高精度超声波测距系统

本设计硬件部分采用单片机AT89C2051做CPU主控制,电路主要由发射电路,接收电路和显示电路几部分组成.本文详细介绍了各部分电路的工作原理.本系统利用超声波传感器实现无接触式空气测距,并充分考虑到测量环境温度对超声波传递速度的影响,通过温度补偿的方法对传递速度予以校正,而且可以马上检测声波在现场的传播速度并被采纳,因此具有非常高的测量精度,能实时地将测量数据上传给PC机,具有硬件结构简单、工作可靠、测量误差小等特点,现该产品已经被上海造纸机械电控技术研究所采用,已用于造纸设备的复卷机的旋转辊的位移检测上,实践证明效果很好,达到了他们所提出的各项指标.     

传递函数快速相关法的激光测速技术研究

激光技术测量是实现传送带、热轧钢板等运动物体测速的主要手段，为了改善测量精度和响应速度，提出系统传递相关分析测速技术。采用计算发射端和接收端之间两路信号的系统传递函数进行相关性分析的方法，进行了理论验证和实验分析，得到了相对误差小于0.1%的实验结果。结果表明，利用系统传递函数相关分析构建激光测速系统，代替解调电路，简化信号调理电路，可降低电路部分引起的不确定度；互功率谱函数法实现快速相关分析和频域求得系统传递函数，可提高系统响应速度；合理设置发射端间距，取样积分提高测量信噪比，降低环境引起的不确定度，测量不确定度小于0.2%。该研究对传送带速率的实时测量有一定指导意义。     

光伏并网输出滤波器的研究与设计

逆变器的输出滤波对于电网安全工作尤为重要.首先对并网逆变器的滤波器进行研究,导出了LCL滤波器的传递函数,分析了不同参数变化对传递函数的影响.其次基于电路模型、传递函数及谐波分量的特点,介绍了LCL滤波器的设计方法并给出了消振措施.最后根据并网控制系统,建立光伏并网系统的仿真模型,对系统输出进行仿真,得到较好的仿真数据,实验证明了这种LCL滤波器设计方法的优越性.     

多时钟域数据传递的FPGA实现

分析了多时钟域数据传递设计中亚稳态的产生以及对整个电路性能和功能的影响,以一款异步并行通信接口芯片的设计为例,详细描述了采用同步器、FIFO实现8位并行数据到16位并行数据的两时钟域异步转换的过程。电路在XilinxISE6.0环境下用Modelsim5.7进行了逻辑仿真,结果表明系统稳定可靠。     

一种新型椭圆低通滤波器的设计与实现

针对现有椭圆滤波器多采用查对曲线方法设计电路参数导致的滤波性能不佳,调试困难等问题[1],设计了一种新型椭圆低通滤波器.该滤波器采用高电位和地之间嫁接复电抗的方法设计电路,按照基于四端网络的分析方法获得滤波电路的传递函数.具有设计方法简单,调试方便,电路参数精确,电路稳定可靠,截止频率易于调节,并能获得较高的滤波技术指标的特点.实际应用结果表明,滤波器滤波效果较好,满足设计要求.     

Time-domain study of a shielding cable system with a nonlinear load

An impulse current of several kiloamperes was injected to the shield of a shielded cable, which was terminated by a varistor. The induced voltage on the inner conductor caused by this impulse current reaches an amplitude in excess of the varistor's threshold level. The clamped voltage across the varistor and the injected current have been studied for different termination conditions of the shielding cable. Furthermore, this paper also presents the use of a lumped circuit to simulate the transfer impedance of an “electrically short” shielded cable in the time domain. In combination with the varistor circuit model, the shielded cable with the nonlinear load, a varistor, was also simulated straightforwardly in the time domain. Good agreement was found between the measured voltage and current oscillograms and the calculated waveforms. It is thereby demonstrated the validity of the developed lumped circuit model for the transfer impedance of a shielded cable     

