利盈娱乐(中国)创新平台有限公司

场效应(ying)管(guan)(guan)的(de)(de)作用(yong)(yong)(yong)：由多数载流子(zi)(zi)参(can)与(yu)导电(dian),称(cheng)为(wei)单(dan)极型晶(jing)体(ti)管(guan)(guan).它也属(shu)于(yu)电(dian)压控制型半导体(ti)器(qi)件(jian).具有(you)输(shu)(shu)入(ru)(ru)电(dian)阻(zu)(zu)(zu)高(gao)（108~109Ω）、噪声小、功(gong)耗低、动态范(fan)围大、易于(yu)集成、没有(you)二(er)次击穿现象(xiang)、安全工(gong)作区域宽等(deng)优(you)点,现已成为(wei)双极型晶(jing)体(ti)管(guan)(guan)和功(gong)率晶(jing)体(ti)管(guan)(guan)的(de)(de)强大竞争者.它有(you)3个极性，栅极，漏极，源(yuan)极，它的(de)(de)特点是栅极的(de)(de)内阻(zu)(zu)(zu)极高(gao)，采用(yong)(yong)(yong)二(er)氧(yang)化(hua)硅材料的(de)(de)可(ke)以(yi)达(da)到几百兆欧，属(shu)于(yu)电(dian)压控制型器(qi)件(jian)。场效应(ying)管(guan)(guan)可(ke)应(ying)用(yong)(yong)(yong)于(yu)放大。由于(yu)放大器(qi)的(de)(de)输(shu)(shu)入(ru)(ru)阻(zu)(zu)(zu)抗(kang)很高(gao)，因(yin)此耦合电(dian)容可(ke)以(yi)容量较小，不必使用(yong)(yong)(yong)电(dian)解电(dian)容器(qi)，很高(gao)的(de)(de)输(shu)(shu)入(ru)(ru)阻(zu)(zu)(zu)抗(kang)非(fei)常适合作阻(zu)(zu)(zu)抗(kang)变换，可(ke)以(yi)常用(yong)(yong)(yong)于(yu)多级放大器(qi)的(de)(de)输(shu)(shu)入(ru)(ru)级作阻(zu)(zu)(zu)抗(kang)变换，允(yun)许(xu)方便地用(yong)(yong)(yong)作恒流源(yuan)、允(yun)许(xu)用(yong)(yong)(yong)作可(ke)变电(dian)阻(zu)(zu)(zu)、允(yun)许(xu)用(yong)(yong)(yong)作电(dian)子(zi)(zi)开关(guan)。

场效应管的(de)测试方法

1、结型场效应管的管脚(jiao)识(shi)别：

场效应(ying)(ying)管(guan)(guan)的(de)(de)栅极(ji)相(xiang)当于(yu)(yu)(yu)晶体管(guan)(guan)的(de)(de)基极(ji)，源极(ji)和(he)(he)漏极(ji)分(fen)(fen)别对应(ying)(ying)于(yu)(yu)(yu)的(de)(de)发射(she)极(ji)和(he)(he)集电(dian)极(ji)。将(jiang)万(wan)用表置于(yu)(yu)(yu)R×1k档，用两(liang)表笔分(fen)(fen)别测量每两(liang)个(ge)管(guan)(guan)脚(jiao)间(jian)的(de)(de)正(zheng)、反向(xiang)(xiang)电(dian)阻。当某两(liang)个(ge)管(guan)(guan)脚(jiao)间(jian)的(de)(de)正(zheng)、反向(xiang)(xiang)电(dian)阻相(xiang)等(deng)，均为数KΩ时(shi)，则这两(liang)个(ge)管(guan)(guan)脚(jiao)为漏极(ji)D和(he)(he)源极(ji)S（可互(hu)换），余下的(de)(de)一个(ge)管(guan)(guan)脚(jiao)即为栅极(ji)G。对于(yu)(yu)(yu)有4个(ge)管(guan)(guan)脚(jiao)的(de)(de)结(jie)型，另外一极(ji)是屏蔽极(ji)（使用中接地(di)）。

2、判定(ding)栅极(ji)

