Showing papers in "International Journal of Electronics in 1987"

Xerographic time of flight experiment for the determination of drift mobility in high resistivity semiconductors

Abstract: Drift mobility in high resistivity semiconductors can be determined from xerographic time of flight (XTOF) techniques whose principles are different from the well known Haynes-Shockley experiment. A practical and inexpensive XTOF apparatus which can be utilized in investigating high resistivity semiconductors is described in detail. Some examples of XTOF transient current waveforms in amorphous selenium-based photoreceptors and method of analysis are presented.

Coupled cavities with mode conversion in gyrotrons

Abstract: The basic features of electrodynamic systems of gyrotrons formed by open coupled cavities with mode conversion (CCMC) are considered. Both the linear and the non-linear theories of gyrotrons with CCMC are given. Experiments on CCMC gyrotrons operating at the second and third cyclotron harmonics have been carried out at power levels up to 150kW. The experimental data are in good agreement with the theoretical results and demonstrate the high efficiency of the systems. The method of plane cross-sections which was used for the calculations is described in the Appendix.

AC electrical properties of vacuum-evaporated SiO/SnO2 films

Abstract: Measurements were carried out on the AC electrical properties of vacuum-evaporated SiO/SnO2 films having different compositions at temperatures between 173 K and 413 K and over the frequency range 200 Hz-1 MHz. The measured conductivity shows a frequency dependence σAC ∝ ωs with s having different values for higher and lower temperatures. AC conductivity at higher frequencies may be due to electronic hopping. The Elliott (1977) model satisfactorily explains the frequency dependence of conductivity and the temperature dependence of s. The value of the dielectric constant remains unchanged at high frequencies irrespective of temperature change, whereas its value increases at higher temperature with the decrease in frequency. Although the capacitance of the sample shows an increase in value with the increase in temperature within the lower frequency range (103–105 Hz), its value remains fairly constant at low temperatures within the measured frequency range. Tan δ, the dielectric loss has been found to incre...

The non-linear theory of fluorescent lamp circuits

Abstract: In contrast to the usual approach, fluorescent lamp circuits are analysed here not with the help of a linear model, but as non-linear systems. With the help of an idealization of the strongly non-linear voltage-current characteristic of the lamp, some new formulae are obtained. The formulae permit a general analysis of some important network properties, e.g. of the sensitivity of power consumption to changes in the amplitude of the voltage source, and also may facilitate the synthesis of ballasts for different possible requirements. The text should be useful for practical engineers. It also gives an analytical introduction into the field of the circuits, omitting considerations of technological details, but permitting the estimation of different circuit parameters and understanding their roles. Theoretically obtained results are compared with experimental and engineering data and, in general, the agreement seems to be satisfactory

Xerographic-mode transient charge technique for probing drift mobility in high-resistivity materials†

Abstract: The xerographic-mode transient charge technique is used to probe the drift mobility in high-resistivity materials. The data from measurements on amorphous selenium-based insulators are very close to those from the conventional electroded transient charge technique and therefore confirm the usefulness of this technique for obtaining charge transport parameters in these materials. This technique is found to be valuable in measuring the drift mobility at high electric field strengths in excess of 5 × 105 V/cm.

Sinusoidal oscillators employing current conveyors

Abstract: The effects of non-zero offset current at terminal z of a current conveyor on the operation of the entire circuit employing it are discussed. Correspondingly, criteria for DC biasing are derived. Application of these criteria leads to a proposal of two new circuits for sinusoidal oscillators. Additional constraints on the value of resistive components required to avoid large DC biasing currents are also considered.

Electrical conduction and observation of local defects in thin sandwich structures of Cu-SiO/CeO2-Cu

Abstract: AC and DC conduction in MIM sandwich structures based on SiO/CeO2 as a dielectric prepared by the co-evaporation technique has been investigated before and after electroforming for different compositions. The electroformed samples show voltage-controlled negative resistance (VCNR), voltage-memory, thermal-voltage-memory and pressure-voltage-memory effects and the results are explained in terms of the filamentary model of electrical conduction. The positive electrode was investigated using a scanning electron microscope to observe the effects of electroforming and the liberation of gas as a result of the application of high electric fields

Two new minimum-component Wien-bridge oscillators using current-conveyors

Abstract: Two new Wien-bridge oscillator circuits are presented. The circuits use the minimum number of active and passive components. The circuits enjoy low sensitivities, and are attractive for integration. Experimental results are included

Electronically tunable all-pole low-pass leapfrog ladder filter with operational transconductance amplifier

Abstract: A general theory of the synthesis of all-pole low-pass filters using only operational transconductance amplifiers and capacitors with the leapfrog design method is presented. Especially the possibility of a simple method for tuning the cut-off frequency will be shown. An estimation of the worst-case sensitivity and a comparison of theory and experiment will complete the paper.