基于准谐振型软开关的高频开关电源变换器

传统高频开关电源变换电路采用硬开关技术,电路功耗大,承受电压、电流应力高。为了克服硬开关技术中开关管在有电流通过的情况下被强制关断,有电压情况下被强制导通而带来的各种不利因素,采用准谐振型软开关技术,即零电流开关（ZCS）准谐振变换器、零电压开关（ZVS）准谐振变换器,由电感、电容组成谐振回路,利用电感、电容之间的能量交换,使主开关管在零电压下导通或零电流下截止,达到了减少开关损耗及电磁干扰的目的。软开关技术在新型开关电源中广泛采用。     

用于线圈磁轴测量的滤波放大电路的设计改进

为了提高脉冲紧线法的测量精确度,对测量系统中的信号处理电路进行改进,首先根据电路的幅频、相频响应得出导致信号畸变的原因,然后根据理论计算得到磁轴倾斜(Tilt)导致的振动波形是基波为30 Hz的方波,磁轴偏轴(Offset)导致的振动波形是5 ms的短脉冲叠加在Tilt波形的变化沿。新的信号处理电路可以实现30 Hz~3 000 Hz之间的信号等幅放大、无相移传输,基本实现了信号基波及主要谐波的无失真传输,使测量结果中磁轴偏轴和磁轴倾斜信号容易区分,减小了测量误差。     

一种集成电路高压传输控制电路结构

集成电路设计中,用逻辑电平控制高压信号传输的情况很多,而传统的高压传输控制电路的结构过于复杂,版图面积较大且受工艺限制.介绍的电路能有效实现高压信号的传输和控制,且电路结构简单,利用两个NMOS实现了数字信号对高压信号的传输控制,大大简化了高压传输控制电路的复杂度.     

Interrelation of equivalent values for linear energy transfer of heavy charged particles and the energy of focused laser radiation

The estimations of equivalent values for linear energy transfer of heavy charged particles based on the results of experimental investigations of sensitivity of LSICs to local radiation effects with the use of the procedure of local laser irradiation are presented. The possibility of recalculation of the energy of laser radiation into equivalent values of linear energy transfer with the use of the measurements of the ionization reaction in the supply circuit of LSIC is substantiated. Uncertainties caused by the characteristics of the interaction of optical radiation with semiconductor structures are eliminated in the suggested procedure.     

一种分数阶巴特沃斯滤波器的有源电路设计

本文将分数阶的低通滤波器的传递函数通式近似设计为Butterworth滤波器,在确定阶数与截止频率之后计算得到传递函数的系数.继而,本文通过该传递函数设计电路,进行仿真并电路实现.本文设计的电路在任意阶数下都只需要修改小部分元件便可得到预计截止频率,具有很强的灵活性,方便对比研究各阶分数滤波器.     

Analysis of the Bridged T-Coil Circuit Using the Extra-Element Theorem

The bridged T-coil (BTC) circuit is often employed to extend the bandwidth of a wideband amplifier beyond the transition frequency f_T of the driver device. Although the optimal design solution is well known, extreme algebraic complexity has caused its derivation to remain arcane. This brief presents an analysis of the BTC circuit using the extra element theorem which breaks the overall problem down into a series of simple network analyses and produces the final result as the product of the transfer function without the "extra element" and a multiplicative correction factor. The design is completed by using pole-zero cancellation to reduce the order of the transfer functions     

A dual-phase-controlled dynamic latched amplifier for high-speedand low-power DRAMs

A dual-phase-controlled dynamic latched (DDL) amplifier for a differential data transfer scheme designed to achieve both high speed and low power in DRAMs is described. This circuit reduces the excessive operating margin caused by device fluctuations by using a pair of dynamic latched amplifiers, controlled by a dual-phase clock, to automatically correct the output data. Two circuit technologies are used in the DDL amplifier to achieve 200-MHz operation in a 1-Gb SDRAM using 0.13-μm technology: a cycle-time-progressive control circuit that increases the operating frequency and a shared DDL amplifier technique that reduces the area penalty of the DDL amplifier. These techniques and circuits reduce the access time to 10 ns, which is 1.2 ns less than that of the conventional dynamic amplifier, while also reducing the operating current to less than 10% that of the static amplifier     

