查询词典 pre-amplifier

S1 is then changed to position 1. The voltage stored on C1 is inserted between the output and inverting input of the amplifier and the output of the amplifier changes by VIN to maintain the amplifier input at the input offset voltage. The output then changes from (VOS + IbiasR2) to (VIN + IbiasR2) as S1 is changed from position 2 to position 1. Amplifier bias current is supplied through R2 from the output of the amplifier or from C2 when S1 is in position 2 and position 1 respectively. R3 serves to reduce the offset at the amplifier output if the amplifier must have maximum linear range or if it is desired to DC couple the amplifier.

接着 S1 拨到位置 1，使 C1 的电压加在放大器的输出端和反相输入端之间，(由于电容端电压不能突变，所以)输出端的电压将产生大小等于 VIN 的变化，使放大器输入端维持输入失调电压，即当开关 S1 从位置 2 拨到位置 1 时，输出端电压将从(VOS + IbiasR2)变为(VIN + IbiasR2)。S1 处于位置 2 时，放大器的偏置电流是由输出端经电阻 R2 提供的，当 S1 转向位置 1 时则由 C2 提供。R3 的作用是降低输出失调电压，如果要求放大器具有最大的线性范围，或者采用直流耦合，就应该使用该电容。

The invention discloses a DC/DC circuit, comprising a PWM controller, a current amplifier, a peak current comparator, an error amplifier, a main switch, a synchronous switch and also an operational amplifier. The non inverting input end of the operational amplifier is used for coupling with input voltage or voltage reference, or used for coupling with the input voltage and the voltage reference; the inverting input end of the operational amplifier is used for coupling with the voltage reference or ground, and the output end thereof is connected with the non inverting input end of the error amplifier.

本发明公开了一种DC/DC电路，包括PWM控制器、电流放大器、峰值电流比较器、误差放大器、主开关和同步开关；还增设运算放大器，其同相输入端用于与输入电压或基准电压耦合，或用于同时与输入电压和基准电压耦合；其反相输入端用于与基准电压或地耦合，其输出端与所述误差放大器的同相输入端连接。

This kind of technology can flex the application of optical amplifier so that a same adaptive amplifier can be used as a pre-amplifier, a boost amplifier as well as a line amplifier.

在光标记交换系统中，可满足由于路由切换导致的光功率损耗大范围动态变化的应用需求。

In the method of the invention, a baseband signal is pre-processed to realize nonlinearity compensation. The pre-processing method comprises the following steps: the filter coefficient and the multinomial coefficient of the high power amplifier are extracted; corresponding gain is calculated for the amplitude value of each point input into the sequence of the baseband signal, and the phase compensation value is calculated according to the amplitude gain; the phase compensation value and the gain which are corresponding to each point are synthesized into re-gain, a pre-processing value pi is obtained, and pre-processing output sequence is formed; the pre-processing output sequence is output into the high power amplifier directly or through a inverse filter.

本发明方法是将基带信号进行预处理来实现抵偿非线性，预处理方法是：提取出高功率放大器的滤波器系数和多项式系数；对输入基带信号序列中的每一点的幅值计算对应的增益，根据幅度增益计算出相位补偿值；每一个点对应的相位补偿值与增益合成复增益，得到预处理值p i ，构成了预处理输出序列；将预处理输出序列直接或经过反向滤波器后输出到高功率放大器中。

When aborted rats were injected with 10 IU/g IFN-γin group D, compared with group A, expression of TNF-αinmmuopositive substance in the nucleus pre-opticus medialis, nucleus supra-opticus, nucleus pre-opticus mango celluaris, nucleus periventricularis hypothalami, nucleus paraventricularis hypothalami, nucleus arcuatus hypothalami were highly increased, conversely, the ones in the nucleus pre-opticus suprachiasmaticus, neurohypophsis, adenohypophysis, ovary were obviously decreased, the change in the uterus was not remarkable; Compared with group B, expression of TNF-αin the arcuatus hypothalami was obviously enhanced, while in the nucleus pre-opticus suprachiasmaticus, nucleus pre-opticus mango celluaris, nucleus periventricularis hypothalami, nucleus paraventricularis hypothalami, nucleus ventromedialis hypothalami, nucleus dorsomedialis hypothalami, neurohypophsis, pars intermedia, ovary, the results were on the contrary, the uterus had no significantly variation; Compared with group C, expression of TNF-αin the nucleus pre-opticus medialis, nucleus supra-opticus, nucleus paraventricularis hypothalami, nucleus arcuatus hypothalami, adenohypophysis and pars intermedia had an obviously risen trend, however, the variation in the nucleus pre-opticus suprachiasmaticus, nucleus periventricularis hypothalami, neurohypophsis, pars intermedia, follicle and corpus luteum was completely opposite, uterus had no obviously change.

