河北農(nóng)業(yè)大學(xué)現(xiàn)科電科專英課后習(xí)題答案.doc

第一單元 英漢互譯1)現(xiàn)代社會的許多產(chǎn)品和服務(wù)都是建立在電氣工程師和計(jì)算機(jī)科學(xué)家的工作基礎(chǔ)上的。在過去幾十年中，數(shù)字電子器件成本的大幅下降已經(jīng)帶來了計(jì)算機(jī)應(yīng)用迅猛的增長。與此同時(shí)，人們對計(jì)算機(jī)科學(xué)認(rèn)識的提高使得開發(fā)新的更強(qiáng)大、更復(fù)雜、更靈活的軟件系統(tǒng)成為可能。2)1971年 11月，英特爾公司的三位工程師發(fā)明了世界上首片商用微處理器4004。以今天的標(biāo)準(zhǔn)看，4004是比較簡單的。它僅包含2300個(gè)晶體管，在一秒內(nèi)可以執(zhí)行約60000次運(yùn)算。今天，微處理器是最復(fù)雜的大量生產(chǎn)產(chǎn)品。它包含幾百萬個(gè)晶體管，1秒鐘可完成數(shù)億次運(yùn)算。3)微處理器是個(gè)人計(jì)算機(jī)的神經(jīng)中樞。在這個(gè)小小的硅片上集成了數(shù)百萬的（數(shù)字）開關(guān)和（數(shù)據(jù)）通路，它們幫助計(jì)算機(jī)作出重要的決定和完成有意義的任務(wù)。但微處理器不是只為計(jì)算機(jī)而設(shè)計(jì)的。人們可以在電話、汽車等許多日常物品中發(fā)現(xiàn)處理器。4)存儲器是計(jì)算機(jī)和嵌入式系統(tǒng)中用來保存信息的部件。在嵌入式應(yīng)用中需要存儲信息，因此，設(shè)計(jì)中總含有某種類型的存儲器?，F(xiàn)在有多種可以利用的存儲器件，因此對于嵌入式用戶存在多種選擇。5)存儲器可以分為兩大類：易失的和非易失的。易失存儲器在系統(tǒng)掉電后就丟失了其存儲內(nèi)容。非易失存儲器系統(tǒng)或者器件掉電后不會丟失數(shù)據(jù)。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.第二單元 英漢互譯1)由于很難定義運(yùn)算放大器的“動態(tài)范圍”（DR）,因此先給“數(shù)模轉(zhuǎn)換器”（DAC）的動態(tài)范圍下定義。DAC的動態(tài)范圍就是其最大輸出電壓和最小輸出電壓之比。2)這個(gè)動態(tài)范圍的定義也可用于運(yùn)算放大器，其最大輸出電壓擺幅為VOUTMAX。輸出電壓擺幅定義為運(yùn)算放大器能達(dá)到的最大輸出電壓（VOH）減去最小輸出電壓（VOL）。從運(yùn)放集成電路數(shù)據(jù)手冊中，可以很容易獲得VOH和VOL。3)噪聲是在一段時(shí)間內(nèi)隨機(jī)變化的，信號或噪聲電平的瞬時(shí)值就不足以描述這種情形。信號和噪聲要用其在較長時(shí)段內(nèi)的平均值（均方根值）來描述。信噪比用于度量噪聲環(huán)境中的信號質(zhì)量。SNR是功率比，是在電路輸出端得到的。我們感興趣的SNR是電壓比（因?yàn)樽杩故浅?shù)），是在運(yùn)算放大器的輸入端得到的。就是說，全部噪聲（包括電阻噪聲）電壓必須在運(yùn)算放大器的輸入端以均方根值進(jìn)行計(jì)算。4)切比雪夫等波紋濾波器的頻域滾降分布在整個(gè)通帶范圍內(nèi)。其通帶內(nèi)波紋較多、而過渡區(qū)的滾降比較陡峭。因其在濾波過程中的Q值較高，切比雪夫等波紋濾波器的暫態(tài)響應(yīng)和階躍響應(yīng)較差。5)芯片封裝就是芯片的外罩。