bluuebunny/crossref_metadata_2025_split huggingface dataset:
A negative‐impedance‐converter circuit for higher frequencies
Authors: Atiya F. S. , El‐Shiekh M. N. 
Published: July 2007

AbstractThe main weakness of the Yanagisawa negative‐impedance‐converter circuit is the large phase shift of its current conversion gain h21 at higher frequencies. The reason for this phase shift is the collector capacitances of the two transistors. The addition is suggested here of a capacitor that balances out the effect of these capacitances as far as h21 is concerned. A real and constant h21 results, up to higher frequencies. Another capacitor compensates for the effect of the transistor capacitances on h22. The remaining two h parameters need no such compensation. Experimental results confirm all these conclusions.
Bounds for the amplitude of quantization error in forced 1st‐order 2‐dimensional digital filters
Authors: Maria G. A. , Fahmy M. M. 
Published: July 2007

AbstractBounds for the amplitude of the error at the output of fixed‐point 1st‐order 2‐dimensional filters due to roundoff after multiplications are obtained. These bounds apply to the transient as well as the steady‐state response when the signal is present.
Further relationships between several types of multiparametric sensitivity
Authors: Mazzoni G. , Liberatore A. 
Published: July 2007

AbstractThe study of sensitivity carried out in previous work1 is resumed and generalized, both with regard to relationships with other sensitivity expressions and with regard to the extension of the study to the 3rd‐degree polynomials that appear in the transfer functions realized by active networks with nonideal operational amplifiers.A study is made of the relationships between the various sensitivity expressions with respect both to the polynomial coefficients of the transfer function and to the physical parameters of the circuit, to show the possibility of measuring some forms of sensitivity hitherto defined analytically.Lastly, emphasis is placed on the difference between the sensitivity of the transfer function in complex form and that of its modulus and phase with respect to the polynomial coefficients, and an attempt is made to relate them, with reference to other studies that have recently appeared in the technical literature1,3.
Recursive digital filters with low roundoff noise
Authors: Szczupak J. , Mitra S. K. 
Published: July 2007

AbstractA novel method is introduced for designing recursive digital filters with very low roundoff noise. The proposed method is based on reducing the magnitudes of the noise transfer functions on the unit circle by ensuring the presence of zeros, while simultaneously synthetizing the prescribed transfer function. The final structure, which exhibits steady‐state roundoff noise with low variance, is simple and economical, and canonic with respect to delay elements, although not always canonical with respect to multipliers. An illustrative example is included. The realization method is also shown to reduce the multiplier coefficient sensitivities.
Analysis of negative‐resistance oscillators with piecewise nonlinearity
Authors: Mamola G. , Sannino M. 
Published: July 2007

AbstractAn iterative method of solution of negative‐resistance oscillators with piecewise‐analytical characteristics is presented. The method allows the determination of the frequency and the harmonic content of the waveform as a function of the circuit parameters and bias of the nonlinear device.An application of the method, extended to the second order, for a polynomial characteristic limited by two straight lines is also reported. The results are compared with those obtained by numerical integration.
2‐parameter root‐loci concepts and some applications
Authors: Zeheb E. , Walach E. 
Published: July 2007

AbstractRoot‐locus concepts are expanded to treat characteristic expressions of systems and circuits with two parameters which vary along straight lines through the origin of the complex plane. Theorems are stated and proved by which the problem of finding the boundary of root regions of such expressions is reduced to the problem of plotting 1‐parameter root loci.The concepts of 2‐parameter root loci are then used to investigate the absolute stability of arbitrarily passively terminated 2‐ports.The following results are obtained by this method:
The complete root regions of the characteristic equation are found, rendering more information about the dynamic behaviour of the 2‐ports than just determining absolute stability.
A new absolute stability criterion is proved which does not necessitate checking a polynomial for nonnegativeness along the imaginary axis.
A new proof of the Llewellyn criterion is arrived at.
A numerical example is also provided for further clarification.
Synthesis of 2‐variable active RC networks
Authors: Mitra S. K. , Ahmed M. T. 
Published: July 2007

