场效(xiao)应管是(shi)作用是(shi)什么,场效(xiao)应管的全面文章,值得收藏！
信息(xi)来源：本(ben)站 日(ri)期：2017-09-22
场(chang)效应管工作原理(li)用(yong)一(yi)(yi)句话说(shuo)(shuo)，就(jiu)是“漏(lou)极(ji)(ji)-源(yuan)(yuan)极(ji)(ji)间(jian)流经沟(gou)(gou)(gou)道的(de)(de)(de)(de)(de)ID，用(yong)以栅(zha)极(ji)(ji)与沟(gou)(gou)(gou)道间(jian)的(de)(de)(de)(de)(de)pn结(jie)形成(cheng)的(de)(de)(de)(de)(de)反偏的(de)(de)(de)(de)(de)栅(zha)极(ji)(ji)电(dian)(dian)(dian)压(ya)控制ID”。更正确地说(shuo)(shuo)，ID流经通路(lu)的(de)(de)(de)(de)(de)宽度(du)，即沟(gou)(gou)(gou)道截(jie)面(mian)积，它(ta)是由pn结(jie)反偏的(de)(de)(de)(de)(de)变化(hua)，产生耗(hao)尽层(ceng)扩展变化(hua)控制的(de)(de)(de)(de)(de)缘故。在VGS=0的(de)(de)(de)(de)(de)非饱和区域，表(biao)示的(de)(de)(de)(de)(de)过(guo)渡(du)层(ceng)的(de)(de)(de)(de)(de)扩展因(yin)为不(bu)很大(da)，根据漏(lou)极(ji)(ji)-源(yuan)(yuan)极(ji)(ji)间(jian)所(suo)加VDS的(de)(de)(de)(de)(de)电(dian)(dian)(dian)场(chang)，源(yuan)(yuan)极(ji)(ji)区域的(de)(de)(de)(de)(de)某些电(dian)(dian)(dian)子(zi)被(bei)漏(lou)极(ji)(ji)拉去(qu)，即从(cong)漏(lou)极(ji)(ji)向源(yuan)(yuan)极(ji)(ji)有电(dian)(dian)(dian)流ID流动。从(cong)门极(ji)(ji)向漏(lou)极(ji)(ji)扩展的(de)(de)(de)(de)(de)过(guo)度(du)层(ceng)将沟(gou)(gou)(gou)道的(de)(de)(de)(de)(de)一(yi)(yi)部(bu)分(fen)构成(cheng)堵(du)塞型，ID饱和。将这(zhei)种状态称为夹断。这(zhei)意(yi)味着过(guo)渡(du)层(ceng)将沟(gou)(gou)(gou)道的(de)(de)(de)(de)(de)一(yi)(yi)部(bu)分(fen)阻(zu)挡(dang)，并不(bu)是电(dian)(dian)(dian)流被(bei)切断。
在过(guo)渡层由(you)于(yu)没有电(dian)(dian)(dian)(dian)(dian)子、空穴的(de)(de)自由(you)移(yi)动，在理想(xiang)状态下(xia)几(ji)乎(hu)具(ju)有绝(jue)缘特性(xing)，通(tong)常电(dian)(dian)(dian)(dian)(dian)流(liu)也(ye)难流(liu)动。但是(shi)此时(shi)(shi)漏极(ji)-源极(ji)间的(de)(de)电(dian)(dian)(dian)(dian)(dian)场(chang)(chang)，实际上(shang)是(shi)两(liang)个过(guo)渡层接触漏极(ji)与门极(ji)下(xia)部(bu)附(fu)近，由(you)于(yu)漂移(yi)电(dian)(dian)(dian)(dian)(dian)场(chang)(chang)拉(la)去的(de)(de)高速电(dian)(dian)(dian)(dian)(dian)子通(tong)过(guo)过(guo)渡层。因漂移(yi)电(dian)(dian)(dian)(dian)(dian)场(chang)(chang)的(de)(de)强度几(ji)乎(hu)不变产生ID的(de)(de)饱和现象(xiang)。其次，VGS向(xiang)负的(de)(de)方向(xiang)变化(hua)，让VGS=VGS(off)，此时(shi)(shi)过(guo)渡层大(da)致成为覆盖(gai)全区(qu)域的(de)(de)状态。而且VDS的(de)(de)电(dian)(dian)(dian)(dian)(dian)场(chang)(chang)大(da)部(bu)分(fen)加到过(guo)渡层上(shang)，将电(dian)(dian)(dian)(dian)(dian)子拉(la)向(xiang)漂移(yi)方向(xiang)的(de)(de)电(dian)(dian)(dian)(dian)(dian)场(chang)(chang)，只(zhi)有靠近源极(ji)的(de)(de)很短部(bu)分(fen)，这(zhei)更使电(dian)(dian)(dian)(dian)(dian)流(liu)不能流(liu)通(tong)。
