基于Howland电流源产生更优线性度三角波的设计

针对三角波发生器性能的改善,按照对方波电流进行积分的拓扑结构,设计了一种基于方波电压控制的Howland电流源积分电路。理论分析验证了设计的正确性,证明了产生波形为线性对称三角波。实验结果表明,Howland电流源恒流误差小于微安级,产生三角波较常用发生器在测试频段内具有最小二乘评价法下更优的线性度和对称性,且频率和幅值均可灵活地进行调节。实现方法结构简单、硬件开销小、产生波形标准、具有很好的应用价值。     

A Simple Schmitt Trigger Circuit with Grounded Passive Elements and Its Application to Square/Triangular Wave Generator

This paper introduces a new simple Schmitt trigger circuit using a plus-type differential voltage-current conveyor (DVCC+) and only two grounded resistors. The proposed circuit is very simple and enjoys adjustable lower and higher threshold voltages as well as the output saturation levels. The application of the proposed Schmitt trigger circuit to the square/triangular wave generator is also given. Moreover, a current feedback operational amplifier (CFOA)-based square/triangular wave generator is derived from the proposed DVCC+-based circuit. Simulation and experimental results are presented to exhibit the performance of the proposed circuits.     

基于FPGA与AD5422的多功能信号发生器的设计

设计了一种以FPGA为核心,基于AD5422实现的高精度多功能信号发生器。该方案能够输出方波、正弦波、三角波、恒压、恒流等多种波形的电压、电流信号,其频率、幅值等在一定范围内任意可调。并设计了人机交互接口,使得系统的控制操作直观方便、容易上手。经调试所设计的信号发生器能够满足设计要求。相对于传统的信号发生器,本系统有处理速度快、方便、灵活、抗干扰能力强等优点。     

用ispPAC20和isp1032实现可编程逐次逼近式A/D转换器的研究

ispPAC20在系统可编程模拟器件集放大器、比较器、D／A转换器为一体、方便地完成放大器、有源滤波器、方波发生器等模拟电路单元的设计。还可将其与isp1032结合实现可编程的逐次逼近式A／D转换。本文给出了一个设计,它具有控制灵活,可8方便地嵌入到电子系统设计中的优点。     

Tunable active network synthesis using ICCIIs

In this work, new tunable basic building blocks employing inverting second-generation current conveyors (ICCIIs) are presented for analogue signal processing. Using two different approaches, ICCII-based tunable active circuit design can be performed. The first approach is the use of MOSFETs operating in the triode region, which are connected between the Y and X terminals of the inverting conveyors. In this case, thanks to the inverting property of ICCIIs, the triode MOSFETs operate very linearly since they receive a balanced differential voltage between their drain and source terminals. In the second approach, the conveyor is modified to a current controlled one (ICCCII), for which, the intrinsic series parasitic resistance of the X terminal (R _X ) is adjustable via a biasing current.     

基于AT89C52单片机的超低频信号发生器设计

设计以单片机AT89C52为核心的超低频信号发生器,详细介绍该信号发生器的工作原理、硬件电路、软件流程及技术关键。实际应用表明,该信号发生器可以产生频率、峰谷值可调的、连续的方波、三角波和正弦波,输出信号的频率范围为0.125 mHz（毫赫兹）80 Hz,幅值为-10＋10 V。与传统信号发生器相比,具有输出波形稳定和低频精度高的特点,对于超低频信号发生器的设计具有重要的参考价值。     

On practical construction of electronically controllable compact current amplifier based on commercially available elements and its application

This paper presents a new concept of a current amplifier (CA) with electronically adjustable features (input resistance and current gain) implemented using commercially available devices. Several variations of basic structure are studied, described and the selected solutions verified by PSpice simulations and, moreover, also by lab experiments. Saving one discrete active device in comparison to already known similar topologies of single-input and single-output version (CA-SISO) is significant benefit whereas all other qualitative features remain very similar to previously reported ones. Simple modification of CA concept to multiple-output version (CA-SIMO), having independent adjustable current gain in each of output branches, is easily available. Experimental tests of features of discussed concepts yield adjustability range of input resistance from 100 Ω to more than 10 kΩ and current gain adjusting from 0.1 to 3.5 with bandwidth (−3 dB) of CA transfer response up to 16 MHz. As an example of application, proposed CA was successfully implemented in quadrature oscillator with a very wide tunability range from 29 kHz to 4.94 MHz. It was achieved by electronic control of several adjustable parameters of proposed CA.     

