A full-wave rectifier using a current conveyor and current mirrors

The realization of a full-wave rectifier using a current conveyor and current mirrors is presented. The proposed rectifier is composed of a voltage-to-current converter, a current mode full-wave rectifier, and a current-to-voltage converter. A voltage input signal is changed into a current signal by the voltage-to-current converter. The current mode full-wave rectifier rectifies this current signal resulting in the current full-wave output signal that is converted into a voltage full-wave output signal by one grounded-resistor. The theory of operation is described. The simulation and experiment results are used to verify the theoretical prediction. Simulated results show that the proposed rectifier yields the minimum voltage rectification to 94µV. Experimental results demonstrate the performance of the proposed rectifier for 50mV_peak signal rectification.     

Bang-bang current control with predecided switching frequency forswitch-mode rectifiers

An active current waveshaping/control technique with continuous conduction of input current and suitable for single-phase switch-mode rectifiers (SMRs) is proposed. The nature of input current is similar to that of bang-bang hysteresis current control. The technique does not require a reference hysteresis window. Current control is achieved with constant switching frequency for a given load current. The switching frequency varies inversely with the load current, but is known and predecided. Simulated performance results and selected experimental results are provided     

Surface recombination current in InGaP/GaAs heterostructure-emitterbipolar transistors

The behavior of the surface recombination current was examined in InGaP/GaAs heterostructure-emitter bipolar transistors (HEBT's) with both exposed GaAs surface and InGaP passivated surface based on the emitter-size effect on current gain. The results indicate that the GaAs surface recombination current has a 1 kT-like dependence in the high current regime and a 2 kT-like dependence in the low current regime which is similar to published experimental results in AlGaAs/GaAs and InGaP/GaAs HBT's. The surface recombination current in devices with an InGaP passivation layer has an order of magnitude lower value in low current regime and more than two orders lower in high current regime than that in devices with exposed GaAs surface     

Experimental comparison of base recombination currents in abrupt and graded AlGaAs/GaAs heterojunction bipolar transistors

The relative importance of the base bulk recombination current and the base-emitter junction space charge recombination current is examined for AlGaAs/GaAs HBTs with different grading schemes in the base-emitter junction. Experimental results demonstrate that, in abrupt HBTs, the base bulk recombination current is larger, and the base current increases with the base-emitter bias with an ideality factor of approximately 1. In contrast, in graded HBTs, the space charge recombination current dominates and the base current ideality factor is approximately 2. These experimental results agree well with a published theoretical calculation.<>     

DC-Link Harmonics of Three-Phase Voltage-Source Converters Influenced by the Pulsewidth-Modulation Strategy—An Analysis

DC-link current harmonics are the predominant factor to be considered for dimensioning dc capacitors in three-phase pulsewidth-modulation (PWM) voltage-source converters. In this paper, an analysis of the dc-link current harmonics applying a double Fourier series is derived. The analytical results for the dc-link current spectra of continuous and discontinuous PWMs are presented and compared with measurement results taken from a converter test setup. A good match between theoretically expected and actually obtained experimental results can be stated. Moreover, characteristic differences between the investigated modulation strategies regarding their dc-link current spectra become evident.     

BiCMOS circuits for high speed current mode D/A converters

A new BiCMOS current cell and a BiCMOS current switch for high speed, self-calibrating, current-steering D/A converters are described. The BiCMOS current cell can be realized in a BiCMOS process or in a conventional CMOS process using a substrate PNP transistor, while the BiCMOS current switch is intended for implementation in a BiCMOS process. The performance of these circuits has been demonstrated in 0.8 μm BiCMOS and 1.2-μm CMOS technologies. A detailed noise analysis of the BiCMOS current cell indicates that noise during the calibration phase limits its relative accuracy to about 150 ppm. This is substantiated by measured results which show a relative matching of about 100-150 ppm, which is the equivalent of about 13 b performance. Measurement results also indicate that the absolute accuracy of the BiCMOS current cell is better than 0.5% over the designed current range, which is better than that of previously reported designs. Test results for the BiCMOS current switch indicate that a 10-90% switching time of 0.9 ns has been achieved. Furthermore, the switching time of the new BiCMOS switch is very insensitive to current level and input waveform compared to conventional CMOS switches. A 4-b D/A converter based on these components has been fabricated, and test results have demonstrated that it is functional. This DAC will be used as the internal DAC of a ΣΔ modulator for over-sampled video and digital radio applications     

The effectiveness of a current flattening circuit as countermeasure against DPA attacks

This paper presents an on-chip current flattening circuit designed in 0.18-μm CMOS technology, which can be integrated with secure microsystems, such as smart cards, as a countermeasure against power analysis attacks. The robustness of the proposed countermeasure is evaluated by measuring the number of current traces required for a differential power analysis attack. We analyze the relationship between the required number of current traces and the dynamic current variations, and we show empirically that the required numbers of current traces is proportional to an inverse of the square of the rms value of the flattened current. Finally, we evaluate the effectiveness of the proposed design by using the experimental results of the fabricated chip. The analysis of the experimental results confirms the effectiveness of the current flattening circuit.     

