bluuebunny/crossref_metadata_2025 huggingface dataset:
Darstellung und Reaktionen Trifluormethylchalkogenyl‐substituierter Alkine
Authors: Haas Alois , Krächter Hans‐Udo
Published: July 2007

(Trifluormethylchalkogenyl)alkine 1 werden durch Reaktion entsprechender Bromalkine mit CuECF3 (E = S, Se) erhalten. Lediglich Bis(trifluormethylthio)ethin (1a) wird nicht direkt, sondern aus BrCHCHBr über die Zwischenstufen CF3SCHCHSCF3, CF3S(Br)CHCH(Br)SCF3 und anschließende HBr‐Eliminierung synthetisiert. Photolyse und Zersetzung von 1a in Gegenwart von (C6H5)P führen zu den Thiophenderivaten 3a,b. Bei der Pyrolyse von 1a entsteht zusätzlich noch das 1,4‐Dithiin 3c, und die Brom‐addition liefert das cis/trans‐Isomerengemisch 2a,b. Cycloadditionen an Dicyclopentadien, Hexachlorcyclopentadien, Anthracen, Tetrachlor‐5,5‐dimethoxycyclopentadien, Tetraphenylcyclopentadienon und Dibromcarben führen zu den Homocyclen 4a–e und 5a. 1,3‐Dipolare Additionen von 1a an Diphenylnitrilimin, PhN3 und R2CN2 (RH, CH3, C6H5) liefern die Heterocyclen 6a,c und 7b–e. Pyrazol 7e zerfällt in 7f und 5b. Die Furanderivate 9a,b werden aus 1,3‐Oxathiolonen 8a,b und 1a gewonnen. Bei Umsetzungen von 1a mit S4N4 bzw. SO3 entstehen die Siebenringe 10 bzw. 11.
Synthesen cyclischer und acyclischer 1,4‐Chinonhydrazone mit Norcaradien‐ und Cycloheptatrien‐Partialstruktur
Authors: Neidlein Richard , Jäschke Uwe
Published: July 2007

Syntheses of Cyclic and Acyclic 1,4‐Quinone Hydrazones with Norcaradiene and Cycloheptatriene Fragments

The syntheses of different triazine and azo dyestuffs 2a–c, 4a, b, 5a, b, and 6c are described.
On state‐space synthesis of reciprocal n‐ports
Authors: Trón T.
Published: July 2007

The paper considers the state‐space synthesis of reciprocal n‐ports with a minimum number of reactive elements. After formulating the synthesis problem new procedures are given for the lossless and for the passive cases which use a directly determinable reciprocal minimal realization as starting point. The methods are presented in terms of admittance matrices and then restated for impedance, hybrid and scattering matrix synthesis.
An improved algorithm for rational approximation of transfer functions
Authors: Kukk V.
Published: July 2007

The calculation of a rational transfer function is considered using a Laguerre expansion of the impulse response. An algorithm is proposed that avoids the appearance of high‐order surplus factors. Results of computer experiments are presented.
State–space formulation of linear circuits containing periodically operated switches
Authors: Köksal M. , Tokad Y.
Published: July 2007

The state–space formulation of linear circuits containing periodically operated switches requires one to obtain the state and output equations. Further, it requires one to obtain the switching equations where discontinuities in the state variables occur at a switching instant. A new method for the computation of the state and output equations is given. Further, a procedure is described to obtain the switching equations, in the most general form, at a switching instant. Examples are given to illustrate these methods in finding the state, the output and the switching equations.
Sensitivity of third‐ and higher‐order filters
Authors: Roy S. C. Dutta , Bhargava D. K.
Published: July 2007

For any realization of a network function F(s) = N(s)/D(s), the sensitivities that can be most readily calculated are those of the coefficients in N(s) and D(s). A simple relationship is derived that enables one to calculate the root (pole and zero) sensitivities of F(s) in terms of the coefficient sensitivities. The root sensitivities, in turn, enable one to calculate the root pair Q and root frequency sensitivities, which can be used to characterize and compare different realizations of F(s). Application to 3rd‐ and 4th‐order filters reveals formulations that are more elegant than those already known in the literature.
Ideal pulse compression via distributed feedback
Authors: Hazony D.
Published: July 2007

Pulse compression plays an important role in signal processing. It is shown that distributed feedback may provide pulse compression in a direct manner. The physical shape of the required feedback path is precisely the same as the prescribed incoming signal.
Determining the periodic response of nonlinear systems by a gradient method
Authors: Nakhla M. S. , Branin F. H.
Published: July 2007

For systems of differential equations of the form ẋ = f(x) or x = f(x, t), a periodic response may be identified by the requirement that x(kT) = x(0), where k = 1, 2, … and T is the period, x(0) = x0 being the initial‐condition vector. We describe a gradient method for finding this x0 vector by minimizing the square magnitude of the ‘discrepancy vector’ δ(x0) = x(T)–x0. The gradient of the scalar function P(x0) = δt(x0)δ(x0) with respect to x0 is calculated by one full‐period forward integration of the original differential equation to obtain δ(x0), and then one full‐period backward integration of the adjoint variational equations, using δ(x0) as the initial‐condition vector. The gradient of P(x0) is then twice the adjoint discrepancy vector. We use Fletcher's method of optimization to minimize P(x0).
Pole‐zero sensitivities of a digital filter due to parameter quantization
Authors: Stojić M. R. , Stojić R. M.
Published: July 2007

