Modeling and improved current control of series resonant converterwith nonperiodic integral cycle mode

A dynamic modeling and an improved current control technique for a series resonant power converter with nonperiodic integral cycle mode are proposed to overcome the disadvantages of an integral cycle mode-controlled series resonant converter. The internal operational characteristics, are investigated in detail and an improved current control technique is developed based on this analysis. Using the proposed control technique, the minimized current ripple with reduced offset current and the fast transient response with negligible overshoot can be obtained. Furthermore, the continuous output voltage levels can also be available by accurately controlling the average filter input current. The usefulness of the proposed technique is verified through computer simulations and experiments     

A power efficient gain enhancing technique for current mirror operational transconductance amplifiers

In this paper, a power efficient voltage gain enhancing technique is described. This technique is suitable for the amplifiers which use current starving method for gain enhancement (explained in the text). The proposed technique makes use of the current which conventionally goes to ground, through a parallel path. In this paper, the new technique is demonstrated for current mirror type of operational transconductance amplifier (OTA). Simulation results show that gain improves by a factor ~2, while consuming the same power as conventional OTA. The added advantage of this technique is that it does not affect the voltage swing while increasing the gain. Compared to the conventional current starving technique, the proposed technique also improves the noise performance and settling speed of the amplifier. The results are compared with the conventional technique, in terms of gain, settling and noise performance. A comparison of FoM (MHz.pF/mA), with other amplifiers, is given at the end as well.     

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     

Tiny-scale “stealth” current sensor to probe power semiconductor device failure

“Stealth” electric current probing technique for power electronics circuits, power device modules and chips makes it possible to measure electric current without any change or disassembling the circuit and the chip connection for the measurement. The technique consists of a tiny-scale magnetic-field coil, a high speed analog amplifier and a digitizer with numerical data processing. This technique can be applied to a single bonding wire current measurement inside IGBT modules, chip scale current redistribution measurement and current measurement for surface mount devices. The “stealth” current measurement can be utilized in the failure mechanism understanding of power devices including IGBT short circuit destruction.     

A Simple Current Collapse Measurement Technique for GaN High-Electron Mobility Transistors

Current collapse in GaN high-electron mobility transistors (HEMTs) is a temporary reduction of drain–current immediately after the application of high voltage. Current collapse limits the output power of the device at high frequencies. Oftentimes, a signature of device degradation is an increase in current collapse. In order to improve the GaN HEMT performance and reliability, understanding the current collapse phenomenon is critical. In this letter, we propose a simple technique to measure current collapse that utilizes common dc device characterization equipment. Our proposed technique produces consistent measurements when compared with the conventional but highly specialized pulse technique. Underlying our proposed technique is the recognition that in a transient current measurement, the traps that produce current collapse have detrapping time constants on the order of seconds.      

Accurate submicroampere controlled current source

A bipolar design technique for a submicroampere current-controlled current source which employs low value resistances and is integrable using standard monolithic processing is described. The circuit is self-starting and provides linear current/voltage control of the output current with higher accuracy and temperature stability than a recently reported technique.     

BUCK变换器的一种多环控制研究

文中研究了一种具有快速动态响应的多环控制方法,介绍了多环控制方法的工作原理,并建立了器件模型,利用Matlab的Power System Blockset对该模型的特性进行了时域仿真,并将仿真结果与传统的电压型。电流型控制方法进行比较,对分析结果进行了验证。     

一种用于电流舵DAC的开关顺序优化技术

提出了一种用于电流舵DAC的开关顺序优化技术。首先,将高位电流源阵列拆分成四个部分并位于四个象限中,在每个象限中采用开关顺序优化技术消除电流源阵列由PVT变化而带来的二阶梯度幅值误差;其次,对开关顺序优化后的电流源阵列根据幅值变化进行排序并重组,形成最终的电流源及开关顺序,消除了一阶梯度幅值误差和其他残余误差。与常规开关顺序优化技术相比,该技术能更有效地降低幅值误差,提高了DAC的静态性能。为了验证提出的开关顺序优化技术,基于40 nm CMOS工艺制作了一个12位200 MS/s采样频率的电流舵DAC。测试结果表明,实施开关顺序优化技术的DAC的INL、DNL分别从0.63 LSB、0.37 LSB降低到0.54 LSB、0.25 LSB。     

一种用于电流舵DAC的SDR校正技术

提出了一种基于电流舵DAC的SDR校正技术。首先采用拆分电流源的方法,增加了待校正电流源的个数。然后采用动态组合的方式,减小了电流源的失配误差,提高了DAC的静态与动态性能。与DMM校正技术相比,该SDR校正技术具有更小的残余误差、更好的静态与动态性能。采用40 nm CMOS工艺实现了一种14位200 MS/s的电流舵DAC,并进行了仿真。结果表明,通过数字校正,该DAC的INL与DNL分别从1.5 LSB和0.5 LSB降低到0.33 LSB和0.25 LSB,SFDR在整个Nyquist带宽内均大于70 dB。     

