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Circuits, Devices and Systems, IEE Proceedings -

Issue 4 • Date Aug 1994

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Displaying Results 1 - 12 of 12
  • Overview of SPICE-like circuit simulation algorithms

    Page(s): 242 - 250
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (644 KB)  

    A tutorially orientated account of the principles underlying circuit level simulation forms the basis for discussing reliability of circuit level simulation. An outline of equation formulation and time discretisation of the equations is followed by consideration of stability of the numerical integration methods. The precision of simulation, which also depends on the integration methods used, is then discussed, with particular reference to the analysis parameters of the SPICE simulator. A descriptive account of the Newton-Raphson method of solving the nonlinear algebraic equations, derived from the discretised differential equations, is then presented again with relation to SPICE parameters. The reasons for convergence failure in both transient and DC simulation are related to the underlying principles of simulation and possible ill conditioning of the circuit. The paper includes some simple simulation examples of problematic situations View full abstract»

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  • New high accuracy pulse width modulation based digital-to-analogue convertor/power amplifier

    Page(s): 315 - 324
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (652 KB)  

    A new high accuracy pulse width modulation based digital-to-analogue convertor is presented. It is suitable for high power applications as well as ordinary low power use. While possessing important advantages, previously proposed convertors of this type have been difficult to realise in hardware and/or have exhibited high distortion. In this paper, digital signal processing (DSP) techniques are used to facilitate hardware implementation and increase performance. Specially designed oversampled noise shaping networks allow reductions in internal modulator clock speed large enough to make a 16 bit quality implementation possible. Also, new premodulation, predistortion DSP algorithms of varying complexity and accuracy are employed to reduce the harmonic distortion inherent to the modulation process typically used. Computer simulations are presented to verify the improvements View full abstract»

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  • Implementing high-order continuity and rate dependence in SPICE models

    Page(s): 251 - 257
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (456 KB)  

    Two proposed techniques simplify and improve the implementation of SPICE device models. The first technique uses nested transformation of node potentials. It avoids the discontinuity in high-order derivatives that is typical of implementations that use conditional functions. This provides the smooth mathematical form distortion and intermodulation improves simulator convergence. The second technique uses state variables to implement descriptions of rate dependent and thermal transient behaviour. This simplifies model implementation by eliminating the need for extra circuit nodes. The paper demonstrates the proposed techniques by describing the implementation of an advanced MESFET model. The techniques will provide models that can simulate the intermodulation and transient behaviour of high-performance communication and signal processing circuits View full abstract»

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  • Large signal periodic time-domain circuit simulation

    Page(s): 285 - 291
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (496 KB)  

    A novel time-domain algorithm has been applied in the field of circuit analysis to model large signal effects under periodic excitation. Conventionally, the need to integrate out initial transients over many cycles had effectively made time-domain simulation impractical. The new algorithm, however, neatly avoids this problem, yielding the periodic steady state directly by simulating over just one cycle. A prototype simulator has been written that implements the algorithm within a circuit context, and it has been used in a preliminary study of large signal harmonic effects in both driven and autonomous circuits. In particular, the following circuits are analysed: a single-stage transistor amplifier, a varicap tuner, a full wave rectifier and a Colpitts oscillator. The nonlinear effect of jump resonance is observed in the varicap tuner circuit. An extension of the basic algorithm beyond harmonic analysis into the realms of mixers and other possibly noncommensurate frequency circuits is proposed. Possibilities regarding mixed-mode circuit/device simulation are also discussed View full abstract»

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  • Effects of the sampling pulse width on the frequency characteristics of a sample-and-hold circuit

    Page(s): 328 - 336
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (448 KB)  

    Frequency characteristics, especially at high frequency, are important in applications such as sample-and-hold circuits for LCD driver ICs where the required signal bandwidth is much wider than the Nyquist rate. The frequency characteristics of a sample-and-hold circuit using analogue switches have hitherto been estimated from the frequency characteristics of a simple RC circuit comprising a storage capacitor and the on-resistance of the analogue switch. However, the effects of sampling pulse width and storage capacitor resetting are not taken into account. By giving an exact frequency-domain analysis of sample-and-hold circuits, the paper clarifies the limitations of conventional RC estimates. It also reveals the effects of storage capacitor resetting. A narrower pulse causes more ripples in the frequency characteristics. Storage capacitor resetting alleviates these ripples although the DC gain deteriorates for a narrow sampling pulse. This analysis was verified by simple experiments. A design for an LCD driver IC is also described as an application example View full abstract»

