《模擬電子線路》全套PPT課件
《模擬電子線路》全套PPT課件,模擬電子線路,模擬,電子線路,全套,PPT,課件
1模擬電子線路模擬電子線路2電子電路電子電路數(shù)字電路數(shù)字電路模擬電路模擬電路低頻電路(處理低頻信號(hào))低頻電路(處理低頻信號(hào))高頻電路(處理高頻信號(hào))高頻電路(處理高頻信號(hào))電子電路分類電子電路分類電子電路電子電路數(shù)字電路數(shù)字電路模擬電路模擬電路線性電路(處理小信號(hào))線性電路(處理小信號(hào))非線性電路(處理大信號(hào))非線性電路(處理大信號(hào))3內(nèi)容簡(jiǎn)介內(nèi)容簡(jiǎn)介第一章第一章 晶體二極管及其基本電路晶體二極管及其基本電路第二章第二章 雙極型晶體管及其放大電路雙極型晶體管及其放大電路第三章第三章 場(chǎng)效應(yīng)管及其基本電路場(chǎng)效應(yīng)管及其基本電路第五章第五章 集成運(yùn)算放大器電路集成運(yùn)算放大器電路第六章第六章 反饋反饋第四章第四章 頻率響應(yīng)頻率響應(yīng)第七章第七章 集成運(yùn)放的應(yīng)用集成運(yùn)放的應(yīng)用第八章第八章 功率放大電路功率放大電路第九章第九章 直流穩(wěn)壓電源直流穩(wěn)壓電源4課程地位與課程體系課程地位與課程體系v是重要的學(xué)科基礎(chǔ)課是重要的學(xué)科基礎(chǔ)課v是電子信息類專業(yè)的主干課程是電子信息類專業(yè)的主干課程v是強(qiáng)調(diào)硬件應(yīng)用能力的工程類課程是強(qiáng)調(diào)硬件應(yīng)用能力的工程類課程v是工程師訓(xùn)練的基本入門課程是工程師訓(xùn)練的基本入門課程v是很多重點(diǎn)大學(xué)的考研課程是很多重點(diǎn)大學(xué)的考研課程很重要很重要!5掌握硬件本領(lǐng)掌握硬件本領(lǐng)v當(dāng)前社會(huì)對(duì)于硬件工程師(特別是具有當(dāng)前社會(huì)對(duì)于硬件工程師(特別是具有設(shè)計(jì)開發(fā)能力的工程師)需求量很大。設(shè)計(jì)開發(fā)能力的工程師)需求量很大。v培養(yǎng)硬件工程師比較困難。培養(yǎng)硬件工程師比較困難。v學(xué)好并掌握硬件本領(lǐng)將使你基礎(chǔ)實(shí),起學(xué)好并掌握硬件本領(lǐng)將使你基礎(chǔ)實(shí),起點(diǎn)高,發(fā)展大,受益無(wú)窮!點(diǎn)高,發(fā)展大,受益無(wú)窮!很有用很有用!6這門課的特點(diǎn)這門課的特點(diǎn)v涉及相關(guān)知識(shí)較多:高等數(shù)學(xué)、電路涉及相關(guān)知識(shí)較多:高等數(shù)學(xué)、電路分析、信號(hào)與系統(tǒng)等分析、信號(hào)與系統(tǒng)等v曾有人戲稱模擬電子電路為曾有人戲稱模擬電子電路為“魔鬼電魔鬼電路路”,簡(jiǎn)稱,簡(jiǎn)稱“魔電魔電”。很難學(xué)很難學(xué)!7學(xué)習(xí)方法學(xué)習(xí)方法“過(guò)四關(guān)過(guò)四關(guān)”v基本器件關(guān)基本器件關(guān)-電路構(gòu)成電路構(gòu)成v工程近似關(guān)工程近似關(guān)-分析方法分析方法vEDA應(yīng)用關(guān)應(yīng)用關(guān)-設(shè)計(jì)能力設(shè)計(jì)能力v實(shí)驗(yàn)動(dòng)手關(guān)實(shí)驗(yàn)動(dòng)手關(guān)-實(shí)踐應(yīng)用實(shí)踐應(yīng)用8 以電阻串、并聯(lián)為例來(lái)進(jìn)以電阻串、并聯(lián)為例來(lái)進(jìn)行說(shuō)明行說(shuō)明 a a 若兩電阻若兩電阻R1、R2 串聯(lián),串聯(lián),如果如果R1 R2(一般(一般R1大大十倍以上即可),則可忽十倍以上即可),則可忽略略R2 。即:。即:R=R1+R2R1 。、近似計(jì)算(估算)、近似計(jì)算(估算)9b、若兩電阻若兩電阻R1、R2 并聯(lián),如果并聯(lián),如果R1 R2(R1大十倍以上即可)大十倍以上即可),則可忽略,則可忽略R1 。即:。即:R=R1|R2R2 。10、交、直流源同時(shí)出現(xiàn)在電路中時(shí),采用疊加原理、交、直流源同時(shí)出現(xiàn)在電路中時(shí),采用疊加原理vO=vo2+VO1求求vo2的過(guò)程稱為的過(guò)程稱為動(dòng)態(tài)分析動(dòng)態(tài)分析求求VO1的的過(guò)程過(guò)程稱為靜態(tài)分析稱為靜態(tài)分析最后利用疊加原理得最后利用疊加原理得直流等效電路直流等效電路交流等效電路交流等效電路11例一:電路如下圖,求例一:電路如下圖,求vOvo=vo1+vo2=es第一步:靜態(tài)分析第一步:靜態(tài)分析vo2=es畫直流等效電路,求畫直流等效電路,求vo1vo1=0V第二步:動(dòng)態(tài)分析第二步:動(dòng)態(tài)分析畫交流等效電路,求畫交流等效電路,求vo212例二:電路如下圖,求例二:電路如下圖,求VO1、VO2第一步:靜態(tài)分析第一步:靜態(tài)分析畫直流等效電路,求畫直流等效電路,求Vo1、Vo2第二步:動(dòng)態(tài)分析第二步:動(dòng)態(tài)分析畫交流等效電路,求畫交流等效電路,求vo2、vo213、非線性元件有條件的線性化???、非線性元件有條件的線性化??蓪⒎蔷€性電路化為線性電路。將非線性電路化為線性電路。二極管的特性二極管的特性 三極管的特性三極管的特性IC VCE I V 14考試成績(jī)?cè)u(píng)定考試成績(jī)?cè)u(píng)定v平時(shí)平時(shí)30%v期末期末70%151 孫肖子孫肖子 等編等編,模擬電子技術(shù)基礎(chǔ)模擬電子技術(shù)基礎(chǔ),西安西安:西安電西安電子科技大學(xué)出版社子科技大學(xué)出版社,2001.2 康華光主編電子技術(shù)基礎(chǔ)(模擬部分,第四康華光主編電子技術(shù)基礎(chǔ)(模擬部分,第四版),北京:高等教育出版社,版),北京:高等教育出版社,19883 謝嘉奎主編電子線路(線性部分,第四版),謝嘉奎主編電子線路(線性部分,第四版),北京:高等教育出版社,北京:高等教育出版社,1999參考書參考書16第一章第一章 晶體二極管及其基本電路晶體二極管及其基本電路1-1 半導(dǎo)體物理基礎(chǔ)知識(shí)半導(dǎo)體物理基礎(chǔ)知識(shí)導(dǎo)體導(dǎo)體 104s/cm半導(dǎo)體半導(dǎo)體在在10-9104s/cm間間絕緣體絕緣體7V時(shí)為雪崩擊穿;時(shí)為雪崩擊穿;UBR 5V時(shí)為時(shí)為齊納擊穿;齊納擊穿;UBR介于介于57V時(shí),兩種擊穿都有。