An analytical procedure for the sensitivity analysis of digital filters is presented. The procedure applies to the sensitivity investigation of digital‐filter poles and zeros due to parameter quantization. Suitably defined sensitivities and a computer‐aided technique, presented in the paper, allow a rapid evaluation of displacements of digital‐filter poles and zeros due to parameter quantization in different realizations of a given digital filter.
Generalized bessel polynomials with application to the design of bandpass filters with approximately flat group delay response
Authors: Fahmy M. F.
Published: July 2007

The continued fraction expansion of the ordinary Bessel polynomials is modified by replacing the complex frequency variable p by p/(1+γp), where γ=⩾0. The resulting polynomials, when a reactance transformation is applied, are capable of providing bandpass filters with an approximately flat group delay response.
Tapered‐magnitude bandpass distributed‐network transfer functions
Authors: Mokari‐Bolhassan M. E. , Ku W. H.
Published: July 2007

Sloped commensurate transmission‐line functions realizable with stubs and cascaded lines 1/8 wavelength long are presented. These functions may be applied to synthetizing matching networks required for slope compensation in microwave amplifiers. Examples for the broadband design of 7–14 GHz chip 1 μm gate f.e.t. and 4–8 GHz packaged f.e.t. amplifiers are given.
Determination of initial conditions in active RLC networks
Authors: Köksal M. , Tokad Y.
Published: July 2007

A new method is described of determining the initial values of state variables in active RLC networks. This method utilizes neither the conservation principle of charges and fluxes nor the theory of distributions. An RLC active network is assumed to be formed at t = 0 by joining or disconnecting the elements that are contained in it, this operation being performed by the use of a set of switches. The new method is based on the consideration of switches as independent sources, and the state equations are extended to cover this situation, and their solution at t = 0+ gives the initial conditions that have been sought. Further, the new method is applicable to any state‐space formulation techniques used.
Microwave bandpass filters consisting of rectangular waveguides with 1‐dimensional offsets
Authors: Kühn E.
Published: July 2007

The computer‐aided analysis and design of direct‐coupled and quarter‐wave‐coupled bandpass filters utilizing monomode rectangular waveguides with 1‐dimensional offset discontinuities are described. The equivalent networks of these discontinuities, which consist of a shunt reactance and additional transmission lines connected at both sides, have been derived from the rigorous field‐theoretical investigations of E‐plane and H‐plane displacements in rectangular waveguide. Both network elements are tabulated in terms of geometry and wavelength with fine steps to allow accurate interpolation by means of computational methods, Simple design formulae for the filter geometry as a function of the electrical specifications are given which are based upon narrow‐band approximations. The analytical relationships required for a computer simulation of the filter's wide‐band performance are summarized. The predicted frequency characteristics showed such close agreement with the experimental results obtained on two X‐band filter models that neither tuning elements in the waveguide sections nor final adjustments of the offset widths had to be provided.
An optimal design of RC active filters using grounded capacitors
Authors: Abougabal M. S. , Bhattacharyya B. B. , Swamy M. N. S.
Published: July 2007

It is desirable, from the point of view of integration, to have all the capacitors grounded in RC active filters. Recently, such a network was reported with only a preliminary design procedure. An optimal design is presented in this paper for the above network. The new design leads to a simpler configuration, simultaneously minimizes the worst‐case deviation in both the pole‐Q(Qp) and the pole frequency ωp and also guarantees that the network is free from unstable modes of operation during activation. Although this design is based on Qp and ωp, it is also suitable for notch and allpass sections. It is shown that the gains of the operational amplifiers (o.a.s.), controlling the poles of the filter, can all be made equal to (4Q2p‐1)1/3; this choice of the gains minimizes the effect of the finite bandwidths of the amplifiers on Qp and ωp. A simple scheme is proposed to compensate for this effect. The effect of compensation on the zeros, in the case of notch and allpass sections, is also studied. It is found that the effect on the notch frequency is negligible, while, for allpass filters, compensation for the poles automatically provides compensation for the zeros. A simple tuning scheme using only resistors is also presented, and the theoretical results are verified experimentally.
A general method for small‐signal circuit analysis considering thermal effects
Authors: Conte G.
Published: July 2007

It is well known that the behaviour of integrated circuits is strongly affected by thermal feedback. A general method for evaluating, by linear analysis, the complete circuit performance is described that considers these effects. The procedure can easily be implemented using only well known computer programs for the circuit analysis. Simple models for a number of devices (diodes, transistors and f.e.t.s) used in integrated circuits are given. Examples, using the circuit‐analysis program ECAP, are shown.
A nonlinear macromodel for operational amplifiers
Authors: Weil P. , McNamee L. P.
Published: July 2007

