【二(er)(er)極(ji)(ji)管的(de)作用】二(er)(er)極(ji)(ji)管在電路中(zhong)有什么作用 二(er)(er)極(ji)(ji)管的(de)特性有哪些

二極管在電路中有什么作用

二極管是電子元件當中一(yi)種具(ju)有(you)兩個電(dian)極(ji)(ji)的(de)(de)裝置，只允許(xu)(xu)電(dian)流(liu)(liu)(liu)由(you)(you)單一(yi)方向(xiang)流(liu)(liu)(liu)過，許(xu)(xu)多的(de)(de)使用(yong)是應用(yong)其整流(liu)(liu)(liu)的(de)(de)功能。而變容二極(ji)(ji)管(guan)(guan)(guan)則用(yong)來當作(zuo)電(dian)子式的(de)(de)可(ke)調電(dian)容器。大(da)部分二極(ji)(ji)管(guan)(guan)(guan)所(suo)具(ju)備(bei)的(de)(de)電(dian)流(liu)(liu)(liu)方向(xiang)性我們(men)通(tong)常稱之為“整流(liu)(liu)(liu)”功能。二極(ji)(ji)管(guan)(guan)(guan)最普遍的(de)(de)功能就是只允許(xu)(xu)電(dian)流(liu)(liu)(liu)由(you)(you)單一(yi)方向(xiang)通(tong)過（稱為順向(xiang)偏壓），反(fan)向(xiang)時阻斷 （稱為逆(ni)向(xiang)偏壓）。因(yin)此，二極(ji)(ji)管(guan)(guan)(guan)可(ke)以想成(cheng)電(dian)子版的(de)(de)逆(ni)止閥(fa)。

該圖片由注冊用戶"橘子de殿堂"提供，版權聲明反饋

二極管是最常用的電子元件之一，它最大的特性就是單向導電，也就是電流只可以從二極管的一個方向流過，二極管的作用有整流電路，檢波電路，穩壓電路，各種調制電路，主要都是由二極管來構成的，其原理都很簡單，正是由于二極管等元件的發明，才有我們現在豐富多彩的電子信息世界的誕生，既然二極管的作用這么大那么我們應該如何去檢測這個元件呢，其實很簡單只要用萬用表打到電阻檔測量一下反向電阻如果很小就說明這個二極管是壞的，反向電阻(zu)如(ru)果很大(da)這就(jiu)說明(ming)這個二極管是好的。

二極管的特性有哪些

正向性

外加(jia)正向(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)時(shi)，在(zai)正向(xiang)(xiang)(xiang)特性的(de)起始部(bu)分，正向(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)很小(xiao)，不(bu)足以克服PN結內(nei)(nei)(nei)電(dian)(dian)(dian)(dian)(dian)(dian)場(chang)的(de)阻擋作用(yong)，正向(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)流幾(ji)乎為(wei)零，這一段稱(cheng)(cheng)為(wei)死(si)(si)區。這個不(bu)能使(shi)二(er)(er)(er)極管(guan)導(dao)(dao)通(tong)的(de)正向(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)稱(cheng)(cheng)為(wei)死(si)(si)區電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)。當正向(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)大(da)于死(si)(si)區電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)以后，PN結內(nei)(nei)(nei)電(dian)(dian)(dian)(dian)(dian)(dian)場(chang)被克服，二(er)(er)(er)極管(guan)正向(xiang)(xiang)(xiang)導(dao)(dao)通(tong)，電(dian)(dian)(dian)(dian)(dian)(dian)流隨電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)增大(da)而迅速(su)上升。在(zai)正常使(shi)用(yong)的(de)電(dian)(dian)(dian)(dian)(dian)(dian)流范(fan)圍內(nei)(nei)(nei)，導(dao)(dao)通(tong)時(shi)二(er)(er)(er)極管(guan)的(de)端電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)幾(ji)乎維持(chi)不(bu)變(bian)，這個電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)稱(cheng)(cheng)為(wei)二(er)(er)(er)極管(guan)的(de)正向(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)。當二(er)(er)(er)極管(guan)兩(liang)端的(de)正向(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)超(chao)過一定數值，內(nei)(nei)(nei)電(dian)(dian)(dian)(dian)(dian)(dian)場(chang)很快被削(xue)弱(ruo)，特性電(dian)(dian)(dian)(dian)(dian)(dian)流迅速(su)增長，二(er)(er)(er)極管(guan)正向(xiang)(xiang)(xiang)導(dao)(dao)通(tong)。叫做門(men)坎(kan)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)或閾值電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)，硅管(guan)約(yue)為(wei)0.5V，鍺(zang)管(guan)約(yue)為(wei)0.1V。硅二(er)(er)(er)極管(guan)的(de)正向(xiang)(xiang)(xiang)導(dao)(dao)通(tong)壓(ya)(ya)(ya)降(jiang)約(yue)為(wei)0.6~0.8V，鍺(zang)二(er)(er)(er)極管(guan)的(de)正向(xiang)(xiang)(xiang)導(dao)(dao)通(tong)壓(ya)(ya)(ya)降(jiang)約(yue)為(wei)0.2~0.3V。