基于DA1230的锯齿波信号发生器的设计

信号发生器作为常用的信号源,被广泛的应用在生产实践、通信、电子测量系统及教学实验等领域。因此,如何设计经济且高效的信号发生器已成为电子测试领域的热点问题。本文采用AT89C51作为主控制器,利用DA1230将数字信号转换成模拟信号来实现锯齿波的产生。本文要求该系统产生的锯齿波幅值为0V-5V,频率为100Hz-1000Hz可调,幅值及频率实时显示。     

Modeling and experimental analysis of an antagonistic energy conversion using dielectric electro-active polymers

Dielectric Electro Active Polymers (DEAP) have shown potential features to be applied into the wave energy harvesting purpose. However, current studies of DEAP in generator mode have not sufficiently provided perfect solutions for practical applications. This paper gives a detailed analysis on an antagonistic energy converter (AEC) using two DEAP generators for wave energy application. Firstly, an accurate model of conventional DEAP generator is investigated and compared with that of Neo-Hookean model. Then, the new AEC structure, which consists of two DEAPs in antagonistic connection mode to increase the harvested energy, is introduced. Elastic forces in relaxation phase of one DEAPs are employed to stretch the remained DEAP. Consequently, the required input mechanical energy for each DEAP in AEC is lower than one of conventional DEAP generator. A physical model DEAP generator is also developed for practical operating conditions. Here, electromechanical model of proposed structure is investigated to analyze the performance of the proposed structure. Finally, experiments have been carried out to investigate the performance of the AEC and energy conversion processes. Favorable results e.g. the good agreement between experiments and the modeling results, significant higher energy harvesting efficiency, compact design, and smoother output energy waveforms show great potential to apply the new AEC in real wave energy application.     

Compact discrete-time chaos generator circuit

A three-transistor CMOS circuit is presented, with adjustable nonlinear characteristics, which can be used as a map that generates discrete-time chaotic signals. A method of constructing a chaos generator using two map circuits is also proposed. The circuit is very compact, which makes it suitable for applications requiring the integration of a large number of random signal generators on a single VLSI chip.     

25 kV高压可调直流发生器的研制与仿真实验

为研究直流高压发生器对镁铝材料晶粒细化的作用机理,文中对传统直流高压发生器体积大、工作稳定性差、电压不可调等不足进行改进,设计了一种25 kV可调高压直流发生器。所设计的可调直流高压发生器采用了线性稳压技术和倍压整流技术,能产生范围宽、稳定性高的电压输出,使其具有较强的通用性、安全性、经济性。通过实验与仿真分析,在0.1 ms时间内,直流可调高压发生器最大输出功率为12.5 W,通过分压器输出稳定幅值为25.2 kV的直流高压,且输出电压可调范围为14.2～25.2 kV,表明直流可调高压发生器可满足设计要求。     

基于可编程控制器多谐振荡器的设计与分析

在数字电路中,常常需要一种不需外加触发脉冲就能够产生具有一定频率和幅度的矩形波电路,特别是要求频率和占空比可调的这种电路,它就是多谐振荡器.文章采用可编程控制器来设计完成该功能,它具有设计简单,完成方便,频率和占空比用软件就可调试,不需要对电路重新组装的特点.     

