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在基本放大电路的三种组态中，输入电阻最大的放大电路是[ ] A.共射放大电路 B.共基放大电路C.共集放大电路D.不能确定在基本共射放大电路中，负载电阻RL 减小时，输出电阻RO将[ ]A.增大B.减少C.不变D.不能确定在三种基本放大电路中，输入电阻最小的放大电路是[ ]A.共射放大电路B.共基放大电路C.共集放大电路D.不能确定在电路中我们可以利用[ ]实现高内阻信号源与低阻负载之间较好的配合。
A 共射电路B 共基电路C 共集电路D 共射-共基电路在基本放大电路的三种组态中，输出电阻最小的是[ ]A.共射放大电路B.共基放大电路C.共集放大电路D.不能确定在由NPN晶体管组成的基本共射放大电路中，当输入信号为1kHz,5mV的正弦电压时，输出电压波形出现了底部削平的失真，这种失真是[ ]A.饱和失真B.截止失真C.交越失真D.频率失真以下电路中，可用作电压跟随器的是[ ] A．差分放大电路 B．共基电路C．共射电路 D．共集电路晶体三极管的关系式iE =f(uEB)|uCB代表三极管的A.共射极输入特性B.共射极输出特性C.共基极输入特性D.共基极输出特性对于图所示的复合管，穿透电流为（设ICEO1、ICEO2分别表示T1、T2管的穿透电流）A.ICEO = ICEO2ICEOB.ICEO =ICEO1+ICEO2C.ICEO =（1+2）ICEO1+ICEO2D.ICEO =ICEO1图 [ ]在由PNP晶体管组成的基本共射放大电路中，当输入信号为1kHz,5mV的正弦电压时，输出电压波形出现了顶部削平的失真，这种失真是[ ] B.饱和失真 B.截止失真 C.交越失真 D.频率失真对于基本共射放大电路， Rb 减小时，输入电阻Ri将[ ]A.增大B.减少C.不变D.不能确定在基本共射放大电路中，信号源内阻RS 减小时，输入电阻Ri将[ ]A.增大B.减少C.不变D.不能确定在三种基本放大电路中，电压增益最小的放大电路是[ ]A.共射放大电路B.共基放大电路C.共集放大电路D.不能确定在三种基本放大电路中，电流增益最小的放大电路是[ ]A.共射放大电路B.共基放大电路C.共集放大电路D.不能确定某放大电路的负载开路时的输出电压为4V，接入3K的负载电阻后输出电压降为3V，这说明放大电路的输出电阻为。
模拟电路（康光华）第二章课后习题答案2.4.1电路如图题2.4.1所示。
（1）利用硅二极管恒压降模型求电路的I D 和 V o 的值；（2）在室温（300K ）的情况下，利用二极管的小信号模型求v o 的变化范围。
解（1）求二极管的电流和电压mA A V R v V I D DD D 6.8106.8101)7.0210(233=⨯=Ω⨯⨯-=-=- V V V V D O 4.17.022=⨯==（2）求v o 的变化范围图题2.4.1的小信号模型等效电路如图解2.4.l 所示，温度 T ＝300 K 。
Ω≈==02.36.826mAmV I V r D T d 当r d1=r d2=r d 时，则mV V r R r V v d d DDO 6)02.321000(02.32122±=Ω⨯+Ω⨯⨯±=+∆=∆O v 的变化范围为)(~)(O O O O v V v V ∆-∆+，即1.406V ～1.394V 。
2.4.3二极管电路如图2.4.3所示，试判断图中的二极管是导通还是截止，并求出AO 两端电压V AO 。
设二极管是理想的。
解 图a ：将D 断开，以O 点为电位参考点，D 的阳极电位为－6 V ，阴极电位为－12 V ，故 D 处于正向偏置而导通，V AO =–6 V 。
图b ：D 的阳极电位为－15V ，阴极电位为－12V ，D 对被反向偏置而截止，V AO ＝－12V 。
图c ：对D 1有阳极电位为 0V ，阴极电位为－12 V ，故D 1导通，此后使D 2的阴极电位为 0V ，而其阳极为－15 V ，故D 2反偏截止，V AO =0 V 。
图d ：对D 1有阳极电位为12 V ，阴极电位为0 V ，对D 2有阳极电位为12 V ，阴极电位为 －6V ．故D 2更易导通，此后使V A ＝－6V ；D 1反偏而截止，故V AO ＝－6V 。
2.4.4 试判断图题 2.4.4中二极管是导通还是截止，为什么？ 解 图a ：将D 断开，以“地”为电位参考点，这时有V V k k V A 115)10140(10=⨯Ω+Ω=V V k k V k k V B 5.315)525(510)218(2=⨯Ω+Ω+⨯Ω+Ω=D 被反偏而截止。
模拟电路习题答案第2章基本放⼤电路题解22.16 试求出图P2.3（c ）所⽰电路Q 点、uA 、R i 和R o 的表达式。
设静态时R 2中的电流远⼤于T 2管的基极电流且R 3中的电流远⼤于T 1管的基极电流。
解：两只晶体管的静态电流、管压降分析如下：BEQ2BQ2CQ2CEQ2BEQ2BQ2CEQ1BEQ1BEQ1CC 212BQ24CQ2CC CQ2BQ1CQ1CQ23BEQ121BEQ1CC BQ1)(U U U U U U U U U V R R R U R I V U I I I R U R R U V I +==+-+≈-==≈-+-≈－－βuA 、R i 和R o 的表达式分析如下： 4o be132i 21be2422be12be2111R R r R R R A A A r R A r r A u u u u u ====+?-=∥∥βββ2.17 设图P2.17所⽰电路所加输⼊电压为正弦波。
试问：图P 2.17（1）1u A =o1U /i U ≈? 2u A =o2U /i U ≈? （2）画出输⼊电压和输出电压u i 、u o 1、u o 2 的波形；解：（1）因为通常β＞＞1，所以电压放⼤倍数分别应为1)1()1(1)1( ee 2ec e be c 1+≈+++=-=≈++-=R r R A R RR r R A be u u ββββ－（1）两个电压放⼤倍数说明 u o 1≈－u i ，u o 2≈u i 。
波形如解图P1.17所⽰。
解图P 1.172.18 电路如图P2.18所⽰，晶体管的β＝80，r b e =1k Ω。
（1）求出Q 点；（2）分别求出R L ＝∞和R L ＝3k Ω时电路的uA 和R i ；（3）求出R o 。
图P 2.18解：（1）求解Q 点：V17.7mA61.2)1(Aµ3.32)1(e EQ CC CEQ BQ EQ eb BEQ CC BQ ≈-=≈+=≈++-=R I V U I I R R U V I ββ（2）求解输⼊电阻和电压放⼤倍数： R L ＝∞时996.0)1()1(k 110])1([ebe ee be b i ≈+++=Ω≈++=R r R A R r R R uβββ∥R L ＝3k Ω时992.0))(1())(1( k 76)])(1([L e be L e L e be b i ≈+++=Ω≈++=R R r R R A R R r R R u∥∥∥∥βββ（3）求解输出电阻：Ω≈++=371beb s e o βr R R R R ∥∥2.19 电路如图P2.19所⽰，晶体管的β＝60，'bb r =100Ω。