MOS场(chang)效应(ying)管(guan)(guan)(guan)也被称(cheng)为金属氧化物(wu)半(ban)(ban)导(dao)(dao)体场(chang)效应(ying)管(guan)(guan)(guan)(MetalOxideSemiconductor FieldEffectTransistor,MOSFET)。它一般有耗(hao)尽(jin)型(xing)(xing)(xing)和(he)增强型(xing)(xing)(xing)两种。增强型(xing)(xing)(xing)MOS场(chang)效应(ying)管(guan)(guan)(guan)可(ke)分为NPN型(xing)(xing)(xing)PNP型(xing)(xing)(xing)。NPN型(xing)(xing)(xing)通常称(cheng)为N沟(gou)(gou)道(dao)(dao)型(xing)(xing)(xing)，PNP型(xing)(xing)(xing)也叫P沟(gou)(gou)道(dao)(dao)型(xing)(xing)(xing)。对(dui)于N沟(gou)(gou)道(dao)(dao)的场(chang)效应(ying)管(guan)(guan)(guan)其源极(ji)(ji)和(he)漏极(ji)(ji)接在(zai)(zai)N型(xing)(xing)(xing)半(ban)(ban)导(dao)(dao)体上，同样对(dui)于P沟(gou)(gou)道(dao)(dao)的场(chang)效应(ying)管(guan)(guan)(guan)其源极(ji)(ji)和(he)漏极(ji)(ji)则接在(zai)(zai)P型(xing)(xing)(xing)半(ban)(ban)导(dao)(dao)体上。场(chang)效应(ying)管(guan)(guan)(guan)的输(shu)出电(dian)流是(shi)由输(shu)入的电(dian)压（或称(cheng)电(dian)场(chang)）控制(zhi)，可(ke)以认为输(shu)入电(dian)流极(ji)(ji)小或没有输(shu)入电(dian)流，这(zhei)使得该器件有很(hen)高的输(shu)入阻抗(kang)，同时这(zhei)也是(shi)我们称(cheng)之为场(chang)效应(ying)管(guan)(guan)(guan)的原因(yin)。
在二极(ji)(ji)(ji)(ji)管(guan)加上正(zheng)(zheng)(zheng)(zheng)(zheng)向(xiang)电(dian)(dian)(dian)压(ya)（P端接(jie)正(zheng)(zheng)(zheng)(zheng)(zheng)极(ji)(ji)(ji)(ji)，N端接(jie)负极(ji)(ji)(ji)(ji)）时(shi)(shi)，二极(ji)(ji)(ji)(ji)管(guan)导(dao)(dao)(dao)(dao)通(tong)，其PN结有电(dian)(dian)(dian)流通(tong)过。这(zhei)是因为(wei)在P型(xing)(xing)(xing)(xing)半(ban)(ban)导(dao)(dao)(dao)(dao)体(ti)(ti)端为(wei)正(zheng)(zheng)(zheng)(zheng)(zheng)电(dian)(dian)(dian)压(ya)时(shi)(shi)，N型(xing)(xing)(xing)(xing)半(ban)(ban)导(dao)(dao)(dao)(dao)体(ti)(ti)内的(de)负电(dian)(dian)(dian)子被(bei)吸引(yin)而(er)涌向(xiang)加有正(zheng)(zheng)(zheng)(zheng)(zheng)电(dian)(dian)(dian)压(ya)的(de)P型(xing)(xing)(xing)(xing)半(ban)(ban)导(dao)(dao)(dao)(dao)体(ti)(ti)端，而(er)P型(xing)(xing)(xing)(xing)半(ban)(ban)导(dao)(dao)(dao)(dao)体(ti)(ti)端内的(de)正(zheng)(zheng)(zheng)(zheng)(zheng)电(dian)(dian)(dian)子则朝N型(xing)(xing)(xing)(xing)半(ban)(ban)导(dao)(dao)(dao)(dao)体(ti)(ti)端运动，从而(er)形成(cheng)导(dao)(dao)(dao)(dao)通(tong)电(dian)(dian)(dian)流。