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Circuits, Devices and Systems, IEE Proceedings G

Issue 3 • Date Jun 1991

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Displaying Results 1 - 23 of 23
  • A systematic method for obtaining state equations using MNA

    Page(s): 341 - 346
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (312 KB)  

    Previously known methods of obtaining state and output equations were based on the graph theoretic approach. The formulation of circuit equations using modified nodal analysis (MNA) is straightforward and easy to implement in computer formulation. Even if paper and pencil methods are used, for simple circuits, the equations can be obtained by inspection. A simple and systematic method for obtaining state equations using the MNA approach is presented View full abstract»

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  • Thermal imaging of electronic devices with low surface emissivity

    Page(s): 390 - 400
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1092 KB)  

    The technique of thermal imaging uses an infrared scanning imager to map the surface temperature of electronic devices and circuits. Often unrealistic thermal distributions are found in thermal images after emissivity correction, particularly where there are areas of low emissivity on the surface being studied. The background principles of temperature measurement are described using this technique and the reason these inconsistencies and errors may arise in measurements on devices having low surface emissivities is explained. A method of dealing with this problem is suggested and some results of measurements on a gallium arsenide MESFET with a very low surface emissivity are presented. These measurements give some guidance and warnings about the accuracy of this method for measuring thermal resistance View full abstract»

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  • Design of partial response data transmission filters with specified stopband attenuation

    Page(s): 347 - 350
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (228 KB)  

    In the paper, a method for optimal design of class 1 partial response filters with low intersymbol interference (ISI) is described. The filter selectivity and stopband attenuation can be easily specified or controlled. It is shown that ISI can be reduced by introducing rolloff around the Nyquist frequency at the expense of a small increase in spectral inefficiency. Class 4 partial response signals are obtained by using class 1 partial response filters. Design examples are given to show that the design method is appropriate for applications View full abstract»

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  • Balanced high-speed residue number VLSI multiplier with error detection

    Page(s): 421 - 423
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (156 KB)  

    A balanced residue number VLSI multiplier is proposed which eliminates the extra delay for an unbalanced residue multiplier. The number of adding stages used in the VLSI multiplier is reduced from three to two. The authors also describe how redundant residue number system (RNS) properties can be used for error detection. These improvements allow a residue multiplier with a 48-72 bit dynamic range, to perform 3.3 M multiplication/s without pipelining or 10 M multiplication/s with pipelining View full abstract»

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  • Triac model for computer aided analysis and design

    Page(s): 430 - 431
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (128 KB)  

    A triac model using current and voltage sources is developed. The on-state characteristic is simulated with single series resistance. The reverse recovery time is defined by simple RC combination. The model is tested using PSPICE. The device presented can be fired by positive or by negative gate pulses View full abstract»

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  • Physically-based method for measuring the threshold voltage of MOSFETs

    Page(s): 351 - 357
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (364 KB)  

    A physically-based technique for measuring the threshold voltage of small geometry MOSFETs is presented. The new method, called the quasi-constant current (QCC) method, is based on the drain current equation in the subthreshold region. It defines the threshold voltage as the gate voltage required for surface band-bending of 2φF. Compared with some other commonly used methods, this technique has the advantages of better fitting accuracy in the subthreshold region, of extracting the threshold voltage, VTH, with a unique value based on a physical definition of the surface band-bending, and of being suitable for MOS devices over a wide range of voltage biases, device dimensions, and temperatures View full abstract»

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  • Use of common factors in numerical synthesis of RLC one ports

    Page(s): 427 - 429
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (136 KB)  

    Opening (short-circuiting) a series (parallel) resistor-capacitor or resistor-inductor subnetwork in an RLC network produces a common factor in the driving-point function. Synthesising the reduced network results in a set of initial element values for the original network. Coefficient matching and an iterative numerical technique then yield the actual element values View full abstract»

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  • Observation of multi-state negative differential conductivity in periodic delta-doped superlattice

    Page(s): 424 - 426
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (204 KB)  

    A novel multi-state S-shaped negative differential conductivity (NDC) δ-doped superlattice structure with long period (Zp =600 Å) is observed and investigated. The multi-state NDC originates from a sequential sub-avalanche multiplication in the superlattice periods. Three different GaAs superlattices, i.e. one-period, three-period, and nine-period δ(n+)-i-δ(p+ )-i δ-doped superlattices, were used. A different number of S-shaped NDCs are exhibited in each superlattice. An interesting hysteresis phenomenon was also apparent in the nine-period superlattice structure. It was attributed to the existence of heavy `trapped' holes View full abstract»

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  • Systematic method for the design of multiamplifier switched-capacitor FIR decimator circuits

    Page(s): 307 - 314
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (444 KB)  