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  • Recombination and Joule heating effects in GTO thyristors with spatially varying lifetimes

    Page(s): 292 - 298
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (416 KB)  

    In the paper the forward conduction characteristics of the GTO thyristor are studied. A two-dimensional simulation is performed which solves the semiconductor device equations self consistently with the equation for lattice heat conduction. The significance of the different recombination mechanisms and spatially varying lifetime is considered, along with the relative effects of different mobility models. An experimental comparison with a 2.5 kV device is made and good agreement is found. The effects of heat dissipation in the structure are also considered View full abstract»

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  • Efficient partitioning-based method to determine the upper bound on the number of operating points in transistor circuits

    Page(s): 258 - 264
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (396 KB)  

    An efficient method to assess the upper bound on the number of DC solutions is presented. It decomposes the original circuit into successive subcircuits by implementing a partitioning procedure, which is based on a topological analysis of the circuit. In a further step the uniqueness of the DC operating point is determined, and how many operating points can occur. Because the obtained subcircuits contain fewer nonlinearities, this process can be carried out in an efficient manner, resulting in a significant saving in the number of calculations. In addition, the circuit is described by a linear transformation of the well known MNA representation. This allows the method to be easily implemented in a simulation environment View full abstract»

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  • MOS analogue circuit simulation with SPICE

    Page(s): 265 - 274
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (620 KB)  

    The paper describes implementation details and imperfections of the SPICE MOSFET models which, together with MOS circuit design techniques, can contribute to inaccurate simulation results and convergence failure. The impact of model parameters on MOS level 2 and 3 drain-source conductance and gate-drain transconductance is analysed, and discontinuities are revealed. A typical CMOS differential amplifier is used to relate design techniques to possible convergence failures. Solutions for convergence are described, based on model parameter/physical effect selection, options specification initialisation techniques and algorithmic choices. Design techniques and simulation difficulties are related to SPICE models to convey the right approach for modelling and simulating analogue MOS designs View full abstract»

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  • Extended harmonic balance method

    Page(s): 275 - 284
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (624 KB)  

    A new approach for frequency domain analysis and periodic steady state analysis of nonlinear circuits is described. Beside the variables generally used in the harmonic balance method (HBM) this method also uses a reduced waveform as a function of time. As a result, the number of harmonics in the HBM is limited to the harmonics requested for output results. The waveform in time is used to ensure the requested accuracy. The approach leads to a large speed improvement compared with ordinary HBM, without reducing accuracy and convergence properties of the Newton iteration process. The speed improvement is demonstrated by an example taken from an actual design View full abstract»

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  • Pole placement algorithm for equiripple bandstop filter design

    Page(s): 325 - 327
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (180 KB)  

    In the paper, a pole placement algorithm for equiripple bandstop filter design is presented. By using the transformed variable the formulae for calculation of the stopband attenuation are given. The proposed algorithm is compatible with existing lowpass and bandpass pole placement algorithms View full abstract»

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  • Decomposition of logic networks with emphasis on signed digit arithmetic systems

    Page(s): 307 - 314
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (448 KB)  

    This paper describes an attempt to combine advantages of the signed digit number representation, applied at the word-level, and the residue number system applied at the digit-level, to achieve arithmetic decomposition of high-radix systems. Also introduced is a new decomposition algorithm for multiple-output Boolean functions based on partition products. Analysis of the proposed new method of arithmetic decomposition, when compared to an approach based on the theory of digit sets, reveals a more efficient use of data storage plus a higher degree of structural uniformity. The practical importance of the proposed method has been tested on a number of designs for the field programmable gate arrays. Comparison with a commercially available CAD system indicates a significant reduction in implementation complexity View full abstract»

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  • Base current reversal in bipolar transistors and circuits: a review and update

    Page(s): 299 - 306
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (496 KB)  

    A detailed study of base current reversal in silicon bipolar transistors and GaAs heterojunction bipolar transistors has been made. The physics of impact ionisation is presented followed by modelling of avalanche multiplication in devices. The effects of base current reversal on analogue and digital circuit operation are discussed View full abstract»

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