電氣自動化專業(yè)英語.ppt

1、Chapter 1 Electric and Electronic Technology Fundamentals,Unit 3 Transistor,Text,New Words and Expressions,Exercises,End,Process of Translation,Unit3 Transistor,A transistor is a semiconductor device used to amplify and switch electronic signals. It is made of a solid piece of semiconductor material

2、, with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistors terminals changes the current flowing through another pair of terminals. Because the controlled (output) power can be much more than the controlling (input) power, the t

3、ransistor provides amplification of a signal. Today, some transistors are packaged individually, but many more are found embedded in integrated circuits.,The transistor is the fundamental building block of modern electronic devices, and is ubiquitous in modern electronic systems. Following its relea

4、se in the early 1950s the transistor revolutionised the field of electronics, and paved the way for smaller and cheaper radios, calculators, and computers, amongst other things.,Unit3 Transistor,Importance The transistor is the key active component in practically all modern electronics, and is consi

5、dered by many to be one of the greatest inventions of the twentieth century. Its importance in todays society rests on its ability to be mass produced using a highly automated process (semiconductor device fabrication) that achieves astonishingly low per- transistor costs.,Unit3 Transistor,Unit3 Tra

6、nsistor,Although several companies each produce over a billion individually packaged (known as discrete) transistors every year, the vast majority of transistors now produced are in integrated circuits (often shortened to IC, microchips or simply chips), along with diodes, resistors, capacitors and

7、other electronic components, to produce complete electronic circuits. A logic gate consists of up to about twenty transistors whereas an advanced microprocessor, as of 2009, can use as many as 2.3 billion transistors (MOSFETs). About 60 million transistors were built this year 2002 . for each man, w

8、oman, and child on Earth.,The transistors low cost, flexibility, and reliability have made it a ubiquitous device. Transistorized mechatronic circuits have replaced electromechanical devices in controlling appliances and machinery. It is often easier and cheaper to use a standard microcontroller and

9、 write a computer program to carry out a control function than to design an equivalent mechanical control function.,Unit3 Transistor,Transistor as a switch Transistors are commonly used as electronic switches, for both high power applications including switched-mode power supplies and low power appl

10、ications such as logic gates. In a grounded-emitter transistor circuit, such as the light-switch circuit shown, as the base voltage rises the base and collector current rise exponentially, and the collector voltage drops because of the collector load resistor. The relevant equations:,Unit3 Transisto

11、r,URC =ICERC, the voltage across the load (the lamp with resistance Rc) URC +UCE =UCC, the supply voltage shown as 6V If UCE could fall to 0 (perfect closed switch) then IC could go no higher than UCC/Rc , even with higher base voltage and current. The transistor is then said to be saturated. Hence,

12、 values of input voltage can be chosen such that the output is either completely off, or completely on. The transistor is acting as a switch, and this type of operation is common in digital circuits where only on and off values are relevant.,Unit3 Transistor,Unit3 Transistor,Transistor as an amplifi

13、er The common-emitter amplifier is designed so that a small change in voltage in (Vin) changes the small current through the base of the transistor and the transistors current amplification combined with the properties of the circuit mean that small swings in Uin produce large changes in Uout. Vario

14、us configurations of single transistor amplifier are possible, with some providing current gain, some voltage gain, and some both. From mobile phones to televisions, vast numbers of products include amplifiers for sound reproduction, radio transmission, and signal processing. The first discrete,tran

15、sistor audio amplifiers barely supplied a few hundred milliwatts, but power and audio fidelity gradually increased as better transistors became available and amplifier architecture evolved. Modern transistor audio amplifiers of up to a few hundred watts are common and relatively inexpensive.,Return,

16、Unit3 Transistor,Unit3 Transistor,Types Transistors are categorized by Semiconductor material: germanium, silicon, gallium arsenide,silicon carbide, etc. Structure: BJT, JFET, IGFET (MOSFET), IGBT, other types Polarity: NPN, PNP (BJTs); N-channel, P-channel (FETs) Maximum power rating: low, medium,

17、high ; Maximum operating frequency: low, medium, high, radio frequency (RF), microwave (The maximum effective frequency of a transistor is denoted by the term fT, an abbreviation for frequency of transition. The frequency of transition is the frequency at which the transistor yields unity gain).,Uni