假期就快到了你有什么计划的英语作文The Best Summer Vacation Ever!Summertime is finally here, and that means no more school for a couple of months! I've been counting down the days until summer vacation. No more homework, no more tests, no more getting up super early. Just sleeping in, playing outside, and having fun!This summer is going to be the best one yet. My family and I have so many awesome plans. First up, we're going to the beach for a whole week! We rented a beach house right on the ocean. I can't wait to swim in the waves, build sandcastles, and try to catch crabs in the tidal pools. Maybe I'll even learn how to surf! My parents said if the weather is good, we'll take a boat out and try fishing too. I really hope I can catch a big fish. That would be so cool!After our beach trip, my cousins are coming to visit us for a few weeks. We're all pretty close in age so we have a total blast when we're together. I'm sure we'll have huge games ofhide-and-seek and tag in the backyard. We might even set up a camp out there and sleep in tents! My dad promised to build us an epic fort too. With blankets and pillows everywhere, it will beour super cool hangout spot. We'll tell spooky stories, play video games, and eat junk food all night long. Having a sleepover that lasts for weeks sounds like heaven to me!My favorite part of summer though is going to sleep-away camp. I get to spend two whole weeks at Camp Wildwood doing all the activities I love. Horseback riding, canoeing, zip-lining, archery - we get to do it all! The mess hall has delicious food too, way better than the stuff they serve at school. I'm especially excited for the big camp dance at the end where we get to dress up fancy. Campfires and s'mores, silly skits, color wars...it's going to be such an incredible experience.I've been going to Camp Wildwood since I was six years old, so a lot of my best friends will be there. We always have an awesome time hanging out together without our parents or teachers around. We stay up late, play pranks, and just get to be kids without any grown-ups nagging us. I'm a little nervous about the high ropes course they added this year, but I know my friends will be there to cheer me on. I can't wait to make more magical memories!When I get back from camp, my family is taking me to an amusement park for my birthday! We're going to Six Flags and they said I can go on any ride I want, even the huge rollercoasters. I've been counting down to finally being tall enough to ride the massive Superman coaster. Just imagining how fast it goes and all the loops makes my heart race with excitement! Hopefully I'm brave enough and don't chicken out at the last second. All my friends who have been on it say it's out of this world awesome. There's also a new water park section that I'm dying to check out. Those hugely tall water slides look so terrifying but fun at the same time.As if that's not enough fun already, we're also going to visit my grandparents out in Colorado for a bit. They live on this beautiful ranch surrounded by mountains. We'll go