有了它，才能把芯片插入（插座安裝）或焊至（表面安裝）印制電路板上。在外行看來，芯片安裝設(shè)計(jì)似乎不太重要；事實(shí)上，芯片封裝技術(shù)確是一個(gè)龐大復(fù)雜的行業(yè)。為尺寸不斷縮減的電路小片（裸片）提供越來越多的“輸入/輸出互連”能力是經(jīng)常出現(xiàn)的問題。除此之外，封裝和半導(dǎo)體電路的“微縮化”均有助于減小蜂窩電話和其他手持設(shè)備的尺寸。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.第三單元 英漢互譯1）定制門陣列邏輯、專用集成電路、球柵陣列、多芯片模塊和亞納米數(shù)字器件的使用為電磁兼容工程師提供了新的挑戰(zhàn)性機(jī)遇。2）工作在高頻的電阻表現(xiàn)為電感和并聯(lián)的電阻、電容之間的級聯(lián)。工作在高頻的電容表現(xiàn)為電感、電阻和電容的級聯(lián)。3）SPICE（側(cè)重集成電路的仿真程序）是一個(gè)廣泛用于模擬電路和混合電路仿真的程序。SPICE解決了多組建立在頻域、穩(wěn)態(tài)和時(shí)域的非線性方程，從而能夠?qū)w管和門電路的設(shè)計(jì)行為進(jìn)行模擬。4）IBIS（輸入/輸出緩沖規(guī)范）是一種用來對集成電路輸入/輸出模擬特性進(jìn)行定義的格式。IBIS模型是ASCII文件。在不泄漏電路設(shè)計(jì)專利的前提下，IBIS模型提供了對器件建模所需的行為信息。5）在多導(dǎo)線系統(tǒng)中，導(dǎo)線間的過量耦合（即“串?dāng)_”）會引發(fā)兩種有害效應(yīng)。首先，串?dāng)_改變了總線中傳輸線的有效特性阻抗和傳輸速度，從而使總線傳輸線的性能發(fā)生改變。此外，串?dāng)_將噪聲感應(yīng)到其他導(dǎo)線上。串?dāng)_現(xiàn)象的這些特點(diǎn)使得系統(tǒng)性能嚴(yán)重的依賴于數(shù)據(jù)模式、導(dǎo)線間距和切換速率。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.第四單元 英漢互譯1）不同的無線射頻鏈路以不同的方式共用頻譜帶寬。這些共用方式稱為“多址模式”。“頻分多址”（FDMA）、“時(shí)分多址”（TDMA）、“碼分多址”（CDMA）和“空分多址”（SDMA）是四種主要的多址模式。2）移動電話系統(tǒng)的服務(wù)區(qū)劃分為一個(gè)個(gè)“蜂窩”小區(qū)。每個(gè)“蜂窩”小區(qū)都有一座基站；通過在無線鏈路上發(fā)送、接收信號，基站和“蜂窩”內(nèi)移動用戶通信?；鞠蛞苿佑脩舭l(fā)送信號稱作“前向鏈路”或“下行鏈路”。移動用戶向基站發(fā)送信號稱作“反向鏈路”或“上行鏈路”。每個(gè)基站都要和“移動交換中心”（MSC）聯(lián)絡(luò)，而MSC的作用是把來往于基站的呼叫和其他蜂窩的移動用戶、公共交換電話網(wǎng)連接起來。3）基站使用兩類無線信道和移動用戶進(jìn)行通信：傳送控制信息的“控制信道”和傳送信息的“信息通道”。4）在FDMA方式中，可用頻道劃分為若干具有一定帶寬的頻道：每個(gè)呼叫都使用不同頻道。第一代蜂窩系統(tǒng)采用的都是FDMA方式。5）在TDMA和FDMA系統(tǒng)中，為了防止信道間干擾，某個(gè)蜂窩小區(qū)使用的頻道不會被鄰近蜂窩小區(qū)使用。在CDMA系統(tǒng)中，可以在臨近蜂窩小區(qū)中使用相同頻率，從而增加了系統(tǒng)容量。6）The generic term channel is normally used to de