A general‐purpose nonlinear macromodel of an operational amplifier is presented. All element values can be derived directly from typical specification sheets eliminating any testing to determine model parameters. The model simulates the following characteristics: voltage and current offsets, input impedance, nonlinear input bias currents, gain, multiple poles, nonlinear slew, common‐mode gain, voltage and current limiting and output impedance.
1‐ports with orthonormal properties
Authors: Czarnecki L. S.
Published: July 2007

The paper deals with the problem of finding the immittance functions of a 1‐port for which, in the case of periodic signals of Ω frequency, the voltage and current are orthogonal to one another, and in which the voltage and current have the same norms, i.e. they are related as a pair of Hilbert transforms. The need for the construction of such 1‐ports arises, for example, in connection with the problem of the measurement of the reactive power of nonsinusoidal waves. Three sets of network functions have been found for the networks in which input and output signals are pairs of Hilbert transforms, and it has been proved that one of them is a set of positive‐real and reactance functions, and that one is a set of transfer functions of all‐pass networks composed of orthonormal 1‐ports.
Use of function elimination filters to reject quasideterministic interference in ask systems
Authors: Plotkin E.
Published: July 2007

The use of the function filtration method to increase immunity to interference in ask systems is discussed. To achieve increased immunity, a function elimination filter (f.e.f.) was constructed to eliminate any sine‐wave interference (s.w.i.) with a priori unknown parameters. When there is no random noise, such a filter provides a zero error probability, in spite of the existence of s.w.i. It is shown that there exist some situations when the use of an f.e.f. provides an error probability less than that achieved by a matched filter (m.f.), even if the input process includes both s.w.i. and random noise.
Noise minimization in RC‐active filters using generalized impedance converters
Authors: Ramakrishna K. , Bruton L. T.
Published: July 2007

A procedure has been given for minimizing the total output noise of a Generalized Impedance Converter (GIC), subject to constraints dictated by signal handling capability of the Operational Amplifiers and ease of microcircuit fabrication. The noise reduction is achieved only by the adjustment of RC elements of the GIC, and the total output noise after optimization in the example cited is close to the theoretical lower limit. The output noise of a higher‐order filter can be reduced by RC‐optimizing the individual GIC's of the active realization. Experimental results on a 20–24 kHz channel bank band‐pass filter demonstrate the effectiveness of the above procedure.
Piecewise‐linear modelling and simulation of nonlinear networks
Authors: Chien Ming‐Jeh
Published: July 2007

This paper presents a method which combines the modelling and simulation of a nonlinear network together. The main idea is to divide the rectangle of interest into simplices by imposing a fixed ordering. It turns out that the creation of a piecewise‐linear model and the computation of an approximate solution are greatly simplified because of the use of simplices. Some examples show that it is possible to apply the method to ‘fixed point’ problems and other types of problems.
Yield estimation for efficient design centring assuming arbitrary statistical distributions
Authors: Abdel‐Malek H. L. , Bandler J. W.
Published: July 2007

Based upon a uniform distribution inside an orthocell in the toleranced parameter space, it is shown how production yield and yield sensitivities can oe evaluated for arbitrary statistical distributions. Formulae for yield and yield sensitivities in the case of a uniform distribution of outcomes between the tolerance extremes are given. A general formula for the yield, which is applicable to any arbitrary statistical distribution, is presented. An illustrative example for verifying the formulae is given. Karafin's bandpass filter has been used for applying the yield formula for a number of different statistical distributions. Uniformly distributed parameters between tolerance extremes, uniformly distributed parameters with accurate components removed and normally distributed parameters were considered. Comparisons with Monte Carlo analysis were made to contrast efficiency.
Explicit expression for the characteristic function of generalized legendre filters
Authors: Rakovich B. D. , Popovich M. V.
Published: July 2007

The explicit formula for the characteristic function of all‐pole lowpass filters with monotonic passband magnitude response is derived. It is shown that the characteristic function of Legendre, Halpern, LSM and other known classes of monotonic magnitude all‐pole filters that are synthesized from the magnitude squared function, can be obtained by assigning different values to a variable parameter in the general expression obtained. The approximation method consists of using a weighted least‐mean‐square norm to minimize the area under the first derivative of the characteristic function.
Optimum realizations of single‐amplifier networks with zero pole frequency sensitivity and with minimized pole‐Q deviation
Authors: Singh N. P. , Ramachandran V. , Bhattacharyya B. B.
Published: July 2007

This paper discusses realizations of second‐order open‐circuit voltage transfer functions by single‐amplifier active RC networks. These realizations are based on the polynomial decompositions having the property that the sensitivity of ω0 with respect to the amplifier gain is zero. In addition, the gain‐sensitivity product of Q is minimized and the element spread is contained to be within acceptable limits. The realizations are suitable for hybrid IC technology.
A fast and reliable computer program for the accurate hurwitz factorization of a polynomial
Authors: Eckelmann Gerd
Published: July 2007