18、t3 Transistor,Application: switch, general purpose, audio, high voltage, super-beta, matched pair Physical packaging: through hole metal, through hole plastic, surface mount, ball grid array, power modules Amplification factor hfe (transistor beta) Thus, a particular transistor may be described as s

19、ilicon, surface mount, BJT, NPN, low power, high frequency switch.,Unit3 Transistor,Packaging Through-hole transistors (tape measure marked in centimetres)Transistors come in many different packages (semiconductor packages) (see images). The two main categories are through-hole (or leaded), and surf

20、ace-mount, also known as surface mount device (SMD). The ball grid array (BGA) is the latest surface mount package (currently only for large transistor arrays). It has solder balls on the underside in place of leads. Because they are smaller and have shorter interconnections, SMDs have better high f

21、requency characteristics but lower power rating.,Unit3 Transistor,Transistor packages are made of glass, metal, ceramic, or plastic. The package often dictates the power rating and frequency characteristics. Power transistors have larger packages that can be clamped to heat sinks for enhanced coolin

22、g. Additionally, most power transistors have the collector or drain physically connected to the metal can/metal plate. At the other extreme, some surface-mount microwave transistors are as small as grains of sand. Often a given transistor type is available in sundry packages. Transistor packages are

23、 mainly standardized, but the assignment of a transistors functions to the terminals is not: other transistor types can assign other functions to the packages terminals. Even for the same transistor type the terminal assignment can vary (normally indicated by a suffix letter to the part number, q.e.

24、 BC212L and BC212K).,New Words and Expressions,transistor n. 晶體管 amplify vt. 放大, 增強 ubiquitous adj. 普遍存在的 calculator n. 計算器 astonishingly adv. 令人吃驚地 discrete adj. 不連續(xù)的, 離散的 MOSFET 金屬氧化物半導(dǎo)體場效應(yīng)晶體管 flexibility n. 彈性, 適應(yīng)性 mechatronic n. 機電一體化 electromechanical adj. 機電的 saturate v. 使飽和, 浸透, 使充滿 milliwatt

25、 n. 毫瓦 gallium arsenide 砷化鎵 silicon carbide 碳化硅 BJT 雙極結(jié)型晶體管(Bipolar Junction Transistor) JFET 結(jié)晶型場效應(yīng)晶體管(junction field effect transistor) IGFET 絕緣柵場效應(yīng)晶體管(isolated-gate field effect transistor ) IGBT, 絕緣柵雙極型晶體管(Insulated Gate Bipolar Transistor) N-channel n溝道 abbreviation n. 縮寫, 縮寫詞 denote vt. 指示, 表示

26、 yield v. 出產(chǎn), 生產(chǎn) super-beta 高倍放大 matched pair 推挽式放大 through hole 透眼, 透孔 surface mount 面封裝式 ball grid array 球柵陣列(封裝) power module 功率模塊(封裝) amplification factor 放大倍數(shù) centimeter n. 厘米, 公分 package n. 包裝，封裝 ceramic n. 陶瓷 collector n. 集電極 drain n. 漏極 grain n. 谷粒, 細(xì)粒 sundry adj. 各式各樣的 assignment n. 分配, 安排

27、suffix n. 后綴, 下標(biāo),Return,Process of Translation,理解階段 主要是通過辨明詞義，弄清各種語法成分及其相互關(guān)系，并把前后句子貫串起來理解，形成對原文的完整印象，真正掌握原文的內(nèi)容和實質(zhì)。,表達(dá)階段 是在理解的基礎(chǔ)上，以忠實于原意為前提，靈活地運用各種翻譯方法和技巧，寫出符合漢語規(guī)范、表達(dá)習(xí)慣以及翻譯標(biāo)準(zhǔn)的譯文。,校核階段 是理解與表達(dá)的進(jìn)一步深化，是對原文內(nèi)容進(jìn)一步核實，對譯文語言進(jìn)一步推敲，進(jìn)行必要的潤色和修改，使譯文符合標(biāo)準(zhǔn)規(guī)范。,Exercises,I. Comprehension,1. Transistors are commonly used as electronic _, for both high power applications including swiched-mode power supplies and low power applications such as logic gates. A. heaters B. transformers C. amplifiers D. switches 2. This arrangement where the emitter (E) is in the controlling cir