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Circuits, Devices and Systems, IEE Proceedings G

Issue 6 • Date Dec 1989

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Displaying Results 1 - 12 of 12
  • Generalised model for GaAs MESFET photodetectors

    Publication Year: 1989 , Page(s): 337 - 343
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (492 KB)  

    The gallium-arsenide MESFET as a ps light-pulse detector has created an environment whereby it is now possible to interface optical fibres and high-speed GaAs analogue-digital circuitry in optical communication links. High switching speed and low operating voltage, together with the optoisolation characteristics of GaAs MESFETs, have resulted in considerable research into uncovering some of the principles that govern the optical characteristics of the GaAs D-MESFET as a photodetector. During the last few years various mechanisms for the photoresponse of MESFETs have been proposed. However, there remains considerable controversy with regard to the mode of operation of the MESFET as an optical detector. In this paper an effort is made to explain the various experimental conditions that resulted in the different conclusions, and subsequently a more complete model is proposed which describes the various modes of operation and provides the basis for comparison between the various proposals. View full abstract»

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  • Method for determination of parasitic resistances in microwave power MESFETs

    Publication Year: 1989 , Page(s): 358 - 360
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (148 KB)  

    A novel method of determining the source and drain series parasitic resistances of the MESFET is presented. This method is particularly suited to power devices since it eliminates the necessity to operate the Schottky gate with high forward bias. In addition, the values of parasitic resistances extracted from low-frequency measurements are confirmed at microwave frequencies. View full abstract»

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  • Modelling of crosstalk among the GaAs-based VLSI interconnections

    Publication Year: 1989 , Page(s): 361 - 368
    Cited by:  Papers (10)  |  Patents (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (380 KB)  

    The authors have developed a computer-efficient model and carried out computer simulations of the crosstalk effects in single, bi- and trilevel high-density interconnections on GaAs-based VHSIC. The self and coupling interconnection capacitances used in the model have been determined by a network analogue method developed for finite-length interconnections, open substrates and finite dimensions of the bottom ground plane, as well as by the method of moments in conjunction with a Green's function appropriate for the geometry of the interconnections. Related software modules have been developed and run successfully on mainframe computers. For a given set of the interconnection dimensions and other parameters, the algorithm takes less than 5 minutes of computer processing time on a mainframe computer. The modules have been used to study the dependence of the crosstalk voltage on the interconnection dimensions such as their lengths, widths, separations and the interlevel distances. View full abstract»

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  • SPICE simulation of latch-up anomalous effects observed by electrical measurements and IR microscopy

    Publication Year: 1989 , Page(s): 293 - 300
    Cited by:  Patents (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (452 KB)  

    Pulsed overvoltage tests have identified anomalies in the electrical characteristics of latch-up in CMOS ICs and 'window' effects, while infra-red (IR) microscopy revealed that latch-up current switching is due to competition between different latch-up paths. The SPICE simulation of a simple, lumped, equivalent circuit model, comprising two or more parasitic structures, allows anomalous effects to be produced and helps in the understanding of latch-up triggering mechanisms. Parasitic bipolar transistors connected to the I/O structure, not involved in latch-up in steady-state, are shown to play a major role in latch-up triggering and in causing anomalous effects. View full abstract»

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  • High-performance filter networks and symmetric matrix systems

    Publication Year: 1989 , Page(s): 327 - 336
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (548 KB)  

    A unified investigation is presented for low-sensitivity and limit-cycle-free filter structures. It is shown that important properties like boundedness and pseudopassivity are closely related to the symmetry of the system matrix description. Negative elements can be incorporated in certain prototypes leading to real advantages in switched-capacitor (SC) realisations. Stability and noise problems are also discussed. According to the realisation, component variations can result in matrix symmetry being maintained, or more generally, in the introduction of asymmetry. Sensitivity considerations are outlined for both situations. Implementation by passive RLC, SC and digital circuits are considered. View full abstract»

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  • On the design of optimal switched-capacitor filters based on the use of lossy frequency-dependent negative-resistance prototype structures

    Publication Year: 1989 , Page(s): 351 - 357
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (484 KB)  