AbstractA general procedure is outlined to realize an arbitrary stable 2‐variable transfer function. The complete realization utilizes only resistors, capacitive elements and operational amplifiers; moreover, it is characterized by low active and passive sensitivities. The method may easily be extended to the realization of multivariable transfer functions.
Symmetry requirements for multidimensional digital filters
Authors: Fettweis A. 
Published: July 2007

AbstractVarious methods for designing multidimensional digital filters exhibiting approximately circular, spherical or hyperspherical attenuation symmetry are discussed. It is shown how, by means of appropriate series expansions, symmetry requirements for filters with any number of dimensions can be fulfilled with arbitrary precision by adopting transformations of correspondingly increased degree. Some of these transformations are generalizations of the known McClellan transformation. Simple means for ensuring excellent symmetry at frequencies remote from the origin are presented.
An accurate rational 2‐port model of a class of tapered lossless and RC lines
Authors: Kumar U. , Roy S. C. Dutta 
Published: July 2007

AbstractA rational 2‐port model of a class of tapered LCand RClines which includes the exponential, hyperbolic, trigonometric and square, or Bessel, lines is presented. The model for the exponential RCline (ERC), considered as an example, accurately describes the actual frequency and transient response for various values of taper factor over wide ranges of frequency and time. In an ERC notch network configuration, application of this model predicts the results very closely for various values of taper factor.
On the design of RC‐active follow‐the‐leader. Feedback filters
Authors: Gensel J. 
Published: July 2007

AbstractFor RC‐active filters of the ‘follow‐the‐leader’ feedback type, a synthesis procedure is presented that is suitable for application also to the general case in which differently tuned biquadratic functional blocks are used. Their losses can either be concentrated in one of the blocks, or given by a prescribed distribution.
A new generalized inverter based on the active hybrid
Authors: Atiya F. S. , Doss M. M. 
Published: July 2007

AbstractThe building block for the new generalized immittance inverter is a 3‐port known as the active hybrid network. One of its ports is bidirectional, and matches a design admittance y0. The second port operates in the send, while the third port operates in the receive direction. The hybrid is constructed from an op‐amp and a 5‐port network composed of a few resistors and the design admittance y0. There are two versions of the hybrid: the voltage‐inverting (i.h.) and the noninverting hybrid (n.i.h.).The inverter consists of an i.h. and an n.i.h. connected at their unidirectional ports in a loop. The gyration admittances are actual driving‐point admittances in the circuit, namely the design admittances y0, y'0 of the two hybrids. Such an inverter, when terminated at its output port by a load admittance y, will give at its input port an input admittance yin = y0y'0/y.Expressions are derived for the y parameters of the inverter at higher frequencies, thus accounting for the finite bandwidth of the op‐amp.Two special cases are particularly treated, and experimental results are obtained for them. The first is the case of the resistive gyrator, for which y0 and y'0 are pure conductances. The second is the case of the capacitive gyrator, for which y0 and y'0 are pure capacitive susceptances. The capacitive gyrator is used to produce the supercapacitor, or f.d.n.r., and the results of measurements on a number of f.d.n.r. networks are given.
Canonic realization of wave digital filters involving unit elements
Authors: Meerkötter K. 
Published: July 2007

AbstractRecently, a method has been developed by means of which canonic wave digital filters can be derived from originally noncanonic ladder wave digital filters. This method applies only to wave digital filters which are derived from pure LC‐ladder reference filters. In the paper, it is shown how noncanonic wave digital filters corresponding to reference filters containing unit elements can be transformed such that a canonic realization of these filters can be obtained as well.
Some topologico‐dynamical properties of linear passive reciprocal networks
Authors: Milić M. M. 
Published: July 2007