外源腹腔注射10 IU/g IFN-γ后，同A组相比：D组TNF-α免疫阳性产物在下丘脑视前内侧核、视上核、视前大细胞核、室周核、室旁核、弓状核显著增高，在视交叉上核显著降低，在其它核团较A组无显著差异，在神经垂体、垂体前叶、卵巢中阳性产物表达均较A组显著降低，在子宫中的表达较A组变化不明显；同B组相比：D组TNF-α免疫阳性产物在弓状核显著增高，在视交叉上核、视前大细胞核、室周核、室旁核、腹内侧核、背内侧核、神经垂体、垂体中间部、卵巢各部阳性物质表达均显著降低，在子宫表达变化不显著；同C组相比：D组下丘脑视前内侧核、视上核、室旁核、弓状核、垂体前叶与中间部均显著增高，在视交叉上核、室周核、神经垂体、卵泡、黄体中均显著降低，子宫中表达变化不明显。

Later, it makes some comparison with four kinds of modulation technique, and finally, it implements the three-level PWM switching power amplifier with the PWM technique. The power of the amplifier is 2kVA, and the frequency bandwidth is 10～3kHz. In the thesis, the author designs and makes the hardwares of the switching power amplifier. The hardwares contain power inverter rank circuit, control system circuit based on DSP, drive and isolation circuit, and protective circuit. The thesis also analyses the potential safety problems and put forward some solutions for the problems. Furthermore, the thesis accomplishes the software design of the control system, and successfully debugs it. The methods of designing higher power ampilfier are also discussed in the thesis. It analyses the feasibility of the methods, outlines the way of how to design higher power switching power amplifier, and does some experiments with the method of switches-parallelling.

根据电动振动试验系统对开关功放的要求，提出了以电感电流瞬时值控制技术为基础的三电平脉宽调制开关功放的设计方案，并通过系统仿真进行了原理性论证；然后设计并制作了开关功放的硬件，包括功率转换电路，基于DSP的控制电路，驱动、隔离电路以及保护电路；针对开关功放数学模型不易得出的特点，细致分析了模糊自适应PID控制方法，在此基础上编写了控制程序；研制出一台功率为2kVA，通频带为10～3kHz的三电平脉宽调制开关功放；论文中还探讨了实现大功率开关功放的方法，分析了各种方法的可行性，给出了实现大功率开关功放的思路，并进行了并联开关管实现大功率开关功放的实验。

For weak nonlinear distortion, the expressions of total harmonic distortion, the second order intermodulation distortion(IM2 ), the third order intermodulation distortion(IM 3) and intercept point(IP 3) are deduced. With the aid of software Multisim, we simulate transistor common emitter amplifier, transistor common emitter amplifier with resistor in emitter, differential amplifier and differential amplifier with resistor between emitters. The simulational results and theoretical analyses are almost the same.

针对弱非线性失真，推导了总谐波人、二阶互调失真( IM2 )、三阶互调失真( IM3)和截点( IP3)的表达式，借助于 Multisim软件，对晶体管共发放大器、发射极带反馈电阻的失发放大器、差分放大器和发射极间带反馈电阻的差分放大器进行了仿真，并与理论结果作了比较，结果令人满意。

Voltage Source and Current Source, Thevenin Theory, Trouble Shooting, Characteristic Curve of Diode, Diode Models, Rectifier Circuits, Input Filtering Capacitor, Voltage Multiplier Circuits, Limiter and Clipper Circuits, DC Clampers and Peak-to-peak Detectors, Zener Diode, Zener Diode Rectifier, Photoelectric Devices, Collector-Emitter Junction, Transistor Characteristics of common-emitter, Base Bias, LED Dirver, Establishing a Stable Q-point, PNP Transistor Biasing, Transistor Biasing, Coupling and By-Pass Capacitors, AC Emitter Resistance, Common-Emitter Amplifier, Other Common-Emitter Amplifiers, Cascaded Common-Emitter Amplifiers, AC Load Line, Emitter Follower, Class B Push-pull Amplifiers, JFET Characteristic Curve, JFET Biasing, JFET Amplifier, VMOS Circuit, Differential Amplifier, Operational Amplifier, Non-inverting Feedback, Negative Feedback.