A second current controlled current conveyor realization using Wilson current mirrors

The paper proposes a Wilson current mirror with double outputs and a bipolar second current controlled current conveyor (CCCII) circuit based on Wilson mirrors. The performance principle of the circuits is analysed and experiment results are given. The CCCII circuit has the following merits: high trace accuracy of voltage and current; high current output impedance; and good current stability.     

Closed-Form Expressions for the Current Densities on the Ground Planes of Asymmetric Stripline Structures

In this paper, closed-form expressions for the current density on the ground planes of an asymmetric stripline structure are derived. The derivation utilizes image theory in order to obtain a suitable quasi-static Green's function for this asymmetric geometry. For the special case of a symmetric stripline geometry and the limiting case of a microstrip line, it is demonstrated that the results obtained here reduce to previously derived results. As expected, it is illustrated that the current densities on the ground planes of an arbitrary asymmetric stripline are bounded by the current distribution of a symmetric stripline and that of a microstrip line. The validity of the analytical results is investigated by comparing to numerically obtained results. Finally, expressions are presented for the total ground-plane currents as fractions of the total current on the signal trace     

High-Performance Planar Isolated Current Sensor for Power Electronics Applications

A planar current sensor, comprised of a magnetic current transformer and a hall-effect element, is presented. The sensor has a broad frequency bandwidth from dc up to 30 MHz, a high current rating (40-A dc), superior linearity, high EMI immunity, small size, robustness, and low realization cost. The main design formulations are given analytically; simulations and finite-element results are presented for verification. Experimental results of current step response and dv/dt immunity are included.     

The design and experimentation of the new cascaded DC-DC boost converter for renewable energy

After renewable energy generated, a direct current value is converted to a direct current value at another level for a power electronics and power system application that is often considered. In this article, the design and application of a new generation multi-time cascaded DC-DC converter are discussed. The dc-to-dc converter is three-levels, and the switches for each step have a working time and a non-working time. Mathematical models are established depending on the relationship between current and voltage according to the operating and non-operating states of the switches at each stage. After these mathematical models are creating, the new generation multi-timed DC-DC converter is run in Matlab Simulink and simulation results are validated in experimentation. The output voltage and inductor current are observed with a scope. Then, the results from the proposed converter are compared with the results of the traditional converters. The results show the effectiveness of the proposed dc-dc converter.     

Fast current controller in three-phase AC/DC boost converter usingd-q axis crosscoupling

In this paper, a new simple current controller with both satisfactory steady-state characteristics and fast transient response is proposed. In this scheme, a reference modification part is incorporated with the generally used synchronous-frame proportional-integral (PI) controller for the fast transient response. Simulation and experimental results are presented and show the effectiveness of the proposed current controller. In the simulation and experimental results, both the current controller and DC-link regulator show conspicuous performance improvement. It is also observed in the simulation and experiment that the proposed current controller has a similar characteristic as the synchronous-frame PI controller in the steady state and as the minimum-time current controller in the transient state     

基于FPGA的超磁致伸缩驱动器程控电流源设计

为满足超磁致伸缩驱动器(giant magnetostrictive actuator,简称GMA)对输入电流微步进、高精度和宽范围的要求,提出一种GMA程控电流源的设计方案。基于该微步进连续调整型电流源的电路原理,设计了微步进控制和恒流源控制电路,并通过电路仿真与实验测试验证设计方案的可行性。结果表明:该GMA程控电流源在电路仿真和实验测试中输出的电流精度分别达到0.5%和3%,电流步进值1.8mA,电流输出范围0A至7A。研究成果表明提出的程控恒流源的电路设计方案符合设计要求。     

A method for the prediction of hot-carrier lifetime in floating SOINMOSFETs

A concept was presented for the prediction of the device lifetimes for the hot-carrier effect (hot-carrier lifetimes) in floating SOI MOSFETs. The concept is that hot-carrier lifetimes in floating SOI MOSFETs can be predicted by estimating the hole current. In order to verify the validity of this concept, the hole current was investigated using device simulation. The results showed that the ratio of the hole current to the drain current in a floating-body SOI MOSFET is approximately equal to the ratio of substrate current to drain current in a body-tied one. Based on this fact, a method for accurately predicting the hot-carrier lifetime in floating-body SOI MOSFETs was proposed. The hot-carrier lifetime predicted with this method agreed well with the experimental results. This study showed that only the drain current difference between floating and body-tied structures results in lifetime differences, and there is no special effect on hot-carrier degradation in floating SOI MOSFETs. In this prediction, therefore, floating SOI MOSFETs can be treated in the same way as bulk MOSFETs. Hot-carrier lifetimes in floating SOI MOSFETs can be predicted using the hole current, while substrate currents are used in bulk MOSFETs     

