IntegratedCircuits集成电路电子信息类专业英语计算机类专业英语文章10页.docx

1、IntegratedCircuits集成电路电子信息类专业英语计算机类专业英语文章10页Integrated Circuits(集成电路)与当今“教师”一称最接近的“老师”概念，最早也要追溯至宋元时期。金代元好问示侄孙伯安诗云：“伯安入小学，颖悟非凡貌，属句有夙性，说字惊老师。”于是看，宋元时期小学教师被称为“老师”有案可稽。清代称主考官也为“老师”，而一般学堂里的先生则称为“教师”或“教习”。可见，“教师”一说是比较晚的事了。如今体会，“教师”的含义比之“老师”一说，具有资历和学识程度上较低一些的差别。辛亥革命后，教师与其他官员一样依法令任命，故又称“教师”为“教员”。 英文原稿:教师范读的

2、是阅读教学中不可缺少的部分，我常采用范读，让幼儿学习、模仿。如领读，我读一句，让幼儿读一句，边读边记；第二通读，我大声读，我大声读，幼儿小声读，边学边仿；第三赏读，我借用录好配朗读磁带，一边放录音，一边幼儿反复倾听，在反复倾听中体验、品味。 The Integrated Circuit我国古代的读书人,从上学之日起,就日诵不辍,一般在几年内就能识记几千个汉字,熟记几百篇文章,写出的诗文也是字斟句酌,琅琅上口,成为满腹经纶的文人。为什么在现代化教学的今天,我们念了十几年书的高中毕业生甚至大学生,竟提起作文就头疼,写不出像样的文章呢?吕叔湘先生早在1978年就尖锐地提出:“中小学语文教学效果差,中

3、学语文毕业生语文水平低,十几年上课总时数是9160课时,语文是2749课时,恰好是30%,十年的时间,二千七百多课时,用来学本国语文,却是大多数不过关,岂非咄咄怪事!”寻根究底,其主要原因就是腹中无物。特别是写议论文,初中水平以上的学生都知道议论文的“三要素”是论点、论据、论证,也通晓议论文的基本结构:提出问题分析问题解决问题,但真正动起笔来就犯难了。知道“是这样”,就是讲不出“为什么”。根本原因还是无“米”下“锅”。于是便翻开作文集锦之类的书大段抄起来,抄人家的名言警句,抄人家的事例,不参考作文书就很难写出像样的文章。所以,词汇贫乏、内容空洞、千篇一律便成了中学生作文的通病。要解决这个问题,

4、不能单在布局谋篇等写作技方面下功夫,必须认识到“死记硬背”的重要性,让学生积累足够的“米”。 Digital logic and electronic circuits derive their functionality from electronic switches called transistor. Roughly speaking, the transistor can be likened to an electronically controlled valve whereby energy applied to one connection of the valve enab

5、les energy to flow between two other connections.By combining multiple transistors, digital logic building blocks such as AND gates and flip-flops are formed. Transistors, in turn, are made from semiconductors. Consult a periodic table of elements in a college chemistry textbook, and you will locate

6、 semiconductors as a group of elements separating the metals and nonmetals.They are called semiconductors because of their ability to behave as both metals and nonmetals. A semiconductor can be made to conduct electricity like a metal or to insulate as a nonmetal does. These differing electrical pro

7、perties can be accurately controlled by mixing the semiconductor with small amounts of other elements. This mixing is called doping. A semiconductor can be doped to contain more electrons (N-type) or fewer electrons (P-type). Examples of commonly used semiconductors are silicon and germanium. Phosph

8、orous and boron are two elements that are used to dope N-type and P-type silicon, respectively. A transistor is constructed by creating a sandwich of differently doped semiconductor layers. The two most common types of transistors, the bipolar-junction transistor (BJT) and the field-effect transisto

9、r (FET) are schematically illustrated in Figure 2.1.This figure shows both the silicon structures of these elements and their graphical symbolic representation as would be seen in a circuit diagram. The BJT shown is an NPN transistor, because it is composed of a sandwich of N-P-N doped silicon. When

10、 a small current is injected into the base terminal, a larger current is enabled to flow from the collector to the emitter.The FET shown is an N-channel FET, which is composed of two N-type regions separated by a P-type substrate. When a voltage is applied to the insulated gate terminal, a current i

11、s enabled to flow from the drain to the source. It is called N-channel, because the gate voltage induces an N-channel within the substrate, enabling current to flow between the N-regions. Another basic semiconductor structure is a diode, which is formed simply by a junction of N-type and P-type sili

12、con. Diodes act like one-way valves by conducting current only from P to N. Special diodes can be created that emit light when a voltage is applied. Appropriately enough, these components are called light emitting diodes, or LEDs. These small lights are manufactured by the millions and are found in

13、diverse applications from telephones to traffic lights. The resulting small chip of semiconductor material on which a transistor or diode is fabricated can be encased in a small plastic package for protection against damage and contamination from the outside world.Small wires are connected within th