    The authors present a systematic method for the design of multiamplifier switched-capacitor (SC) decimator circuits with finite impulse response (FIR) transfer functions. From a formal description of previously proposed architectures, a set of closed form equations are derived to determine the resulting capacitance values in the circuits as a function of the desired impulse response coefficients and signal handling capability. The systematic design of two multiamplifier FIR SC decimators is then illustrated considering the practical example of an application suitable for video signal processing View full abstract»

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  • Switching properties of polysilicon emitter transistor operating in saturation

    Page(s): 358 - 362
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (304 KB)  

    Saturation behaviour of a polysilicon emitter transistor is studied using the analysis of the most fundamental parameter, the saturation time constant, and correlated with the physical structure. The analysis takes into account the effect of the polysilicon/monosilicon interface in the emitter and n/n + type transition interface due to be buried layer diffusion in the collector. The effect of the polysilicon/monosilicon interface becomes crucial to the transistor behaviour at smaller emitter junction depths. The interface contributes to a significant amount of charge storage in the emitter region and is independent of charge storage in the collector region bounded by the n/n+ interface recombination velocity. The increase in saturation time constant because of charge storage in the emitter and collector regions should be taken into consideration in the design of BiCMOS VLSI circuits View full abstract»

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  • Performance analysis of a solar array under shadow condition

    Page(s): 301 - 306
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (364 KB)  

    The investigation deals with performance studies of a solar array consisting of two modules, each having 25 cells in series. The load characteristics of the array are studied experimentally and it is observed that, as the shadowed area increases, the overall performance of the array is significantly degraded. Theoretical analysis of such an array has also been carried out to explore the possible mechanisms responsible for array degradation. In the analysis, the authors consider an additional series resistance for the dark region, whereas earlier workers have overestimated the contribution of the dark region because they have always taken into account identical series resistances for the illuminated, as well as the dark, region. Simulation of the enhanced series resistance of the dark region in the present work has been done by the effective surface resistance of the emitter layer caused by a metallic grid, because of the biasing of the dark region by the illuminated area View full abstract»

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  • Extended Remez algorithms for filter amplitude and group delay approximation

    Page(s): 289 - 300
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (688 KB)  

    Various Remez-type algorithms for the computation of rational filter functions of a general form are proposed. They allow filter amplitude and group delay functions to be arbitrarily shaped and tapered. Such functions can be applied to predistort for undesirable effects in communication systems such as sinc (x), transmission line weighting or distortion due to nonideal components. High-order touch points are introduced as a generalisation of the concept of maximum flatness. They are used to trade off between the amplitude, group delay and passive sensitivity properties of a filter. The high-order touch points can be used directly to design a passive ladder prototype by an iterative algorithm View full abstract»

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  • Primitive operator digital filters

    Page(s): 401 - 412
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (708 KB)  

    The authors outline a design methodology for the realisation of digital filtering structures with significantly reduced numbers of elementary arithmetic operations. The directed acyclic graphs which result from the design algorithms completely describe the filter arithmetically and may be mapped directly onto hardware or software realisations. Vertex rearrangement, retiming and edge elimination techniques are presented which facilitate the generation of a logical graph with an efficient allocation of pipeline registers. An example of the technique is given for a bit-serial realisation employing a bit-level pipeline View full abstract»

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  • Design of digital differentiators satisfying prescribed specifications using optimisation techniques

    Page(s): 315 - 320
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (264 KB)  

    A procedure is described which can be used to design digital differentiators satisfying prescribed specifications. The procedure, which entails two distinct but similar methods, involves formulating the error between the practical and ideal digital differentiators as a quadratic function which can be readily minimised using standard optimisation algorithms or routines. The new methods are more efficient than methods based on the Remez algorithm, and the designs obtained are more precise or economical than designs based on the window method View full abstract»

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  • Modelling of three-port RF transformers

    Page(s): 325 - 328
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (232 KB)  

    A new model of a three-port transformer, with a ferrite core is presented. The transformer's operating frequency lies in the VHF and lower UHF range. The presented model is compatible with most common computer programs for network analysis and synthesis. A measurement method is given for model parameter extraction, including a discussion of stray elements and loss mechanisms. Application of the transformer model to a feedback amplifier with two stages, each with a ferrite transformer in its feedback network, proves the validity of the model View full abstract»

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  • Performance analysis of phase-locked loops in the frequency search mode of operation

    Page(s): 418 - 420
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (164 KB)  

    A method is proposed to evaluate the acquisition statistics of phase-locked loops in the frequency search mode of operation. The frequency sweep rate limit and the relevant statistical characteristics of a high-gain second-order phase-locked loop are given. Loop performance is optimised with respect to minimum acquisition time, and a suboptimum loop is reported View full abstract»