A method is explained for the decomposition of an even polynomial into the product of a Hurwitz polynomial and an Anti‐Hurwitz polynomial. This problem arises, for instance, in network synthesis. A computer program is presented and its application is explained. Several examples show the properties of the proposed method.
An edge‐oriented adjacency list for undirected graphs
Authors: Chen L. K. , Ting B. S. , Sangiovanni‐Vincentelli A.
Published: July 2007

A new data structure, called the Edge‐Oriented Adjacency List (EOAL), for representing undirected graphs is presented. It provides more information on the edges and requires less storage space than the conventional adjacency list. Furthermore, it is superior to the conventional adjacency list in both insertion and deletion operations.
Existence of hybrid matrices for active n‐ports encountered in the analysis of transistor networks
Authors: Nielsen Richard O. , Willson Alan N.
Published: July 2007

It is shown that hybrid matrices exist for certain types of active n‐ports constructed using resistors and controlled sources. Furthermore, it is shown that the existence of these hybrid matrices implies that a certain well‐known set of necessary and sufficient conditions, which guarantees the uniqueness of solutions to the nonlinear DC equations of transistor networks, can be simplified. Additional results are presented which show how the amount of computation required to verify these conditions can be reduced.
Parametric representation of brune functions
Authors: Fettweis Alfred
Published: July 2007

It is shown that a parametric representation for Brune functions can be given which, although being more complicated than for Foster functions, is simple enough to be of practical interest. This holds in particular if use is made of substantial simplifications obtainable by eliminating certain subclasses of Brune functions which are of no practical interest. Applications to broadband matching and switched networks are pointed out.
Statistical multiparameter sensitivity measures for transfer gain and phase functions
Authors: Acar Cevdet
Published: July 2007

New statistical multiparameter sensitivity measures are defined for the transfer, gain and phase functions. The integrands of these sensitivity measures include mean values as well as variances of element variations. It is shown that a very simple relationship exists between transfer, gain and phase measures even though element variations are large. General formulae are derived for small element variations, which would simplify evaluation of the measures. These formulae are helpful in the comparison of various low sensitivity networks.
Minimizing the roundoff‐noise in digital filters by the branch and bound method
Authors: Lanfer H. , Lüder E.
Published: July 2007

The branch and bound method is used for minimizing the roundoff‐noise in cascaded 2nd‐order filter sections. The degrees of freedom are the pole‐zero assignment and the ordering of the stages in the cascade, whereas the structure chosen is always the 2D‐form. During the search an upper and a lower limit for the noise power provide an estimate of how close the solution is to the optimum. Thus, the search may be stopped if no further substantial improvement can be expected. The optimum is reached when the two limits coincide. The efficiency of the procedure is demonstrated by optimizing three filters with up to 22nd‐order transfer functions.
Efficient computation of frequency response of digital networks
Authors: Prasad K. P. , Reddy P. S.
Published: July 2007

A major requirement in the analysis of multi‐input‐multi‐output digital networks is to compute the frequency response at a large number of points from a knowledge of the graph of a network with specified input and output nodes. Though the usual method of analysis by solving linear equations is more efficient than matrix inversion, solution of linear equations at each frequency may still require a large amount of computation. A more efficient method is to determine the poles and zeros of the desired system function and then calculate the frequency response from them. Though poles of the system function could be readily identified as contained in the eigenvalues of the state matrix of the network, difficulty is seen to arise in the determination of zeros which can not so easily be calculated. A simple and efficient method is proposed reducing the determination of zeros to a standard eigenvalue problem.
Design of stable two‐dimensional analogue and digital filters with applications in image processing
Authors: Ramamoorthy P. A. , Bruton L. T.
Published: July 2007

A method is proposed for the frequency domain design of linear two‐dimensional analogue and digital filters with guaranteed stability. The technique used is based on the result that the numerator and the denominator of the input immittance of a two‐variable network (which is passive and lossy) are strictly Hurwitz polynomials. One of these strictly Hurwitz polynomials is assigned to the denominator of a two‐variable analogue transfer function and the network elements are then used as the variables of optimization thereby guaranteeing the stability of the analogue transfer function. The transfer function of the corresponding two‐dimensional discrete (digital) filter is obtained from the analogue transfer function by the bilinear transformation. Examples illustrating the versatility of the technique in designing 2D digital filters of arbitrary order approximating a given magnitude and group delay response are presented. These filters are used to process a simple binary image. The results obtained demonstrate the importance of linear phase in image processing applications.

