模拟-数字转换器

In front of the A/D converter in an analog conversion system is usually located a sample-and-hold circuit.

在模拟量转换系统中在模/数转换器的前端通常都会有一个采样-保持电路。

The project will develop a bandpass sigma-delta analog-to-digital converter for digital audio broadcasting system in three years. In the first year, we had finished the system simulation for IF receiver using conventional high speed ADC and bandpass sigma-delta ADC, respectively. We also had done the analysis and design of high-order bandpass sigma-delta modulator structure. In this year, we have developed a coefficient synthesis method for high order bandpass sigma-delta modulator using high order filter transfer functions (inverse Chebyshev bandreject filter function).

本计划将在三年内发展一个能应用在数位音讯广播系统的带通sigma-delta类比/数位转换器(analog-to-digital converter，ADC)，在第一年度中我们分别以传统高速类比/数位转换器及带通SD类比/数位转换器的接收系统为例，并结合编码正交多工器(Coded Orthogonal Frequency Division Multiplex，COFDM)的技术，建立一套DAB系统模拟的方法，同时并研究有关高阶带通SD类比/数位调变器的架构及电路，并已成功开发出一个由高阶滤波器合成的高阶带通调变器。

This high voltage electrostatic precipitation controller has 7 channels of analog input,2 channels of analog output, 12 digital inputs and 16 digital outputs. The analog input includes primary current, secondary current, primary voltage, secondary voltage, etc. Controller uses MAX 187 as the A/D converter, which ensure the sampling speed and the conversion precision in the same time. The processor unit is RCM2250 module. Rabit 2000 processor, a 128K SRAM and a 256K Flash Rom are integrated in RCM2250, which improves the performance of pricipitation controller. MAX504 is used to produce the 4~20mA current output.

模拟量输入采集的信号有升压变压器一次电流、一次电压、二次电流、二次电压等，采用12位逐次比较式A/D转换器MAX187，兼顾采样速率和转换精度；中央处理单元采用以8位嵌入式处理器Rabbit2000为基础的RCM2250模块，外扩128KSRAM和256K Flash ROM，内部资源丰富，提高了控制器的整体性能；模拟量输出采用内带基准源的10位电压输出数模转换器MAX504，实现了标准4～20mA电流信号输出；控制器通过控制算法在相应开关量点上输出可控硅的触发脉冲。

The effect of this modeling method is proved by appling it to the analysis of a fly-back ZCS-QRC. The result show that the proposed method can give important physical insight of the relationship between the compensator and the controlled plant.

为了实际验证这种模型化方法在分析设计上的有效性，本文以一返驰式直流—直流转换器为例予以详细分析，并配合MATLAB的模拟，结果证明这种模型化方法不仅能够简化具有多重回授的转换器分析，并且对补偿器与转换器性能间关系的了解有所助益。

By utilizing the cross-gain modulation effect and the period-one oscillation harmonic frequency-locked in an optically injected semiconductor laser, we can extract the wavelength conversional individual channel optical clock from the optical-time-division-multiplexing signal. In a FP-LD, we numerically simulate the extraction of 20 GHz optical clock at 1550 nm from the 2×20 Gb/s OTDM signal at 1555 nm, and experimentally obtain the -105 dBc/Hz phase noise frequency division clock of 12.36 GHz to 6.18 GHz with simultaneous wavelength conversion from 1550.24 nm to 1545.91 nm.

采用一个FP半导体激光器作为全光分路时钟提取及波长转换器，数值模拟实现了从波长为1555 nm、速率为2×20 Gb/s的光时分复用信号中提取出波长转换为1550 nm、重复频率为20 GHz的分路光时钟，实验完成了从波长为1550.24 nm、重复频率为12.36 GHz光脉冲信号中提取出相位噪声为-105 dBc/Hz的波长为1545.91 nm、重复频率6.18 GHz的分频光时钟。

ICL(7106)3_(1/2) bit A/D convertor through the encoder convert the sectional code into BCD code. The BCD output is interfaced with the microcomputer system,when through se- veral aualog channel qnantity is collected we can use the multiplexor. Our experiment has proved that the system has simple circuit with reliabe operation and it is cheap.

本文介绍了 ICL(7107)3_(1/2)位 A/D 转换器段码输出与微机系统的接口电路，ICL(7106)3_(1/2)位 A/D 转换器经编码器，将段码转换为 BCD 码输出与微机系统收接，当对多个模拟量进行检测时可应用多路开关，实验证明联接线路简单，运行可靠，装置便宜。

Using staircase concatenation method SCM,the optimum coupling conditions were achieved for wedge-shaped fiber wedge angle,cylindrical endface lens curvature radius,semimajor axis of planar lightwave circuit elliptical field,aspect ratio of planar lightwave circuit elliptical field,misalignment tole.

在多量子阱-平面光波光路前置模斑转换器和不加模斑转换器的情况下，用阶梯串联法数值模拟并优化设计了楔形光纤-平面光波光路间最佳耦合参量：楔形光纤楔角45°、端面圆柱透镜曲率半径2。

The results show that the propagation delay is less than 1ns, the ratio of input and output impedance is up to 10〓, realizing a little insert dissipation at high-speed operation, laying a solid foundation for the materialization of high-resolution one-way analog switch A/D converter. 2. A new structure of the high-speed CMOS voltage comparator circuit for the improved nonoffset cancel circuit, which can satisfy the needs of the 8-bit linearity.

模拟结果表明，基于CMOS工艺实现的BiCMOS单向模拟开关的传播延迟小于1ns，开关的输入输出阻抗比高达10〓以上，实现了高速工作下的极小插入损耗，为实现高精度单向隔离模拟开关分步法A/D转换器奠定了基础； 2、基于满足八位线性要求的前提，本文提出了一种改进的无失调取消电路的高速CMOS电压比较器新结构。

Critical aspects on the use of the Δ∑ A/D converter described in the paper including :the necessary of using the highly integrated Δ∑ A/D converter in portable Sunphotometer, the principle diagram interfacing CS5528 to 89C52,the software of initialing CS5528 and the results of experiment.

本文介绍了便携式太阳辐射计的组成原理，分析了在便携式太阳辐射计中使用高集成度Δ∑型A/D转换器的必要性，给出了高集成度Δ∑型A/D转换器CS5528与系统微处理器的连接图、测量初始化程序及模拟测量结果。

In this design, hardware circuit adopts liquid crystal screen and program sensor keyboard as interactive interface, 96 single-chip as chief controller, analog multi-circuit switch as transmission signal. To improve conversion accuracy, I also bond an analog to digital converter%26mdash;AD1674, so the programs mainly contain the display program design of the LCD module, the key-board control program and cyclical monitoring of various parameters and so on.

本文的硬件电路采用液晶显示屏和触摸式键盘作为人机交互界面，用80C196KB作为主控制器，用模拟多路开关传输信号，并且为了提高转换精度，外接了模数转换器AD1674，所以本设计的程序主要包括液晶显示程序、键盘管理程序、控制巡回采样等模块。

Neither the killing of Mr Zarqawi nor any breakthrough on the political front will stop the insurgency and the fratricidal murders in their tracks.

在对危险的南部地区访问时，他斥责什叶派民兵领导人对中央集权的挑衅行为。

In fact,I've got him on the satellite mobile right now.

实际上 我们已接通卫星可视电话了