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Circuits and Systems I: Fundamental Theory and Applications, IEEE Transactions on

Issue 4 • Date Apr 1992

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Displaying Results 1 - 13 of 13
  • Transmission-line models for the modified Schur algorithm

    Publication Year: 1992 , Page(s): 290 - 296
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (648 KB)  

    Transmission-line models for the modified Schur algorithm that handles functions that are bounded on the unit circle and have a finite number of poles inside the unit disc are presented. The first application of these models is the physical interpretation of procedures for root distribution with respect to the unit circle: for every polynomial p(z), the transmission-line model for the all-pass p#(z)/p(z) has a special structure from which the number of stable and unstable zeros can be calculated by inspection. Three other applications are to problems from analytic function theory and linear algebra: the matching of Taylor coefficients; the factorization of certain indefinite Hermitian matrices; and the Schur-Takagi extension problem. It is shown that these three problems can be solved using the transmission-line models and their physical properties such as causality and energy conservation View full abstract»

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  • Simple CMOS analog square-rooting and squaring circuits

    Publication Year: 1992 , Page(s): 312 - 315
    Cited by:  Papers (15)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (292 KB)  

    Two closely related CMOS circuits are described. In the first circuit, the input signal is a current, and the output is a voltage proportional to the square root of input current. In the second circuit, the input is a voltage, and the output is the current proportional to the square of the input voltage. Each circuit includes an operational amplifier and two nested transistors. One of these transistors is in pinch-off, the other in the triode region of operation. The transistor mismatch and the effect of the amplifier offset are evaluated. The experimental data are provided View full abstract»

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  • A fast algorithm for evaluating the matrix polynomial I+ A+. . .+AN-1

    Publication Year: 1992 , Page(s): 299 - 300
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (164 KB)  

    D. Westreich (ibid., vol.36, no.1, p.162-4, 1989) gave a practical algorithm for the evaluation of the matrix polynomial I+A +A2+. . .+AN-1, which requires at most 3 log2N matrix multiplications. The authors present a new method, which only requires at most 2[log2 N]-1 matrix multiplications. The listing of a BASIC program is given View full abstract»

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  • z-domain synthesis of discrete-time reactance functions

    Publication Year: 1992 , Page(s): 316 - 324
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (536 KB)  

    Discrete-time images of lossless LC one-port ladder networks are presented. Such images are obtained by expanding discrete-time reactance functions into z-domain continued fractions to obtain the discrete-time counterparts of Cauer-1, Cauer-2, and mixed-Cauer expansions. A methodology for synthesis of discrete-time reactance functions similar to the one known for the synthesis of a continuous-time reactance function in the s-domain is presented. The type of reactance functions used is related to the continuous-time counterpart by the lossless-discrete-integrator (LDI) s-to-z transform. Simple first- and second-order discrete-time reactance networks using delay elements, multipliers, and adders are proposed and used in a step-by-step procedure to realize higher-order networks. The methodology is valid for any discrete-time reactance function using any of the three z-domain Cauer expansions, giving rise to three different ladder structures. An algorithm for the computer implementation of the synthesis procedure is developed and a BASIC listing is given View full abstract»

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  • Shrinking stability regions and voltage collapse in power systems

    Publication Year: 1992 , Page(s): 271 - 289
    Cited by:  Papers (26)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1552 KB)  

    The dynamic process of voltage collapse is analyzed based on three mechanisms: on-load tap-changing, load dynamics, and generator excitation limiting. The interaction among these mechanisms and how the voltage collapse takes place are thoroughly investigated in a general interconnected network model under the assumption that system frequency remains unchanged. It is found that, so long as an equilibrium exists, there is a maximal equilibrium. It is also established that there is a region in the state space corresponding to a monotonic fall of system voltages. When the reactive capability of generator(s) is reached, this region expands, whereas the voltage stability region shrinks. The system trajectory may eventually exit the stability region, whereupon the voltage begins to drop monotonically. It is shown that locking the tap-changers at an appropriate time helps the system voltage to reach a steady state, and therefore avoid the collapse. Numerical examples for a realistic power system are given to illustrate the theory View full abstract»

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  • IIR double-sampled switched-capacitor decimators for high-frequency applications

    Publication Year: 1992 , Page(s): 300 - 304
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (364 KB)  

    The possibility of implementing the double-sampling (DS) techinque in infinite impulse response (IIR) first- and second-order switched-capacitor (SC) decimators is considered. The DS-SC circuits that result are designed using the same procedure as standard IIR decimators, and only a different SC implementation results with a reorganized clock phasing. The main advantage is that the time allowed for the op-amps to settle can be equal to the output sampling period rather than one half of it. Using the proposed DS decimators allows the design of high-frequency SC filtering systems (an antialiasing SC decimator filter and a `core' DS-SC filter) where the op-amp speed requirements are the same in each block View full abstract»

