Showing papers in "International Journal of Electronics in 1999"

Inverting second generation current conveyors: the missing building blocks, CMOS realizations and applications

Abstract: The concept of voltage mirror is introduced and used, together with the current mirror, to ideally represent the current and voltage inverting properties of some analogue building blocks. The properties of the nullor and mirror elements are used to relate the different devices in the ideal case as well as to define the adjoint network for each building block. Two new types of second generation current conveyor (CCII) are introduced. One is the adjoint of the CCII+ and is named the inverting second generation current conveyor ‘negative’ (ICCII–); the other is the ICCII+. CMOS realizations of the ICCII– are presented and new ICCII– based current mode circuits are obtained by applying a voltage-to-current-mode transformation to the CCII+ based circuits.

Quantum-dot cellular automata : computing with coupled quantum dots

Abstract: We discuss novel nanoelectronic architecture paradigms based on cells composed of coupled quantum-dots. Boolean logic functions may be implemented in specific arrays of cells representing binary information, the so-called quantum-dot cellular automata (QCA). Cells may also be viewed as carrying analogue information and we outline a network-theoretic description of such quantum-dot nonlinear networks (Q-CNN). In addition, we discuss possible realizations of these structures in a variety of semiconductor systems (including GaAs/AlGaAs, Si/SiGe, and Si/SiO2), rings of metallic tunnel junctions, and candidates for molecular implementations. We report the experimental demonstration of all the necessary elements of a QCA cell, including direct measurement of the charge polarization of a double-dot system, and direct control of the polarization of those dots via single electron transitions in driver dots. Our experiments are the first demonstration of a single electron controlled by single electrons.

All-pass filters using a single current conveyor

Abstract: Current conveyors are unity gain active elements exhibiting high linearity, wide dynamic range and better high frequency performance compared with their voltage mode counterparts. In this study a set of single positive-type second generation current conveyor based all-pass filters is presented and a catalogue of canonical topologies is given with some properties in tabular form. In contrast with single topology presentations, 22 different topologies are presented which exhibit identical transfer functions but differ in the number of passive components, component matching constraints, possibility of gain adjustment and other properties.

Universal voltage-mode filter with four inputs and one output using two CCII s

Abstract: A novel universal voltage-mode second-order filter with four inputs and one output employing only two plus-type second-generation current conveyors (CCII+s), two capacitors and three resistors is presented. The proposed circuit offers the advantageous features: realization of lowpass, bandpass, highpass, notch and allpass signals from the same configuration, orthogonal control of ω0 and Q and low active and passive sensitivities. The use of only CCII+s simplifies the configuration except for class-A operation.

Array pattern synthesis with null steering using genetic algorithms by controlling only the current amplitudes

Abstract: In this paper, the technique for antenna array pattern synthesis with null steering using the genetic algorithms (GA) by controlling only the excitation current amplitudes is presented. This technique is capable of synthesizing the array pattern with nulls imposed at the directions of undesired interferences while simultaneously maintaining the main beam directed toward the desired signal with prescribed sidelobe level and null depth level. The proposed technique is simple and easy to implement compared to conventional array pattern synthesis techniques. The versatility of the proposed technique is also demonstrated by changing the weighting factors of the fitness function constructed for genetic algorithms. Numerical results show the effectiveness of the proposed technique in comparison with published results.

Fast power cycling test for insulated gate bipolar transistor modules in traction application

Abstract: The numerous advantages of insulated gate bipolar transistor (IGBT) power modules and their ongoing development for higher voltage and current ratings make them interesting for traction applications. These applications imply high reliability requirements. One important requirement is the ability to withstand power cycles. Power cycles cause temperature changes which lead to a mechanical stress that can result in a failure. Lifting of bond wires is thereby the predominant failure mechanism. A fast power cycling test method activating the main failure mechanism has been developed which allows to reproduce millions of temperature changes in a short time. The applicability of fast testing is supported by a mechanical analysis. Test results show the number of cycles to failure as a function of temperature changes for an IGBT single switch. A descriptive model is deduced from the results.

Current-mode and voltage-mode universal biquads using a single current-feedback amplifier

Abstract: A new current-mode universal biquad and a new voltage-mode universal biquad using a single current-feedback amplifier are proposed in this paper. Both biquads enjoy the following advantages: realization of highpass, bandpass and lowpass filtering from each configuration, avoidance of input voltage tracking error in a current-feedback amplilfier; only one active component; no requirement for match components; low passive and active sensitivities. An inverting amplifier is used to form a notch filter. Experimental results are obtained to prove the theoretical analyses.