The method presented here can be extended to the design of stable m‐dimensional analogue and digital filters.
The use of the shifted jacobi polynomials in the synthesis of lowpass filters
Authors: Beccari Claudio
Published: July 2007

It is shown that the shifted Jacobi polynomials are particularly useful in solving the approximation problem of both the general and the monotonic polynomial lowpass filters. A new type of least squares monotonic filter is introduced.
Generalized technique for designing broadband varactor‐tuned negative resistance oscillators
Authors: Rauscher Christen , Carlin Herbert J.
Published: July 2007

A powerful method for designing broadband varactor‐tuned negative resistance oscillators is presented. The CAD procedure stems from a novel way of employing Hilbert transform techniques. The method is capable of realistically taking into account the decisive factors governing oscillator performance and directly processes measured large‐signal data of the active device without relying on an approximate circuit model for the device. Device—circuit interactions at higher harmonic frequencies are not considered in the context. A transferred‐electron oscillator design example is used to illustrate the method.
A unified theory of symmetry for nonlinear multiport and multiterminal resistors
Authors: Chua Leon O. , Vandewalle Joos
Published: July 2007

Simple group‐theoretic concepts are used to develop a rigorous and comprehensive theory of symmetry for nonlinear multiport and multiterminal resistors which do not rely on geometrical arguments or other ad hoc techniques normally invoked in such studies. This theory unifies all forms of symmetry, including rotation, reflection and complementary symmetry, into a single framework. It also includes all known nonlinear symmetry principles as special cases. Moreover, a general method for identifying all symmetry characteristics possessed by a nonlinear multiport and multiterminal element is given.

The main results of this paper:

Several algorithms for synthesizing a nonlinear multiport or multiterminal element having any prescribed form of symmetry are presented. In particular, various examples are given which illustrate how these algorithms can be used to derive well‐known symmetrical nonlinear circuit modules such as push‐pull amplifiers, complementary‐symmetric amplifiers, rectifiers, modulators, etc.;

A reduction algorithm is presented which allows a complicated symmetric element to be analysed by a much simpler reduced element;

A general principle is derived for applying symmetry to achieve frequency separation in nonlinear communication circuits where the even harmonic components are separated from the odd harmonic components.
Stability properties of lagrangian networks
Authors: Gruszczyćski Walerian , Szatkowski Andrzej
Published: July 2007

This paper presents the qualitative properties of the solutions of the state equations for Lagrangian networks. Some theorems on the stability of this class of networks are proved.
Some new results on the controllability and observability of linear systems and networks
Authors: Lin P. M. , Kuo Y. L.
Published: July 2007

This paper introduces the concept of ‘hybrid‐dual systems’ and presents some new results on the controllability and observability of these systems. Theorem 1 states that for hybrid‐dual systems, which include dual systems as a special case, controllability of one implies observability of the other. Theorem 2 gives the topological conditions for RLC n‐ports such that controllability and observability imply each other. Theorem 2 also shows that for any RLC n‐port, observability implies controllability, but the converse is not true.
Nonconventional two‐port matrix decompositions and their realization
Authors: Moos Petr , Pospíšil Jiří
Published: July 2007

General conditions for sum and product matrix decomposition are applied to the sum of the chain matrices and the product of the immittance and the hybrid matrices. The corresponding connection of the partial two‐ports is realized by special three‐ports containing operational amplifiers and current and voltage controlled sources.
On the generation and optimization of equivalent ladder networks
Authors: Ulbrich W. , Dasch B.
Published: July 2007

The impedance scaling process and Norton's transformation are formulated in a uniform manner as a Cauer‐Howitt transformation with diagonal matrices. For passive two‐element‐kind ladder networks the realizability conditions are reduced to linear inequality constraints. An algorithm is given to enumerate all vertices of the realizability polyhedrons which represent all equivalent networks with a minimum number of elements. In addition a cost function meeting practical requirements is stated and optimized, taking into account various orders of network complexity.
Active rc filters using an operational transconductance amplifier and an operational amplifier
Authors: Deliyannis T.
Published: July 2007

An operational transconductance amplifier (OTA) and an operational amplifier are being used to synthesize various second‐order cascadable active RC filters. Two of them are active R filters. The filters are studied both theoretically and experimentally and are found to have low sensitivity to variations in their component values. They work satisfactorily in practice, except that some of them have a rather limited dynamic range.
A transmission line transformer having frequency independent matching properties
Authors: Roy Suhash C. Dutta
Published: July 2007

In this paper, we present a new transmission line transformer which is capable of matching a load resistance RL to a given source of internal resistance Rg in a frequency independent manner. This matching can be made perfect at all frequencies if RL/Rg = 4; for RL/Rg ≠ 4, the matching can still be made frequency independent but the power transferred to the load becomes less than the maximum available power.
Dual‐amplifier expansion and the design of very‐low‐frequency (VLF) hybrid integrated active filters
Authors: Moschytz G. S. , Horn P.
Published: July 2007