同理，当(dang)二极(ji)(ji)(ji)(ji)管(guan)加上反向(xiang)电(dian)(dian)(dian)压(ya)（P端接(jie)负极(ji)(ji)(ji)(ji)，N端接(jie)正(zheng)(zheng)(zheng)(zheng)(zheng)极(ji)(ji)(ji)(ji)）时(shi)(shi)，这(zhei)时(shi)(shi)在P型(xing)(xing)(xing)(xing)半(ban)(ban)导(dao)(dao)(dao)(dao)体(ti)(ti)端为(wei)负电(dian)(dian)(dian)压(ya)，正(zheng)(zheng)(zheng)(zheng)(zheng)电(dian)(dian)(dian)子被(bei)聚集(ji)在P型(xing)(xing)(xing)(xing)半(ban)(ban)导(dao)(dao)(dao)(dao)体(ti)(ti)端，负电(dian)(dian)(dian)子则聚集(ji)在N型(xing)(xing)(xing)(xing)半(ban)(ban)导(dao)(dao)(dao)(dao)体(ti)(ti)端，电(dian)(dian)(dian)子不(bu)移动，其PN结没有电(dian)(dian)(dian)流通(tong)过，二极(ji)(ji)(ji)(ji)管(guan)截止。在栅(zha)极(ji)(ji)(ji)(ji)没有电(dian)(dian)(dian)压(ya)时(shi)(shi)，由前面分析可(ke)知，在源(yuan)极(ji)(ji)(ji)(ji)与漏(lou)极(ji)(ji)(ji)(ji)之(zhi)间不(bu)会有电(dian)(dian)(dian)流流过，此时(shi)(shi)场(chang)(chang)效(xiao)应管(guan)处与截止状(zhuang)态（图(tu)7a）。当(dang)有一(yi)个正(zheng)(zheng)(zheng)(zheng)(zheng)电(dian)(dian)(dian)压(ya)加在N沟(gou)(gou)道(dao)的(de)MOS场(chang)(chang)效(xiao)应管(guan)栅(zha)极(ji)(ji)(ji)(ji)上时(shi)(shi)，由于电(dian)(dian)(dian)场(chang)(chang)的(de)作用(yong)，此时(shi)(shi)N型(xing)(xing)(xing)(xing)半(ban)(ban)导(dao)(dao)(dao)(dao)体(ti)(ti)的(de)源(yuan)极(ji)(ji)(ji)(ji)和(he)漏(lou)极(ji)(ji)(ji)(ji)的(de)负电(dian)(dian)(dian)子被(bei)吸引(yin)出来而(er)涌向(xiang)栅(zha)极(ji)(ji)(ji)(ji)，但由于氧化(hua)膜(mo)的(de)阻挡(dang)，使得电(dian)(dian)(dian)子聚集(ji)在两(liang)个N沟(gou)(gou)道(dao)之(zhi)间的(de)P型(xing)(xing)(xing)(xing)半(ban)(ban)导(dao)(dao)(dao)(dao)体(ti)(ti)中(zhong)（见图(tu)7b），从而(er)形成(cheng)电(dian)(dian)(dian)流，使源(yuan)极(ji)(ji)(ji)(ji)和(he)漏(lou)极(ji)(ji)(ji)(ji)之(zhi)间导(dao)(dao)(dao)(dao)通(tong)。可(ke)以想像为(wei)两(liang)个N型(xing)(xing)(xing)(xing)半(ban)(ban)导(dao)(dao)(dao)(dao)体(ti)(ti)之(zhi)间为(wei)一(yi)条(tiao)沟(gou)(gou)，栅(zha)极(ji)(ji)(ji)(ji)电(dian)(dian)(dian)压(ya)的(de)建立相当(dang)于为(wei)它(ta)们(men)之(zhi)间搭(da)了(le)一(yi)座(zuo)桥(qiao)梁(liang)，该桥(qiao)的(de)大小(xiao)由栅(zha)压(ya)的(de)大小(xiao)决(jue)定。
