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Electronic Circuits and Systems, IEE Proceedings G

Issue 1 • Date February 1987

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Displaying Results 1 - 8 of 8
  • Sine-wave synthesis using walsh functions

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (561 KB)  

    An investigation of the synthesis of sine waves from a truncated series of Walsh waves of ascending sequency is described. Computer simulation of the model is carried out in establishing potential circuit performance. A prototype circuit has been built and tested to add validity to the theoretical results. View full abstract»

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  • Wide-band precision rectification

    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (944 KB)  

    Operational-amplifier supply-current sensing is employed in the design of high-performance precision rectification. The designs presented in this paper compare favourably with conventional precision rectifier circuits both in linearity and bandwidth, and are constructed from low supply bias-current operational amplifiers and current mirrors. Application of this new rectifying technique in the design of precision peak-detector circuits is also described. View full abstract»

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  • Single-fault diagnosis of nonlinear resistive networks

    Page(s): 16 - 22
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (844 KB)  

    The paper presents a simulation-aftertest algorithm for fault diagnosis of a nonlinear resistive network. Fault diagnosis equations are expressed in terms of a modified nodal description of the test network. The linear programming technique is used to obtain different solutions of these equations. It is assumed that the maximum number of simultaneous faults in the circuit is bounded. This enables us to apply logical analysis to these solutions and to obtain the diagnosis problem solution. In addition, theoretical conditions under which a faulty element can be located uniquely are discussed. Several numerical examples are given to illustrate the implementation of these algorithms. View full abstract»

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  • Analysis of filter bank transfer functions

    Page(s): 23 - 30
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1020 KB)  

    Parallel filter banks are used for realtime signal analysis, e.g. spectrum or speech analysis. The problem to be solved in filter bank realisation is to achieve as high selectivity of individual filters as possible and simultaneously meet the amplitude and phase characteristic specification of the bank. A design method for a bank of analogue filters is presented in the paper. An algorithm for the analysis of the amplitude, phase and group delay characteristics of the bank is given. The applicability of various types of transfer function (Bessel, Scanlan, Coung-Neirynck, Butterworth and Cheby¿chev linear phase approximation) is investigated. To study the other possibilities of realising a filter bank, the so-called modified Scanlan filter has been formed by applying an automated optimisation procedure. This filter retains the performance of the Scanlan filter, but the Q factor of the critical pole pair is reduced. The examples of uniform and constant percentage bandwidth filter banks are presented to illustrate the comparative characteristics of filter banks designed on the basis of these six approximations with 12th-order filters. View full abstract»

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  • Oscillators with amplitude control by restoration of capacitor initial conditions

    Page(s): 31 - 37
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (805 KB)  

    The paper describes oscillators where the amplitude is controlled by the restoration of initial conditions at the energy storage elements. If these elements are capacitors, the control circuit includes a window comparator, a polarity comparator, an AND gate, a switch and a source of reference voltage. This control circuit momentarily connects (each oscillation period) the oscillator capacitor to the source of reference voltage at the instant when energy in another storage element (a capacitor or an inductor) is absent. If the reference voltage is modulated, the new value of the oscillation amplitude is established without an amplitude transient in the oscillators with two energy storage elements (with a possible delay of up to one oscillation period). The oscillators with more than two storage elements will have an amplitude transient which can be calculated period by period. In steady-state oscillations the output voltage wave is the repetition of a damped sinusoid (with the addition of small exponential components in the oscillators with three and more energy storage elements). The wave shape is calculated in the closed form and its harmonic content can be established. The experimental waveforms (steady state and amplitude transients) are given for the Wien-bridge and twin-T bridge RC-oscillators. View full abstract»

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  • Minimax design of one-dimensional recursive digital filters of a given approximation type: a closed form approach

    Page(s): 38 - 44
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (681 KB)  

    Minimax design of 1-dimensional recursive digital filters is currently achieved by using iterative methods based on linear or nonlinear programming. The methods need extensive computation and their convergence cannot be always guaranteed. Recently Charalambous developed a closed form approach for designing minimax elliptic filters. In the present paper, the Charalambous approach is extended into developing a closed form approach for designing 1-dimensional recursive minimax digital filters of any given approximation type satisfying prescribed specifications. The amount of computation needed by the new approach is insignificant. A general-purpose computer program has also been developed that embodies the classical and minimax Butterworth, Cheby¿chev and elliptic approximations. View full abstract»

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  • Simplified analysis off arbitrary switched-capacitor networks

    Page(s): 45 - 53
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1384 KB)  

    A general method is presented which allows a closed-form analysis of switchedcapacitor (SC) networks with several phases, arbitrary duty cycles and with nonideal operational amplifiers. The method is based on a new equivalent representation of SC networks in the zdomain and on flow-graph techniques. The equivalent z-domain representations of SC networks proposed in this paper are compatible with classical circuit-theory considerations, and they are simpler and require a smaller number of elements than the equivalent circuits previously proposed. The usefulness and efficiency of the method proposed is illustrated with some examples. Moreover, it is shown how to transform the z-domain SC networks into equivalent time-continuous (analogue) circuits to analyse them in the frequency and/or time domain by use of conventional general-purpose circuit simulation programs. A user-ready implementation on SPICE is also proposed. View full abstract»

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