河北农业大学现科电科专英课后习题答案.doc

第一单元 英汉互译1)现代社会的许多产品和服务都是建立在电气工程师和计算机科学家的工作基础上的。在过去几十年中，数字电子器件成本的大幅下降已经带来了计算机应用迅猛的增长。与此同时，人们对计算机科学认识的提高使得开发新的更强大、更复杂、更灵活的软件系统成为可能。2)1971年 11月，英特尔公司的三位工程师发明了世界上首片商用微处理器4004。以今天的标准看，4004是比较简单的。它仅包含2300个晶体管，在一秒内可以执行约60000次运算。今天，微处理器是最复杂的大量生产产品。它包含几百万个晶体管，1秒钟可完成数亿次运算。3)微处理器是个人计算机的神经中枢。在这个小小的硅片上集成了数百万的（数字）开关和（数据）通路，它们帮助计算机作出重要的决定和完成有意义的任务。但微处理器不是只为计算机而设计的。人们可以在电话、汽车等许多日常物品中发现处理器。4)存储器是计算机和嵌入式系统中用来保存信息的部件。在嵌入式应用中需要存储信息，因此，设计中总含有某种类型的存储器。现在有多种可以利用的存储器件，因此对于嵌入式用户存在多种选择。5)存储器可以分为两大类：易失的和非易失的。易失存储器在系统掉电后就丢失了其存储内容。非易失存储器系统或者器件掉电后不会丢失数据。6) Modern electronic systems are increasingly digital in nature, exceedingly complex, and would be inconceivable without todays VLSI chip technology. Indeed, such systems are so complex that the principles of their design bear great similarities to the design principles of large software systems. Thus, computer science and electronic system design require similar backgrounds in many respects, and computer aids to design are essential in this ever-expanding domain of engineering.7) A chip is a small piece of semiconducting material on which an integrated circuit is embedded. A typical chip is less than 1 square inches and can contain millions of transistors. There are different types of chips. For example, CPU chips contain an entire processing unit, whereas memory chips contain blank memory.8) A microprocessor is a silicon chip that contains a CPU. There are three basic characteristics differentiate microprocessor; instruction set, bandwidth and clock speed.9) There are several reasons to use Flash memory instead of a hard disk: Flash memory allows faster access. It is noiseless, lighter, and smaller in size and has no moving parts.10) Memory is the part of a computer system that used to run programs and store data. The main memory is built from Random Access Memory chips. The amount of memory available determines the size of programs that can be run, and whether more than one program can run at a time. Main memory is temporary, and the data is lost when the computer is turned off. It is distinguished form more permanent internal Read Only Memory, and external storage. ROM contains the computers essential programs in the general sense, Memory can be any device that can hold data in machine-readable format.第二单元 英汉互译1)由于很难定义运算放大器的“动态范围”（DR）,因此先给“数模转换器”（DAC）的动态范围下定义。DAC的动态范围就是其最大输出电压和最小输出电压之比。2)这个动态范围的定义也可用于运算放大器，其最大输出电压摆幅为VOUTMAX。输出电压摆幅定义为运算放大器能达到的最大输出电压（VOH）减去最小输出电压（VOL）。从运放集成电路数据手册中，可以很容易获得VOH和VOL。3)噪声是在一段时间内随机变化的，信号或噪声电平的瞬时值就不足以描述这种情形。信号和噪声要用其在较长时段内的平均值（均方根值）来描述。信噪比用于度量噪声环境中的信号质量。SNR是功率比，是在电路输出端得到的。我们感兴趣的SNR是电压比（因为阻抗是常数），是在运算放大器的输入端得到的。就是说，全部噪声（包括电阻噪声）电压必须在运算放大器的输入端以均方根值进行计算。4)切比雪夫等波纹滤波器的频域滚降分布在整个通带范围内。其通带内波纹较多、而过渡区的滚降比较陡峭。因其在滤波过程中的Q值较高，切比雪夫等波纹滤波器的暂态响应和阶跃响应较差。5)芯片封装就是芯片的外罩。有了它，才能把芯片插入（插座安装）或焊至（表面安装）印制电路板上。在外行看来，芯片安装设计似乎不太重要；事实上，芯片封装技术确是一个庞大复杂的行业。为尺寸不断缩减的电路小片（裸片）提供越来越多的“输入/输出互连”能力是经常出现的问题。除此之外，封装和半导体电路的“微缩化”均有助于减小蜂窝电话和其他手持设备的尺寸。