大三下英语课件课程unit12

SpecialEnglishforElectronicsandInformation电子信息专业英语

1-2Howdoesalogicgateinamicrochipwork?Agateseemslikeadevicethatmustswingopenandclosed,yetmicrochipsareetchedontosiliconwafersthathavenomovingparts.Sohowcanthegateopenandclose?门似乎是一种必须打开和关闭的装置，然而，微芯片刻蚀到硅晶片上，并没有移动部件。那么门是如何打开和关闭的呢？1-2Howdoesalogicgateinamicrochipwork?LarryWissel,ASICApplicationsEngineeratIBMMicroelectronics,replies:“Thoseofuswhodesignlogicgatesforcomputersseldomreminisceonhowthetermsweusetodescribetechnologycameintouse.Thevisionofagateswingingbackandforthclearlydoesnotliterallyrepresentthestructuresonasiliconchip.Butthereasonfortheusageoftheterm‘gate’forcomputerlogiccanbeappreciatedbyexaminingthebasicfunctionofagate:tocontrolaflow.”拉里维塞尔，一名IBM微电子的ASIC应用工程师，回答道：我们这些为计算机设计逻辑门电路的人很少能够回忆起我们使用的术语如何描述投入使用的技术。一个来回摆动清晰的门的视觉形象并不能表示硅芯片的结构。但是使用术语“门”作为计算机逻辑的原因可以理解为门基本功能的检查：控制电路。1-2Howdoesalogicgateinamicrochipwork?LarryWissel,ASICApplicationsEngineeratIBMMicroelectronics,replies:“Thoseofuswhodesignlogicgatesforcomputersseldomreminisceonhowthetermsweusetodescribetechnologycameintouse.Thevisionofagateswingingbackandforthclearlydoesnotliterallyrepresentthestructuresonasiliconchip.Butthereasonfortheusageoftheterm‘gate’forcomputerlogiccanbeappreciatedbyexaminingthebasicfunctionofagate:tocontrolaflow.”拉里维塞尔，一名IBM微电子的ASIC应用工程师，回答道：我们这些为计算机设计逻辑门电路的人很少能够回忆起我们使用的术语如何描述投入使用的技术。一个来回摆动清晰的门的视觉形象并不能表示硅芯片的结构。但是使用术语“门”作为计算机逻辑的原因可以理解为门基本功能的检查：控制电路。1-2Howdoesalogicgateinamicrochipwork?Onafarm,gatesmaybeusedtocontrolthe‘flow’ofsheeporgoatsbetweenpens.Inthiscase,thegateconsistsofaphysicalbarrierwhosepositioniscontrolledbyafarmer.Thefarmermakesadecisionabouttheflowofanimalsandthenmovesthephysicalbarriertopermitthedesiredflow.在农场中，门可以用来控制围栏之间山羊或绵羊的流通。这种情况下，门是由农民控制的一个物理屏障组成。农民对动物的流通作出决策。通过移动物理屏障以允许期望的流通量。1-2Howdoesalogicgateinamicrochipwork?Inacomputer,agatecontrolstheflowofelectriccurrentthroughacircuit.Thegateconsistsoftransistors;thetransistorsareselectedbythechipdesignerfromtwotypes(PMOSandNMOStransistors)thatarefoundintheubiquitousCOMS(complementarymetal-oxidesemiconductor)technology在电脑中，门控制着通过电路的电流。门电路由晶体管组成,而这些晶体管是由芯片设计者从广泛应用的COMS（互补金属氧化物半导体）技术中出现的两种基本类型的晶体管（PMOS晶体管和NMOS晶体管）中选择的。1-2Howdoesalogicgateinamicrochipwork?Thecurrentthatflowsthroughagateestablishesavoltageataparticularpointinthecircuit.Thisvoltagerepresentsasingle'bit'ofinformation.Thevoltagemayeitherbehigh(representingthevalue'1’)orlow(representingthevalue'0')."通过一个门的电流在电路的特定的点确立一个电压。这个电压代表一比特的信息，该电压可以为高电平（1），也可以为低电平（0）。1-2Howdoesalogicgateinamicrochipwork?Toestablisha1onacircuit,thecurrentflowissteeredtothecircuit(controlled)by‘turningon’aPMOStransistorconnectedbetweenthecircuitandthepositivesupplyvoltage.Thesupplyvoltageisusuallyanindustry-standardvaluesuchas3.3or5.0volts.电流被驱动送到一个电路上，是通过“接通”一个连接该电路点和正向电源电压的PMOS管来控制的。供电电压通常是一个行业标准值，比如3.3v或5.0v。1-2Howdoesalogicgateinamicrochipwork?For

theverybriefintervalthatisrequiredforalogicgatetoswitch(ontheorderofananosecond,orabillionthofasecond),currentwillflowthroughaPMOStransistorfromthepositivepowersupplytothecircuit.对于一个逻辑门的切换需要在很短的时间间隔内（纳秒、或十亿分之一秒），电流将从电源正极流经PMOS管到达该电路点。1-2Howdoesalogicgateinamicrochipwork?Thecurrentflowthatchargesthecircuitnodetoa0issteeredawayfromthecircuitthroughadifferentkindoftransistor(NMOS)connectedbetweenthecircuitandthenegativesupplyvoltage,orelectricalground.Again,currentwillflowtroughtheNMOStransistorforaverybriefinterval,butfortheNOMSthecurrentisbetweenthecircuitandthenegativesupply.电路上的“0”值的确立是通过另一种连接该电路点和负极电压或接地的晶体管（NMOS）来实现的。并且，电流将在很短的时间内流过NMOS晶体管，但是对于NMOS晶体管，电流处于电路和负电源之间。1-2Howdoesalogicgateinamicrochipwork?Ineithercase,thecurrentflowresultsinach