用(yong)(yong)(yong)(yong)万(wan)用(yong)(yong)(yong)(yong)表(biao)(biao)(biao)(biao)(biao)(biao)黑表(biao)(biao)(biao)(biao)(biao)(biao)笔碰(peng)触管(guan)(guan)子的(de)(de)(de)(de)一个电(dian)(dian)(dian)(dian)(dian)(dian)极(ji)(ji)，红表(biao)(biao)(biao)(biao)(biao)(biao)笔分(fen)别碰(peng)触另外(wai)两(liang)个电(dian)(dian)(dian)(dian)(dian)(dian)极(ji)(ji)。若两(liang)次测出的(de)(de)(de)(de)阻(zu)(zu)(zu)值(zhi)都(dou)很小(xiao)，说明均是(shi)正向电(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)，该(gai)管(guan)(guan)属于(yu)N沟道(dao)场(chang)效应管(guan)(guan)，黑表(biao)(biao)(biao)(biao)(biao)(biao)笔接(jie)的(de)(de)(de)(de)也(ye)(ye)是(shi)栅(zha)(zha)(zha)(zha)极(ji)(ji)。制造(zao)工(gong)艺决定了源极(ji)(ji)和(he)漏极(ji)(ji)是(shi)对称的(de)(de)(de)(de)，可(ke)以互换使(shi)用(yong)(yong)(yong)(yong)，并不(bu)(bu)影响电(dian)(dian)(dian)(dian)(dian)(dian)路的(de)(de)(de)(de)正常工(gong)作，所以不(bu)(bu)必(bi)加(jia)(jia)以区(qu)分(fen)。源极(ji)(ji)与漏极(ji)(ji)间的(de)(de)(de)(de)电(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)约为(wei)几(ji)千(qian)欧。注意不(bu)(bu)能(neng)用(yong)(yong)(yong)(yong)此法判定绝(jue)缘(yuan)栅(zha)(zha)(zha)(zha)型(xing)场(chang)效应管(guan)(guan)的(de)(de)(de)(de)栅(zha)(zha)(zha)(zha)极(ji)(ji)。因为(wei)这(zhei)种(zhong)管(guan)(guan)子的(de)(de)(de)(de)输(shu)入电(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)极(ji)(ji)高，栅(zha)(zha)(zha)(zha)源间的(de)(de)(de)(de)极(ji)(ji)间电(dian)(dian)(dian)(dian)(dian)(dian)容又很小(xiao)，测量时(shi)只要有(you)少量的(de)(de)(de)(de)电(dian)(dian)(dian)(dian)(dian)(dian)荷，就可(ke)在(zai)极(ji)(ji)间电(dian)(dian)(dian)(dian)(dian)(dian)容上(shang)形成很高的(de)(de)(de)(de)电(dian)(dian)(dian)(dian)(dian)(dian)压，容易将管(guan)(guan)子损坏。估测场(chang)效应管(guan)(guan)的(de)(de)(de)(de)放大(da)能(neng)力将万(wan)用(yong)(yong)(yong)(yong)表(biao)(biao)(biao)(biao)(biao)(biao)拨到(dao)R×100档，红表(biao)(biao)(biao)(biao)(biao)(biao)笔接(jie)源极(ji)(ji)S，黑表(biao)(biao)(biao)(biao)(biao)(biao)笔接(jie)漏极(ji)(ji)D，相当于(yu)给场(chang)效应管(guan)(guan)加(jia)(jia)上(shang)1.5V的(de)(de)(de)(de)电(dian)(dian)(dian)(dian)(dian)(dian)源电(dian)(dian)(dian)(dian)(dian)(dian)压。这(zhei)时(shi)表(biao)(biao)(biao)(biao)(biao)(biao)针(zhen)指示出的(de)(de)(de)(de)是(shi)D-S极(ji)(ji)间电(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)值(zhi)。然(ran)后用(yong)(yong)(yong)(yong)手指捏(nie)栅(zha)(zha)(zha)(zha)极(ji)(ji)G，将人体(ti)的(de)(de)(de)(de)感应电(dian)(dian)(dian)(dian)(dian)(dian)压作为(wei)输(shu)入信号加(jia)(jia)到(dao)栅(zha)(zha)(zha)(zha)极(ji)(ji)上(shang)。