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

Issue 6 • Date Jun 1995

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Displaying Results 1 - 14 of 14
  • Enhanced current dumping

    Publication Year: 1995 , Page(s): 314 - 320
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (516 KB)  

    A method is proposed for improving the performance of current dumping audio amplifiers that allows an increase in the distortion rejection ratio and (or) desensitizes the circuit balance condition. The distortion reduction properties of the existing topologies are reviewed. A novel approach is outlined and extended to show a prototype amplifier circuit in detail. The design is supported by a range of simulations and measurements to validate the technique View full abstract»

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  • Linear modulators based on RF synthesis: realization and analysis

    Publication Year: 1995 , Page(s): 321 - 333
    Cited by:  Papers (8)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (788 KB)  

    A technique for generating a gain and phase modulated high power radio signal is described using RF synthesis. The realization, which uses a unique twin VCO design, can give a theoretical near 100% amplifier efficiency with excellent linearity. A number of architectures are presented supported by both analytical and simulation results. Laboratory tests have verified the predicted performance for π/4 QPSK modulation View full abstract»

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  • Optimal capacitance assignment of switched-capacitor biquads

    Publication Year: 1995 , Page(s): 334 - 342
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (648 KB)  

    An algorithm is presented for the optimal capacitance assignment of conventional switched-capacitor biquads. It maximizes the dynamic range and minimizes the total capacitance simultaneously, with results presented in analytical forms. This is made possible by the development of a canonical representation of second-order transfer functions in the z-domain, which gives simple relations among three sets of parameters: (1) the pole-and zero-frequencies, and pole- and zero-Q's of the s-domain prototype; (2) the key parameters of the bilinear-transformed z-domain transfer function; and (3) the capacitance ratios of the final switched-capacitor realization. Analytical results are derived and compared with those from using existing assignment techniques. This shows a reduction of 12% in total capacitance for some biquads. An extension of the algorithm to very large time-constant biquads is also discussed; the improvement is even larger for these circuits View full abstract»

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  • An RRI-RRO unity-gain buffer

    Publication Year: 1995 , Page(s): 369 - 370
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (240 KB)  

    A linear, noninverting unity-gain buffer with both rail-to-rail input and rail-to-rail output (RRI-RRO) features is proposed and verified through simulation. The circuit is composed of a rail-to-rail operational amplifier and two identical nonlinear circuits connected in a direct function-inverse function configuration View full abstract»

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  • Characterization and design of GaAs SCFL latched comparators based on improved linearized models

    Publication Year: 1995 , Page(s): 362 - 365
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (440 KB)  

    This brief presents characterization and design considerations of high-speed and high-precision GaAs latched comparators consisting of source coupled FET logic (SCFL) flip flops. In order to characterize the comparators, linearized equivalent circuit models are improved for the SCFL flip flops. Based on the models, critical design parameters such as recovery time, regeneration time and input voltage sensitivity are determined for the comparators. Circuit configurations for increasing circuit speed and accuracy are characterized and compared. One comparator is optimized and implemented in a 0.5 μm GaAs E/D HEMT technology. Measurement results demonstrate the implemented comparator achieves an average voltage sensitivity of 11.5 mV at low frequencies and an optimal voltage sensitivity of 10.0 mV at an input signal frequency of 2 GHz and a clock frequency of 4 GHz. Predicted voltage sensitivities are also verified to be in good agreement with the measured results View full abstract»

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  • Is the Colpitts oscillator a relative of Chua's circuit?

    Publication Year: 1995 , Page(s): 373 - 376
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (336 KB)  

    The topological resemblance of the Colpitts oscillator to that of Chua's circuit suggests that the two circuits may also be similar in their dynamic behavior. The similarity in the dynamics is demonstrated in the present communication by resorting to computer simulation. We deal in particular with the unknown chaotic behavior of the Colpitts oscillator. It is shown by referring to recently published articles that the Colpitts oscillator and Chua's circuit are in fact topologically conjugate one to another View full abstract»

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  • Controlling spatiotemporal chaos in a chain of the coupled logistic maps

    Publication Year: 1995 , Page(s): 352 - 357
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (456 KB)  

    A method of controlling spatiotemporal chaos in a chain of the logistic maps, based on the Ott, Grebogi, Yorke (OGY) approach, is proposed in the paper. Forms of spatiotemporal disturbances of a system parameter are determined analytically to stabilize desired spatiotemporal states. The results are illustrated by numerical experiments. Transitions of the system under control from the regime of spatiotemporal chaos to the regular homogeneous regime with temporal period one, two, four, and also to more complicated regular regimes with different spatial and temporal periods have been demonstrated View full abstract»

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  • Analysis of a three-layered piezoelectric ceramic transformer filter

