fangdadianlushiyizhongnengliangzhuanhuanqi，tabukenengchuangzaonengliang。jingtisanjiguanshiyongjijidianliudeweixiaobianhuakongzhijidianjidianliufashengjiaodadebianhua
，dianziguanyuchangxiaoyingguanshiyongzhajidianyadeweixiaobianhuakongzhipingjidianliufashengjiaodadebianhua，yinci
，changxiaoyingguanyudianziguanshidianyakongzhiqijian，erjingtiguanshidianliukongzhiqijian。

 

放(fang)大(da)電(dian)路(lu)不(bu)像(xiang)放(fang)大(da)鏡(jing)一(yi)樣(yang)，直(zhi)接(jie)放(fang)大(da)被(bei)觀(guan)看(kan)的(de)文(wen)字(zi)或(huo)物(wu)體(ti)。放(fang)大(da)電(dian)路(lu)將(jiang)交(jiao)流(liu)信(xin)號(hao)疊(die)加(jia)在(zai)直(zhi)流(liu)信(xin)號(hao)之(zhi)上(shang)，由(you)交(jiao)流(liu)信(xin)號(hao)的(de)變(bian)化(hua)，引(yin)起(qi)直(zhi)流(liu)信(xin)號(hao)的(de)變(bian)化(hua)，再(zai)通(tong)過(guo)負(fu)載(zai)電(dian)阻(zu)，將(jiang)直(zhi)流(liu)信(xin)號(hao)的(de)變(bian)化(hua)轉(zhuan)化(hua)為(wei)交(jiao)流(liu)信(xin)號(hao)的(de)變(bian)化(hua)。放(fang)大(da)電(dian)路(lu)中(zhong)的(de)晶(jing)體(ti)三(san)極(ji)管(guan)就(jiu)是(shi)起(qi)這(zhe)種(zhong)轉(zhuan)換(huan)作(zuo)用(yong)，由(you)基(ji)極(ji)電(dian)流(liu)微(wei)小(xiao)的(de)變(bian)化(hua)控(kong)製(zhi)集(ji)電(dian)極(ji)電(dian)流(liu)較(jiao)大(da)的(de)變(bian)化(hua)
，相(xiang)當(dang)於(yu)放(fang)大(da)了(le)基(ji)極(ji)電(dian)流(liu)。

 

zaifangdaqizhongjiyouzhiliuchengfen，youyoujiaoliuchengfen，weilefenxidianlufangbian
，changjiangzhiliuchengfensuotongguodelujingchengweizhiliutonglu
，erjiangjiaoliuxinhaosuotongguodelujingchengweijiaoliutonglu。yindianrongjuyougezhiliutongjiaoliudezuoyong
，zaihuazhiliudengxiaodianlushi，yingjiangdianrongqishiweikailu，qitabubian。

 

 

 

在分析直流通路時，一定要從電源的正極回到電源的負極，形成一個閉合通路;在zai畫hua交jiao流liu等deng效xiao電dian路lu時shi，電dian容rong器qi應ying視shi為wei短duan路lu
，直zhi流liu電dian源yuan因yin其qi兩liang端duan電dian壓ya不bu會hui變bian化hua，無wu交jiao流liu壓ya降jiang產chan生sheng，也ye視shi為wei短duan路lu，其qi他ta不bu變bian。在zai分fen析xi交jiao流liu通tong路lu時shi，不bu必bi每mei一yi級ji重zhong複fu分fen析xi，而er是shi要yao掌zhang握wo整zheng個ge信xin號hao從cong何he外wai來lai
，經jing過guo哪na些xie元yuan器qi件jian
，發fa生sheng了le哪na些xie變bian化hua，最zui終zhong到dao達da何he處chu。

 

放fang大da電dian路lu通tong常chang具ju有you靜jing態tai和he動dong態tai兩liang種zhong工gong作zuo狀zhuang態tai。靜jing態tai是shi指zhi輸shu入ru信xin號hao為wei零ling時shi，直zhi流liu電dian源yuan給gei三san極ji管guan的de各ge個ge電dian極ji提ti供gong一yi個ge合he適shi的de直zhi流liu工gong作zuo電dian壓ya，使shi三san極ji管guan工gong作zuo在zai放fang大da區qu，也ye就jiu是shi說shuo三san極ji管guan放fang大da的de外wai部bu條tiao件jian是shi發fa射she結jie正zheng偏pian，集ji電dian結jie反fan偏pian。動dong態tai是shi指zhi在zai放fang大da電dian路lu的de輸shu入ru端duan加jia上shang輸shu入ru信xin號hao後hou
，主zhu要yao分fen析xi放fang大da電dian路lu對dui信xin號hao的de放fang大da能neng力li。

 

因此在分析放大電路時，先靜態後動態
，即先分析靜態直流通路，看晶體管、電子管
、changxiaoyingguandegongzuodianyashifouzhengchang，zaijingtaigongzuodianzhengchanghou，zaifenxidongtaijiaoliutonglu。erjiaoliutongluyuzhiliutonglushigongcunyutongyidianluzhizhong，tamenjihuxianglianxi
，youhuxiangqubie。jiaoliuxinhaodianyashidiejiazaizhiliugongzuodianyazhishang，erqiedianludejiaoliuxingnengyoushoudao 直流工作點的影響和製約。如果直流偏置電壓不穩定，或有故障，則交流通路會受到影響而出現故障。

 

在zai負fu反fan饋kui電dian路lu中zhong出chu現xian輸shu出chu信xin號hao幅fu度du增zeng大da，失shi真zhen故gu障zhang現xian象xiang的de主zhu要yao原yuan因yin是shi，放fang大da電dian路lu中zhong負fu反fan饋kui元yuan件jian損sun壞huai

，負fu反fan饋kui作zuo用yong消xiao失shi，使shi放fang大da器qi的de增zeng益yi變bian大da，導dao致zhi輸shu出chu信xin號hao幅fu度du增zeng大da。此ci時shi應ying重zhong點dian檢jian查zha電dian路lu中zhong的de負fu反fan饋kui元yuan件jian是shi否fou出chu現xian開kai路lu、虛焊、電阻變值等現象。如果輸出信號出現失真，說明放大器已工作在非線性區(飽和或截 止狀態)，應重點測量放大器的工作點電壓
，蘇業緶分械牡繾枋欠裾常、放大管的參數是否發生變化。