由于(yu)管(guan)(guan)子的(de)(de)(de)(de)放大(da)作用(yong)(yong)(yong)(yong)，UDS和(he)ID都(dou)将发生变化，也(ye)(ye)相当于(yu)D-S极(ji)(ji)间电(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)发生变化，可(ke)观察(cha)到(dao)表(biao)(biao)(biao)(biao)(biao)(biao)针(zhen)有(you)较大(da)幅度的(de)(de)(de)(de)摆(bai)(bai)(bai)动(dong)(dong)(dong)(dong)。如(ru)果手捏(nie)栅(zha)(zha)(zha)(zha)极(ji)(ji)时(shi)表(biao)(biao)(biao)(biao)(biao)(biao)针(zhen)摆(bai)(bai)(bai)动(dong)(dong)(dong)(dong)很小(xiao)，说明管(guan)(guan)子的(de)(de)(de)(de)放大(da)能(neng)力较弱；若表(biao)(biao)(biao)(biao)(biao)(biao)针(zhen)不(bu)(bu)动(dong)(dong)(dong)(dong)，说明管(guan)(guan)子已经损坏。由于(yu)人体(ti)感应的(de)(de)(de)(de)50Hz交流电(dian)(dian)(dian)(dian)(dian)(dian)压较高，而不(bu)(bu)同的(de)(de)(de)(de)用(yong)(yong)(yong)(yong)电(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)档测量时(shi)的(de)(de)(de)(de)工(gong)作点可(ke)能(neng)不(bu)(bu)同，因此用(yong)(yong)(yong)(yong)手捏(nie)栅(zha)(zha)(zha)(zha)极(ji)(ji)时(shi)表(biao)(biao)(biao)(biao)(biao)(biao)针(zhen)可(ke)能(neng)向右摆(bai)(bai)(bai)动(dong)(dong)(dong)(dong)，也(ye)(ye)可(ke)能(neng)向左(zuo)摆(bai)(bai)(bai)动(dong)(dong)(dong)(dong)。少数(shu)的(de)(de)(de)(de)管(guan)(guan)子RDS减小(xiao)，使(shi)表(biao)(biao)(biao)(biao)(biao)(biao)针(zhen)向右摆(bai)(bai)(bai)动(dong)(dong)(dong)(dong)，多(duo)数(shu)管(guan)(guan)子的(de)(de)(de)(de)RDS增大(da)，表(biao)(biao)(biao)(biao)(biao)(biao)针(zhen)向左(zuo)摆(bai)(bai)(bai)动(dong)(dong)(dong)(dong)。无(wu)论表(biao)(biao)(biao)(biao)(biao)(biao)针(zhen)的(de)(de)(de)(de)摆(bai)(bai)(bai)动(dong)(dong)(dong)(dong)方向如(ru)何(he)，只要能(neng)有(you)明显(xian)地摆(bai)(bai)(bai)动(dong)(dong)(dong)(dong)，就说明管(guan)(guan)子具(ju)有(you)放大(da)能(neng)力。本(ben)方法也(ye)(ye)适用(yong)(yong)(yong)(yong)于(yu)测MOS管(guan)(guan)。为(wei)了保护MOS管(guan)(guan)，必(bi)须用(yong)(yong)(yong)(yong)手握住螺(luo)钉旋(xuan)具(ju)绝(jue)缘(yuan)柄，用(yong)(yong)(yong)(yong)金属杆去(qu)碰(peng)栅(zha)(zha)(zha)(zha)极(ji)(ji)，以防止人体(ti)感应电(dian)(dian)(dian)(dian)(dian)(dian)荷直(zhi)接(jie)加(jia)(jia)到(dao)栅(zha)(zha)(zha)(zha)极(ji)(ji)上(shang)，将管(guan)(guan)子损坏。

MOS管每次测(ce)量完(wan)毕，G-S结电容(rong)上会(hui)充有少量电荷，建立起(qi)电压(ya)UGS，再接(jie)着测(ce)时表针可能不动，此(ci)时将G-S极间短路一(yi)下(xia)即可。

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