放fang大da電dian路lu是shi一yi種zhong能neng量liang轉zhuan換huan器qi，它ta不bu可ke能neng創chuang造zao能neng量liang。晶jing體ti三san極ji管guan是shi用yong基ji極ji電dian流liu的de微wei小xiao變bian化hua控kong製zhi集ji電dian極ji電dian流liu發fa生sheng較jiao大da的de變bian化hua
，電dian子zi管guan與yu場chang效xiao應ying管guan是shi用yong柵zha極ji電dian壓ya的de微wei小xiao變bian化hua控kong製zhi屏ping極ji電dian流liu發fa生sheng較jiao大da的de變bian化hua，因yin此ci，場chang效xiao應ying管guan與yu電dian子zi管guan是shi電dian壓ya控kong製zhi器qi件jian

，而er晶jing體ti管guan是shi電dian流liu控kong製zhi器qi件jian。

 

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)。

 

fangdadianlutongchangjuyoujingtaihedongtailiangzhonggongzuozhuangtai。jingtaishizhishuruxinhaoweilingshi，zhiliudianyuangeisanjiguandegegedianjitigongyigeheshidezhiliugongzuodianya，shisanjiguangongzuozaifangdaqu
，yejiushishuosanjiguanfangdadewaibutiaojianshifashejiezhengpian，jidianjiefanpian。dongtaishizhizaifangdadianludeshuruduanjiashangshuruxinhaohou

，zhuyaofenxifangdadianluduixinhaodefangdanengli。

 

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、場chang效xiao應ying管guan的de工gong作zuo電dian壓ya是shi否fou正zheng常chang


，在zai靜jing態tai工gong作zuo點dian正zheng常chang後hou
，再zai分fen析xi動dong態tai交jiao流liu通tong路lu。而er交jiao流liu通tong路lu與yu直zhi流liu通tong路lu是shi共gong存cun於yu同tong一yi電dian路lu之zhi中zhong
，它ta們men既ji互hu相xiang聯lian係xi，又you互hu相xiang區qu別bie。交jiao流liu信xin號hao電dian壓ya是shi疊die加jia在zai直zhi流liu工gong作zuo電dian壓ya之zhi上shang，而er且qie電dian路lu的de交jiao流liu性xing能neng又you受shou到dao 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。