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Circuits and Systems, IEEE Transactions on

Issue 9 • Date September 1981

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Displaying Results 1 - 13 of 13
  • Comments on "Active RC Single-Opamp Design of Driving-Point Impedances

    Publication Year: 1981 , Page(s): 939
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  • Authors' reply to Comments on 'Active RC Single-Opamp Design of Driving-Point Impedances'

    Publication Year: 1981 , Page(s): 939 - 940
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  • The identification of essential variables of systems of algebraic equations applying Gauss- Jordan elimination

    Publication Year: 1981 , Page(s): 867 - 876
    Cited by:  Papers (1)
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    We propose, to the best of our knowledge, a new heuristic approach to the identification of a minimal essential set of variables of a system of algebraic equations, such as, for instance, a companion model of an electrical circuit. In particular we study the impact of numerical elimination (actually Gauss-Jordan elimination) for the case that the equation system contains a subset of linear constant equations with numerically known coefficients. The study reveals that the number of essential variables may be reduced substantially by elimination in some cases. View full abstract»

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  • Realization of Matrix Transfer Functions via a State-Space Approach

    Publication Year: 1981 , Page(s): 934 - 939
    Cited by:  Papers (3)
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    A state-space technique is presented for minimal realization of an impedance matrix or a voltage transfer function matrix without using integrators or the combination of integrators and multiwinding transformers. The Cauer II type passive RC ladder multiport and state-space concepts are employed for the realization. A new similarity transformation matrix is derived to transform a state-space equation in a RC-type Cauer second form into a state-space equation in a block companion form. View full abstract»

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  • On multivariable half-plane analyticity and positive realness

    Publication Year: 1981 , Page(s): 927 - 930
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (464 KB)  

    A new set of necessary and sufficient conditions for positive realness of a rational multivariable function is derived. The conditions render correct results, whether or not there exist nonessential singularities of the first or second kind. The derivation of this set of conditions is based on necessary and sufficient conditions for a zero set of a rational function in a complex variable s depending on n complex parameters, to be confined to the closed left half complex plane. This latter set of conditions, in addition to a set of conditions where the confinement is to the open left half complex plane, are corollaries following a theorem which was published recently. These are stated without proof. View full abstract»

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  • A two-variable approach to the model reduction problem with Hankel norm criterion

    Publication Year: 1981 , Page(s): 912 - 924
    Cited by:  Papers (19)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1624 KB)  

    A two-variable approach to the model reduction problem with Hankel norm criterion is discussed. The problem is proved to be reducible to obtaining a two-variable all-pass rational function, interpolating a set of parametric values at specified points inside the unit circle. A polynomial formulation and the properties of the optimal Hankel norm approximations are then shown to result directly from the general form of the solution of the interpolation problem considered. View full abstract»

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  • A stochastic model for interconnections in custom integrated circuits

    Publication Year: 1981 , Page(s): 888 - 894
    Cited by:  Papers (10)
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    A stochastic model for interconnections in integrated circuits composed of unequal size logic blocks separated by routing channels is described. An algorithm, based on the model, is given for estimating channel widths and chip area. The effectiveness of the algorithm is tested through an example. Applications of the model to placement and routing of integrated circuits are discussed. View full abstract»

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  • Passivity considerations in stability studies of numerical integration algorithms

    Publication Year: 1981 , Page(s): 857 - 866
    Cited by:  Papers (29)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (904 KB)  

    In this paper we introduce the concept of algorithmic passiv- in in ity and indicate its role in circuit and timing simulation programs. Algorithmic passivity shows the overall stability--or lack thereof--inherent in forward Euler, backward Euler, and trapezoidal one-step integration approximations as well as Gear's two-step method. Passivity can be applied to - Vi_ _ Vn-i+ i integration algorithms to provide sufficient conditions for the overall stability of simulation programs that may employ them on an intermixed basis. View full abstract»

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  • Linear phase analog active filters with equiripple passband responses

    Publication Year: 1981 , Page(s): 925 - 927
    Cited by:  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (344 KB)  

    The theory and design of analog active filters with an approximately linear phase characteristic and equiripple passband response is presented. The filters are similar to conventional linear phase transversal filters but do not have a periodic passband response. Hence prefiltering is not required. View full abstract»

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  • Recursive digital low-pass filters with predetermined phase or group delay and Chebyshev stopband attenuation

    Publication Year: 1981 , Page(s): 905 - 912
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (920 KB)  

    A method is presented for determining the transfer function of recursive digital low-pass filters with a Chebyshev characteristic of its attenuation in the stopband and phase or group delay specifiable independently of the attenuation. If the maximally flat criterion is chosen for the approximation of a prescribed constant group delay, the transfer function will be obtained in an explicit form. In other cases, the group delay or phase prescription must first be approximated numerically, while the attenuation property can always be achieved explicitly without numerical optimization. A peculiarity of the method is that, in opposition to analog filters, one can obtain for a specific phase or group delay property several transfer functions, which differ in the numerator polynomial and thus in the minimum value of the attenuation in the stopband. The results will be demonstrated with the aid of an example. View full abstract»

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  • Expected value analysis of digital networks with memory

    Publication Year: 1981 , Page(s): 876 - 887
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    The expected values of the binary signals within a digital network have a number of uses in the design of these networks. These expected value "signals" may be obtained by computationally expensive Monte Carlo methods. Alternately, probabilistic models of digital network elements may be constructed to allow the calculation of expected value information far more efficiently. The treatment of combinational logic networks was carried out in [1]. Here we probabilistically model flip flops and develop an expected value analysis for simple digital feedback networks. View full abstract»

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  • Operational amplifier circuits for the Wien-bridge oscillator

    Publication Year: 1981 , Page(s): 930 - 934
    Cited by:  Papers (21)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (504 KB)  

    As the frequency of operation increases, the poles of the Wien-bridge oscillator depart from the imaginary axis because of the frequency dependence of the amplifier gain. By properly shaping the magnitude and phase response of the amplifier, it is possible to keep the poles on the imaginary axis at much higher frequencies than is normally expected, thus extending the range of operation of the oscillator. Experimental results verify the vast improvement that is predicted. View full abstract»

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  • Controlled rounding arithmetics, for second-order direct-form digital filters, that eliminate all self-sustained oscillations

    Publication Year: 1981 , Page(s): 894 - 905
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1400 KB)  

    Quantization often allows a recursive second-order filter to oscillate even when the underlying linear model is absolutely stable and there is no external signal present to excite the filter. One of the significant innovative ideas recently introduced to combat this condition is "controlled rounding" which utilizes memory in the rounding decision process. Specifically, the selection at time (n+ 1) of the state variable of filter, x_(n+1) depends not only on the quantity to be rounded, but also on the two previous outputs of the rounding operation, x_n and x_{n-1} ; the latter two quantities are anyhow readily available at the time of decision. This paper gives controlled rounding arithmetics that suppress all selfsustained oscillations in all direct-form second-order filters for which the underlying ideal linear model is stable. Not just rounding but also overflow, and hence all the features that make a digital filter a finite state machine, are taken into account. The incremental cost of the hardware which is mostly on account of the additional logic is reckoned to be slight. View full abstract»

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