改善高精度数字闭环光纤陀螺阈值方法研究

研究了改善高精度光纤陀螺阈值的方法,提出导致阈值增大的原因是陀螺存在死区,而死区主要由调制解调电路中的电子交叉耦合干扰引起。对光纤陀螺仪的数字闭环传递模型进行了修正,增加了反馈通道对前向通道中探测器输出信号的电子交叉耦合干扰项,并利用此模型对死区进行了实时动态仿真,仿真分析结果基本和实验现象吻合。与采取随机调制的方法不同,本文主要采取优化电子电路设计、改善电路电磁兼容性等方法抑制死区,同样取得了较好的效果。提出了一种新的测试光纤陀螺仪的阈值方法,测试结果表明,优化设计后,陀螺仪的阈值与陀螺的噪声水平相当。     

一种基于低温共烧陶的无引线键合封装

为提高微机电系统(MEMS)加速度计的可靠性,减小因为引线键合断裂造成的传感器失效,该文设计了一种基于低温共烧陶瓷的无引线键合封装。该封装采用阳极键合技术将低温共烧陶瓷基板与芯片连接,同时将电路转接板同步集成。结果表明,该封装结构可减小传感器的封装尺寸,有效提高了MEMS加速度计的可靠性。     

A Method of Transformation from Symbolic Transfer Function to Active-RC Circuit by Admittance Matrix Expansion

Active-RC circuits containing 2-terminal linear passive elements and ideal transistors or operational amplifiers are derived from symbolic voltage or current transfer functions by admittance matrix transformations without any prior assumption concerning circuit architecture or topology. Since the method is a reversal of symbolic circuit analysis by Gaussian elimination applied to a circuit nodal admittance matrix, it can generate all circuits using the specified elements that possess a given symbolic transfer function. The method is useful for synthesis of low-order circuits, such as those used for cascade implementation, for deriving alternative circuits with the same transfer function as an existing circuit or for realizing unusual transfer functions, as may arise, for example, where a transfer function is required that contains specific tuning parameters     

专用VXI总线嵌入式计算机1150通讯故障排除

计算机通讯异常问题,有的是由于电磁干扰引起的,有的是由于设计不完善造成的。设计不完善大都是接口电路不匹配,电路参数选取不当造成。本文介绍了专用VXI总线嵌入式计算机1150外围电路电容值没有按推荐电路要求选取,而产生的通讯异常问题。说明采用推荐电路一定要确保电路的各项参数满足推荐电路要求,并应留有余量。     

备用发电机组的接地和中性线的转换

分析了传统的采用3极转换开关的转换电路存在的问题；介绍了采用4极转换开关的转换电路；最后提出了关于备用发电机组接地和转换开关选择的建议。     

一种新的不受寄生电容影响的电容式传感器接口电路

给出了一种新的用于微小电容检测的接口电路 .在电荷传送电路的基础上,引入了一个用于参考微变电容读出的电荷传送电路部分,将检测电路与参考电路的输出进行差分放大,从而大大提高了电路的稳定性和检测灵敏度,同时此电路也保持了电荷传送电路检测微小电容变化不受寄生电容影响的特性.     

Small signal equivalent circuit modeling of resonant converters

A general analytical procedure is presented for the equivalent circuit modeling of resonant converters, using the series and parallel resonant converters as examples. The switched tank elements of a resonant converter are modeled by a lumped parameter equivalent circuit. The tank element circuit model consists, in general, of discrete energy states, but may be approximated by a low-frequency continuous time model. These equivalent circuit models completely characterize the terminal behavior of the converters and are solvable for any transfer function or impedance of interest. With the approximate model it is possible to predict the lumped parameter poles and zeros, and to quickly determine the relevant DC gains of the output impedance and the control to output transfer function. Closed-form solutions are given for the equivalent circuit models of both converter examples. Experimental verification is presented for the control-to-output transfer functions of both series and parallel resonant converters, and good agreement between theoretical prediction and experimental measurement is obtained