AbstractThe paper considers the complete solvability and the order of complexity of passive RLCT (T = multiwinding ideal transformer) networks. A topological approach based on the determinant polynomial of the matrix of hybrid equations, formed as a set of 1st‐order differential and algebraic equations, reveals the structure of the formulation tree and the subnetworks accountable for degeneracies. Topological and algebraic degeneracies are defined. Necessary and sufficient conditions for complete solvability are derived, and two algorithms are given to determine the order of complexity topologically, i.e. without having an explicit state‐space representation.
An efficient method for obtaining element values of ladder filters whose transfer functions possess complex zeros and whose reactive components have freely assignable losses
Authors: Nightingale C. 
Published: July 2007

AbstractAn efficient method for designing doubly terminated ladder filters in which reactive components have freely assignable losses is described. The method uses partial knowledge of the driving‐point impedance of such filters to generate a set of algebraic equations which are easily solved using a computer program. An example of the application of the method to the design of an active filter is included.
Application of brune's tests to a class of network interconnections
Authors: Zelyakh E. W. 
Published: July 2007

AbstractIn most cases, checking the regularity of an interconnection of 4‐terminal networks with the aid of Brune's tests represents no difficulties. However, there is a class of interconnections for which Brune's procedure is not clear, and requires more subtle consideration. The method of application of Brune's tests to such interconnections is shown. The formulae determining the matrices of some regular interconnections of the said class are also given.
Critical block analysis for the transfer, gain and phase functions in multiple‐loop feedback networks
Authors: Acar C. , Ghausi M. S. , Laker K. R. 
Published: July 2007

AbstractMeasures for determining the most and least critical blocks in multiple‐loop feedback networks are defined for the transfer, gain and phase functions. Simple and systematic procedures for computing their values, thus determining the ordered hierarchy of critical blocks, are provided. The knowledge of the most and least critical blocks is shown to provide useful guidance for modifying component tolerances to produce higher yield or lower component costs. The tolerance assignment procedure described differs from those described elsewhere in that multiple component tolerances are assigned simultaneously on a block‐by‐block basis.
On a generalization of the wave digital filter concept
Authors: Lawson Stuart S. 
Published: July 2007

AbstractThe design of digital filter structures imitating the behaviour of classical analogue networks has received considerable interest in the literature. Of particular interest has been the Wave Digital Filter first considered by Fettweis. We examine here a generalization in which the relationships between the voltages, currents and wave variables are considered as a linear transformation on the ABCD matrix of the analogue two‐port network. The linear transformation is examined in some detail and conditions are derived which impose constraints on the elements of the matrices involved in the transformation. Finally a table giving thirteen transformations known to yield realizable digital filter structures is presented.
Amplifier nonlinearities in the multiple‐negative‐feedback bandpass filter
Authors: Bowron P. , Mohamed M. A. 
Published: July 2007

AbstractA unified treatment is presented of the effect of both linear and nonlinear imperfections in an operational amplifier on the frequency response of a bandpass multiple‐negative‐feedback active filter. Linear computer models and describing‐function techniques are used to evaluate performance for comparison with measurements. The critical peak‐input voltage to avoid jump resonance is derived and performance limits illustrated on a Q–frequency plane.
A note on high‐Q active networks
Authors: Tow James , Gadenz Renato N. 
Published: July 2007

AbstractLevi's and Zeheb's approach for approximating a high‐Q second‐order section by n sections with lower Q's is compared with the optimal solution of this problem proposed by Khazanov. Tables relating the maximum error in the approximation to the values of n and the achievable Q‐reduction (QR) are also given. They should prove useful to the designer. Finally, some comments on sensitivities are added.
A universal active R biquad
Authors: Soliman Ahmed M. , Fawzy Mahmoud 
Published: July 2007

AbstractA universal active R biquad structure is presented which uses only resistors and two operational amplifiers. The network provides general biquadratic, band‐pass and low‐pass characteristics and is suitable for high‐frequency applications at medium pole Q values. When the network is adjusted to realize a high‐pass characteristic it becomes a special case from Schaumann's circuit N. The biquad circuit is recommended for monolithic integration.
Roundoff noise properties of second‐order digital notch filters
Authors: Roy S. C. Dutta , Patney R. K. 
Published: July 2007