    The authors introduce a new relatively stray-insensitive switched-capacitor filter (SCF) based on lossy frequency-dependent negative-resistance (FDNR) structures. The filter is derived by use of the lossless discrete integrator (LDI) and the backward-difference analogue-discrete (s-z) frequency transformations. An optimisation technique is used both to eliminate the distortion of the frequency response caused by the s-z transformations, and to deal with total capacitance minimisation-an important practical problem. The importance of these filter structures include their relative economy in realisation, leading to relatively low silicon utilisation compared with most standard SCF design techniques, and their very low sensitivity to parasitic capacitances. View full abstract»

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  • Spectrum of a nonlinearly quantised sinusoid (ADC)

    Publication Year: 1989 , Page(s): 313 - 316
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (216 KB)  

    A simple approach is proposed for obtaining analytical expressions for the harmonic distortion resulting from nonlinear quantisation of a single sinusoid using an actual analogue-digital convertor exhibiting nonlinearity error. The actual-digital converter characteristic is split into two nonlinear characteristics; the first represents the nonlinearity error and the second represents the quantisation. Whereas the nonlinearity error characteristics is modelled by a third-order polynomial, the quantisation is modelled by an ideal staircase. Series expressions are obtained for the output spectra of an actual analogue-digital convertor excited by a single sinusoid. Special cases are considered where the series expressions can be reduced to simple analytical expressions. Also, the feasibility of minimising the total harmonic distortion is explored. View full abstract»

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  • The least complex parallel Massey-Omura multiplier and its LCA and VLSI designs

    Publication Year: 1989 , Page(s): 345 - 349
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (288 KB)  

    It is known that for m>or=4 there is more than one irreducible polynomial which generates a GF(2m) represented in normal basis. Therefore, a parallel Massey-Omura multiplier in GF(2m) has more than one structure for m>or=4. The number of these structures is equal to the number of irreducible polynomials which can generate that specific Galois field in a normal-basis representation. In this paper, as an illustrative example, the structure of GF(25) multipliers for different generator polynomials are compared. Based on this comparison, the least complex structure for this multiplier is introduced. The implementation of this structure using LCA (logic cell array) and VLSI (very large scale integration) technologies is given. Their complexities and propagation delays are compared. View full abstract»

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  • Multidimensional continued fraction inversion

    Publication Year: 1989 , Page(s): 307 - 312
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (248 KB)  

    A computationally simple algorithm for the inversion of multidimensional continued fraction expansions (mDCFE) is presented. The approach is based on the interpretation of an mDCFE as a driving-point admittance. To facilitate the inversion procedure a cyclic function Ti(z1, z2, . . , zm) is introduced. Several examples are given for inverting 3-D and 4-D systems to illustrate the efficiency of the algorithm. View full abstract»

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  • Multidimensional ellipsoidally and spherically symmetric recursive digital-filter design with reduced number of optimised coefficients

    Publication Year: 1989 , Page(s): 301 - 305
    Cited by:  Patents (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (332 KB)  

    A method for the design of multidimensional ellipsoidally and spherically symmetric recursive digital filters using one-dimensional analogue filters is presented. The number of coefficients required to be optimised is very much reduced and the stability of the resultant filter can be guaranteed. This method is suitable for the design of moderately precise digital filters. View full abstract»

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  • Current conveyors, operational amplifiers and ors

    Publication Year: 1989 , Page(s): 317 - 322
    Cited by:  Papers (4)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (376 KB)  

    Nullors are used to provide a common framework for considering both current-conveyor and operational-amplifier circuits. A condition is established under which a current-conveyor circuit an an op-amp circuit can be said to be equivalent. A procedure is given for generating equivalent op-amp and current-conveyor circuits from a given op-amp (current-conveyor) circuit. View full abstract»

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  • Harmonic and intermodulation generation due to hot electrons in semiconductors

    Publication Year: 1989 , Page(s): 323 - 326
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (184 KB)  

    An exponential equation describing the nonlinear velocity-field relationship in a semiconductor is presented. Using this equation, closed-form expressions are obtained for the harmonics and intermodulation products generated due to hot electrons in semiconductors. View full abstract»

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