realizations with minimum sensitivity.
On the parametrization of linear memoryless 2‐ports
Authors: Recski Andras , Zoller Vilmos 
Published: July 2007

AbstractA parametric description of all homogeneous linear memoryless 2‐ports is given using the Grassmann‐Plücker co‐ordinates of algebraic geometry. Unlike the usual (impedance, scattering, chain, etc.) descriptions, this one presents a 1–1 correspondence between the set of all 2‐ports and certain 4‐tuples. The physical meaning of these parameters is related to reciprocity, passivity and losslessness, hence every important transformation of the 2‐port (not only negative and inverse but dual and adjoint as well) can directly be obtained.A remark on linear network solvability is included.
An analysis of slew‐induced distortion in single‐amplifier active filters using the volterra‐wiener series technique
Authors: Borys Andrzej 
Published: July 2007

AbstractA model of an operational amplifier suitable for small‐signal non‐linear analysis is developed in the present paper. The model, based on the Volterra‐Wiener functional series expansion, contains the slew‐rate non‐linearity. By performing an accuracy analysis, the limits of its validity are also given. The stability of the single‐amplifier basic structure considered as a non‐linear network is studied. On the basis of the results obtained, the field on an amplitude‐frequency plane for a small‐signal non‐linear case (FAF) is introduced for single‐amplifier active filters containing operational amplifiers. It is shown that this FAF is simply related to the threshold of the input‐signal amplitude at which slew‐induced distortion (SID) begins.
On the dynamic spaces and on the equations of motion of non‐linear
Authors: Szatkowski Andrzej 
Published: July 2007

AbstractThe problems of the qualitative theory of non‐linear RLC networks are considered from a geometric point of view. Several general properties of the dynamic space of the network are presented. The concept of the vector field generated by the network on its dynamic space is introduced and discussed. The equations of motion are formulated in the forms which are useful in the qualitative analysis of the solutions.
Approximation method for decomposable filter pairs
Authors: Carlin Charles‐Henri 
Published: July 2007

AbstractThe decomposable filter pair is presented, starting from the general form of the scattering matrix of a lossless reciprocal 3‐port. The restrictions with respect to the general case are discussed. The two general categories of requirements imposed to a filter pair are presented and their incompatibility is established. An algorithm is described, allowing one to approximate simultaneously the two main transfer functions of a filter pair.
Sensitivity analysis of RLC nullor networks
Authors: Svoboda J. A. , Wojcik R. J. 
Published: July 2007

AbstractLinear active networks can be represented either as RLC‐dependent source networks or as RLC nullor networks. The calculation of the sensitivities of the transfer functions of active networks modelled by RLC nullor networks is considered. Three methods for calculating sensitivity are applied to the class of RLC‐nullor networks. Some simplifications resulting from the absence of coupled elements in such networks are observed. The resulting algorithms are implemented as FORTRAN programs and the execution times are compared.
Sensitivity analysis and dynamic range of quad filters and some comparative results
Authors: Nur Gönüleren Ali 
Published: July 2007

AbstractThe paper considers general sensitivity analysis and dynamic range of quad filters. The use of quad structures in the design of symmetrical and/or unsymmetrical active filters is studied from the sensitivity and dynamic range points of view and these are compared with other design methods. Determination of gain constants of biquadratic blocks either according to overloading or noise immunity or both for quad realization are also considered. It is shown that, especially for symmetrical transfer functions, the design equations are simple and that the sensitivity performance is as good as the FLF and LF configurations and better than GFLF. Furthermore, it is shown with an example that quad realization also yields better dynamic range as compared to GFLF.
Selective linear phase filters possessing a pair of J‐axis transmission zeros
Authors: Rhodes J. D. , Zabalawi I. H. 
Published: July 2007

AbstractA design technique is developed for prototype selective linear phase filters which have an equiripple passband amplitude response and a pair of j‐axis transmission zeros in the stopband while maintaining a linear phase characteristic in the passband. Since the basic technique requires numerical optimization techniques, the element values for several cases have been tabulated together with detailed response characteristics.One important result is that for certain characteristics, one internal cross‐coupling element may be designed to be zero. As a result, in the sixth degree case with only one extra cross‐coupling element between elements 1 and 6 a significant improvement in both the amplitude and group delay performance can be achieved as compared to the Chebyshev case. Owing to its importance, this case is investigated in detail and a 2.6 GHz post decoupled combline filter has been constructed based upon this prototype.
The (p+q)‐port transformer
Authors: Chua L. O. , Lin G. N. , Lum J. J. 
Published: July 2007

AbstractTwo approaches for realizing a (p+q)‐port transformer using operational amplifiers are presented. Unlike iron‐core transformers, our realization is valid from d.c. to a relatively high frequency limited only by the op amp's frequency response. The stability and limitation of the two approaches are analysed and compared. Examples are given to illustrate two unique and indispensible applications of the (p+q)‐port transformer: Synthesis of non‐linear n‐ports and non‐linear programming.
On hilbert space design of least‐weighted‐squares digital filters
Authors: Bromba Manfred U. A. , Ziegler Horst 
Published: July 2007