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  • A chaotic switched-capacitor circuit for 1/f noise generation

    Publication Year: 1992 , Page(s): 325 - 328
    Cited by:  Papers (7)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (220 KB)  

    A switched-capacitor circuit is reported for the generation of 1/ fy noise. The circuit is described by a chaotic first-order piecewise-linear discrete map which yields a hopping transition between regions of chaotic motions, and hence produces 1/fy noise. Experimental results form a parasitics-insensitive prototype are included, demonstrating the circuit performance View full abstract»

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  • On the equivalence of digital all-pass and analog reactance functions

    Publication Year: 1992 , Page(s): 304 - 305
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (156 KB)  

    Frequency transformations for continuous- and discrete-time systems are derived based on the classical work of F.M. Reza (1958). Using Reza's multiplication theorem, it is shown that the analog counterpart of a digital all-pass function is a reactance function View full abstract»

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  • An novel treatment of robust stability of continuous-time systems

    Publication Year: 1992 , Page(s): 309 - 312
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (356 KB)  

    The four-vertices concept of Kharitonov's theorem is one of the most important results in the area of robust stability of linear time-invariant continuous-time systems. If the coefficients of the characteristic polynomial of a given system are dependent, the vertex concept cannot be applied in general. If the coefficients are linearly dependent, various results can be achieved. The case where the coefficients are partly dependent is considered, and more general vertex theorems on robust stability are given where the set considered in the coefficient space does not need to be convex. The notion of the vertex polynomial is generalized. The results are based on a modified Hermite-Biehler theorem, which presents an irredundant characterization of a reactance function. A new geometrical interpretation of stability conditions is also given. Further results are presented for low-order polynomials View full abstract»

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  • The effects of lower Q values on the filters having equal ripples in passband

    Publication Year: 1992 , Page(s): 305 - 309
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (332 KB)  

    In cascade realization of active RC, switched-capacitor, and OTA filters, it is desirable to have lower Q values of the pole pairs. The author compares various Q-reducing methods in the design of filters having equal ripples in passband. Two examples are provided to quantitatively illustrate the relative merits of each method in time domain as well as frequency domain View full abstract»

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  • Noise in active resonators and the available dynamic range

    Publication Year: 1992 , Page(s): 296 - 299
    Cited by:  Papers (36)  |  Patents (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (356 KB)  

    Active resonators used to make bandpass filters are shown to suffer from a fundamental deterioration in available dynamic range with increasing Q, which is shown to arise from the dissipation in the transistors simulating inductance or performing an equivalent function. An active resonator with Q>1 may only attain a specified dynamic range with the use of a larger tuning capacitance than its passive counterpart, and with a consequent larger lower dissipation at a given frequency of operation. This poses a serious limitation on the integrated circuit realization of high-frequency filters with high- Q poles View full abstract»

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  • Effect of sinusoidal excitation on the Chua's circuit

    Publication Year: 1992 , Page(s): 264 - 270
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1064 KB)  

    The authors examine the effect of an external periodic excitation on the Chua's piecewise-linear circuit. Under the action of such a force this circuit exhibits a large variety of bifurcation sequences, including period-doubling, period-adding, and windows in the chaos regime. In addition, at certain parameters equal periodic bifurcations, hysteresis, quasi-periodic, and intermittent behavior and coexistence of multiple attractors have also been observed. A bifurcation diagram that classifies the attractors in the forcing parameters plane is presented View full abstract»

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  • A general class of current amplifier-based biquadratic filter circuits

    Publication Year: 1992 , Page(s): 257 - 263
    Cited by:  Papers (29)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (564 KB)  

    A general class of current amplifier-based biquadratic filter circuits capable of realizing arbitrary filter functions including the low-pass, high-pass, and bandpass transfer functions is presented. These realizations are derived from a class of well-known low sensitivity single amplifier biquadratic (SAB) filter circuits using the principle of adjoint networks. The salient features of the proposed circuits are that they are synthesized using the same procedure as their op-amp-based SAB circuit counterparts, and they possess the same sensitivities to component variations as the original SAB circuits. However, it is demonstrated experimentally that unlike op-amp-based SAB realizations whose effective operating bandwidth is much less than the unity-gain bandwidth of the op-amp, these current-based filter circuits are effective over the entire bandwidth of the current amplifier View full abstract»

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