6) In one respect, voltage is like water: you dont appreciate its value until your supply runs low. Low-voltage systems, defined here as a single power supply less than 5V, teach us to appreciate voltage.7) Ohms law is stated as V=IR, and it is fundamental to all electronics. Ohms law can be applied to a single component, to any group of components, or to a complete circuit. When the current flowing through any portion of a circuit is known, the voltage dropped across that portion of the circuit is obtained by multiplying the current times the resistance.8) Circuits are a mix of passive and active components. The components are arranged in a manner that enables them to perform some desired function. The resulting arrangement of components is called a circuit or sometimes a circuit configuration. The art portion of analog design is developing the circuit configuration.9) Noise sets a limit on the information and signals that can be handled by a system. The ability of an amplifier, receiver, or other device to discern a signal is degraded by noise. Noise mixed with the incoming signal, noise generated by the opamp, resistor noise, and power supply noise ultimately determine the size of the signal that can be recovered and measured.10) A Butterworth (maximally flat) filter is the most commonly used generalpurpose filter. It has a monotonic passband with the attenuation increasing up to its 3dB point, which is known as the natural frequency. This frequency is the same regardless of the order of the filter. However, by increasing the order of the filter, the roll-off in the passband moves closer to its natural frequency and the roll-off in the transition region between the natural frequency and the stopband becomes sharper.第三单元 英汉互译1）定制门阵列逻辑、专用集成电路、球栅阵列、多芯片模块和亚纳米数字器件的使用为电磁兼容工程师提供了新的挑战性机遇。2）工作在高频的电阻表现为电感和并联的电阻、电容之间的级联。工作在高频的电容表现为电感、电阻和电容的级联。3）SPICE（侧重集成电路的仿真程序）是一个广泛用于模拟电路和混合电路仿真的程序。SPICE解决了多组建立在频域、稳态和时域的非线性方程，从而能够对晶体管和门电路的设计行为进行模拟。4）IBIS（输入/输出缓冲规范）是一种用来对集成电路输入/输出模拟特性进行定义的格式。IBIS模型是ASCII文件。在不泄漏电路设计专利的前提下，IBIS模型提供了对器件建模所需的行为信息。5）在多导线系统中，导线间的过量耦合（即“串扰”）会引发两种有害效应。首先，串扰改变了总线中传输线的有效特性阻抗和传输速度，从而使总线传输线的性能发生改变。此外，串扰将噪声感应到其他导线上。串扰现象的这些特点使得系统性能严重的依赖于数据模式、导线间距和切换速率。6）Crystal is a transparent quartz material that contains a uniform arrangement of molecules.7）As high-speed digital systems become more complex, it is becoming increasingly difficult to manage timings and signal integrity.8）Crosstalk is the coupling of energy from one line to another. It will occur whenever the electromagnetic fields from different structures interact.9）In digital designs the occurrence of crosstalk is very widespread. Crosstalk will occur on the chip, on the PCB board, on the connectors, on the chip package, and on the connector cables.10）Many systems operate at high frequencies at which conductors no longer behave as simple wires, but instead exhibit high-frequency effects and behave as transmission lines. If these transmission lines are not handled properly, they can unintentionally ruin system timing.第四单元 英汉互译1）不同的无线射频链路以不同的方式共用频谱带宽。这些共用方式称为“多址模式”。“频分多址”（FDMA）、“时分多址”（TDMA）、“码分多址”（CDMA）和“空分多址”（SDMA）是四种主要的多址模式。2）移动电话系统的服务区划分为一个个“蜂窝”小区。每个“蜂窝”小区都有一座基站；通过在无线链路上发送、接收信号，基站和“蜂窝”内移动用户通信。基站向移动用户发送信号称作“前向链路”或“下行链路”。移动用户向基站发送信号称作“反向链路”或“上行链路”。每个基站都要和“移动交换中心”（MSC）联络，而MSC的作用是把来往于基站的呼叫和其他蜂窝的移动用户、公共交换电话网连接起来。3）基站使用两类无线信道和移动用户进行通信：传送控制信息的“控制信道”和传送信息的“信息通道”。4）在FDMA方式中，可用频道划分为若干具有一定带宽的频道：每个呼叫都使用不同频道。第一代蜂窝系统采用的都是FDMA方式。5）在TDMA和FDMA系统中，为了防止信道间干扰，某个蜂窝小区使用的频道不会被邻近蜂窝小区使用。在CDMA系统中，可以在临近蜂窝小区中使用相同频率，从而增加了系统容量。6）The generic term channel is normally used to de