The problem of designing very‐low frequency (VLF) active filters in hybrid‐integrated form is discussed. It is shown that a class of single‐amplifier second‐order filters exists with which VLF active filters can be built while at the same time satisfying the constraints imposed by hybrid‐integrated circuit technology (i.e. limited resistor and capacitor values). However, with decreasing pole frequency, the gain required of the single amplifier becomes excessive, the gain‐sensitivity product (GSP) intolerably high. A solution to the problem is to introduce a second amplifier into the circuit and to distribute the required gain between the two amplifiers. This ‘dual‐amplifier expansion’ (DAX) significantly reduces the GSP, enhances the stability of the filter response, and reduces the susceptibility of the filter characteristics to nonideal amplifier effects. On the other hand DAX may not be arbitrarily introduced into a single‐amplifier circuit without taking the effect of the limited gain‐bandwidth product of the two amplifiers into account. It is shown that the degree by which the gain may be distributed between them is limited by the gain‐bandwidth product ratio of the two amplifiers. Much can be improved in this respect by proper frequency compensation of the two amplifiers. It is shown that a combination of the so‐called T‐compensation and the single‐pole single‐capacitor compensation produces results that are close to those obtainable with ideal amplifiers with unlimited bandwidth.
Transfer function determination from impulse response via walsh functions
Authors: Paraskevopoulos P. N. , Varoufakis S. J.
Published: July 2007

This paper presents a new method for calculating a rational transfer function matrix using a Walsh expansion of the impulse response matrix. The algorithm proposed appears to be computationally convenient owing to certain properties of the Walsh functions. An example is given to illustrate the method.
A new a priori ordering method for sparse systems of equations based on an ordered output set
Authors: Bhat Kabekode V. S. , Kinariwala Bharat
Published: July 2007

In the context of solution to the sparse systems of equations arising in computer‐aided analysis and design of electrical networks using the Gaussian elimination (GE) process it is well‐known that an a priori reordering for equations and unknowns is almost mandatory. In this paper we present a new approach for a priori ordering for the equations and unknowns using the theory of output sets. Our approach yields an ordered output set as the pivot sequence for an associated GE process. Our algorithm is simple and is more general than the existing ones and leads to an s‐minimal GE process. An example is presented for illustrating the algorithm and the computational complexity of the new method has been analysed. Additional work needed in the area is indicated.
The generalized chebyshev low‐pass prototype filter
Authors: Rhodes J. D. , Alseyab S. A.
Published: July 2007

A synthesis method is presented for the class of low‐pass prototype filters having an equiripple passband response with a single transmission zero at infinity and the remainder at a finite real frequency. To synthesize the network, the even mode or the odd mode is obtained directly using the alternating pole technique and little accuracy is lost for networks up to degree 19. Tables of element values for commonly used specifications are included. Finally, the practical advantages of this prototype when used to design certain classes of filters are discussed.
Synthesis of symmetrical dual mode in‐line prototype networks
Authors: Rhodes J. D. , Zabalawi I. H.
Published: July 2007

An analytic synthesis technique is developed for symmetrical dual mode in‐line prototype networks up to and including degree 12 networks. Due to the symmetrical realization, the even mode coupling matrix completely defines the network and one particular form representing the double cross‐coupled array, may be obtained directly from the transfer function. Commencing with this matrix, rotational transformation are used to transform the even mode matrix into the form required for a dual mode in line structure. Analytical solutions are obtained for degrees up to and including 12 and the necessary realizability conditions are determined for each case. Explicit formulas for the angles of rotation are given and for degrees up to and including 10, a complete set of explicit formulas are provided for the final coupling matrix. To assist in the design of the in‐line structure, tables of element values for filters having 20 dB and 26 dB return loss and possessing the minimum number of transmission zeros at infinity are tabulated.
Multiple real‐pole equal‐ripple rational (MRPER) approximation for lowpass RC‐active filters
Authors: Biey Mario , Premoli Amedeo
Published: July 2007

A new class of lowpass rational transfer functions is defined, with equal‐ripple behaviour both in the passband and in the stopband. The proposed functions have a multiple real pole, which allows the realization of lowpass RC‐active filters by cascading more (than one) 3rd‐order blocks.

These new functions, called multiple real‐pole equal‐ripple rational (MRPER), improve the attenuation performance with respect to a classical solution employing the same number of 2nd‐order blocks and hence may allow a reduction in the required number of active elements and, eventually, in power consumption and in noise‐to‐signal ratio. However, even if the number of active blocks cannot be reduced, the better attenuation performance, which results, allows component tolerances to relax.
Orthogonal cascade realization of real multiport digital filters
Authors: Deprettere E. , Dewilde P.
Published: July 2007

A generally applicable theory for multiport orthogonal digital filter synthesis is discussed, using a direct algebraic method. Standard (complex) degree 1 and irreducible (real) degree 2 chain scattering matrices are derived and the computability problem which normally occurs in such filters is discussed and solved for the general case. It is shown that any finite causal and lossless real multivariate system can be realized as a computationally compatible cascade of real degree 1 and degree 2 factors consisting of an orthogonal constant interconnecting part and a lossless dynamic portion. In order to increase the practical interest of the paper, realizations of these sections are explicitly given. The known scalar wave digital filter ‘adaptors’ emerge as a special case of the theory presented in this paper. The general results are of interest in multiport digital signal processing, in multivariate interpolation theory and in multichannel prediction and modelling theory and techniques.
Passive approach to switched‐capacitor circuits
Authors: Martinelli G. , Salerno M.
Published: July 2007