時(shí),兩種擊穿都有。68擊穿的可逆性擊穿的可逆性v電擊穿是電擊穿是可逆的可逆的(可恢復(fù),當(dāng)有限流電阻時(shí))(可恢復(fù),當(dāng)有限流電阻時(shí))。v電擊穿后如無(wú)限流措施,將發(fā)生熱擊穿電擊穿后如無(wú)限流措施,將發(fā)生熱擊穿現(xiàn)象。現(xiàn)象。v熱擊穿會(huì)破壞熱擊穿會(huì)破壞PNPN結(jié)結(jié)構(gòu)(燒壞)結(jié)結(jié)構(gòu)(燒壞)v熱擊穿是熱擊穿是 不可逆不可逆 的。的。691-2-4 PN結(jié)的電容特性結(jié)的電容特性 PN 結(jié)的耗盡區(qū)與平板電容器相似,外加電結(jié)的耗盡區(qū)與平板電容器相似,外加電壓變化,耗盡區(qū)的寬度變化,則耗盡區(qū)中的正負(fù)壓變化,耗盡區(qū)的寬度變化,則耗盡區(qū)中的正負(fù)離子數(shù)目變化,即存儲(chǔ)的電荷量變化。離子數(shù)目變化,即存儲(chǔ)的電荷量變化。一、一、勢(shì)壘電容勢(shì)壘電容CT70多子擴(kuò)散多子擴(kuò)散在對(duì)方區(qū)形成非平衡少子的濃度分布在對(duì)方區(qū)形成非平衡少子的濃度分布曲線曲線偏置電壓變化偏置電壓變化分布曲線變化分布曲線變化非平衡少非平衡少子變化子變化電荷變化。電荷變化。二、擴(kuò)散電容二、擴(kuò)散電容CD71圖圖112 P區(qū)少子濃度分布曲線區(qū)少子濃度分布曲線 72結(jié)電容結(jié)電容Cj=CT+CD結(jié)結(jié) 論論因?yàn)橐驗(yàn)镃T和和CD并不大,所以在高頻工作時(shí),才考并不大,所以在高頻工作時(shí),才考慮它們的影響。慮它們的影響。正偏時(shí)以擴(kuò)散電容正偏時(shí)以擴(kuò)散電容CD為主,為主,Cj CD,其值通常為幾十至幾百其值通常為幾十至幾百pF;反偏時(shí)以勢(shì)壘電容反偏時(shí)以勢(shì)壘電容CT為主,為主,Cj CT,其值通常為幾至幾十其值通常為幾至幾十pF。(如:。(如:變?nèi)荻O變?nèi)荻O管管)731-3 晶體二極管及其基本電路晶體二極管及其基本電路PN結(jié)加上電極引線和管殼就形成晶體二極管。結(jié)加上電極引線和管殼就形成晶體二極管。圖圖1-13 晶體二極管結(jié)構(gòu)示意圖及電路符號(hào)晶體二極管結(jié)構(gòu)示意圖及電路符號(hào) P區(qū)區(qū)N區(qū)區(qū)正極正極負(fù)極負(fù)極(a)結(jié)構(gòu)示意圖)結(jié)構(gòu)示意圖(b)電路符號(hào))電路符號(hào)PN正極正極負(fù)極負(fù)極741-3-1 二極管特性曲線二極管特性曲線二極管特性曲二極管特性曲線與線與PN結(jié)基本結(jié)基本相同,略有差相同,略有差異。異。圖圖1-14 二極管伏安特性曲線二極管伏安特性曲線 i/mAu/V(A)0102030-5-10-0.50.5硅硅 二二 極極 管管75一、正向特性一、正向特性硅硅:UD(on)=0.7V;1.導(dǎo)通電壓或死區(qū)電壓導(dǎo)通電壓或死區(qū)電壓2.曲線分段:曲線分段:鍺鍺:UD(on)=0.3V。3.小功率二極管正常工作的電流范圍內(nèi),管壓降小功率二極管正常工作的電流范圍內(nèi),管壓降變化比較小。變化比較小。指數(shù)段(小電流時(shí))、直線段(大電流時(shí))。指數(shù)段(小電流時(shí))、直線段(大電流時(shí))。一般硅:一般硅:0.60.8V,鍺:,鍺:0.10.3V。i/mAu/V(A)0102030-5-10-0.50.5硅硅 二二 極極 管管76二、反向特性二、反向特性2.小功率二極管的小功率二極管的反向電流很小。反向電流很小。一般硅管一般硅管0.1 A,鍺,鍺管管幾十微安。幾十微安。1.反向電壓加大時(shí),反反向電壓加大時(shí),反向電流也略有增大。向電流也略有增大。i/mAu/V(A)0102030-5-10-0.50.5硅硅 二二 極極 管管771-3-2 二極管的主要參數(shù)二極管的主要參數(shù)一、直流電阻一、直流電阻 圖圖1-15 二極管電阻的幾何意義二極管電阻的幾何意義IDUDQ1RD=UD/IDRD 的的幾何意義幾何意義:iu0Q2(a)直流電阻直流電阻RDQ點(diǎn)到原點(diǎn)直線斜率的倒數(shù)。點(diǎn)到原點(diǎn)直線斜率的倒數(shù)。RD不是恒定的不是恒定的,正向的,正向的RD隨工隨工作電流增大而減小,反向的作電流增大而減小,反向的RD隨反向電壓的增大而增大。隨反向電壓的增大而增大。781.正向電阻:幾百歐姆;正向電阻:幾百歐姆;反向電阻:幾百千歐姆;反向電阻:幾百千歐姆;2.Q點(diǎn)不同,測(cè)出的電阻也不同;點(diǎn)不同,測(cè)出的電阻也不同;結(jié)結(jié) 論論 因此,因此,PN結(jié)具有單向?qū)щ娞匦?。結(jié)具有單向?qū)щ娞匦浴?9二二、交流電阻、交流電阻二極管在其工作狀態(tài)二極管在其工作狀態(tài)(I DQ,UDQ)下的電壓微變量下的電壓微變量與電流微變量之比。與電流微變量之比。iu0Q i u(b)交流電阻交流電阻rDrD 的的幾何意義幾何意義:Q(IDQ,UDQ)點(diǎn)處切線斜率的倒數(shù)。點(diǎn)處切線斜率的倒數(shù)。80與與IDQ成反比,并與溫度有關(guān)。成反比,并與溫度有關(guān)。81例:例:已知已知D為為Si二極管,流過(guò)二極管,流過(guò)D的直流電流的直流電流ID=10mA,交流電壓有效值,交流電壓有效值 U=10mV,求室溫下,求室溫下流過(guò)流過(guò)D的交流電流有效值的交流電流有效值 I=?10VDR0.93K UID解:交流電阻解:交流電阻交流電流有效值為:交流電流有效值為:82三、最大整流電流三、最大整流電流 I F四四、最大反向工作電壓最大反向工作電壓 URM五五、反向電流反向電流IR允許通過(guò)的最大正向平均電流。