反向性

外加反向電壓不超過一定范圍時，通過二極管的電流是少數載流子漂移運動所形成反向電流。由于反向電流很小，二極管處于截止(zhi)狀態。這個反(fan)向(xiang)電流(liu)(liu)(liu)又稱為反(fan)向(xiang)飽和(he)電流(liu)(liu)(liu)或漏(lou)電流(liu)(liu)(liu)，二極管(guan)的反(fan)向(xiang)飽和(he)電流(liu)(liu)(liu)受溫(wen)度影響(xiang)很大。一般硅(gui)管(guan)的反(fan)向(xiang)電流(liu)(liu)(liu)比鍺管(guan)小(xiao)(xiao)得多，小(xiao)(xiao)功率(lv)硅(gui)管(guan)的反(fan)向(xiang)飽和(he)電流(liu)(liu)(liu)在nA數量級，小(xiao)(xiao)功率(lv)鍺管(guan)在μA數量級。溫(wen)度升高時，半導體受熱激發，少(shao)數載流(liu)(liu)(liu)子數目(mu)增加，反(fan)向(xiang)飽和(he)電流(liu)(liu)(liu)也隨(sui)之增加。

反向擊穿

齊納擊穿

反向擊穿按機理(li)分為齊(qi)納擊穿和雪(xue)崩(beng)擊穿兩種情況。在高摻(chan)雜濃(nong)度(du)的情況下，因勢壘區(qu)寬度(du)很小，反向電(dian)(dian)壓較(jiao)大時，破壞了勢壘區(qu)內共價鍵(jian)結構，使價電(dian)(dian)子脫離(li)共價鍵(jian)束(shu)縛，產生電(dian)(dian)子-空穴對，致使電(dian)(dian)流急劇增大，這種擊穿稱為齊(qi)納擊穿。如果摻(chan)雜濃(nong)度(du)較(jiao)低，勢壘區(qu)寬度(du)較(jiao)寬，不(bu)容易(yi)產生齊(qi)納擊穿。

雪崩擊穿

另一種擊(ji)穿(chuan)為(wei)雪(xue)(xue)崩擊(ji)穿(chuan)。當反向電(dian)(dian)(dian)(dian)壓增加(jia)(jia)到較大數值時，外加(jia)(jia)電(dian)(dian)(dian)(dian)場(chang)(chang)使(shi)(shi)電(dian)(dian)(dian)(dian)子(zi)(zi)漂移速(su)(su)度加(jia)(jia)快，從(cong)而與共(gong)價(jia)(jia)鍵中的價(jia)(jia)電(dian)(dian)(dian)(dian)子(zi)(zi)相碰撞(zhuang)(zhuang)，把價(jia)(jia)電(dian)(dian)(dian)(dian)子(zi)(zi)撞(zhuang)(zhuang)出(chu)共(gong)價(jia)(jia)鍵，產生新(xin)的電(dian)(dian)(dian)(dian)子(zi)(zi)-空穴(xue)對(dui)。新(xin)產生的電(dian)(dian)(dian)(dian)子(zi)(zi)-空穴(xue)被電(dian)(dian)(dian)(dian)場(chang)(chang)加(jia)(jia)速(su)(su)后(hou)又(you)撞(zhuang)(zhuang)出(chu)其它價(jia)(jia)電(dian)(dian)(dian)(dian)子(zi)(zi)，載流子(zi)(zi)雪(xue)(xue)崩式地增加(jia)(jia)，致使(shi)(shi)電(dian)(dian)(dian)(dian)流急劇增加(jia)(jia)，這(zhe)種擊(ji)穿(chuan)稱為(wei)雪(xue)(xue)崩擊(ji)穿(chuan)。無論(lun)哪種擊(ji)穿(chuan)，若(ruo)對(dui)其電(dian)(dian)(dian)(dian)流不加(jia)(jia)限制，都可(ke)能造成PN結永久性損(sun)壞(huai)。