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场效应管-场效应管工作原理(li)视频详解(jie) 秒懂系(xi)列-KIA MOS管

信息(xi)来源：本站　日期：2018-10-08　

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场效应管工作原理

场效应管(guan)工作原理用(yong)一(yi)句话说(shuo)，就是“漏(lou)(lou)(lou)极(ji)(ji)(ji)-源(yuan)极(ji)(ji)(ji)间(jian)流(liu)(liu)经(jing)沟(gou)(gou)道(dao)(dao)的(de)(de)(de)(de)ID，用(yong)以栅(zha)(zha)极(ji)(ji)(ji)与沟(gou)(gou)道(dao)(dao)间(jian)的(de)(de)(de)(de)pn结形成的(de)(de)(de)(de)反偏(pian)的(de)(de)(de)(de)栅(zha)(zha)极(ji)(ji)(ji)电压控制ID”。更正确地(di)说(shuo)，ID流(liu)(liu)经(jing)通路的(de)(de)(de)(de)宽度，即(ji)沟(gou)(gou)道(dao)(dao)截(jie)面(mian)积，它(ta)是由pn结反偏(pian)的(de)(de)(de)(de)变(bian)化，产生耗尽(jin)层扩展变(bian)化控制的(de)(de)(de)(de)缘故。在VGS=0的(de)(de)(de)(de)非饱(bao)和区域(yu)，表示的(de)(de)(de)(de)过(guo)渡层的(de)(de)(de)(de)扩展因为(wei)不(bu)很大(da)，根(gen)据(ju)漏(lou)(lou)(lou)极(ji)(ji)(ji)-源(yuan)极(ji)(ji)(ji)间(jian)所(suo)加VDS的(de)(de)(de)(de)电场，源(yuan)极(ji)(ji)(ji)区域(yu)的(de)(de)(de)(de)某些电子被漏(lou)(lou)(lou)极(ji)(ji)(ji)拉去，即(ji)从漏(lou)(lou)(lou)极(ji)(ji)(ji)向源(yuan)极(ji)(ji)(ji)有电流(liu)(liu)ID流(liu)(liu)动。从门(men)极(ji)(ji)(ji)向漏(lou)(lou)(lou)极(ji)(ji)(ji)扩展的(de)(de)(de)(de)过(guo)度层将沟(gou)(gou)道(dao)(dao)的(de)(de)(de)(de)一(yi)部分构成堵(du)塞型，ID饱(bao)和。将这种状态称为(wei)夹(jia)断。这意味着(zhe)过(guo)渡层将沟(gou)(gou)道(dao)(dao)的(de)(de)(de)(de)一(yi)部分阻挡(dang)，并不(bu)是电流(liu)(liu)被切(qie)断。

在过(guo)渡层由于没有(you)电(dian)(dian)子、空(kong)穴的(de)自由移动(dong)，在理想状态下几乎具有(you)绝(jue)缘特性，通常(chang)电(dian)(dian)流也难流动(dong)。但是此时(shi)漏极(ji)-源极(ji)间(jian)的(de)电(dian)(dian)场(chang)，实际上是两个过(guo)渡层接触漏极(ji)与门极(ji)下部(bu)(bu)附近，由于漂移电(dian)(dian)场(chang)拉去的(de)高速电(dian)(dian)子通过(guo)过(guo)渡层。因(yin)漂移电(dian)(dian)场(chang)的(de)强(qiang)度(du)几乎不(bu)变产生ID的(de)饱和现象。其次，VGS向负的(de)方向变化，让(rang)VGS=VGS(off)，此时(shi)过(guo)渡层大致成为覆盖全区域的(de)状态。而(er)且VDS的(de)电(dian)(dian)场(chang)大部(bu)(bu)分加到过(guo)渡层上，将(jiang)电(dian)(dian)子拉向漂移方向的(de)电(dian)(dian)场(chang)，只有(you)靠(kao)近源极(ji)的(de)很短部(bu)(bu)分，这(zhei)更使电(dian)(dian)流不(bu)能(neng)流通。