允許通過(guò)的最大正向平均電流。通常取通常取U(BR)的一半,超過(guò)的一半,超過(guò)U(BR)容易發(fā)生反容易發(fā)生反向擊穿。向擊穿。未擊穿時(shí)的反向電流。未擊穿時(shí)的反向電流。IR越小,單向?qū)щ娦栽叫?,單向?qū)щ娦阅茉胶媚茉胶谩?3六六、最高工作頻率最高工作頻率 f M 需要指出,手冊(cè)中給出的一般為典型值,需需要指出,手冊(cè)中給出的一般為典型值,需要時(shí)應(yīng)通過(guò)實(shí)際測(cè)量得到準(zhǔn)確值。要時(shí)應(yīng)通過(guò)實(shí)際測(cè)量得到準(zhǔn)確值。工作頻率超過(guò)工作頻率超過(guò) f M時(shí),二極管的單向?qū)щ娦阅軙r(shí),二極管的單向?qū)щ娦阅茏儔?。變壞?4v對(duì)對(duì)電電子子線線路路進(jìn)進(jìn)行行分分析析(定定量量分分析析)時(shí)時(shí),電電路路中中的的實(shí)實(shí)際際器器件件必必須須用用相相應(yīng)應(yīng)的的電電路路模模型型來(lái)來(lái)等效表示,這稱為:等效表示,這稱為:“建模建模”。v計(jì)算機(jī)輔助分析計(jì)算要使用管子的模型。計(jì)算機(jī)輔助分析計(jì)算要使用管子的模型。一、一、二極管的大信號(hào)等效電路二極管的大信號(hào)等效電路1-3-3 晶體二極管模型晶體二極管模型85由于二極管的非線性特由于二極管的非線性特性,當(dāng)電路加入二極管時(shí),性,當(dāng)電路加入二極管時(shí),便成為非線性電路。實(shí)際應(yīng)便成為非線性電路。實(shí)際應(yīng)用時(shí)可根據(jù)二極管的應(yīng)用條用時(shí)可根據(jù)二極管的應(yīng)用條件作合理近似,得到相應(yīng)的件作合理近似,得到相應(yīng)的等效電路,化為線性電路等效電路,化為線性電路非線性非線性近似近似線性線性 i/mAu/V(A)0102030-5-10-0.50.5硅硅 二二 極極 管管86圖圖1-16 二極管特性的折線近似及電路模型二極管特性的折線近似及電路模型硅管:硅管:UD(on).7 V 鍺管:鍺管:UD(on).3 ViA1uBUD(on)C0(a)折線近似特性折線近似特性UUD(on)U UD(on)12UD(on)rD(on)(b)近似電路模型近似電路模型87圖圖1-16 二極管特性的折線近似及電路模型二極管特性的折線近似及電路模型iAuBUD(on)C0(a)折線近似特性折線近似特性UUD(on)U UD(on)12UD(on)(c)簡(jiǎn)化電路模型簡(jiǎn)化電路模型88圖圖1-16 二極管特性的折線近似及電路模型二極管特性的折線近似及電路模型iA2uB0C0(a)折線近似特性折線近似特性U0U 012(d)理想電路模型理想電路模型89二極管大信號(hào)模型二極管大信號(hào)模型v以以上上三三種種電電路路模模型型(近近似似、簡(jiǎn)簡(jiǎn)化化、理理想想)均均為二極管線性化模型。為二極管線性化模型。v對(duì)不同電路模型可在不同需求時(shí)采用。對(duì)不同電路模型可在不同需求時(shí)采用。90一、二極管整流電路一、二極管整流電路v把交流電轉(zhuǎn)變?yōu)橹绷麟姺Q為把交流電轉(zhuǎn)變?yōu)橹绷麟姺Q為“整流整流”。v反之稱為反之稱為“逆變逆變”。整流整流交流電交流電直流電直流電逆變逆變1-3-4 二極管基本應(yīng)用電路二極管基本應(yīng)用電路91圖圖1-17 1-17 二極管半波整流電路及波形二極管半波整流電路及波形t tu ui i0 0 u uo ot t0 0(b)(b)輸入、輸出波形關(guān)系輸入、輸出波形關(guān)系V VR RL Lu ui iu uo o(a)a)電路電路 二極管二極管近似為理想模型近似為理想模型 思考:思考:二極管二極管近似為簡(jiǎn)化模型的電路輸出?近似為簡(jiǎn)化模型的電路輸出?92u ui it t0 010V0.7V93二、二極管限幅電路二、二極管限幅電路v又稱為:又稱為:“削波電路削波電路”。v能能夠夠把把輸輸入入電電壓壓變變化化范范圍圍加加以以限限制制,常用于波形變換和整形。常用于波形變換和整形。94圖圖1-20 1-20 二極管上限幅電路及波形二極管上限幅電路及波形(b)(b)輸入、輸出波形關(guān)系輸入、輸出波形關(guān)系t t0 0 u uo o/V/V2.72.7-5-5t t u ui i/V/V0 0-5-55 5(a)a)電路電路E E2 2V VV VR Ru ui iu uo o 二極管二極管近似為簡(jiǎn)化模型近似為簡(jiǎn)化模型95判別原則:判別原則:ui-E UD(ON)時(shí)時(shí),V 導(dǎo)通,否則截止。導(dǎo)通,否則截止。當(dāng)當(dāng)當(dāng)當(dāng)u i 2.7V,V導(dǎo)通導(dǎo)通,uo=E+0.7=2.7 V 當(dāng)當(dāng)u i 2.7V時(shí)時(shí),V截止,即開路截止,即開路,uo=u i。即:即:即:即:E E2 2V VV VR Ru ui iu uo o96三、二極管電平選擇電路三、二極管電平選擇電路v能能夠夠從從多多路路輸輸入入信信號(hào)號(hào)中中選選出出最最低低電電平平或或最高電平的電路稱為電平選擇電路。最高電平的電路稱為電平選擇電路。97輸入數(shù)字量時(shí)為與邏輯。輸入數(shù)字量時(shí)為與邏輯。5V981.穩(wěn)壓二極管的正向特性、反向特性與普通二極穩(wěn)壓二極管的正向特性、反向特性與普通二極管基本相同,區(qū)別僅在于反向擊穿時(shí),特性曲線管基本相同,區(qū)別僅在于反向擊穿時(shí),特性曲線更加陡峭更加陡峭。2.穩(wěn)壓管在反向擊穿后,能通過(guò)調(diào)節(jié)自身電流,穩(wěn)壓管在反向擊穿后,能通過(guò)調(diào)節(jié)自身電流,實(shí)現(xiàn)穩(wěn)定電壓的功能。實(shí)現(xiàn)穩(wěn)定電壓的功能。電壓幾乎不變,為電壓幾乎不變,為-UZ。