Measurement of ultralow gate tunneling currents using floating-gate integrator technique

We report for the first time that a gate tunneling current measurement sensitivity better than 3/spl times/10/sup -22/ A has been achieved by using a floating-gate integrator technique. The technique involves monitoring the charge change in the floating-gate integrated with an on-chip op-amp and an on-chip feedback capacitor. We used this technique to study the stress-induced leakage current (SILC) and its cycling dependence of 70 /spl Aring/ oxides in the direct tunneling region at oxide voltage as low as 1.9 V. The technique has been validated through correlation to direct measurement on MOSFET arrays and theoretical calculations. The measured SILC current is modeled with an Inelastic trap-assisted tunneling model.     

大容量并联型有源电力滤波器的软启动技术

分析大容量并联型有源电力滤波器的系统模型和工作特点的基础上,提出了大容量并联型有源电力滤波器软启动的方法。电流环软启动通过输出电流指令递增实现,电压环软启动则比较了直流侧电压指令逐步升高法、恒定电流充电法、变PI参数调节法三种策略。实验结果表明并联型有源电力滤波器投入电网时直流侧电压上升平稳无超调,输出电流也无冲击现象,证明此软启动方法是有效的。     

A new gate current extraction technique for measurement of on-statebreakdown voltage in HEMTs

We present a new simple three-terminal technique for measuring the on-state breakdown voltage in HEMTs. The gate current extraction technique involves grounding the source, and extracting a constant current from the gate. The drain current is then ramped from the off-state to the on-state, and the locus of drain voltage is measured. This locus of drain current versus drain voltage provides a simple, unambiguous definition of the on-state breakdown voltage which is consistent with the accepted definition of off-state breakdown. The technique is relatively safe and repeatable so that temperature dependent measurements of on-state breakdown can be carried out. This helps illuminate the physics of both off-state and on-state breakdown     

A novel current-assisted output voltage control technique forswitch-mode-rectifier converters

A current-assisted voltage control technique for high-power switch-mode-rectifier (SMR) converters is proposed. This technique implements a fast-forward AC current loop by sensing the current through the output filter capacitor. The control loop forces the AC current component of the output filter inductance to be synchronized with a symmetrical triangular reference waveform. As a result, the converter behaves like a fixed-frequency current-regulated voltage source with a low-output impedance and an increased bandwidth. A small-signal linear model is derived and the dynamic performance of a buck-derived SMR using the proposed control technique is analyzed. Simulation and experimental results are presented     

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.     

电子装置的过压和过流保护与器件

阐述了电子装置过压、过流的三维防护技术，结合三维防护技术论述了浪涌保护系统和浪涌保护器件，介绍了过压、过流保护新器件的发展和应用。     

开关电流技术：一种新的模拟抽样数据处理方法

开关电流（ＳＩ）技术是一种新的模拟抽样数据处理技术，介绍了开关电流电路的基本单元结构，讨论了目前开关电流技术中存在的问题及其解决方法。对开关电流技术与开关电容技术的一些基本特征进行了比较，ＳＩ技术不仅结构简单，而且与标准ＣＭＯＳ工艺兼容，可望替代开关电容电路。     

Determination of AlGaAs/GaAs HEMT parasitic resistances

An improved technique has been developed to measure source and drain parasitic resistances of AlGaAs/GaAs HEMTs. Similar to the measurement technique typically used for MESFETs, a positive d.c. gate crowding current is applied. Because of the structure of the HEMT, this gate current must be kept very small in order to prevent significant leakage into the AlGaAs layer, which would result in current paths not present in normal operation of the device. The small d.c. gate current necessary to limit the current in this leakage path did not yield a usable signal-to-noise ratio of the measured gate-source, gate-drain and drain-source voltages needed to calculate the parasitic resistances. To overcome this problem, modulation of the drain current with a low-frequency a.c. signal coupled with lock-in techniques to measure the desired voltages was implemented. The resulting improvement in signal-to-noise ratio has made the gate crowding technique suitable for measuring the parasitic resistances of AlGaAs/GaAs HEMTs.     

Efficient current reuse for low-power transceivers

Current boosting is a method where the performance of an active circuit block is optimized by placing a constant current source in parallel with the active signal path to provide optimal biasing for different components. In this paper, a technique to replace the constant dc current source with active building blocks typically required in transceivers is proposed. By using this method the total current consumption of the transceiver can be efficiently reduced without modifying its performance. A design example where the proposed technique reduces the receiver current consumption by 45% is given.