    Publication Year: 1995 , Page(s): 307 - 313
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (544 KB)  

    A transformer filter is fabricated with three piezoelectric ceramic disk transducers and two sheets of thin insulator. Its equivalent circuit is derived from the Mason's model of a thickness-driven piezoelectric transducer. The electric input near its fundamental resonance frequency is applied to the center transducer and the output voltages across the left and right transducers are connected in parallel or in series to the resistor load. The load characteristics at resonance frequencies under various resistor loads and the frequency characteristics near the resonance frequency under no load have been investigated. Moreover, symbolic expressions for input impedances, voltage ratios, resonance frequencies, phase angles between the input and output voltages, and bandwidths have been derived. The values calculated from those symbolic expressions are shown to agree well with the measurement values View full abstract»

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  • Nonpositive Hopfield networks for unidirectional error correcting coding

    Publication Year: 1995 , Page(s): 293 - 306
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1304 KB)  

    We consider a class of symmetric Hopfield networks, with nonpositive synapses and zero thresholds. We call such networks Nonpositive Hopfield networks and address a variety of design and analysis issues connected with their application to a specific form of Error Correcting Coding. In particular we show that this class is naturally suited to work in a unidirectional error environment and hence can find application in unidirectional error correcting coding. We give a necessary and sufficient condition for a set of codewords to be storable in a Nonpositive network. We propose a simple word storage algorithm, which is amenable to on line implementation, and guarantees storage of all storage compatible words. We show that the storage algorithm creates a network that is fundamentally maximally tolerant to physical faults and is free from spurious stationary points, whenever that freedom is available. We also give a word forgetting algorithm; a tight, deterministic bound on the storage capacity, and conditions under which the network created by our storage scheme tolerates a given number of arbitrary physical faults View full abstract»

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  • Controlling chaos in the modified oscillator with inertial nonlinearity

    Publication Year: 1995 , Page(s): 366 - 368
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (232 KB)  

    In this brief, the possibility of effective control of chaos in electronic autonomous auto-oscillatory system-the modified oscillator with inertial nonlinearity (MOIN)-is investigated by numerical simulation. Controlling chaos in the MOIN is achieved by means of the external forcing and the additional linear oscillator View full abstract»

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  • Sensitivity to errors in artificial neural networks: a behavioral approach

    Publication Year: 1995 , Page(s): 358 - 361
    Cited by:  Papers (21)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (380 KB)  

    The problem of sensitivity to errors in artificial neural networks is discussed here considering an abstract model of the network and the errors that can affect a neuron's computation. Feed-forward multilayered networks are considered; the performance taken into account with respect to error sensitivity is their classification capacity. The final aim is evaluation of the probability that a single neuron's error will affect both its own classification capacity and that of the whole network. A geometrical representation of the neural computation is adopted as the basis for such evaluation. Probability of error propagation is evaluated with respect to the single neuron's output as well as to the complete network's output. The information derived is used to evaluate, for a specific digital network architecture, the most critical sections of the implementation as far as reliability is concerned and thus to point out candidates for ad-hoc fault-tolerance policies View full abstract»

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  • Fixed points incompatibility in neural networks with local interactions

    Publication Year: 1995 , Page(s): 371 - 373
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (244 KB)  

    Two conditions of incompatibility between fixed points are proved, which hold for a wide class of discrete-time, discrete-state, nonlinear neural networks with local interactions and no self-feedback. These conditions, which can be checked easily by inspection, can be stated briefly as follows: Let the network be defined on a two-dimensional array. A pair of states cannot both be fixed points of the network dynamics if: (1) in the neighborhood of a different component, there is no other different component; and (2) in the neighborhood of an equal component, there is no other equal component View full abstract»

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  • On the compensation of the (sin x)/x distortion in discrete-time to continuous-time signal conversions

    Publication Year: 1995 , Page(s): 343 - 351
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (700 KB)  

    Discrete-time to continuous-time signal conversions introduce the well known (sin x)/x spectral distortion. This paper presents an analytical methodology which adjusts the Q-factors and/or the pole magnitudes of the system to compensate the distortion. From this methodology three compensation methods are derived. Each method establishes a distinct tradeoff between precision and computational effort. The compensation techniques are very simple to implement and do not modify the order of the uncompensated system. The initial formulation is extended to include the compensation of z-domain transfer functions. Examples and comparisons demonstrate the effectiveness and applicability of the proposed methodology View full abstract»

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  • On the relationship between the chaotic Colpitts oscillator and Chua's oscillator

    Publication Year: 1995 , Page(s): 376 - 379
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (272 KB)  

    In this letter, we show that the two-region third-order piecewise-linear dynamics of the chaotic Colpitts oscillator may be mapped to a Chua's oscillator with an asymmetric nonlinearity View full abstract»

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