hiking, fishing at the lake, and look for wildlife like elk and bears. My grandpa promised to take me horseback riding too! I can't wait to trot along the trails while taking in the fresh pine-scented air. Every night we'll cozy up by the fireplace and roast marshmallows. Getting to run around in the great outdoors like that is my definition of the perfect vacation.When we finally return home, my friends and I are determined to have the most epic backyard waterpark day ever! We're going to set up tons of sprinklers, slip 'n slides, and have crazy water balloon fights. Maybe we can even construct a makeshift waterslide or pool out of tarp! I'll make my famouslemonade and we can indulge in popsicles galore. Spending a day just splashing around with my besties will be the ideal way to beat the summer heat. We'll play until we're pruney and exhausted, making memories that will last forever.I've been dreaming of this summer for months now. Between beach adventures, camp shenanigans, amusement park thrills, and outdoor exploration, it's guaranteed to be an absolute blast! No more teachers, no more books - just non-stop fun and freedom. This is what being a kid is all about. I can't wait to wake up each morning bursting with excitement over what amazing activities the new day will bring. These next couple months are going to be legendary. A whole summer spent making fabulous memories and having the time of my life? Sounds perfect to me!。
第二章 习题与思考题◆ 题 2-1 试判断图 P2-1中各放大电路有无放大作用,简单说明理由。
解：<a> 无放大作用,不符合"发射结正偏,集电结反偏"的外部直流偏置要求； <b> 不能正常放大,三极管发射结没有偏置〔正偏； <c> 无放大作用,三极管集电结没有偏置〔反偏； <d> 无放大作用,三极管发射结没有偏置〔正偏； <e> 有放大作用〔电压放大倍数小于1；<f> 无放大作用,电容C 2使输出端对地交流短路,输出交流电压信号为0；<g> 无放大作用,电容C b 使三极管基极对地交流短路,输入交流信号无法加至三极管基极； <h> 不能正常放大,场效应管栅源之间无直流偏置；<i> 无放大作用,VGG 的极性使场效应管不能形成导电沟道。
本题的意图是掌握放大电路的组成原则和放大原理。
◆题 2-2 试画出P2-2中各电路的直流通路和交流通路。
设电路中的电容均足够大,变压器为理想变压器。
解：本题的意图是掌握直流通路和交流通路的概念,练习画出各种电路的直流通路和交流通路。
◆题 2-3 在NPN 三极管组成的单管共射放大电路中,假设电路其他参数不变,分别改变以下某一项参数时,试定性说明放大电路的I BQ 、I CQ 、U CEQ 将增大、减小还是不变。
① 增大Rb ；②增大VCC ；③增大β。
解：①↓↓⇒↓⇒↑⇒CEQ CQ BQ b U I I R②不定)(↑-↑=↑⇒↑⇒↑⇒CQ c CC CEQ CQ BQ CC I R V U I I V ③⎩⎨⎧↓↑⇒↑⇒CC CQBQ V I I 基本不变β本题的意图是理解单管共射放大电路中各种参数变化时对Q 点的影响。
◆题 2-4 在图所示NPN 三极管组成的分压式工作点稳定电路中,假设电路其他参数不变,分别改变以下某一项参数时,试定性说明放大电路的I BQ 、I CQ 、U CEQ 、r be 和||uA 将增大、减小还是不变。
习题2-1 如图2-51所示，判断三极管处于截止、放大还是饱和状态？ 解：a 放大状态。
b 饱和状态。
c 截止状态。
d 放大状态。
2-2 在电路中，三极管各管脚对地电位，试分析三极管A 、B 、C 各是什么电极，该管是NPN 还是PNP ，硅管还是锗管？（1）U A =3.8V ，U B =3.1V ，U C =8V ； （2）U A =7.2V ，U B =7V ，U C =3V 。
解：（1）A 是三极管基极；根据三极管发射结正偏，导通的特点，导通压降为0.7V ，则B 是三极管发射极，C 是三极管集电极；该管是NPN 型硅管。
（2）B 是三极管基极；根据三极管发射结正偏，导通的特点，导通压降为0.2V ，则A 是三极管发射极，C 是三极管集电极；该管是PNP 型锗管。
2-3 某三极管的极限参数I CM =20mA ，P CM =100mW ，U （BR ）CEO =15V ，试分析下列条件下，三极管能否正常工作？（1）I C =15m A ，U CE =8V ； （2）I C =19mA ，U CE =3V ； （3）I C =30mA ，U CE =4V 。
解：（1）U CE =8V ＜U （BR ）CEO ，I C =15mA ＜I CM ，P C =U CE I C =120mW ＞P CM ，所以不能正常工作。
（2）U CE =3V ＜U （BR ）CEO ，I C =19m A ＜I CM ， P C =U CE I C =57mW ＜P CM ，所以能正常工作。
（3）U CE =4V ＜U （BR ）CEO ，但I C =30mA ＞I CM ，所以不能正常工作。
2-4试判断图2-52中各电路有无放大作用，简单说明理由。
图2-51 习题2-1图abcd2V解：a 无放大作用。
电源极性与三极管不符。
b 无放大作用。
I B =0。
c 无放大作用。
交流通路输入短路。
d 无放大作用。