14、is package between the semiconductor sandwich and pins that protrude from the package to make electrical contact with other parts of the intended circuit. Once you have several discrete transistors, digital logic can be built by directly wiring these components together. The circuit will function, b

15、ut any substantial amount of digital logic will be very bulky, because several transistors are required to implement each of the various types of logic gates. At the time of the invention of the transistor in 1947 by John Bardeen, Walter Brattain, and William Shockley, the only way to assemble multi

16、ple transistors into a single circuit was to buy separate discrete transistors and wire them together. In 1959, Jack Kilby and Robert Noyce independently invented a means of fabricating multiple transistors on a single slab of semiconductor material. Their invention would come to be known as the int

17、egrated circuit, or IC, which is the foundation of our modern computerized world. An IC is so called because it integrates multiple transistors and diodes onto the same small semiconductor chip. Instead of having to solder individual wires between discrete components, an IC contains many small compo

18、nents that are already wired together in the desired topology to form a circuit. A typical IC, without its plastic or ceramic package, is a square or rectangular silicon die measuring from 2 to 15 mm on an edge. Depending on the level of technology used to manufacture the IC, there may be anywhere f

19、rom a dozen to tens of millions of individual transistors on this small chip. This amazing density of electronic components indicates that the transistors and the wires that connect them are extremely small in size. Dimensions on an IC are measured in units of micrometers, with one micrometer (1mm)

20、being one millionth of a meter. To serve as a reference point, a human hair is roughly 100mm in diameter. Some modern ICs contain components and wires that are measured in increments as small as 0.1mm! Each year, researchers and engineers have been finding new ways to steadily reduce these feature s

21、izes to pack more transistors into the same silicon area, as indicated in Figure 2.2. When an IC is designed and fabricated, it generally follows one of two main transistor technologies: bipolar or metal-oxide semiconductor (MOS). Bipolar processes create BJTs, whereas MOS processes create FETs. Bip

22、olar logic was more common before the 1980s, but MOS technologies have since accounted the great majority of digital logic ICs. N-channel FETs are fabricated in an NMOS process, and P-channel FETs are fabricated in a PMOS process. In the 1980s, complementary-MOS, or CMOS, became the dominant process

23、 technology and remains so to this day. CMOS ICs incorporate both NMOS and PMOS transistors. Application Specific Integrated Circuit An application-specific integrated circuit (ASIC) is an integrated circuit (IC) customized for a particular use, rather than intended for general-purpose use. For exam

24、ple, a chip designed solely to run a cell phone is an ASIC. In contrast, the 7400 series and 4000 series integrated circuits are logic building blocks that can be wired together for use in many different applications. As feature sizes have shrunk and design tools improved over the years, the maximum

25、 complexity (and hence functionality) possible in an ASIC has grown from 5,000 gates to over 100 million.Modern ASICs often include entire 32-bit processors, memory blocks including ROM, RAM, EEPROM, Flash and other large building blocks. Such an ASIC is often termed a SoC (System-on-Chip). Designer

26、s of digital ASICs use a hardware description language (HDL), such as Verilog or VHDL, to describe the functionality of ASICs. Field-programmable gate arrays (FPGA) are the modern day equivalent of 7400 series logic and a breadboard, containing programmable logic blocks and programmable interconnect

27、s that allow the same FPGA to be used in many different applications. For smaller designs and/or lower production volumes, FPGAs may be more cost effective than an ASIC design. The non-recurring engineering cost (the cost to setup the factory to produce a particular ASIC) can run into hundreds of th

28、ousands of dollars.The general term application specific integrated circuit includes FPGAs, but most designers use ASIC only for non-field programmable devices and make a distinction between ASIC and FPGAs.HistoryThe initial ASICs used gate array technology. Ferranti produced perhaps the first gate-

29、array, the ULA (Uncommitted Logic Array), around 1980. Customization occurred by varying the metal interconnect mask. ULAs had complexities of up to a few thousand gates. Later versions became more generalized, with different base dies customized by both metal and polysilicon layers. Some base dies

30、include RAM elements.Standard cell designIn the mid 1980s a designer would choose an ASIC manufacturer and implement their design using the design tools available from the manufacturer. While third party design tools were available, there was not an effective link from the third party design tools t

31、o the layout and actual semiconductor process performance characteristics of the various ASIC manufacturers.Most designers ended up using factory specific tools to complete the implementation of their designs. A solution to this problem that also yielded a much higher density device was the implemen

32、tation of Standard Cells. Every ASIC manufacturer could create functional blocks with known electrical characteristics, such as propagation delay, capacitance and inductance; that could also be represented in third party tools.Standard cell design is the utilization of these functional blocks to ach

33、ieve very high gate density and good electrical performance. Standard cell design fits between Gate Array and Full Custom design in terms of both its NRE (Non-Recurring Engineering) and recurring component cost.By the late 1980s, logic synthesis tools, such as Design Compiler, became available. Such tools could compile HDL descriptions into a g