Effects of temperature on current instabilities caused by recombination centers in semiconductors

With the carrier distribution function approximated by a displaced Maxwellian function the current-voltage characteristics for a semiconductor containing repulsive Coulomb recombination centers have been derived, and the current instabilities in n-GaAs as functions of temperature and applied field have been experimentally studied. The experimental results show that the threshold current for the onset of the current instabilities is not sensitive to temperature, but the corresponding threshold field decreases with increasing temperature; and that the current oscillation frequency increases and the amplitude decreases with increasing temperature. These results are in good agreement with the theory.     

A Modified Harmonics Reduction Technique for a Three-Phase Controlled Converter

Three-phase controlled converters have many applications especially in adjustable speed drives and renewable energy. A three-phase controlled converter is a good option in these applications due to its low cost, simplicity, and maintainability with respect to other solutions like a full-bridge insulated gate bipolar transistor converter or a Vienna rectifier. Line current harmonics in this converter is very high; therefore, a harmonics reduction technique is needed to remedy the problem. In this paper, an improved injection current technique is introduced to reduce line current harmonics. The optimal amplitude and phase angle of the injection current for different loads and firing angles have been mathematically determined. Simulation for this technique has been performed by using the PSIM simulation program. An experimental prototype has been built to verify the mathematical and simulation results. The simulation and experimental results show a sensitive variation in the total harmonic distortion of the line current for the amplitude and angle of injection current variations. The simulation and experimental results prove the superiority of this technique in mitigating the requirements for harmonics standards.     

Oxide roughness effect on tunneling current of MOS diodes

Two-dimensional (2-D) device simulation is used to investigate the tunneling current of metal ultra-thin-oxide silicon tunneling diodes with different oxide roughness. With the conformal nature of ultrathin oxide, the tunneling current density is simulated in both direct tunneling and Fowler-Nordheim (FN) tunneling regimes with different oxide roughness. The results show that oxide roughness dramatically enhances the tunneling current density and the 2-D electrical effect is responsible for this increment of tunneling current density. Furthermore, a set of devices with controlled oxide roughness is fabricated to verify the simulation results and our model qualitatively agrees with the experiment results.     

Scanning voltage microscopy on buried heterostructure multiquantum-well lasers: identification of a diode current leakage path

We report scanning voltage microscopy (SVM) results on actively driven buried heterostructure (BH) multiquantum-well (MQW) lasers that exhibit current blocking failure at high current injection operation. The measured two-dimensional image of local voltage distribution delineates the buried structures of the BH laser. The results, in combination with light-current-voltage (L-I-V) measurements, connect macroscopic external performance to measurements on the nanometer scale. Our experimental results suggest that the current blocking breakdown observed in the MQW BH lasers correlates with the turn-on of a diode leakage path when the devices are biased at high current injection.     

基于氟等离子体表面处理技术的AlGaN/GaN HEMT器件栅正向泄漏电流研究

The gate forward leakage current in AlGaN/GaN high electron mobility transistors(HEMTs) is investigated. It is shown that the current which originated from the forward biased Schottky-gate contributed to the gate forward leakage current.Therefore,a fluorine-plasma surface treatment is presented to induce the negative ions into the AlGaN layer which results in a higher metal-semiconductor barrier.Consequently,the gate forward leakage current shrinks.Experimental results confirm that the gate forward leakage current is decreased by one order magnitude lower than that of HEMT device without plasma treatment.In addition,the DC characteristics of the HEMT device with plasma treatment have been studied.     

Modeling and Small-Signal Analysis of a Switch-Mode Rectifier With Single-Loop Current Sensorless Control

The conventional multiloop control with one inner current loop and one outer voltage loop is often applied to a single-phase boost-type switch-mode rectifier where the output of the voltage loop is a current amplitude signal. In the duty phase control (DPC) proposed recently, the output of the voltage loop is a phase signal used to generate the switching signals without current loop and sensing current. To improve the clamped current waveform of DPC, a single-loop current sensorless control (SLCSC) with some nominal parameters had also been proposed to compensate for the voltage drops across the switch, diodes, and inductor resistance. In this paper, the effect of the differences between nominal and real circuit parameters on the input current waveforms of SLCSC are addressed in detail. The results are helpful in the design of SLCSC. From the simulated and experimental results, we can find that the output voltage is well regulated by the only voltage loop and the input current harmonics are significantly improved.