一、三極管符號是什么
三極管的(de)文字符號國(guo)外一(yi)般(ban)用宇母QR或Q表示,在國(guo)內一(yi)般(ban)用VT或V表示。
此(ci)外三極管參數中文(wen)(wen)字符號英文(wen)(wen)對照(zhao):
1、Pcm集電(dian)極最大耗散功率。
2、Icm集電(dian)極最(zui)大允許電(dian)流。
3、V(br)cbo發射極開路時,集電極與(yu)基極間反向擊(ji)穿電壓。
4、V(br)ceo基極開路時,集(ji)電極與發射極間反(fan)向(xiang)擊穿電壓(ya)。
5、V(br)ebo集電極(ji)(ji)開路(lu)時,發射(she)極(ji)(ji)與基極(ji)(ji)間(jian)反(fan)向(xiang)擊(ji)穿(chuan)電壓。
6、Icbo發射(she)極開路時,集(ji)電極與基極間(jian)反向漏電流。
二、三極管放大電路放大的是電流還是電壓
三極管是一個電流控制元件,其可以通過小電流來控制大電流,所以三極管是電流放大器件。
要使三極(ji)管(guan)(guan)(guan)處(chu)于放大(da)(da)(da)狀態(tai),其基(ji)極(ji)電(dian)(dian)(dian)流必須大(da)(da)(da)于零且小于飽和電(dian)(dian)(dian)流。例如鍺材(cai)料的三極(ji)管(guan)(guan)(guan),它(ta)處(chu)于放大(da)(da)(da)狀態(tai)時(shi),集電(dian)(dian)(dian)極(ji)與(yu)發射極(ji)之間的電(dian)(dian)(dian)壓(ya)大(da)(da)(da)于1,基(ji)極(ji)與(yu)發射極(ji)之間電(dian)(dian)(dian)壓(ya)大(da)(da)(da)于零,基(ji)極(ji)與(yu)集電(dian)(dian)(dian)極(ji)之間電(dian)(dian)(dian)壓(ya)小于零。也就(jiu)是說(shuo),鍺材(cai)料的三極(ji)管(guan)(guan)(guan)處(chu)于放大(da)(da)(da)狀態(tai)時(shi),其發射結正(zheng)偏,反(fan)射結反(fan)偏。
三極(ji)(ji)管(guan)處(chu)于放(fang)大狀(zhuang)態(tai)時,其(qi)(qi)基(ji)極(ji)(ji)電(dian)(dian)(dian)流(liu)與集(ji)電(dian)(dian)(dian)極(ji)(ji)電(dian)(dian)(dian)流(liu)之間(jian)有唯一的(de)對(dui)應關系,即基(ji)極(ji)(ji)電(dian)(dian)(dian)流(liu)增(zeng)加(jia)(jia),集(ji)電(dian)(dian)(dian)極(ji)(ji)電(dian)(dian)(dian)流(liu)也隨之增(zeng)加(jia)(jia)。所以,三極(ji)(ji)管(guan)的(de)集(ji)電(dian)(dian)(dian)極(ji)(ji)電(dian)(dian)(dian)流(liu)主(zhu)要(yao)受其(qi)(qi)基(ji)極(ji)(ji)電(dian)(dian)(dian)流(liu)控制變(bian)化,而(er)且集(ji)電(dian)(dian)(dian)極(ji)(ji)電(dian)(dian)(dian)流(liu)的(de)變(bian)化比其(qi)(qi)基(ji)極(ji)(ji)電(dian)(dian)(dian)流(liu)變(bian)化大的(de)多(duo)。
所以說,三極(ji)(ji)(ji)管的是電(dian)流(liu)(liu)(liu)(liu)放大器(qi)件。把(ba)基(ji)極(ji)(ji)(ji)電(dian)流(liu)(liu)(liu)(liu)流(liu)(liu)(liu)(liu)向(xiang)發(fa)射(she)極(ji)(ji)(ji)的電(dian)流(liu)(liu)(liu)(liu)叫(jiao)基(ji)極(ji)(ji)(ji)電(dian)流(liu)(liu)(liu)(liu),把(ba)集(ji)電(dian)極(ji)(ji)(ji)電(dian)流(liu)(liu)(liu)(liu)流(liu)(liu)(liu)(liu)向(xiang)發(fa)射(she)極(ji)(ji)(ji)的電(dian)流(liu)(liu)(liu)(liu)叫(jiao)集(ji)電(dian)極(ji)(ji)(ji)電(dian)流(liu)(liu)(liu)(liu)。三極(ji)(ji)(ji)管的放大作(zuo)用(yong)就(jiu)是集(ji)電(dian)極(ji)(ji)(ji)電(dian)流(liu)(liu)(liu)(liu)受基(ji)極(ji)(ji)(ji)電(dian)流(liu)(liu)(liu)(liu)的控(kong)制并且是基(ji)極(ji)(ji)(ji)電(dian)流(liu)(liu)(liu)(liu)變化(hua)很小,就(jiu)引起集(ji)電(dian)極(ji)(ji)(ji)電(dian)流(liu)(liu)(liu)(liu)很大變化(hua),且滿(man)足一定(ding)的比例關系。