基于CPLD的可调频波形发生器的设计

该波形发生器是以CPLD(复杂可编程逻辑控制器)为核心部件,辅以输入控制、D/A转换及数码显示等模块,利用VHDL语言在MaxplusⅡ软件中完成设计,可以输出递增斜波、递减斜波、三角波、阶梯波、正弦波及方波等6种波形信号。文中介绍了在CPLD上产生上述信号的基本原理,并对该波形发生器与传统波形发生器的优缺点进行了分析。     

基于液晶的太赫兹可调谐超材料吸波体

文中设计了一种液晶太赫兹电控超材料吸波体,通过外部电场改变液晶层的等效介电常数,实现对于太赫兹反射波的调控。对器件的传输性能进行计算,分析了谐振频点处的表面电流分布和能量损耗密度情况。采用紫外光刻以及湿法刻蚀技术,制作了30×30单元超材料吸波体阵列并对其进行测试验证。结果表明,当偏置电压在0~30 V之间变化时,吸波体的谐振频点可实现101.5~117.95 GHz范围内的动态调控,综合可调率达到13.9%,整个工作频段内,吸收率始终维持在90%以上。     

风力发电变桨电机用动力软电缆的研制

风力发电变桨电机用动力软电缆是中央变桨控制柜与变桨电机之间的动力电源线,其安装在风力发电机的轮毂内。详细介绍了风力发电变桨电机用动力软电缆的应用场合和使用要求、产品结构设计和选材、生产工艺流程,并与国外同类产品进行了比较。所研制的变桨电机用动力软电缆在1．5Mw变桨风力发电机组的变桨自动控制系统中使用了一年多,运行稳定可靠。     

High-Performance Flexible Schottky DC Generator via Metal/Conducting Polymer Sliding Contacts

Dynamic Schottky direct-current (DC) generators hold great promise for ambient mechanical energy harvesting as it overcomes the low-current output limitation in conventional approaches. However, the lack of a fundamental understanding of DC generation in conducting polymer-based Schottky generators has hindered their application for self-powered wearable and implantable electronics. Here, a high-performance, flexible Schottky DC generator with metal/conducting polymer sliding contact system is demonstrated, which exhibits a large current density (J) up to 20 A m^–2 for single contact geometry and a scaled-up DC output reaching 200 µA (J = 0.73 A m^–2) and 0.8 V. The design of flexibility in such a Schottky DC generator is inherited from the long-chain polymer concept, leading to the demonstration of a variety of device configuration of free-standing thin film, supported thin film and nanocomposite prototype toward practical applications. It is revealed that the sliding junctions may exhibit a different mechanical energy conversion mechanism compared to the compressive conducting polymer Schottky junctions. It is also proven that the magnitude and polarity of DC generation is determined by the Schottky contact formation and interfacial electric field. The concept of a flexible Schottky generator not only shows great promise for next-generation, self-powered wearable devices, but also provides potential mechanisms for developing novel wearable sensors.     

Magnetic flux compression Generators

Magnetic flux compression generators offer the largest pulsed power output per unit size or weight when compared with other more conventional systems. They have found widespread use as pulsed power sources for hydrodynamics programs and high magnetic field research at national laboratories or in commercial applications, including exploration for oil and minerals and mine detection. Also, due to their nature as a true one-time-use device with superior energy density, a large portion of applications is defense related. A variety of basic magnetic flux compression generator designs have been developed and tested during the past four decades. All of them rely on the explosive-driven deformation of a system of conductors having an initial, preferably large, inductance. The most successful basic design is the helical flux compression generator, which is capable of producing a high-energy output into large impedance loads, just as it is needed for a practical pulsed power source. This paper will review the advances and state of the art of primarily helical magnetic flux compression generators mainly developed as pulsed power sources and will offer new insights gained as a result of a recently completed five-year AFOSR/DoD Multidisciplinary University Research Initiative program that studied the basic physics and engineering aspects of helical flux compression generators.     

Current-mode square wave generators based on a single CDTA

This paper proposes two designs for current-mode square wave generators based on a current-differencing transconductance amplifier (CDTA). Both the proposed circuits are compact and employ a single CDTA with only two external passive components. The first circuit has a fixed duty-cycle topology and can generate a symmetrical square wave with variable frequency. The second circuit has a variable duty-cycle design and can operate in a current-controlled dual duty-cycle mode with a single-circuit topology. The proposed generators allow independent control of the operating frequency, output amplitude, and duty cycle by tuning diverse circuit parameters. This paper discusses several previous designs for square wave generators and presents the circuit principles, related governing formulas, and nonideal problems for the proposed circuits. In addition, computer simulations and experimental results, which are consistent with those of the theoretical analyses and confirm the feasibility of the new generators, are presented.