AbstractNumerical convolution operations, executed on noise contaminated signals, are approximated by FIR digital filters in such a way that the effect of random coloured noise is minimized. Using elementary Hilbert space techniques, the filter functions of certain least‐weighted‐squares digital filters are derived explicitly by the use of discrete orthogonal functions (e.g. Hahn polynomials). the approach is suitable especially for narrowband operations such as smoothing, narrowband differentiation, and narrowband deconvolution (resolution enhancement). Examples of linear‐phase lowpasses with monotone passband, obtained with the aid of Hahn polynomials, are discussed in detail. Also the well‐known maximally flat digital lowpasses which can be derived with the aid of Krawtchouk polynomials, and narrowband differentiators are considered. In the case of least‐weighted‐squares approximation by Hahn polynomials, powerful recursive realizations can be developed to reduce computational requirements.
Scaling techniques for switched‐capacitor filters employing voltage inverter switches
Authors: Pandel Jürgen 
Published: July 2007

AbstractSome realizations of scaling elements in cascade connection with unit elements and gyro‐elements will be described. It will be shown that the voltage distribution inside the filter and the spread of capacitor values can be optimized in two steps using two independent parameters for each scaling element. the influence of these scaling elements is such that the very low sensitivity of the attenuation characteristic with respect to element variations is fully retained despite the fact that according to the usual definition the losslessness of the reference filter is not preserved. the SC circuits described in this paper are insensitive to ‘bottom plate’ parasitic capacitances. Top plate parasitics correspond largely to element variations in the reference filter so that also their influence is strongly reduced. A numerical example of a 14th‐order unit element bandpass filter is given.
Non‐linear optimization with constraints: A cook‐book approach
Authors: Chua L. O. , Lin G. N. 
Published: July 2007

AbstractBased on the stationary co‐content theorem in non‐linear circuit theory and the penalty function approach in non‐linear programming theory, a canonical circuit for simulating general non‐linear programming problems with equality and/or inequality constraints has been developed. the task of solving a non‐linear optimization problem with constraints reduces to that of finding the solution of the associated canonical circuit using a circuit simulation program, such as SPICE.A catalogue of canonical circuits is given for each class of non‐linear programming problem. Using this catalogue, an engineer can solve non‐linear optimization problems by a cook‐book approach without learning any theory on non‐linear programming. Several examples are given which demonstrate how SPICE can be used, without modification, for solving linear programming problems, quadratic programming problems, and polynomial programming problems.
Stray capacitance eliminating transformations for switched capacitor circuits
Authors: Hasler Martin , Saghafi Morad 
Published: July 2007

AbstractTransformations are given that eliminate the influence of part or all of the stray capacitances to ground in a switched capacitor circuit, while leaving the transfer functions and, conditionally, their sensitivities to nominal capacitor ratios invariant. the transformations increase the number of operational amplifiers to the minimum that is required, as we prove, for stray capacitance insensitive circuits. the number of capacitors usually also increases, giving rise to constraint equations.
Design of wave‐sc filters using building blocks
Authors: Kleine U. 
Published: July 2007

AbstractBesides switched‐capacitor (SC) filters developed for high volume production, e.g. the PCM‐codec lowpass filter, numerous low volume applications exist in the area of solid‐state filtering. to open up this application field for SC filters, a novel wave‐SC filter structure is presented. the filter design using this concept requires only moderate design and layout skills since only a limited library of highly modular building blocks is required. It is also suitable for analogue gate array applications. As will be shown, the wave equations which are known from the theory of wave digital filters can be realized using stray‐insensitive SC integrators and SC amplifiers only. Exemplary designs of a lowpass, a highpass, and a bandpass filter will be carried out with the building blocks presented. the theoretical results are verified by measurements at the breadboarded lowpass filter.
On the stability of non‐linear two‐port amplifiers
Authors: Baranyi A. , Ladvanszky J. 
Published: July 2007

AbstractBased on the two‐port describing function characterization, frequency domain stability conditions are derived for non‐linear two‐port amplifiers. the conditions are applied to the case of a turned transistor amplifier with saturated class‐C type transfer characteristic. the theoretical considerations and the experimental results are in close agreement.
Non‐linear op‐amp circuits: Existence and uniqueness of solution by inspection
Authors: Nishi Tetsuo , Chua Leon O. 
Published: July 2007

AbstractEven simple circuits containing only one op amp and linear resistors can have multiple d.c. operating points. Using a realistic non‐linear d.c. op‐amp model which includes the saturation characteristics, this paper gives the necessary and sufficient conditions for an arbitrary op‐amp circuit (containing op amps, linear resistors, strictly‐increasing non‐linear resistors and independent sources) to have a unique solution for all values of circuit parameters. These conditions are remarkable because they are couched strictly in topological terms. For many op‐amp circuits (e.g. those containing only one op amp), the necessary and sufficient conditions can be checked by inspection.
Active RC realization of high‐order bandpass filter functions by cascading biquartic sections
Authors: Fotopoulos S. , Deliyannis T. 
Published: July 2007

AbstractHigh‐order bandpass filter functions are realized by cascading active RC biquartic sections. A design procedure is proposed, which leads to an optimized circuit with regard to sensitivity, signal distortion and noise. It is shown that the resulting filters have low sensitivity, similar to that of the multiple‐loop feedback (MF) filter and better noise performance than the shifted‐companion‐form and cascade filters.
Maximum power transfer in non‐linear source‐load systems
Authors: Vachtsevanos G. J. , Kalaitzakis K. C. 
Published: July 2007

AbstractThis paper is concerned with the conceptual design and realization of matching networks for the continuous transfer of maximum power from a non‐linear source with randomly varying characteristics to a load. Such sources are commonly encountered in the use of photovoltaic arrays or wind energy conversion systems for the production of electric power. Experimental studies as well as computer simulation results verify the validity of the design and point to methods for its practical implementation.