Single-electron logic and memory devices

Abstract: Single-electronics is believed to be the leading candidate for future digital electronics which will be able to operate at ~ 10 nm size scale and below. However, the problems of integrated single-electronics are quite serious whereby the future prospects are still uncertain. In this paper we discuss the operation principles and required parameters of several proposed families of single-electron logic, including the logic based on single-electron transistors, wireless single-electron logic and single-electron parametron. We also briefly discuss the single-electron memory which is easier to implement than logic and, hence, is more important from the practical point of view. As an example, we consider the background-charge-insensitive hybrid SET/FET memory.

A fully digital hysteresis current controller for an active power filter

Abstract: An active power filter is used to eliminate current harmonics produced by nonlinear loads. This paper discusses a fully digital method of controlling a power inverter used to inject the active filter compensating currents into the power system. A digital signal processor performs the harmonic isolation and generates a digital reference current. A hysteresis current controller has been implemented in a field programmable gate array that generates the inverter switching signals using this reference. This reduces the analogue circuitry and enhances the system's immunity to electromagnetic interference. The performance of a small-scale inverter under completely digital control is presented and discussed.

Chaos in voltage-mode controlled DC drive systems

Abstract: Remarkably complex behaviour, namely chaos, in voltage-mode controlled DC drive systems has been investigated. An iterative mapping that describes the nonlinear system dynamics in the continuous conduction mode is derived. It shows that different bifurcation diagrams can be obtained from different system parameters, and that the systems generally exhibit a period-doubling route to chaos. Analytical modelling of period-1 and hence the period-p orbits, as well as their stability analysis using the characteristic multipliers, is presented. Thus the stable ranges of various system parameters can be determined. The theoretical results are verified by using experimental measurement.

Sampled-Data Modeling and Analysis of the Power Stage of PWM DC-DC Converters

Abstract: The power stage of the PWM DC–DC converter is modelled and analysed using the sampled-data approach. The work addresses both continuous and discontinuous conduction mode under voltage mode control, and continuous conduction mode under current mode control. For each configuration, nonlinear and linearized sampled-data models, and control-to-output transfer functions are derived. Using this approach, both current mode control and discontinuous conduction mode can be handled systematically in a unified framework, making the modelling for these cases simpler than with the use of averaging. The results of this paper are similar to results of Tymerski, but they are presented in a simpler manner tailored to facilitate immediate application to specific circuits. It is shown how sampling the output at certain instants improves the obtained phase response. Frequency responses obtained from the sampled-data model are more accurate than those obtained from various averaged models. In addition, a new (‘lifted’) contin...

Silicon single-electron devices

Abstract: Silicon single-electron transistors (SETs) were fabricated by using very flat silicon-on-insulator (SOI) substrates, high resolution electron beam (EB) lithography and etching techniques. In addition, we developed a special fabrication method called pattern-dependent oxidation with which a one-dimensional Si wire can be converted into a small Si island with a tunnelling barrier at each end. Since the Si island is around 10 nm, we could observe the conductance oscillation in the SET even at room temperature. The controllability and reproducibility of this method were confirmed through analysing the effects of size on electrical characteristics. We were also able to observe single-electron memory effects by using these novel techniques.

Factors affecting the glow-to-arc transition at the cathode of an electric discharge at atmospheric pressure

Abstract: The glow-to-arc transition has been studied in an electric discharge at atmospheric pressure. Although this transition is a cathode effect, the cathode and the positive column have both been seen to affect the current at which the transition occurs. If the cathode is relatively small, the discharge passes through the abnormal glow region before the glow to arc transition takes place. If the cathode is sufficiently large, increasing the current causes the positive column to contract and the transition takes place directly from the normal glow without passing through the abnormal region. The oscillation phenomenon is explained in terms of the Steenbeck minimum principle and related to the power dissipated at the cathode root, which decreases when the glow changes to an arc. If the power dissipated at the cathode in the arc regime is insufficient to sustain electron emission the arc will revert to a glow. Variation of the slope of the load line alters the frequency of oscillation of the glow-to-arc transitio...

A new effective patch radius expression obtained by using a modified tabu search algorithm for the resonant frequency of electrically thick circular microstrip antennae

Abstract: A new, very simple expression for the effective patch radius is presented for the resonant frequency of electrically thick circular microstrip patch antennae. It is obtained by using a modified tabu search algorithm, and is useful for the computer-aided design (CAD) of microstrip antennae. The theoretical resonant frequency results obtained by using this new effective patch radius expression are in very good agreement with the experimental results available in the literature.

Universal two-input two-output current-mode active biquad using FTFNs

Abstract: A universal active biquad using the four-terminal floating nullors (FTFNs) is presented. The proposed circuit uses two FTFNs, two capacitors and two resistors. The proposed circuit has two input currents and can provide two highimpedance output currents. Without changing the circuit topology, the output currents can realize lowpass, highpass, bandpass, and allpass transfer functions. A notch transfer function can be obtained by adding a voltage-to-current converter using an additional FTFN. The proposed circuit enjoys low passive sensitivities and orthogonal tuning of the parameters ωo and ωo/Qo.