即當(dāng)即當(dāng)一、穩(wěn)壓二極管的特性一、穩(wěn)壓二極管的特性1-3-5 穩(wěn)壓二極管及穩(wěn)壓電路穩(wěn)壓二極管及穩(wěn)壓電路99圖圖1-21 穩(wěn)壓穩(wěn)壓二極管及其特性曲線二極管及其特性曲線(a)電路符號(hào)i/mAu/V IZmax0-UZ IZmin(b)伏安特性曲線100二、穩(wěn)壓二極管主要參數(shù)二、穩(wěn)壓二極管主要參數(shù)v穩(wěn)壓電壓穩(wěn)壓電壓 UZv額定功耗額定功耗 Pzv穩(wěn)定電流穩(wěn)定電流 Izv動(dòng)態(tài)電阻動(dòng)態(tài)電阻 rzv溫度系數(shù)溫度系數(shù) 101穩(wěn)壓電壓穩(wěn)壓電壓UZv指管子長(zhǎng)期穩(wěn)定時(shí)的工作電壓值。指管子長(zhǎng)期穩(wěn)定時(shí)的工作電壓值。102額定功耗額定功耗Pzv與材料、結(jié)構(gòu)、工藝有關(guān)。與材料、結(jié)構(gòu)、工藝有關(guān)。v使用時(shí)不允許超過(guò)此值。使用時(shí)不允許超過(guò)此值。103穩(wěn)定電流穩(wěn)定電流Izv穩(wěn)穩(wěn)壓壓二二極極管管正正常常工工作作時(shí)的參考電流。時(shí)的參考電流。vIZminIZIZmax,如如 果果電電流流小小于于IZmin時(shí)時(shí),不不能能穩(wěn)穩(wěn)壓壓,大大于于IZmax時(shí),容易燒壞管子。時(shí),容易燒壞管子。i/mAu/V IZmax0-UZ IZmin(b)伏安特性曲線104動(dòng)態(tài)電阻動(dòng)態(tài)電阻rzv是是在在擊擊穿穿狀狀態(tài)態(tài)下下,管管子子兩兩端端電電壓壓變變化化量量與與電流變化量的比值。電流變化量的比值。v反反映映在在特特性性曲曲線線上上,是是工工作作點(diǎn)點(diǎn)處處切切線線斜斜率率的倒數(shù)。的倒數(shù)。v一一般般為為幾幾歐歐姆姆到到幾幾十歐姆(越小越好)。十歐姆(越小越好)。i/mAu/V IZmax0-UZ IZmin(b)伏安特性曲線105溫度系數(shù)溫度系數(shù) v指管子穩(wěn)定電壓受溫度影響的程度。指管子穩(wěn)定電壓受溫度影響的程度。v7V是正溫系數(shù)是正溫系數(shù)(雪崩擊穿雪崩擊穿);v5V是負(fù)溫系數(shù)是負(fù)溫系數(shù)(齊納擊穿齊納擊穿);v57V溫度系數(shù)最小。溫度系數(shù)最小。106所謂穩(wěn)壓指當(dāng)所謂穩(wěn)壓指當(dāng)Ui、RL變化時(shí),變化時(shí),UO保持恒定。保持恒定。圖圖1-22 穩(wěn)壓穩(wěn)壓二極管穩(wěn)壓電路二極管穩(wěn)壓電路R ILIZVZ RLUiUo三、穩(wěn)壓三、穩(wěn)壓二極管穩(wěn)壓電路二極管穩(wěn)壓電路穩(wěn)壓原理穩(wěn)壓原理:若若Ui不變,不變,RLIzILUO基本不變;基本不變;若若RL不變,不變,UiIzURUO基本不變基本不變 107限流電阻限流電阻R的選擇:的選擇:選擇選擇R的限制條件:當(dāng)?shù)南拗茥l件:當(dāng)Ui、RL變化時(shí),變化時(shí),Iz應(yīng)滿應(yīng)滿足足IzminIzIzmax 設(shè)外界條件為設(shè)外界條件為:UiminUiUimax;RLminRLRLmax 圖圖1-22 穩(wěn)壓穩(wěn)壓二極管穩(wěn)壓電路二極管穩(wěn)壓電路R ILIZVZ RLUiUo108圖圖1-22 穩(wěn)壓穩(wěn)壓二極管穩(wěn)壓電路二極管穩(wěn)壓電路R ILIZVZ RLUiUo分析過(guò)程:分析過(guò)程:根據(jù)電路:根據(jù)電路:Iz何時(shí)取最大值?何時(shí)取最大值?ui=Uimax,RL=RLmax109圖圖1-22 穩(wěn)壓穩(wěn)壓二極管穩(wěn)壓電路二極管穩(wěn)壓電路R ILIZVZ RLUiUo110圖圖1-22 穩(wěn)壓穩(wěn)壓二極管穩(wěn)壓電路二極管穩(wěn)壓電路R ILIZVZ RLUiUoIz何時(shí)取最小值?何時(shí)取最小值?ui=Uimin,RL=RLmin111Rmin R 00V Vappliedapplied00thediodeisinforwardbias0thediodeisinforwardbiasandisactinglikeaperfectconductorso:andisactinglikeaperfectconductorso:IID D=V=VA A/R/RS S=5V/50=5V/50 =100mA=100mAb)WithVb)WithVA A0thediodeisinreversebias0thediodeisinforwardbias0thediodeisinforwardbiasandisactinglikeaperfectconductorandisactinglikeaperfectconductorsowriteaKVLequationtofindIsowriteaKVLequationtofindID D:0=V0=VA AIID DR RS S-V-V I ID D=V=VA A-V-V =4.7V=4.7V=94mA=94mARRS S5050 V V +V V +134DiodeCircuitModelsTheIdealDiodeTheIdealDiodewithBarrierwithBarrierPotentialandPotentialandLinearForwardLinearForwardResistanceResistanceThismodelisthemostaccurateofthethree.ItincludesaThismodelisthemostaccurateofthethree.Itincludesalinearforwardresistancethatiscalculatedfromtheslopeoflinearforwardresistancethatiscalculatedfromtheslopeofthelinearportionofthetransconductancethelinearportionofthetransconductancecurve.However,curve.However,thisisusuallynotnecessarysincetheRthisisusuallynotnecessarysincetheRF F(forward(forwardresistance)valueisprettyconstant.Forlow-powerresistance)valueisprettyconstant.Forlow-powergermaniumandsilicondiodestheRgermaniumandsilicondiodestheRF