The possibility of developing a passive approach to switched‐capacitor circuits is explored in the present paper with particular reference to the determination of a valid scheme for the parallel LC resonator and for the inductor. The schemes proposed for these switched‐capacitor components are shown to be valid in the typical situations of operation. The results of several tests, carried out both on prototypes and on the digital computer by simulation, illustrate the behaviour of the proposed circuits and confirm their effectiveness.
Contribution to the qualitative theory of non‐linear systems and networks
Authors: Szatkowski Andrzej
Published: July 2007

This paper deals with the qualitative theory of non‐linear systems and networks. Several theorems on the boundedness of the solutions and on the stability of equilibrium points are proved. The problem of the synthesis of non‐linear systems and networks with the prescribed trajectories is considered. Some geometric properties of the limit sets of the solutions are presented.
Classification and generation of active compensated non‐inverting VCVS building blocks
Authors: Soliman Ahmed M.
Published: July 2007

It is shown that the active compensated non‐inverting voltage controlled voltage source (VCVS) structures employing two operational amplifiers (op‐amps) may be classified into two major classes. Class 1, in which the phase compensation condition does not depend on the unity‐gain bandwidth of the op‐amps used, and class 2, in which the phase compensation condition depends on the unity‐gain bandwidth of both op‐amps. Detailed comparison tables which include the condition for phase compensation, the phase error, the magnitude error and the realizable bandwidth are given.
Hierarchic decomposition method for the topological analysis of electronic networks
Authors: Starzyk Janusz , Sliwa Edward
Published: July 2007

This paper concerns a new approach to the topological analysis of linear networks. It gives a description of the hierarchic decomposition method (i.e. multiple decomposition of a decomposed network) which can be applied in computer analysis of electronic networks. A new universal algorithm for generation of k‐trees is presented.
The impact of generalized symmetry on computer‐aided design of cascaded structures
Authors: Bandler J. W. , Biernacki R. M. , Rizk M. R. M.
Published: July 2007

New theoretical and computational tools are presented which deal with generalized symmetry concepts related to the computer‐aided design of cascaded structures. The presentation includes the computational implications of networks consisting of symmetrically located reverse adjoint subnetworks with and without scaling, as well as antisymmetry. Formulas presented are designed to be used in simulation, sensitivity and tolerance analyses as well as in optimal design.
Floating inductor with two current conveyors
Authors: Patranabis D. , Paul A. N.
Published: July 2007

There have been considerable efforts towards the realization of ideal floating inductors where mostly three active blocks are required. The reduction in the number of active blocks to two was however achieved with considerable increase in the number of resistances and passive parameter constraints. The proposed scheme suggests a method to produce a floating inductor with a series negative resistance using two current conveyors, only three resistors and one capacitor, involving only one restrictive constraint. The realized inductor was also used to design a third order Butterworth filter. Experimental results confirm the applicability of the realized immittance.
Algorithms for solution updating due to large changes in system parameters
Authors: Hajj Ibrahim N.
Published: July 2007

A set of algorithms for solution updating due to large changes in system parameters is derived. The algorithms are derived by partitioning the changes in the values of the elements from the remainder of the system and then applying tearing procedures to solve tthe partitioned system of equations. The algorithms obtained include new ones as well as most of the previously proposed ones for solving this problem. Sparse matrix solution techniques are used whenever possible, and the computational requirements of the algorithms are assessed and compared.
Transmission parameter representation of non‐uniform transmission line Green's functions
Authors: Haley Stephen B.
Published: July 2007

The Green's function G(x, x') of a non‐uniform transmission line is formulated exactly in terms of partial transmission matrix parameters associated with different segments of the line. Exact differential expressions relate the transmission parameters to each other, and it is shown that G(x, x') can be expressed entirely in terms of a single transmission parameter B(x, x') and its derivatives. The voltage response V(x) on any doubly‐terminated line with arbitrary current source density along the line is given. A new perturbation technique, based on a Volterra integral equation, is developed which determines V(x) in terms of known functions and arbitrary perturbing immittances on the line.
Singular perturbations in the state space approach of linear electrical networks
Authors: Sannuti P.
Published: July 2007

Networks whose dynamic order is less than the number of energy storing elements they contain are considered. By adding parasitic elements, their dynamic order is restored. After selecting the state variables properly, singular perturbation theory is used to analyse the network behaviour with respect to the parasitic elements and to calculate the initial jumps in the network variables. Parasitic elements are seen to play a dominating role in dictating the stability of a network. The need for generalizing the presently available singular perturbation theory is pointed out by means of an example.
The adjoint switched capacitor network and its application to frequency, noise and sensitivity analysis
Authors: Vandewalle J. , De Man H. , Rabaey J.
Published: July 2007

Given a linear network of capacitors, periodically controlled switches and sources we derive its adjoint network and show how it can be used to reduce the computational complexity of the frequency, noise and sensitivity analysis.

The construction of the adjoint switched capacitor circuit turns out to be quite simple, even for switched capacitor networks with more than two phases or with a continuous input‐output path. Moreover this construction can be performed equivalently in the time domain or on the equivalent circuit.