Analysis of an azimuthally periodic vane-loaded cylindrical waveguide for a gyro-travelling-wave tube

Abstract: A cylindrical waveguide, provided with wedge-shaped metal vanes projecting radially inward from the wall of the guide, excited in the transverse electric (TE) mode, was analysed. The analysis was carried out considering the angular harmonics generated by the angular positioning of the vanes. A set of equations was generated in the Fourier amplitudes of field constants. The condition for nontrivial solutions for the field constants gave the dispersion relation of the structure. From the expression of power flow down the structure, its interaction impedance was also estimated. The shape of the dispersion characteristics and the value of the cutoff frequency as well as the interaction impedance characteristics of the waveguide were found to depend on the vane parameters their number as well as their radial and angular dimensions. The optimum vane parameters were obtained corresponding to the minimum variation of the slope of the ω-β dispersion plot, such parameters being useful from the standpoint of the ban...

Optimal improvement in bistable measurement device performance via stochastic resonance

Abstract: The notion of noise-activated systems has been well known since the 1950s. A number of natural phenomena have been investigated by means of this theory and an improvement in the performance of several systems has also been achieved. Recently the stochastic resonance (SR) phenomenon was introduced as an innovative approach for both understanding the behaviour and improving the performance of several classes of systems. In the present work some new results regarding the influence of forcing signal parameters on the persistence of the SR condition are given. Both theoretical results and numerical simulations have been carried out to emphasize the suitability of the proposed noise tuning methodology.

A multiple output active filter based on current followers

Abstract: In this paper a multiple output current follower (CF)-based active filter (MOCFF) is presented. The construction of basic filtering oriented biquadratic transfer functions (low-pass, high-pass, band-pass, band-notch and all-pass) is realized by means of two independent stages of identical topology. Each of them incorporates three CFs appropriately interconnected with R,C branches; a CF-based adder (CFA) in conjunction with a versatile CF-incorporating mutual feedback symmetric circuit (MFSC) implement three different frequency responses. The pair of CFs composing the MFSC should be visualized as a voltage transfer function generator. The MOCFFs salient feature is the current-based signal processing while voltage remains the input and output variable. Taking into consideration the innate CF current tracking error, transfer function modifications owing to CF non-ideality are provided. Our theoretical analysis is confirmed by HSPICE simulation results with the CF block function implemented by a properly modi...

A new anisotropic perfectly matched layer medium for mesh truncation in finite difference time domain analysis

Abstract: In this paper an unsplit anisotropic perfectly matched layer (PML) medium, previously utilized in the context of finite element analysis, is implemented in the finite difference time domain (FDTD) algorithm. The FDTD anisotropic PML is easy to implement in the existing FDTD codes, and is well suited for truncating inhomogeneous and layered media without special treatment required in the conventional PML approach. A further advantage of the present approach is improved performance at lower frequencies. The applications of the unsplit anisotropic PML/FDTD method are illustrated by considering the problems of a plane wave propagation and an open microstrip line.

A control method for the active power filter in unsymmetrical voltage systems

Abstract: In this paper, the authors propose a calculation method for the compensating current reference of the active power filter, where a nonlinear load exists in a three-phase, three-wire unsymmetrical voltage system. This new method has been named the extension pq method. The authors have experimented with the extension pq method and the pq method, using the same current-controlled intelligent power module inverter for both methods. The results of the experiments proved that in the unsymmetrical voltage system the source current was distorted in the case of the pq method, but undistorted in the case of the extension pq method.

Inverting and/or non-inverting biquad circuit using second-generation current conveyors

Abstract: A configuration for realizing high input impedance inverting and/or non-inverting voltage-mode filters using second-generation current conveyors (CCIIs) is presented This configuration uses only three second-generation current conveyors, four (or three) grounded resistors and two (or three) grounded capacitors and can simultaneously realize bandpass and lowpass or bandpass and highpass responses The resonance angular frequency and the quality factor can be orthogonally controllable PSPICE simulation results are also included current conveyors (CCIIs) is

A new soft-switching vector control approach for resonant snubber inverters

Abstract: A new concept of soft-switching vector (SSV) is proposed for soft-switching inverters, especially those resonant snubber inverters (RSIs). The SSV control approach is not only useful for achieving the soft-switching condition, but also provides some definite advantages—namely the reduction in power loss and the elimination of over-current problem in the main switches. In this paper, softswitching inverters are firstly classified by their operating principles. Then, the operating modes of a RSI with and without using SSV control are presented. Both simulation and experimental results verify the theoretical analysis, showing that the use of SSV control can provide the above advantages.

