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1、第一章Electronicamplifiersareusedmainlytoincreasethevoltage,current,orpowerofasignal.电子放大器主要是用来增强电压,电流或信号(信号功率)的强度Alinearamplifierprovidessignalamplificationwithlittleornodistortion,sothattheoutputisproportionaltotheinput.线性的放大器能几乎无失真地放大信号,从而使输出与输入相称Anonlinearamplifier
2、mayproduceaconsiderablechangeinthewaveformofthesignal.非线性放大器在信号的波形方面会产生相当大的变动Linearamplifiersareusedforaudioandvideosignals,whereasnonlinearamplifierfinduseinoscillators,powerelectronics,modulators,mixers,logiccircuits,andotherapplicationswhereanamplitudecutoffisdes
3、ired.线性放大器用于音频信号,而非线性放大器用于振荡器,电力电子学,调节器,混音器,逻辑电路以及其他的要求振幅中断的器材Althoughvacuumtubesplayedamajorroleinamplifiersinthepast,todayeitherdiscretetransistorcircuitsorintegratedcircuitsaremostlyused.尽管真空管在过去的放大器中充当了主要的角色,而如今最常用的是离散的晶体管电路或集成电路第二章Configurablecomputingisstillan
4、extremelyyoungfield.可配置计算仍然是极年轻的领域AlthoughGeraldEstrinoftheUniversityofCaliforniaatLosAngelesproposedconfigurablecomputinginthelate1960s,thefirstdemonstrationsdidnotoccuruntilafewyearsago,andcurrentFPGAs,withupto100,000logicelements,stilldonotcomeclosetoexploitingth
5、efullpossibilitiesofthetechnique.虽然可配置计算是由洛杉矶加州大学的杰拉尔德艾斯特林在1960年代末期提出的,但是在几年前才首次展示给世人,甚至,含有十万个逻辑元件的电流FPGA(现场可编程门阵列)仍未能开发出其技术的全部潜力FutureFPGAswillbemuchlarger,aswithmanyotherintegratedcircuits,thenumberofelementsonasingleFPGAhasdoubledroughlyevery18months.正如许多其他的集成电路一
6、样,未来的FPGA会(比目前的)大的多,单一的FPGA中的元件的数量约每隔一年半就会翻倍。Beforethedecadeisout,weexpecttoseeFPGAsthathaveamillionlogicelements.十年之后,我们期盼着会出现含有一百万个逻辑元件的FPGASuchchipswillhavemuchbroaderapplication,includinghighlycomplexcommunicationsandsignal-processingalgorithms.这些芯片应用范围更广,包括应用于高
7、度合成的通讯系统和信号加工算法。第三章Variable-lengthinstructionsaremoredifficultforachiptoprocess,though,andthelongerCISCinstructionsareespeciallycomplex.可变长度指令使芯片更难处理,而较长的CISC(复杂指令集计算)指令特别复杂。Nonetheless,tomaintainsoftwarecompatibility,modernchipssuchasIntel’sPentiumIIIandAdvancedMic
8、roDevicesInc.’sAthlonmuststillworkwithalltroublesomeCISCinstructionsthatweredesignedinthe1980s,eventhoughtheiroriginaladvantage-memorycons