一、三極管符號是什么
三極管的(de)文(wen)字符號國外一般用宇母QR或(huo)(huo)Q表(biao)示，在國內一般用VT或(huo)(huo)V表(biao)示。
此(ci)外三極(ji)管(guan)參數中(zhong)文(wen)字符號英文(wen)對照：
1、Pcm集電極最(zui)大(da)耗散功率。
2、Icm集電(dian)極(ji)最大(da)允許電(dian)流。
3、V（br）cbo發射極(ji)(ji)(ji)開(kai)路(lu)時，集電極(ji)(ji)(ji)與基極(ji)(ji)(ji)間(jian)反向(xiang)擊(ji)穿電壓(ya)。
4、V（br）ceo基極開路時，集電(dian)極與發(fa)射(she)極間反向擊穿電(dian)壓。
5、V（br）ebo集電(dian)極開路時，發射極與基極間反向擊(ji)穿電(dian)壓。
6、Icbo發(fa)射極(ji)開路時(shi)，集電極(ji)與基極(ji)間反向漏(lou)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(san)(san)極管(guan)處于(yu)(yu)放大狀態(tai)，其(qi)基極電(dian)流(liu)必(bi)須大于(yu)(yu)零且小于(yu)(yu)飽和電(dian)流(liu)。例如鍺材(cai)料(liao)的(de)三(san)(san)極管(guan)，它(ta)處于(yu)(yu)放大狀態(tai)時(shi)，集電(dian)極與(yu)發(fa)射(she)極之(zhi)間(jian)的(de)電(dian)壓(ya)(ya)大于(yu)(yu)1，基極與(yu)發(fa)射(she)極之(zhi)間(jian)電(dian)壓(ya)(ya)大于(yu)(yu)零，基極與(yu)集電(dian)極之(zhi)間(jian)電(dian)壓(ya)(ya)小于(yu)(yu)零。也就是(shi)說，鍺材(cai)料(liao)的(de)三(san)(san)極管(guan)處于(yu)(yu)放大狀態(tai)時(shi)，其(qi)發(fa)射(she)結正偏(pian)，反射(she)結反偏(pian)。
三極(ji)(ji)(ji)管處于(yu)放大狀態時，其基(ji)極(ji)(ji)(ji)電(dian)(dian)(dian)(dian)流(liu)(liu)與集(ji)電(dian)(dian)(dian)(dian)極(ji)(ji)(ji)電(dian)(dian)(dian)(dian)流(liu)(liu)之(zhi)間有唯一的對應(ying)關(guan)系，即基(ji)極(ji)(ji)(ji)電(dian)(dian)(dian)(dian)流(liu)(liu)增加，集(ji)電(dian)(dian)(dian)(dian)極(ji)(ji)(ji)電(dian)(dian)(dian)(dian)流(liu)(liu)也隨之(zhi)增加。所(suo)以，三極(ji)(ji)(ji)管的集(ji)電(dian)(dian)(dian)(dian)極(ji)(ji)(ji)電(dian)(dian)(dian)(dian)流(liu)(liu)主要(yao)受其基(ji)極(ji)(ji)(ji)電(dian)(dian)(dian)(dian)流(liu)(liu)控制(zhi)變(bian)化，而且(qie)集(ji)電(dian)(dian)(dian)(dian)極(ji)(ji)(ji)電(dian)(dian)(dian)(dian)流(liu)(liu)的變(bian)化比其基(ji)極(ji)(ji)(ji)電(dian)(dian)(dian)(dian)流(liu)(liu)變(bian)化大的多。
所以(yi)說，三極(ji)(ji)管(guan)的(de)(de)(de)是(shi)電(dian)(dian)(dian)流(liu)(liu)放(fang)大器件。把基(ji)極(ji)(ji)電(dian)(dian)(dian)流(liu)(liu)流(liu)(liu)向(xiang)發(fa)射(she)極(ji)(ji)的(de)(de)(de)電(dian)(dian)(dian)流(liu)(liu)叫基(ji)極(ji)(ji)電(dian)(dian)(dian)流(liu)(liu)，把集電(dian)(dian)(dian)極(ji)(ji)電(dian)(dian)(dian)流(liu)(liu)流(liu)(liu)向(xiang)發(fa)射(she)極(ji)(ji)的(de)(de)(de)電(dian)(dian)(dian)流(liu)(liu)叫集電(dian)(dian)(dian)極(ji)(ji)電(dian)(dian)(dian)流(liu)(liu)。三極(ji)(ji)管(guan)的(de)(de)(de)放(fang)大作用就(jiu)是(shi)集電(dian)(dian)(dian)極(ji)(ji)電(dian)(dian)(dian)流(liu)(liu)受基(ji)極(ji)(ji)電(dian)(dian)(dian)流(liu)(liu)的(de)(de)(de)控制并且是(shi)基(ji)極(ji)(ji)電(dian)(dian)(dian)流(liu)(liu)變化(hua)很小(xiao)，就(jiu)引起(qi)集電(dian)(dian)(dian)極(ji)(ji)電(dian)(dian)(dian)流(liu)(liu)很大變化(hua)，且滿足一定的(de)(de)(de)比例關系(xi)。