AbstractWith regard to their roundoff noise properties, canonical second‐order recursive digital notch filters, with zeros on the unit circle and poles near them, are shown to fall in three distinct groups depending upon the zeros of their noise transfer functions (NTF's).One of the groups, having all‐pole NTF'S, shows large noise magnitudes but the noise behaviour is well defined. The second group shows low noise magnitudes that heavily depend upon the location of the zeros of their NTF's; these zeros are related to the transfer function coefficients in a particularly simple manner. When this dependence gets complicated, as for the third group, the noise properties are ill behaved.
Complete stability of autonomous reciprocal nonlinear networks
Authors: Chua Leon O. , Wang Niantsu N. 
Published: July 2007

AbstractSeveral sufficient conditions are presented which guarantee that an autonomous nonlinear reciprocal network having multiple equilibrium states is completely stable in the sense that every trajectory of the network tends to an equilibrium state and hence no oscillation of other exotic mode of spurious behaviour can occur. Stability criteria are derived with the help of the concept of the generalized inverse of a maxtrix for both complete and noncomplete networks. The results on noncomplete networks depend crucially on the introduction of a pseudopotential function called pseudo‐hybrid content and on the imposition of a local solvability condition. Most of the hypotheses are algorithmic in the sense that either explicit bounds are provided for computation purposes, or equivalent topological tests are given for checking the nonquantitative conditions.Most results presented are applicable to networks containing multiport and multi‐terminal elements which are represented by coupled two‐terminal elements. Examples are given which demonstrate that some of our results on complete stability are the best possible that can be obtained for the class of networks under consideration.
Multiport converters and inverters
Authors: Silva Manuel M. 
Published: July 2007

AbstractTwo‐port immittance converters and inverters are well known active‐network ‘components’. In this paper the concepts of conversion and inversion are generalized so as to apply to multiports. A definition of multiport hybrid converter is proposed, and the necessary and sufficient conditions that the matrix description of this multiport must satisfy are derived from the definition. Multiport admittance and impedance converters and inverters are introduced as special cases of hybrid converters, and it is pointed out that, whereas 2‐port admittance converters or inverters are always also impedance converters or inverters, and vice‐versa, this is not generally true for the multiport converters or inverters proposed here.Multiwinding transformers, multiport gyrators, and most of the circuits that can be used for the simulation of floating inductors are shown to be special cases of multiport converters or inverters. It is believed that the theory of multiport conversion and inversion presented here provides a better understanding of these special cases and is also useful as a contribution to multiport theory in general.
(n +p)‐node realizability of Y‐matrices of (n + 1)‐node resistance n‐port networks
Authors: Thulasiraman K. , Swamy M. N. S. , Reddy P. S. 
Published: July 2007

AbstractSufficient conditions are established for the (n +p)‐node, p>2, realizability of Y‐matrices of (n + 1)‐node resistance n‐port networks. It is shown that these conditions are a generalization of the previous known results for p = 2 and p =n.
A new result in negative‐feedback theory, and its application to audio power amplifiers
Authors: Cherry E. M. 
Published: July 2007

AbstractA nest of differentiating loops is described by means of which a very large amount of negative feedback can be applied to a specified stage in an amplifier (normally the output stage) with progresively less being applied to other stages. The effects of nonlinearity (other than hard limiting) in the specified stage can be virtually eliminated. The structure enables Bode's limit for loop‐gain roll‐off to be exceeded for the specified stage; both the frequency up to which loop gain is maintained constant and the frequency at which loop gain falls through unity are free design variables. As a result, practical difficulties associated with excess phase shift in low‐frequency power transistors are minimized. The structure does not increase the susceptibility to transient overload and the resulting intermodulation. A practical amplifier using output transistors with fT∼2 MHz has an output‐stage loop gain of 25,000 (88 dB) at 20 kHz and 0.002 per cent harmonic distortion.
On second‐order cofactors and null return difference in feedback amplifier theory
Authors: Chen Wai‐Kai 
Published: July 2007