MOS场(chang)效应管电源开关电路

MOS场(chang)(chang)效(xiao)应管(guan)(guan)(guan)也(ye)被称为(wei)(wei)金属氧化物半(ban)导体场(chang)(chang)效(xiao)应管(guan)(guan)(guan)(MetalOxideSemiconductor FieldEffect Transistor, MOSFET)。它一般(ban)有耗尽型(xing)(xing)(xing)和(he)增强型(xing)(xing)(xing)两种。增强型(xing)(xing)(xing)MOS场(chang)(chang)效(xiao)应管(guan)(guan)(guan)可(ke)分为(wei)(wei)NPN型(xing)(xing)(xing)PNP型(xing)(xing)(xing)。NPN型(xing)(xing)(xing)通常称为(wei)(wei)N沟(gou)道型(xing)(xing)(xing)，PNP型(xing)(xing)(xing)也(ye)叫P沟(gou)道型(xing)(xing)(xing)。对(dui)于N沟(gou)道的(de)(de)场(chang)(chang)效(xiao)应管(guan)(guan)(guan)其源极(ji)(ji)(ji)(ji)和(he)漏(lou)极(ji)(ji)(ji)(ji)接在N型(xing)(xing)(xing)半(ban)导体上，同(tong)样对(dui)于P沟(gou)道的(de)(de)场(chang)(chang)效(xiao)应管(guan)(guan)(guan)其源极(ji)(ji)(ji)(ji)和(he)漏(lou)极(ji)(ji)(ji)(ji)则接在P型(xing)(xing)(xing)半(ban)导体上。场(chang)(chang)效(xiao)应管(guan)(guan)(guan)的(de)(de)输(shu)出电(dian)(dian)流是由输(shu)入(ru)的(de)(de)电(dian)(dian)压（或(huo)称电(dian)(dian)场(chang)(chang)）控制，可(ke)以认为(wei)(wei)输(shu)入(ru)电(dian)(dian)流极(ji)(ji)(ji)(ji)小或(huo)没(mei)有输(shu)入(ru)电(dian)(dian)流，这(zhei)使得该器件有很高的(de)(de)输(shu)入(ru)阻抗，同(tong)时这(zhei)也(ye)是我们称之为(wei)(wei)场(chang)(chang)效(xiao)应管(guan)(guan)(guan)的(de)(de)原因。