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  • Review of carrier injection in the silicon/silicon-dioxide system

    Page(s): 377 - 389
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (736 KB)  

    A variety of carrier injection mechanisms have been proposed for the silicon/silicon-dioxide system. The discussion primarily centres on injection phenomena observed in both VLSI and ULSI devices and the ability of the proposed models to fit experimental data. The basic physics of the carrier injection mechanisms is reviewed, including the energy band diagrams and the resulting gate currents due to carrier injection. Both the advantages as well as the limitations of these models are examined View full abstract»

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  • Design of 2-D linear phase variable recursive digital filters for parallel form implementation

    Page(s): 335 - 340
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (380 KB)  

    The magnitude and phase characteristics of digital filters are determined by the transfer function coefficients. These characteristics are often required to vary in real-time in the course of signal processing. This requirement can be achieved by filters with coefficients that are directly computable from the spectral parameters. Such filters are referred to as variable filters. An optimisation technique is proposed for the design of two-dimensional linear phase variable recursive digital filters using the parallel form. The variable coefficients are expressed as computable analytic functions of the spectral parameters defining the desired frequency response. Computer simulations show that the proposed approach can design an entire family of filters using just one variable filter structure. Examples are presented to illustrate the method View full abstract»

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  • Thermal simulation of transients in microwave devices

    Page(s): 329 - 334
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (460 KB)  

    The optimal design of solid state microwave power devices, taking thermal and electrical parameters into consideration is a complex subject requiring extensive use of numerical simulation tools. The authors address the problem of the thermal simulation of pulsed microwave solid state power sources designed to operate at a particular duty cycle. The electrical design dictates that the device be as small as possible, in conflict with the thermal criteria. The size of the device will increase with increasing duty cycle and the length of each power pulse it is required to handle. A significant factor is the amount of computing resource necessary to simulate the thermal transient for a sufficiently large number of duty cycles so that the device will reach its maximum working temperature. A solution to this problem is presented that requires the combination of one steady state, and one transient simulation, to predict the maximum working temperature for a given duty cycle and any pulse length. A particular hetero-junction bipolar transistor (HBT) operated under varying duty cycle is analysed as an example View full abstract»

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  • Improvement of the electrical properties of metal-SiO2-silicon capacitors by a preoxidation HF/ethanol clean of the substrate

    Page(s): 321 - 324
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (204 KB)  

    The influence of a HF-ethanol dip as the last preoxidation cleaning step in the fabrication of metal-thin insulator-silicon capacitors is investigated. The experimental procedure and main advantages of this cleaning step for the electrical properties such as breakdown characteristics, I/V characteristics and interface state density are presented View full abstract»

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  • Design of FIR equalisers by sharpening identical subfilters

    Page(s): 413 - 417
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (252 KB)  

    In the paper the design of FIR amplitude response equalisers employing the sharpening technique is proposed. These equalisers are useful in generating low-complexity FIR filters when applied in the prefilter-equaliser scheme. The authors also discuss the relationship between the sharpening of comb filters and well known interpolated FIR equalisers. A complete example is presented to illustrate the design procedure View full abstract»

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  • Current programmed control nonresonant coupled parallel resonant convertor

    Page(s): 372 - 376
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (240 KB)  

    In the nonresonant coupled parallel resonant convertor operated below unity gain, the inductor current at the switching points has a maximum value which is determined by the convertor gain and the output load. By switching transistors at predetermined inductor current levels, it is possible to regulate the output voltage due to output current and input voltage variations. The peak inductor current, which can be limited to desirable values, is regulated by the control circuit. By using nonresonant coupling in the output circuit, the maximum capacitor voltage is clamped to the output voltage level; thus, the convertor has low voltage stresses. In the paper, the authors introduce the analysis and design of this convertor. The performance characteristics of the convertor are also presented. Computer simulation results are used to verify the authors' theoretical work View full abstract»

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  • Comparison of computer-aided tuning algorithms applied to the amplitude response of passive analogue filters

    Page(s): 363 - 371
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (588 KB)  

    Computer aided filter tuning methods have been based on a sensitivity analysis of the network function of interest. Two tuning algorithms, one proposed by Antreich, Gleissner and Muller (1975) and one by Jobe (1979) were first compared using a Monte-Carlo type analysis of fifty different circuit simulations. The method proposed by Antreich et al. was found to be the more efficient. Two low-pass passive L /C elliptic filters were then tuned. The magnitude responses of these filters were particularly suited to the application of both algorithms. The results showed that both methods were capable of tuning the filters to within the specification using a maximum of three iterations or only eighteen measurements providing that the adjustable inductors were operating over an approximately linear portion of their inductance against turns characteristic View full abstract»

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