Design-oriented analysis of common switching DC to DC converters

Abstract: A general, computer-aided analysis of power electronic circuit dynamics is proposed. An automatic generation of dynamic models from a circuit specification is the starting point for a symbolic, automatable, exact, ‘top-down’ procedure, that contrasts with circuit-specific analyses. The algorithm is suitable for analysing any converter containing two reactive elements, covering the common switching power stages: buck, boost, buck-boost converters. The method is illustrated by application to the computation of the transient response of a boost converter; the computer results are compared with those obtained by applying the ‘state space averaging’ method and with laboratory results.

Time-harmonic and time-dependent radiation by bifractal dipole arrays

Abstract: The potential utility of fractal concepts in designing antenna arrays is explored. In particular, whereas the time-harmonic far-field response of a bifractal array of hertzian dipoles is also a bifractal, its time-dependent far-field response is shown to be a unifractal.

Semiconductor electronic concepts for neural network emulation

Abstract: The existence of neuron-like transient phenomena in simple circuits containing silicon p +-n-n+ diodes indicates that such devices could provide a natural hardware basis for the fabrication of neural networks. Development of this hardware basis is pursued through exploratory work on circuits which exhibit some basic features of biological neural networks. The features discussed include action potentials, refractory periods, excitation, inhibition, summation over synaptic inputs, synaptic weights, temporal integration, memory, network connectivity modification based on experience, pacemaker activity, firing thresholds, coupling to sensors with graded signal outputs and the dependence of firing rate on input current.

Research note A new OTA-based active-C oscillator

Abstract: A new resistorless active-C OTA-based oscillator is presented. The circuit uses four OTAs and two capacitors. The oscillation frequency can be electronically tuned without affecting the condition of oscillation. The circuit enjoys relatively low sensitivities.

Invited paper Current processing circuits with translinear operational current amplifiers

Abstract: The basic properties of the translinear operational current amplifier (TOCA), a versatile active element which has been introduced recently, are described. This differential-input active device is used in conjunction with passive RC block-elements to obtain the standard configurations of new current transfer functions. The active sensitivities have been considered in order to determine the domain suitable to filtering applications. A circuit prototype with adjustable values for the current transfers was implemented. Experimental results which confirm the theoretical analysis are given.

Analysis of pulse-fed power electronic circuits using Walsh function

Abstract: A new operational method for the analysis of pulse–fed power electronic circuits is suggested, where input waveforms are expressed by a series combination of Walsh functions. The output response is obtained in terms of Walsh functions after operation by Walsh operational transfer function (WOTF). The current waveform of a DC chopper fed R-L load is approximated by piecewise constant solution and various average and r.m.s. currents of the same power electronic circuit are computed as an illustration.

Applications of multi-valued logic to testing of binary and MVL circuits

Abstract: Binary linear feedback shift registers (LFSR's) have acquired great importance in their implementation of a method of data compaction used in the testing of digital circuits. In this paper a new idea is examined: using multiple-valued LFSR's for the testing of MVL circuits and of binary circuits. For MVL circuits a non-binary LFSR avoids the need of decoding the signals and its implementation requires fewer digits than the binary tester. For binary circuits, a multi-valued LFSR tester shows higher effectiveness while maintaining a smaller implementation. An analysis is given of fault coverage for binary and multi-valued circuits, and optimal implementations of multi-valued LFSR's are presented.

A simple non-saturated multivibrator for low voltage power supply

Abstract: The circuit of a simple multivibrator which does not include saturated switches is proposed. It can be used for design of high frequency multivibrators operating with low voltage power supply. The circuit operation is described and the design limitations are introduced. The frequency of operation ƒ0, and its additional variation with temperature due to non-saturated operation are calculated. An example of circuit realisation for 2 V power supply is given. The design was verified experimentally using a 3096 transistor array for low frequency of operation (ƒ0 is up to 400 kHz) and discrete transistors for high (ƒ0 is up to 2 MHz) frequency of operation

The effect of annealing on the AC electrical properties of SiO/SnO2 amorphous thin films

Abstract: AC electrical properties of unannealed and annealed amorphous SiO/SnO2 thin films having different compositions and thicknesses and prepared by vacuum evaporation at 2 x 10-6 torr are investigated. Measurements were taken over the frequency range 200 Hz-1 MHz. The density of localized states (N) before and after annealing for different compositions have been calculated. A decrease in N after annealing accounts for the behaviour of electrical characteristics and indicates the occurrence of some structural changes of the thin films.

Theory of the multi-cavity phase locked gyrotron oscillator

Abstract: A perturbation theory is developed for investigation of the two cavity phase locked oscillator. In this theory, the unperturbed state is the free running oscillator. The prebunching current then slightly perturbs the frequency and field profile, and one can calculate the condition for phase lock. The theory is analytically tractable, and as in the analogous case of the gyroklystron amplifier, the dimensionality of the parameter space is greatly reduced.