Fvalueisusuallyinthevalueisusuallyinthe2to5ohmsrange,whilehigherpowerdiodeshaveaR2to5ohmsrange,whilehigherpowerdiodeshaveaRF F valuecloserto1ohm.valuecloserto1ohm.LinearPortionofLinearPortionoftransconductancetransconductance curvecurveV VD DI ID DV VDDI IDDR RF F=V VD DI ID DKristinAckerson,VirginiaTechEEKristinAckerson,VirginiaTechEESpring2002Spring2002+V V R RF F135DiodeCircuitModelsTheIdealDiodeTheIdealDiodewithBarrierwithBarrierPotentialandPotentialandLinearForwardLinearForwardResistanceResistanceKristinAckerson,VirginiaTechEEKristinAckerson,VirginiaTechEESpring2002Spring2002Example:Assumethediodeisalow-powerdiodeExample:Assumethediodeisalow-powerdiodewithaforwardresistancevalueof5ohms.Thewithaforwardresistancevalueof5ohms.Thebarrierpotentialvoltageisstill:Vbarrierpotentialvoltageisstill:V =0.3volts(typical=0.3volts(typicalforagermaniumdiode)DeterminethevalueofIforagermaniumdiode)DeterminethevalueofID DififV VA A=5volts.=5volts.+_ _V VA AI ID DR RSS=50=50 V V +R RF FOnceagain,writeaKVLequationOnceagain,writeaKVLequationforthecircuit:forthecircuit:0=V0=VA AIID DR RS S-V V -I-ID DR RF FI ID D=V=VA A-V V =50.3=85.5mA=50.3=85.5mAR RS S+R+RF F50+550+5136DiodeCircuitModelsKristinAckerson,VirginiaTechEEKristinAckerson,VirginiaTechEESpring2002Spring2002ValuesofIDfortheThreeDifferentDiodeCircuitModelsValuesofIDfortheThreeDifferentDiodeCircuitModelsIdealDiodeModelIdealDiodeModelwithBarrierPotentialVoltageIdealDiodeModelwithBarrierPotentialandLinearForwardResistanceID100mA94mA85.5mAThesearethevaluesfoundintheexamplesonpreviousThesearethevaluesfoundintheexamplesonpreviousslideswheretheappliedvoltagewas5volts,thebarrierslideswheretheappliedvoltagewas5volts,thebarrierpotentialwas0.3voltsandthelinearforwardresistancepotentialwas0.3voltsandthelinearforwardresistancevaluewasassumedtobe5ohms.valuewasassumedtobe5ohms.137TheQPointKristinAckerson,VirginiaTechEEKristinAckerson,VirginiaTechEESpring2002Spring2002TheoperatingpointorQpointofthediodeisthequiescentorno-TheoperatingpointorQpointofthediodeisthequiescentorno-signalcondition.TheQpointisobtainedgraphicallyandisreallyonlysignalcondition.TheQpointisobtainedgraphicallyandisreallyonlyneededwhentheappliedvoltageisveryclosetothediodesbarrierneededwhentheappliedvoltageisveryclosetothediodesbarrierpotentialvoltage.Theexamplepotentialvoltage.Theexample3 3belowthatiscontinuedonthenextbelowthatiscontinuedonthenextslide,showshowtheQpointisdeterminedusingtheslide,showshowtheQpointisdeterminedusingthetransconductancetransconductancecurveandtheloadline.curveandtheloadline.