在(zai)(zai)(zai)二极(ji)(ji)管(guan)加(jia)(jia)上正(zheng)(zheng)向(xiang)电(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)(ya)(ya)(ya)（P端(duan)接(jie)正(zheng)(zheng)极(ji)(ji)，N端(duan)接(jie)负极(ji)(ji)）时(shi)(shi)，二极(ji)(ji)管(guan)导(dao)(dao)通，其PN结有(you)(you)电(dian)(dian)(dian)(dian)(dian)(dian)流通过。这(zhei)(zhei)是因为在(zai)(zai)(zai)P型(xing)(xing)(xing)(xing)(xing)半(ban)(ban)导(dao)(dao)体(ti)(ti)(ti)(ti)端(duan)为正(zheng)(zheng)电(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)(ya)(ya)(ya)时(shi)(shi)，N型(xing)(xing)(xing)(xing)(xing)半(ban)(ban)导(dao)(dao)体(ti)(ti)(ti)(ti)内(nei)的(de)(de)(de)负电(dian)(dian)(dian)(dian)(dian)(dian)子(zi)(zi)被吸引而涌向(xiang)加(jia)(jia)有(you)(you)正(zheng)(zheng)电(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)(ya)(ya)(ya)的(de)(de)(de)P型(xing)(xing)(xing)(xing)(xing)半(ban)(ban)导(dao)(dao)体(ti)(ti)(ti)(ti)端(duan)，而P型(xing)(xing)(xing)(xing)(xing)半(ban)(ban)导(dao)(dao)体(ti)(ti)(ti)(ti)端(duan)内(nei)的(de)(de)(de)正(zheng)(zheng)电(dian)(dian)(dian)(dian)(dian)(dian)子(zi)(zi)则朝N型(xing)(xing)(xing)(xing)(xing)半(ban)(ban)导(dao)(dao)体(ti)(ti)(ti)(ti)端(duan)运动(dong)，从(cong)而形成(cheng)导(dao)(dao)通电(dian)(dian)(dian)(dian)(dian)(dian)流。同理，当(dang)二极(ji)(ji)管(guan)加(jia)(jia)上反向(xiang)电(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)(ya)(ya)(ya)（P端(duan)接(jie)负极(ji)(ji)，N端(duan)接(jie)正(zheng)(zheng)极(ji)(ji)）时(shi)(shi)，这(zhei)(zhei)时(shi)(shi)在(zai)(zai)(zai)P型(xing)(xing)(xing)(xing)(xing)半(ban)(ban)导(dao)(dao)体(ti)(ti)(ti)(ti)端(duan)为负电(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)(ya)(ya)(ya)，正(zheng)(zheng)电(dian)(dian)(dian)(dian)(dian)(dian)子(zi)(zi)被聚集(ji)在(zai)(zai)(zai)P型(xing)(xing)(xing)(xing)(xing)半(ban)(ban)导(dao)(dao)体(ti)(ti)(ti)(ti)端(duan)，负电(dian)(dian)(dian)(dian)(dian)(dian)子(zi)(zi)则聚集(ji)在(zai)(zai)(zai)N型(xing)(xing)(xing)(xing)(xing)半(ban)(ban)导(dao)(dao)体(ti)(ti)(ti)(ti)端(duan)，电(dian)(dian)(dian)(dian)(dian)(dian)子(zi)(zi)不移动(dong)，其PN结没有(you)(you)电(dian)(dian)(dian)(dian)(dian)(dian)流通过，二极(ji)(ji)管(guan)截止。在(zai)(zai)(zai)栅极(ji)(ji)没有(you)(you)电(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)(ya)(ya)(ya)时(shi)(shi)，由(you)前(qian)面分析(xi)可(ke)知，在(zai)(zai)(zai)源极(ji)(ji)与(yu)漏极(ji)(ji)之(zhi)间(jian)(jian)不会有(you)(you)电(dian)(dian)(dian)(dian)(dian)(dian)流流过，此(ci)时(shi)(shi)场效应管(guan)处(chu)与(yu)截止状态（图7a）。当(dang)有(you)(you)一(yi)个正(zheng)(zheng)电(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)(ya)(ya)(ya)加(jia)(jia)在(zai)(zai)(zai)N沟道(dao)的(de)(de)(de)MOS场效应管(guan)栅极(ji)(ji)上时(shi)(shi)，由(you)于(yu)电(dian)(dian)(dian)(dian)(dian)(dian)场的(de)(de)(de)作(zuo)用(yong)，此(ci)时(shi)(shi)N型(xing)(xing)(xing)(xing)(xing)半(ban)(ban)导(dao)(dao)体(ti)(ti)(ti)(ti)的(de)(de)(de)源极(ji)(ji)和漏极(ji)(ji)的(de)(de)(de)负电(dian)(dian)(dian)(dian)(dian)(dian)子(zi)(zi)被吸引出(chu)来而涌向(xiang)栅极(ji)(ji)，但由(you)于(yu)氧(yang)化膜的(de)(de)(de)阻挡(dang)，使(shi)得电(dian)(dian)(dian)(dian)(dian)(dian)子(zi)(zi)聚集(ji)在(zai)(zai)(zai)两个N沟道(dao)之(zhi)间(jian)(jian)的(de)(de)(de)P型(xing)(xing)(xing)(xing)(xing)半(ban)(ban)导(dao)(dao)体(ti)(ti)(ti)(ti)，从(cong)而形成(cheng)电(dian)(dian)(dian)(dian)(dian)(dian)流，使(shi)源极(ji)(ji)和漏极(ji)(ji)之(zhi)间(jian)(jian)导(dao)(dao)通。可(ke)以想像为两个N型(xing)(xing)(xing)(xing)(xing)半(ban)(ban)导(dao)(dao)体(ti)(ti)(ti)(ti)之(zhi)间(jian)(jian)为一(yi)条沟，栅极(ji)(ji)电(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)(ya)(ya)(ya)的(de)(de)(de)建立相当(dang)于(yu)为它们之(zhi)间(jian)(jian)搭了一(yi)座桥梁，该桥的(de)(de)(de)大(da)小由(you)栅压(ya)(ya)(ya)(ya)(ya)的(de)(de)(de)大(da)小决(jue)定。