On the realization of the current controlled current-mode amplifier using the current controlled conveyor

Abstract: The current controlled current-mode amplifier proposed by Fabre et al. (1996, IEEE Transactions on Circuits and Systems—I, 43, 82) is reanalysed to show that it can work not only under small signal conditions, as suggested by Fabre et al., but also under large signal conditions. Simulation results which confirm the theory presented are included.

Silicon MOS controlled bipolar power switching devices using trench technology

Abstract: The next generation of power devices are likely to extend MOS controlled bipolar (MCB) device concepts to cover very high voltage (up to 8kV) applications. Such devices will be based on utilizing the advantages brought about by trench gate MOSFETs to control bipolar current flow. In this paper we give a review of development of trench gate IGBTs and we describe briefly new promising device structures based on trench technology which use PIN diode and thyristor type carrier distributions to reduce power losses within the device.

MRTD analysis of a transient electromagnetic pulse propagating through a dielectric layer

Abstract: On the basis of a scaling function based multiresolution time domain (MRTD) scheme, we analyse a transient electromagnetic pulse propagating through a dielectric layer in conjunction with an anisotropic perfectly matched layer (APML) for mesh truncation. Herein we have carefully investigated three different cases including TEM x , TE z and TM z waves that are normally incident on an open or PEC parallel-plate bounded propagation system. Purposely, we employ a similar notation in formulations to that applied in the conventional finite difference time-domain (FDTD) method for their comparison, rather than using the state-space representation. It is found that the computed reflected coefficients for all configurations are in good agreement with those obtained with the FDTD and analytic methods, while its corresponding requirement on computational memory and CPU time is considerably reduced.

New high-resolution digital sinusoidal oscillator structure with extremely low frequency and sensitivity

Abstract: An efficient extremely low frequency digital sinusoidal oscillator with high resolution and extremely low sensitivity is presented. The proposed oscillator structure can generate frequencies much lower than all structures known in the literature without the need to increase the width of the multiplier coefficient. The proposed oscillator utilizes two low sensitivity complex digital oscillators with two different multiplier coefficients. The simulation results verify the analytical results and demonstrate the performance as measured in terms of total harmonic distortion.

Design and fabrication of a micromachined resonant gyroscope

Abstract: The micromachined gyroscope is rapidly gaining popularity as a rate sensor for application in areas such as automotive and aerospace systems, where low power consumption, high sensitivity, low temperature drift and good stability are prerequisites. In this paper, the overall design and fabrication process of a reactive ion-etched inertial resonant gyroscope based on the capacitive sensing principle is reported. The experimental results are also discussed.

A new method of analysis for PWM switching power converters

Abstract: A new method of analysis for pulse-width modulation (PWM) switching power converters is presented. It allows one to find an approximate periodic solution for the converter vector state variable. The converter is modelled by a differential equation with periodic coefficients. This equation is substituted by an equivalent system of linear differential equations with constant coefficients. Only the forced (steady-state) solutions should be found for each equation of this system. The equations are solved in sequence. The final steady-state solution of the PWM differential equation is obtained as the sum of these forced solutions. The method allows one to find the converter dc transfer function and efficiency, to evaluate their frequency dependences, and to find the critical frequency and ripple. The first three equations of the equivalent system are usually adequate for practical purposes, and these equations are obtained by an easy formal procedure. One can also obtain the dynamic equation of the state varia...

Application of the complex beam parameter to the design of a quasioptical transmission line for a submillimetre wave gyrotron

Abstract: The complex beam parameter can be used to facilitate the design of a quasi-optical transmission line which converts the output of a submillimetre wave gyrotron into a wellcollimated, linearly polarized beam. Thequalityof thebeam produced by the quasi-optical antenna is improved further by removing any sidelobes. Only a small fraction of the beam power is sacrificed.

Development of high efficiency and crowbar switchless dc power supply for 1MW CW CPD gyrotron

Abstract: A high efficiency and high power dc main power supply for the collector potential depression (CPD) gyrotron was developed and operated successfully with a real CPD gyrotron. The capacity of the power supply is 5 MW, 100 kV output voltage and 50 A maximum current, adopting a dc 100 kV IGBT switch for fast switching and a pair of 3-phase ac thyristor switches for dc output voltage control. The IGBT switch consists of 100 insulated gate bipolar transistors (IGBTs) connected in series. The switch can protect the CPD gyrotron by fast switching which achieves input energy below 10 J and has first turn-on performance within 10 mus. The ac thyristor switch controls the output voltage of the power supply using feedback control and feedforward control, so as to regulate the voltage in the case of load transition from no load to rated load at the IGBT switch turn-on timing. The combination of feedback and feedforward controls enables us to maintain the voltage stability of the main power supply between −1.0% and +3%...