+_ _V VA A=6V=6VI ID DR RSS=1000=1000 V V +FirsttheloadlineisfoundbysubstitutinginFirsttheloadlineisfoundbysubstitutingindifferentvaluesofVdifferentvaluesofV intotheequationforIintotheequationforIDDusingusingtheidealdiodewithbarrierpotentialmodelforthetheidealdiodewithbarrierpotentialmodelforthediode.WithRdiode.WithRS Sat1000ohmsthevalueofRat1000ohmsthevalueofRF F wouldnthavemuchimpactontheresults.wouldnthavemuchimpactontheresults.I IDD=V=VAAVV RRS SUsingVUsingV valuesof0voltsand1.4voltsweobtainvaluesof0voltsand1.4voltsweobtainI IDDvaluesof6mAand4.6mArespectively.Nextvaluesof6mAand4.6mArespectively.Nextwewilldrawthelineconnectingthesetwopointswewilldrawthelineconnectingthesetwopointsonthegraphwiththetransconductanceonthegraphwiththetransconductancecurve.curve.Thislineistheloadline.Thislineistheloadline.138TheQPointI ID D(mA(mA)V VD D(Volts)(Volts)2 24 46 68 8101012120.20.20.40.40.60.60.80.81.01.01.21.21.41.4TheThetransconductancetransconductancecurvebelowisforacurvebelowisforaSilicondiode.TheSilicondiode.TheQpointinthisQpointinthisexampleislocatedexampleislocatedat0.7Vand5.3mAat0.7Vand5.3mA.4.64.6KristinAckerson,VirginiaTechEEKristinAckerson,VirginiaTechEESpring2002Spring20020.70.75.35.3QPoint:QPoint:TheintersectionoftheTheintersectionoftheloadlineandtheloadlineandthetransconductancetransconductancecurve.curve.139CapacitanceandVoltageofPNJunctionsDiodeOperationAnimationDiodeOperationAnimationWebpageLinkWebpageLink140DynamicResistanceKristinAckerson,VirginiaTechEEKristinAckerson,VirginiaTechEESpring2002Spring2002ThedynamicresistanceofthediodeismathematicallydeterminedThedynamicresistanceofthediodeismathematicallydeterminedastheinverseoftheslopeofthetransconductanceastheinverseoftheslopeofthetransconductancecurve.curve.Therefore,theequationfordynamicresistanceis:Therefore,theequationfordynamicresistanceis:r rF F=V VT TI ID DThedynamicresistanceisusedindeterminingthevoltagedropThedynamicresistanceisusedindeterminingthevoltagedropacrossthediodeinthesituationwhereavoltagesourceisacrossthediodeinthesituationwhereavoltagesourceissupplyingasinusoidalsignalwithadcoffset.supplyingasinusoidalsignalwithadcoffset.TheaccomponentofthediodevoltageisfoundusingtheTheaccomponentofthediodevoltageisfoundusingthefollowingequation:followingequation:v vF F=v=vacacr rF F r rF F+R+RS SThevoltagedropthroughthediodeisacombinationoftheacandThevoltagedropthroughthediodeisacombinationoftheacanddccomponentsandisequalto:dccomponentsandisequalto:V VD D=V=V +v+vF F141DynamicResistanceKristinAckerson,VirginiaTechEEKristinAckerson,VirginiaTechEESpring2002Spring2002Example:Example:UsethesamecircuitusedfortheQpointexamplebutchangeUsethesamecircuitusedfortheQpointexamplebutchangethevoltagesourcesoitisanacsourcewithadcoffset.Thesourcethevoltagesourcesoitisanacsourcewithadcoffset.Thesourcevoltageisnow,vvoltageisnow,vinin=6+sin(wt)Volts.Itisasilicondiodesothebarrier=6+sin(wt)Volts.Itisasilicondiodesothebarrierpotentialvoltageisstill0.7volts.potentialvoltageisstill0.7volts.