测试传导性干扰的模态噪声,是设计电磁干扰(EMI)滤波器的前提条件。共模扼流圈能够抑制共模模态,而不影响差模电流的输出。根据共模扼流圈这一特点,设计一种由两个共模扼流圈为核心的共模/差模分离网络,实现共模电压和差模电压的同时输出。仿真结果表明,在150 kHz~30 MHz的测试频带,输入端口阻抗基本在50Ω,并且共模传递比(CMTR)、差模抑制比(DMRR)、差模传递比(DMTR)及共模抑制比(CMRR)四个结果显示了该分离网络的良好模态分离效果。

Testing for conducted electromagnetic interference is a precondition for design of EMI filters. The common mode choke can reject the common mode(CM)modal,but does nothing with the output of differential mode(DM)current. According to this characteristic of CM choke,a novel separation network for CM and DM EMI was designed to carry out the voltage output of both CM and DM,which consists of two common mode chokes. The simulation results indicates that the input impedances holds on 50 Ω at the frequency range of 150 kHz~30 MHz. The four results of CM transmission ratio(CMTR),DM rejection ra-tio (DMRR),DM transmission ratio (DMTR) and CM rejection ratio (CMRR) revealed the perfect mode separation perfor-mance of this separation network.

本文介绍了基于CSMC 0.5μm CMOS工艺的仪表放大器电路设计，该仪表放大器是心电信号放大电路的重要组成部分。本文设计的仪表放大器电路结构在前人的基础上进行了细微的改进，减少了专门给补偿电路提供电压偏置的9个MOS管，并保持原有的功能和指标不变。仿真结果表明，本文介绍的仪表放大器可通过片外电阻调节增益，放大倍数为14倍时，3dB 带宽为380kHz，共模输入范围为-1.4V至1.4V，共模抑制比和电源抑制比均远大于100dB。

This paper describes the instrumentation amplifier circuit design based on the CSMC 0.5μm CMOS technology. The instrumentation amplifier is a important component of ECG amplifier circuit. The circuit structure in this paper has been improved slightly on the basis of the others’ previous work.The voltage bias which consists of nine MOS tubes for compensation circuit is reduced while original features and indicators do not change.The simulation shows that:this instrumentation amplifier can adjust its gain by the out-chip resistance and 3dB bandwidth is 380kHz when magnification is 14. Its common-mode input range is -1.4V to 1.4V. CMRR and PSRR is larger than 100dB.

基于近红外(near-infrared,NIR)光谱,提出一种血液酒精的检测方法,并设计一种低噪声、低漂移、高精度的前置预放大电路,该电路用于准确检测血液中酒精的体积分数。在本设计电路中的电流电压转化部分,选择使用2种电路对比的方法,通过Multisim电路仿真软件模拟来比较电路的漂移和误差,同时利用Matlab进行数据处理;预放大电路部分利用高共模抑制比的AD620设计了差分放大电路,来提高电路的共模抑制比(common mode rejection ratio,CMRR)。结果表明,使用对称补偿型低温漂电流电压变换电路,能够很好的抑制漂移降低误差,与常用的OP07电流电压转换电路相比,可降低误差约2%,可降低漂移约97%,为微弱信号的处理提供了依据。

A blood alcohol detection method was investigated based on NIR(near-infrared) spectroscopy.And a low-noise, low-drift and high-precision preamplifier was designed to detect the blood alcohol volume fraction accurately.In the current-voltage conversion section, the simulation of drift and error of two kinds of circuits were carried out by Mul-tisim software.AD620 was selected in the preamplifier part which could improve the CMRR(common mode rejection ratio) of circuits.The results of simulation showed that the current-voltage conversion circuit of symmetrical compensa-tional low-temperature drift can suppressed the drift and reduced error better.Compared with the OP07 current-voltage conversion circuit, the error could be reduced by 2%, while the draft could be reduced by 97%, which could support weak signal analyzing.

微波源工作时内部的电磁干扰可以通过电源输入线耦合出来,干扰其他电力电子设备。研究三相输入电源线的传导干扰文献很多,但分离的共模(CM)和差模(DM)电流局限于相线之间,缺少对中线上干扰的分析。使用电流探头测试3 kW磁控管微波源输入线的传导干扰,利用矢量网络分析仪校准电流探头,从而获得150 kHz~30 MHz频带内相线和中线的传导干扰电流,并分离出CM电流与DM电流。通过对比DM电流和中线上干扰的频谱,分析了中线上传导干扰成分。测试数据表明,在150 kHz~8 MHz频带内差模干扰电流比共模干扰电流大10 dB以上;中线上的干扰与DM干扰幅值一致,表明中线上的干扰主要是差模成分。该干扰分布规律有助于提出有效的干扰抑制手段。

Electromagnetic interference ( EMI) inside the microwave source case can couple outside along the power lines to affect other power electronic equipment when it is working. There exists many literatures for research on conducted EMI of the three-phase input power lines, in which the separated common-mode ( CM) current and differential-mode ( DM) current between three-phase lines are only considered, but the analysis of conducted EMI on neutral line is absent. In this paper,a current sensor, which is cali-brated in a vector network analyzer, is used to measure the conducted EMI of 3 kW magnetron microwave source power lines, then the interference current on phase line and neutral line at 150 kHz~30 MHz is ob-tained, and the CM and DM current is separated. EMI mode on the neutral line is analyzed by comparing the DM current spectrum with the interference spectrum on the neutral line. The tested data shows that DM interference magnitude is above 10 dB larger than CM interference at 150 kH

搭建了一套基于铥钬共掺光纤的激光放大系统,包含1个2μm增益开关主振荡器和一级铥钬共掺光纤放大器.获得了平均功率大于300 m W的2μm脉冲输出,放大器平均功率增益达11 dB ,放大斜率效率达30％,这些性能指标与双包层掺铥光纤放大器相当.输出脉冲重频在40 kHz时,最高脉冲能量为7.27μJ ,脉宽88 ns ,对应的峰值功率为82.6 W .放大过程中,激光光谱宽度小于0.3nm,边模抑制比大于35dB.

A Tm-Ho codoped fiber amplifier system is built , and it?s amplification properties are investigated . The results show that an average output power of 300 mW is obtained with an amplification gain bigger than 11 dB , w hich is comparable with that of the 793 nm pumped Tm-doped double clad fiber ,and the maximum pulse energy generated is about 7 .27 μJ with a pulse duration of 88 ns ,corresponding to a peak power of 82 .6 W at repeti-tive rate of 40 kHz . During the amplification process , gain-switching and gain-switched mode-locking are observed , the laser output enjoys a narrow linewidth of no bigger than 0 .3 nm ,and the side-mode suppression ratio is bigger than 35 dB .