Pulse width modulation method of a single-phase multilevel inverter

Abstract: A novel pulse-width modulation method for a multilevel single-phase inverter is proposed. The proposed method has the feature that the output voltage changes at each level, compared with the conventional method in which output voltage jumps from zero to the maximum level. Therefore, the adverse effects on load due to the high dv/dt are decreased. The method of determining pulse width is discussed, and the harmonic distortion factors and harmonic contents are analysed. Further improvement by increasing the number of pulses and the experimental results are also described.

Two-minimum-component single current conveyor RC oscillators

Abstract: Two minimum-component RC-sinusoidal oscillator circuits using current conveyors are presented. Each circuit uses a single current conveyor, two resistors and two capacitors. The two circuits enjoy low sensitivities.

Loeb's criterion and ‘latch-up’ effect in second order oscillators with single OA

Abstract: The aim of this paper is to show that Loeb's criterion in 2nd-order oscillators with a single operational amplifier enables a linear interpretation. The ‘latch-up’ effect in these systems can be also predicted by a linear theory

Non-linear analogue-to-digital conversion through PWM

Abstract: A method for finding non-linear functions digitally is described. The design is based on pulse width modulating (PWM) the analogue signal by applying a specially shaped reference waveform in the modulator. The number of pulses of a high frequency clock entering in a binary counter during the high state period of the PWM will provide a digital number proportional to the first, square, cubic or forth order root at the input voltage. Exponential form functions also can be found digitally.

New logical-sum and logical-product circuits using CMOS transistors and their applications to four-valued combinational circuits

Abstract: In this paper, the new CMOS circuits for logical-sum and logical-product are proposed. In the case of two inputs, each of such proposed circuits can be composed of a pair of PMOS and NMOS transistors with threshold voltages close to zero volts. The model-parameters of such transistors are presented. It is shown that they are also very well suited for the traditional two-valued logic circuits. Various inverter-circuits to be used in the multiple-valued logic circuits, as well as the above proposed circuits, are also presented. The design method for four-valued combinational circuits using these circuits, together with the examples of their applications, are introduced. The simulation results of such combinational circuits using SPICE-2 are shown with satisfactory characteristics.

Field dependence of optical band gap in manganese phosphate glasses

Abstract: Photoconduction measurements are made in the spectral energy range l·5-6·2eV on a manganese phosphate glass with composition 40mol% MnO and 60mol% P2O5. The values of energy band gap are deduced by extrapolation of the linear region of the spectral dependence curves, obtained at various applied fields. These values decrease slowly with increasing field, and a band gap value of 5·07 eV is derived for zero field. The results can be explained in terms of energy bands for amorphous materials, and are similar to those obtained for other metal phosphate glasses

Design of a single layer frequency-selective surface

Abstract: This paper discusses the design of a single-layer frequency selective surface to be used in a dual frequency band satellite antenna operating from 10-7-11-7 GHz and 18-2-20GHz. Relevant design equations and considerations are presented together with an optimized practical design.

Invited paper Application of the least mean fourth (LMF) adaptive algorithm to signals associated with gaussian noise

Abstract: This paper considers the applicability of the least mean fourth (LM F) power gradient adaptation criteria with 'advantage' for signals associated with gaussian noise, the associated noise power estimate not being known. The proposed method, as an adaptive spectral estimator, is found to provide superior performance than the least mean square (LMS) adaptation for the same (or even lower) speed of convergence for signals having sufficiently high signal-to-gaussian noise ratio. The results include comparison of the performance of the LMS-tapped delay line, LMF-tapped delay line, LMS-lattice and LMF-lattice algorithms, with the Burg's block data method as reference. The signals, like sinusoids with noise and stochastic signals like EEG, are considered in this study.

Kinetic theory of the surface recombination of electrons and ions on glass surfaces

Abstract: Maxwell theory of two-dimensional electron gases with ions trapped in impact craters in glass gives a relation between the recombination coefficient, crater dimensions and ion surface number density. Both surface and volume approaches can operate inside craters.

On the design of CMOS ternary logic circuits using T-gates

Abstract: This paper presents a synthesis method for three-valued CMOS logic circuits that is essentially based on the use of the T-gate. P and N modules, subsets of the ternary T-gate, are defined and used as building blocks together with four types of ternary inverters to realize three-valued logic systems. First unary functions are realized, then multi-variable circuits are synthesized. Minimization techniques of ternary logic circuits based on the proposed synthesis method are also discussed.

Ternary logic based on a novel MOS building block circuit

Abstract: A pair of ternary logic circuits which cyclically permute the logic levels 0, 1, 2 are described. The circuits are implemented in CMOS augmented with depletion loads. Practical ranges for logic levels and threshold voltages are shown to exist and time dependent behaviour is discussed. The logic properties of the circuits (called permutators) and their derivatives are described. This ternary logic family is shown to be a natural extension of the binary logic family based on the inverter and its derivatives NAND and NOR circuits. The central idea behind the extension is that the permutators and the inverter all implement cyclic permutations (and not inversions) of the logic levels involved. Finally a ternary parallel multiplier is constructed as an example and compared with the binary parallel multiplier in transistor count, power consumption and speed.