C-MOS场(chang)效应管（增强型(xing)MOS场(chang)效应管）

电(dian)(dian)(dian)(dian)路(lu)(lu)将一(yi)个增(zeng)强型(xing)P沟(gou)道(dao)MOS场(chang)(chang)效应(ying)(ying)管(guan)和(he)(he)一(yi)个增(zeng)强型(xing)N沟(gou)道(dao)MOS场(chang)(chang)效应(ying)(ying)管(guan)组合在(zai)(zai)一(yi)起使(shi)用。当输(shu)(shu)入端(duan)(duan)(duan)为低电(dian)(dian)(dian)(dian)平时，P沟(gou)道(dao)MOS场(chang)(chang)效应(ying)(ying)管(guan)导(dao)(dao)通(tong)，输(shu)(shu)出端(duan)(duan)(duan)与电(dian)(dian)(dian)(dian)源正(zheng)极接通(tong)。当输(shu)(shu)入端(duan)(duan)(duan)为高电(dian)(dian)(dian)(dian)平时，N沟(gou)道(dao)MOS场(chang)(chang)效应(ying)(ying)管(guan)导(dao)(dao)通(tong)，输(shu)(shu)出端(duan)(duan)(duan)与电(dian)(dian)(dian)(dian)源地(di)接通(tong)。在(zai)(zai)该(gai)电(dian)(dian)(dian)(dian)路(lu)(lu)中，P沟(gou)道(dao)MOS场(chang)(chang)效应(ying)(ying)管(guan)和(he)(he)N沟(gou)道(dao)MOS场(chang)(chang)效应(ying)(ying)管(guan)总是(shi)在(zai)(zai)相反(fan)的状(zhuang)态下工作(zuo)，其(qi)相位输(shu)(shu)入端(duan)(duan)(duan)和(he)(he)输(shu)(shu)出端(duan)(duan)(duan)相反(fan)。通(tong)过这种工作(zuo)方式我们可以获得(de)较大的电(dian)(dian)(dian)(dian)流输(shu)(shu)出。同(tong)时由于漏电(dian)(dian)(dian)(dian)流的影响(xiang)，使(shi)得(de)栅(zha)压(ya)在(zai)(zai)还没有(you)(you)到0V，通(tong)常在(zai)(zai)栅(zha)极电(dian)(dian)(dian)(dian)压(ya)小于1到2V时，MOS场(chang)(chang)效应(ying)(ying)管(guan)既被关断。不(bu)同(tong)场(chang)(chang)效应(ying)(ying)管(guan)其(qi)关断电(dian)(dian)(dian)(dian)压(ya)略有(you)(you)不(bu)同(tong)。也正(zheng)因为如此(ci)，使(shi)得(de)该(gai)电(dian)(dian)(dian)(dian)路(lu)(lu)不(bu)会因为两管(guan)同(tong)时导(dao)(dao)通(tong)而造成电(dian)(dian)(dian)(dian)源短(duan)路(lu)(lu)。