In order to facilitate the implementation in a computer‐aided‐design program all derivations are performed in the modified nodal analysis formulation (MNA).
Lossless 2‐ports between non‐reactive terminations
Authors: Hasler Martin
Published: July 2007

Lossless reciprocal 2‐ports between terminations with even impedance functions are considered. They are the unifying concept for the synthesis of FDNR and leapfrog RC‐active filters in their most general form. The scattering matrix of lossless reciprocal 2‐ports with respect to such terminations is defined, its canonic form deduced and the transfer of active power discussed. This scattering matrix is related to the usual scattering matrix of the same 2‐port but with respect to unit resistance terminations. In such a way the precise structure of the 2‐port as an LC ladder can be deduced from properties of the original transfer function and the termination impedances and the LC synthesis can be performed by conventional methods and programs. An exhaustive enumeration of the different cases that may arise is given. It can give a general outlook on the different RC‐active filters that may be obtained.
A practical closed form solution for systems with variable eigenvalues via bilinear system theory
Authors: Brandenbusch Wolfgang , Stehle Werner
Published: July 2007

This paper treats systems in state variable formulation with non‐constant, parameter controlled system matrices. The synthesis of a system with controlled eigenvalues (ECS) is given. The synthesized system is a commutative bilinear system. Its solution has a closed form and is based on the solution of just one time invariant system although as many arbitrary time functions are involved as the system has independent states. The ECS is homologous to any system with a system matrix being an arbitrary, possibly time‐dependent function of a single constant system matrix.

All results are deduced for multiple eigenvalues of the system matrix including single eigenvalues as a special case. They are fully analogous to the solution of time invariant systems by means of the Laplace transformation.
Lossless chain scattering matrices and optimum linear prediction: The vector case
Authors: Dewilde Patrick , Dym Harry
Published: July 2007

In this paper we give a systematic treatment of the exact and approximate realization of a positive real matrix‐valued function on the open unit disc by means of a lossless circuit connected to a passive load. We discuss the mathematical properties of the chain scattering matrix which describes the lossless circuit and rederive a form of the classical Darlington synthesis theorem generalized to roomy matrix‐valued transmission functions. We then develop a matrix version of an algorithm due to Schur for the construction of approximate realizations which produces (minimal degree) Nevanlinna–Pick approximants to the original positive real matrix. We further identify the normalized inverse of one of the outer factors of the approximant to the positive real matrix as the orthogonal projection of the identity onto a suitably defined subspace, give its interpretation as a reproducing kernel, and establish strong convergence under mild conditions on the growth of the order of the approximation. Finally we interpret and apply the mathematical theory developed in the body of the paper to the theory of prediction for vector‐valued second order stationary stochastic sequences and briefly discuss connections with the theory of maximum entropy extensions and of inverse scattering.
On the role of the Nevanlinna–Pick problem in circuit and system theory
Authors: Delsarte Ph. , Genin Y. , Kamp Y.
Published: July 2007

The paper is concerned with applications of the standard Nevanlinna–Pick problem in various technical domains, namely the following: interpolation by reflectance functions, polynomial stability checking, cascade synthesis of passive one‐ports, and model reduction with a Hankel norm criterion. Some fundamental results on the Nevanlinna–Pick problem are shown to be of a definite interest in each of these subjects.
The state‐space realization of an n‐dimensional transfer function
Authors: Galkowski Krzysztof
Published: July 2007

In this paper the non‐minimal real state‐space realization for n‐dimensional transfer functions with polylinear numerators and denominators is stated and proved. It is also shown that the every existing realization of an n‐dimensional transfer function can be achieved from the companion matrix of some (n + 1)‐variable polynomial linear with respect to one of its variables.
Unification of active filters with passive sections having a single internal node
Authors: Bowron P. , Al‐Kabbani A. S. S.
Published: July 2007

A linear graph representation of the passive section in a multiple‐amplifier active filter is used to characterize the general transfer‐function matrix. This enables unification of a wide range of single and double‐amplifier circuits. In the case of a single internal node, some familiar active‐RC and new active‐R configurations emerge. As examples, a second‐order lowpass ‘partial active‐R’ structure of low sensitivity is developed as well as a two‐amplifier active‐R filter which exploits the internal node to provide higher selectivity and increased tuning facility.
Theory of an iterative, two mode transmission network
Authors: Skipping C. R. , Moore B. N. , Oakes M. E.
Published: July 2007

A general investigation of the nature of an iterative, LC lattice structure, shown to function as a transmission channel capable of carrying two distinct wave modes, is carried out. Both a uniform system and an inhomogeneous case where the capacitor values vary slowly down the lattice structure are considered. Emphasis is placed on a formal and numerical investigation of basic wave properties and their significance with regard to signal transmission, crosstalk suppression, plus the particularly interesting phenomenon of one mode converting to the other which is found to occur in the inhomogeneous case. Potential uses of the lattice such as simulated wave studies, among others, are suggested. Relations for termination impedances are derived, and special cases involving different combinations of excitation and termination conditions are considered.