一、三極管符號是什么
三極(ji)管(guan)的文字(zi)符號國外一般用(yong)宇母QR或(huo)Q表(biao)示，在(zai)國內一般用(yong)VT或(huo)V表(biao)示。
此外三極管參數中(zhong)文(wen)字符號英文(wen)對照：
1、Pcm集電極(ji)最大耗散(san)功率。
2、Icm集電極(ji)最大(da)允(yun)許(xu)電流。
3、V（br）cbo發射極(ji)開路(lu)時，集電(dian)極(ji)與基極(ji)間反向擊(ji)穿(chuan)電(dian)壓。
4、V（br）ceo基極(ji)開路時(shi)，集(ji)電極(ji)與發(fa)射極(ji)間反向擊穿電壓。
5、V（br）ebo集電(dian)極開路時，發(fa)射極與基極間(jian)反向擊穿電(dian)壓。
6、Icbo發射極開(kai)路(lu)時，集(ji)電(dian)極與基(ji)極間反(fan)向(xiang)漏電(dian)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)極(ji)管(guan)處于放大狀態，其基(ji)極(ji)電(dian)流(liu)必須大于零(ling)(ling)且小(xiao)(xiao)于飽和電(dian)流(liu)。例如鍺(zang)材料的三(san)極(ji)管(guan)，它處于放大狀態時，集(ji)電(dian)極(ji)與(yu)(yu)發射極(ji)之(zhi)(zhi)間的電(dian)壓大于1，基(ji)極(ji)與(yu)(yu)發射極(ji)之(zhi)(zhi)間電(dian)壓大于零(ling)(ling)，基(ji)極(ji)與(yu)(yu)集(ji)電(dian)極(ji)之(zhi)(zhi)間電(dian)壓小(xiao)(xiao)于零(ling)(ling)。也就是說(shuo)，鍺(zang)材料的三(san)極(ji)管(guan)處于放大狀態時，其發射結正偏，反射結反偏。
三極(ji)管(guan)處于放大狀態時，其(qi)基極(ji)電(dian)(dian)流與集(ji)(ji)電(dian)(dian)極(ji)電(dian)(dian)流之(zhi)間(jian)有唯一的(de)對應關系，即基極(ji)電(dian)(dian)流增加(jia)，集(ji)(ji)電(dian)(dian)極(ji)電(dian)(dian)流也隨之(zhi)增加(jia)。所以，三極(ji)管(guan)的(de)集(ji)(ji)電(dian)(dian)極(ji)電(dian)(dian)流主要受其(qi)基極(ji)電(dian)(dian)流控(kong)制變(bian)化(hua)，而且集(ji)(ji)電(dian)(dian)極(ji)電(dian)(dian)流的(de)變(bian)化(hua)比其(qi)基極(ji)電(dian)(dian)流變(bian)化(hua)大的(de)多。
所以說，三(san)極(ji)管的是電(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)放(fang)大器件。把(ba)基(ji)(ji)極(ji)電(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)流(liu)(liu)(liu)(liu)向發(fa)(fa)射極(ji)的電(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)叫基(ji)(ji)極(ji)電(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)，把(ba)集(ji)電(dian)(dian)(dian)(dian)極(ji)電(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)流(liu)(liu)(liu)(liu)向發(fa)(fa)射極(ji)的電(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)叫集(ji)電(dian)(dian)(dian)(dian)極(ji)電(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)。三(san)極(ji)管的放(fang)大作用就是集(ji)電(dian)(dian)(dian)(dian)極(ji)電(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)受(shou)基(ji)(ji)極(ji)電(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)的控制(zhi)并(bing)且是基(ji)(ji)極(ji)電(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)變(bian)化很(hen)小，就引起集(ji)電(dian)(dian)(dian)(dian)極(ji)電(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)很(hen)大變(bian)化，且滿(man)足一定的比例(li)關系。