AbstractLike the general return difference, the general null return difference is defined as the ratio of the two functional values assumed by the second‐order cofactor of the elements associated with the input and output terminals of the indefinite‐admittance matrix of a feedback amplifier under the condition that the element of interest assumes its nominal value and the condition that the element assumes its reference value. It is shown that this algebraic definition is entirely consistent with the classical physical formulation of the null return difference.
Application of the mixed potential for formulating normal form equations for nonlinear rlc‐networks with ideal transformers
Authors: Horneber E.‐H. 
Published: July 2007

AbstractFor the class of complete nonlinear RLC‐networks the normal form equations can be established by a method given in Brayton and Moser1 using the mixed potential. Before applying this approach it is a crucial point to investigate whether a network is complete. To this end in the present paper an algorithm is given which additionally leads to a partitioning of the network under consideration. Two theorems are given enabling the direct construction of the mixed potential starting from the obtained subnetworks. It is shown that complete nonlinear RLC‐networks with ideal two‐port transformers (RLCT‐networks) can be remodelled into complete RLC‐networks using a new approach to model non‐hybrid transformers. Noncomplete RLCT‐networks often can be remodelled into complete RLCT‐networks by inserting additional branches containing controlled sources which do not affect the mixed potential. Further simplifications are possible using the rules given to derive the so‐called ‘potential‐equivalent’ networks which contain less controlled sources but lead to the same normal form equations. Finally some theorems are given concerning the existence and uniqueness of solutions of a complete network where the conditions can be examined directly at the network before establishing the network equations.
A nonlinear lumped circuit model for gunn diodes
Authors: Chua L. O. , Sing Y. W. 
Published: July 2007

AbstractA nonlinear lumped circuit model for Gunn diodes which includes the effects due to domain extinction and nucleation phenomena is presented. The model is based upon physical principles and allows an arbitrary nonlinear drift velocity curve v(E) and a nonlinear diffusion curve D(E) to be specified by the user. It is valid for simulating arbitrary Gunn‐diode circuits operating in any matured high‐field domain mode, or in the LSA mode. Under additional assumptions, the model simplifies to other existing models. Several computer‐simulated examples of Gunn‐diode circuits operating under both steady‐state and transient regimes are presented. Finally, a rigorous definition of a ‘DC’ I‐V curve for Gunn diodes is offered and shown to be rather useful for predicting the qualitative behaviour of Gunn‐diode circuits during all time intervals where a matured domain exists.
A class of nonrealizable paramount matrices
Authors: Loughlin Timothy A. , Slepian Paul 
Published: July 2007

AbstractAlthough paramountcy1 is a necessary and sufficient condition for the realizability of a 3 by 3 matrix as either an open‐circuit impedance matrix or a short‐circuit admittance matrix of a resistive 3‐port,2 Weinberg's 4 by 4 example3,5 shows that paramountcy, although necessary for open‐circuit impedance realization, is not sufficient. Here we exhibit a class of 4 by 4 completely irreducible paramount matrices, including Weinberg's example, no member of which is realizable as an open‐circuit impedance matrix. This is accomplished by examining those topological constraints inherited by a realizing network when algebraic conditions are imposed on the paramount matrix which the network realizes. Our development deals with an n‐port network, for arbitrary n, and also provides new criteria guaranteeing nonrealizability of an irreducible1 paramount matrix.
Transfer functions with arbitrary phase characteristics
Authors: Fahmy M. F. 
Published: July 2007

AbstractA simplified method—based on Thiele's continued fraction—is proposed for the derivation of transfer functions whose phase responses interpolate a desired phase characteristics at a set of prescribed frequencies, the maximally flat delay aproximation being recovered as a degenerate one. Illustrative examples showing the application of this procedure in the design of linear delay networks are also given.