电子学实验( S0704)(1，1)/应用电子学实验( S0472)(1，1)电压源和电流源、戴维宁定理、故障排除、二极体特性曲线、二极体近似模型、整流电路、电容-输入型滤波器、倍压电路、限制器电路和峰值检测电路、直流定位器与峰对峰检测器、齐纳二极体、齐纳二极体整流器、光电元件、集射极接面、集极特性曲线、基极偏压、LED驱动器、建立一个稳定的工作点 Q 、 PNP 电晶体偏压、电晶体偏压、耦合及旁路电容、交流射极电阻、共射极放大器、其他 CE 放大器、串接共射极放大器、交流负载线、射极随耦器、 B 类推挽式放大器、 JFET 特性曲线、 JFET 偏压、 JFET 放大器、 VMOS 电路、差动放大器、运算放大器、非反向电压回授、负回授。

Our company adopt advanced production technology and equipment, to paint in different modified resin system pre-dispersion, used for high-grade inks, paints and coatings production, the main products are lipid soluble and alcohol soluble nitrocellulose pre-dispersed pigment-based color films, water-based acrylic paints pre-dispersed color tablets, chlorine vinegar pre-dispersed pigment color polymer films, cellulose acetate butyrate pre-dispersed pigment color films, polyvinyl butyral pre-dispersed pigments, such as color film.

本公司采用先进的生产技术和设备，把颜料在不同的改性树脂体系中进行预先分散，用于高档油墨、油漆和涂料的生产，主要产品有脂溶和醇溶型硝化棉预分散颜料色片、水性丙烯酸预分散颜料色片、氯醋聚合物预分散颜料色片、乙酸丁酸纤维素预分散颜料色片、聚乙烯醇缩丁醛预分散颜料色片等。

The first part is the introduction, which generally introduces the research purpose and significance of this thesis, the summary of the financial pre-warning researches both home and abroad, and the research main contexts and research methods; The second part is the comparison on the financial pre-warning methods existent, which compares the different methods by categories, makes a further analysis on the limits of existent methods, and proposes the improve thoughts of this research based on that; The third part is the basic theory, which makes a summary of the referent theories exerted on the research, and exposit the comparing mechanism of the grey prediction theory and the artificial neural network method concise; The fourth part is the frame work of the model, which illuminates the research designs step by step, such as the definition of the financial crisis, the method of sample select, the select and definition of the pre-warning variables, and makes an exposition of the establishment procedures of the whole models at last; The fifth part is the financial pre-warning based on the theory of grey prediction and artificial neural network, which mainly demonstrate the model establishment in the concrete, dividing into four part to carry out the part of pragmatic research integrally, building of indexes system, establishment of BP neural networks, dynamic financial pre-warning and test, analysis on the pre-warning result; The sixth part is conclusion, which sums up the main results of the whole research, clarifies the innovative points, and makes a discussion on the limits and future study directions of the research in this thesis.

其中，第一部分为导论，总括性概述本文的研究目的与意义，国内外研究综述，以及本文的研究内容和方法；第二部分为现有财务预警研究方法剖析，通过对现有预警方法进行分类比较，进一步分析现有预警方法的局限性，并在此基础上提出本文研究的改进思路；第三部分基本理论，对本文研究中运用的相关理论进行扼要概述，并简要阐述灰色预测理论与人工神经方法的融合机理；第四部分为模型研究框架，逐步阐释模型对财务困境的界定，样本数据的选取方法，预警变量的选取与定义等各个部分的研究设计，并对整体模型的构建步骤进行简要阐述；第五部分为基于灰色神经网络模型的财务预警，主要论述动态预警模型的具体实现过程，分模型指标体系的建立，BP神经网络的建立，动态财务预警与检验，以及预警结果分析四个部分全面阐述本文实证分析过程；第六部分为结论，总结本文研究得到的主要研究结论，以及本文研究中的创新之处，并对论文的不足与后续发展研究进行探讨。

In the chapter 2, the theoretic knowledge about the photosensitive resin and the grinding tools was firstly introduced.

第二章阐述了光固化树脂结合剂磨具的相关理论研究。

Do not use the program's indenting or margin-setting features; these will be added during typesetting.

不要使用缩排，页面边缘设置之类的选项，偶看不大懂。