电(dian)(dian)(dian)路将一(yi)(yi)个增强(qiang)型P沟道(dao)(dao)MOS场(chang)(chang)(chang)效(xiao)应(ying)管(guan)(guan)(guan)和(he)一(yi)(yi)个增强(qiang)型N沟道(dao)(dao)MOS场(chang)(chang)(chang)效(xiao)应(ying)管(guan)(guan)(guan)组合在一(yi)(yi)起使(shi)用。当输入(ru)(ru)端(duan)(duan)(duan)为低电(dian)(dian)(dian)平(ping)时(shi)，P沟道(dao)(dao)MOS场(chang)(chang)(chang)效(xiao)应(ying)管(guan)(guan)(guan)导通，输出端(duan)(duan)(duan)与电(dian)(dian)(dian)源(yuan)正极(ji)接通。当输入(ru)(ru)端(duan)(duan)(duan)为高电(dian)(dian)(dian)平(ping)时(shi)，N沟道(dao)(dao)MOS场(chang)(chang)(chang)效(xiao)应(ying)管(guan)(guan)(guan)导通，输出端(duan)(duan)(duan)与电(dian)(dian)(dian)源(yuan)地接通。在该(gai)电(dian)(dian)(dian)路中(zhong)，P沟道(dao)(dao)MOS场(chang)(chang)(chang)效(xiao)应(ying)管(guan)(guan)(guan)和(he)N沟道(dao)(dao)MOS场(chang)(chang)(chang)效(xiao)应(ying)管(guan)(guan)(guan)总是在相(xiang)反的(de)状态(tai)下(xia)工作，其相(xiang)位(wei)输入(ru)(ru)端(duan)(duan)(duan)和(he)输出端(duan)(duan)(duan)相(xiang)反。通过这种工作方式我们可以获得较大的(de)电(dian)(dian)(dian)流输出。同时(shi)由(you)于(yu)(yu)漏电(dian)(dian)(dian)流的(de)影响，使(shi)得栅(zha)压(ya)(ya)在还没有到0V，通常在栅(zha)极(ji)电(dian)(dian)(dian)压(ya)(ya)小于(yu)(yu)1到2V时(shi)，MOS场(chang)(chang)(chang)效(xiao)应(ying)管(guan)(guan)(guan)既被关(guan)断(duan)。不同场(chang)(chang)(chang)效(xiao)应(ying)管(guan)(guan)(guan)其关(guan)断(duan)电(dian)(dian)(dian)压(ya)(ya)略有不同。也正因为如(ru)此，使(shi)得该(gai)电(dian)(dian)(dian)路不会因为两管(guan)(guan)(guan)同时(shi)导通而造成电(dian)(dian)(dian)源(yuan)短路。
1、场效(xiao)应(ying)(ying)管(guan)可应(ying)(ying)用于放(fang)大(da)。由于场效(xiao)应(ying)(ying)管(guan)放(fang)大(da)器的输入阻抗(kang)很高，因此耦合电容可以容量(liang)较(jiao)小，不必使(shi)用电解电容器。
2、场效(xiao)应管(guan)很高的输(shu)入阻(zu)抗非常适合作(zuo)阻(zu)抗变换。常用于多级放大器的输(shu)入级作(zuo)阻(zu)抗变换。
3、场效应管可(ke)以用(yong)作可(ke)变电阻。
4、场效应管可以方便地(di)用作恒流源。
5、场效(xiao)应管可以用作电子开关(guan)。
联系方式：邹先生
联系电话：0755-83888366-8022
手机：18123972950
QQ：2880195519
联系地(di)址：深圳市福田区车公庙天安数(shu)码城天吉大(da)厦(sha)CD座5C1
关注(zhu)KIA半导体工程(cheng)专辑请搜微信(xin)号:“KIA半导体”或点击本文(wen)下方(fang)图片扫一扫进(jin)入官方(fang)微信(xin)“关注(zhu)”
长(zhang)按二维码识别关注