+v vininI ID DR RSS=1000=1000 V V +TheDCcomponentofthecircuitistheTheDCcomponentofthecircuitisthesameasthepreviousexampleandsameasthepreviousexampleandthereforeIthereforeID D=6V0.7V6V0.7V=5.2mA=5.2mA10001000 r rF F=V VTT=1*26mV1*26mV=4.9=4.9 I IDD5.3mA5.3mA =1isagoodapproximationifthedc=1isagoodapproximationifthedccurrentisgreaterthan1mAcurrentisgreaterthan1mAasitisinthisasitisinthisexample.example.v vF F=v=vacacrrF F=sin(wt)V4.9=sin(wt)V4.9 =4.88sin(wt)mV=4.88sin(wt)mVrrF F+R+RS S4.94.9 +1000+1000 Therefore,VTherefore,VD D=700+4.9sin(wt)mV(thevoltagedropacrossthe=700+4.9sin(wt)mV(thevoltagedropacrossthediode)diode)142KristinAckerson,VirginiaTechEEKristinAckerson,VirginiaTechEESpring2002Spring2002TypesofDiodesandTheirUsesPNJunctionPNJunctionDiodes:Diodes:AreusedtoallowcurrenttoflowinonedirectionAreusedtoallowcurrenttoflowinonedirectionwhileblockingcurrentflowintheoppositewhileblockingcurrentflowintheoppositedirection.Thepndirection.Thepnjunctiondiodeisthetypicaldiodejunctiondiodeisthetypicaldiodethathasbeenusedinthepreviouscircuits.thathasbeenusedinthepreviouscircuits.A AK KSchematicSymbolforaPNSchematicSymbolforaPNJunctionDiodeJunctionDiodeP Pn nRepresentativeStructureforRepresentativeStructureforaPNJunctionDiodeaPNJunctionDiodeZenerZenerDiodes:Diodes:ArespecificallydesignedtooperateunderreverseArespecificallydesignedtooperateunderreversebreakdownconditions.Thesediodeshaveaverybreakdownconditions.Thesediodeshaveaveryaccurateandspecificreversebreakdownvoltage.accurateandspecificreversebreakdownvoltage.A AK KSchematicSymbolforaSchematicSymbolforaZenerZenerDiodeDiode143TypesofDiodesandTheirUsesKristinAckerson,VirginiaTechEEKristinAckerson,VirginiaTechEESpring2002Spring2002SchottkySchottky Diodes:Diodes:ThesediodesaredesignedtohaveaveryfastThesediodesaredesignedtohaveaveryfastswitchingtimewhichmakesthemagreatdiodeforswitchingtimewhichmakesthemagreatdiodefordigitalcircuitapplications.Theyareverycommondigitalcircuitapplications.Theyareverycommonincomputersbecauseoftheirabilitytobeswitchedincomputersbecauseoftheirabilitytobeswitchedonandoffsoquickly.onandoffsoquickly.A AK KSchematicSymbolforaSchematicSymbolforaSchottkySchottkyDiodeDiodeShockleyShockleyDiodes:Diodes:TheShockleydiodeisafour-layerdiodewhileotherTheShockleydiodeisafour-layerdiodewhileotherdiodesarenormallymadewithonlytwolayers.diodesarenormallymadewithonlytwolayers.ThesetypesofdiodesaregenerallyusedtocontrolThesetypesofdiodesaregenerallyusedtocontroltheaveragepowerdeliveredtoaload.theaveragepowerdeliveredtoaload.A AK KSchematicSymbolforaSchematicSymbolforafour-layerShockleyDiodefour-layerShockleyDiode144TypesofDiodesandTheirUsesKristinAckerson,VirginiaTechEEKristinAckerson,VirginiaTechEESpring2002Spring2002Light-EmittingLight-EmittingDiodes:Diodes:Light-emittingdiodesaredesignedwithaverylargeLight-emittingdiodesaredesignedwithaverylargebandgapsomovementofcarriersacrosstheirbandgapsomovementofcarriersacrosstheirdepletionregionemitsphotonsoflightenergy.depletionregionemitsphotonsoflightenergy.LowerbandgapLEDs(Light-EmittingDiodes)emitLowerbandgapLEDs(Light-EmittingDiodes)emitinfraredradiation,whileLEDswithhigherbandgapinfraredradiation,whileLEDswithhigherbandgapenergyemitvisiblelight.Manystoplightsarenowenergyemitvisiblelight.ManystoplightsarenowstartingtouseLEDsstartingtouseLEDsbecausetheyareextremelybecausetheyareextremelybrightandlastlongerthanregularbulbsforabrightandlastlongerthanregularbulbsforarelativelylowcost.relativelylowcost.A AK KSchematicSymbolforaSchematicSymbolforaLight-EmittingDiodeLight-EmittingDiodeThearrowsintheLEDThearrowsintheLEDrepresentationindicaterepresentationindicateemittedlight.emittedlight.145TypesofDiodesandTheirUsesKristinAckerson,VirginiaTechEEKristinAckerson,VirginiaTechEESpring2002Spring2002Photodiodes:Photodiodes:WhileLEDsemitlight,PhotodiodesaresensitivetoWhileLEDsemitlight,Photodiodesaresensitivetoreceivedlight.Theyareconstructedsotheirpnreceivedlight.Theyareconstructedsotheirpn junctioncanbeexposedtotheoutsidethroughajunctioncanbeexposedtotheoutsidethroughaclearwindoworlens.clearwindoworlens.InPhotoconductivemodethesaturationcurrentInPhotoconductivemodethesaturationcurrentincreasesinproportiontotheintensityoftheincreasesinproportiontotheintensityofthereceivedlight.ThistypeofdiodeisusedinCDreceivedlight.ThistypeofdiodeisusedinCDplayers.players.InPhotovoltaicmode,whenthepnInPhotovoltaicmode,whenthepnjunctionisjunctionisexposedtoacertainwavelengthoflight,thediodeexposedtoacertainwavelengthoflight,thediodegeneratesvoltageandcanbeusedasanenergygeneratesvoltageandcanbeusedasanenergysource.Thistypeofdiodeisusedinthesource.Thistypeofdiodeisusedintheproductionofsolarpower.productionofsolarpower.A AK KA AK KSchematicSymbolsforSchematicSymbolsforPhotodiodesPhotodiodes 146SourcesDailey,Denton.Dailey,Denton.ElectronicDevicesandCircuits,DiscreteandIntegrated.ElectronicDevicesandCircuits,DiscreteandIntegrated.PrenticeHall,NewPrenticeHall,NewJersey:2001.(pp2-37,752-753)Jersey:2001.(pp2-37,752-753)22Figure1.10.ThediodetransconductanceFigure1.10.Thediodetransconductancecurve,pg.7curve,pg.7Figure1.15.Determinationoftheaverageforwardresistanceofadiode,pg11Figure1.15.Determinationoftheaverageforwardresistanceofadiode,pg113 3Examplefrompages13-14Examplefrompages13-14LiouLiou,J.J.andYuan,J.S.SemiconductorDevicePhysicsandSimulation.PlenumPress,J.J.andYuan,J.S.SemiconductorDevicePhysicsandSimulation.PlenumPress,NewYork:1998.NewYork:1998.NeamenNeamen,Donald.,Donald.SemiconductorPhysics&Devices.BasicPrinciples.SemiconductorPhysics&Devices.BasicPrinciples.McGraw-Hill,McGraw-Hill,Boston:1997.(pp1-15,211-234)Boston:1997.(pp1-15,211-234)1 1Figure6.2.Thespacechargeregion,theelectricfield,andtheforcesactingonFigure6.2.Thespacechargeregion,theelectricfield,andtheforcesactingonthechargedcarriers,pg213.thechargedcarriers,pg213.KristinAckerson,VirginiaTechEEKristinAckerson,VirginiaTechEESpring2002Spring2002147RobertBoylestadDigital ElectronicsCopyright2002byPearsonEducation,I
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