区分MOS管P沟道(dao)N沟道(dao)方法详解-NMOS与PMOS介绍及工(gong)作原(yuan)理-KIA MOS管
信(xin)息来源：本站 日(ri)期：2018-07-25
PMOS是指n型衬底、p沟(gou)道，靠空穴的(de)流(liu)动运(yun)送(song)电(dian)(dian)流(liu)的(de)MOS管(guan)。P沟(gou)道MOS晶(jing)体(ti)管(guan)的(de)空穴迁移率低，因(yin)而在MOS晶(jing)体(ti)管(guan)的(de)几何(he)尺寸和工(gong)(gong)作电(dian)(dian)压(ya)(ya)绝(jue)对值相(xiang)等(deng)的(de)情(qing)况(kuang)下，PMOS晶(jing)体(ti)管(guan)的(de)跨(kua)导(dao)(dao)小(xiao)于N沟(gou)道MOS晶(jing)体(ti)管(guan)。此(ci)外(wai)，P沟(gou)道MOS晶(jing)体(ti)管(guan)阈(yu)值电(dian)(dian)压(ya)(ya)的(de)绝(jue)对值一般偏高，要求有(you)较高的(de)工(gong)(gong)作电(dian)(dian)压(ya)(ya)。它的(de)供电(dian)(dian)电(dian)(dian)源的(de)电(dian)(dian)压(ya)(ya)大小(xiao)和极性，与双极型晶(jing)体(ti)管(guan)——晶(jing)体(ti)管(guan)逻辑电(dian)(dian)路不兼容。PMOS因(yin)逻辑摆幅大，充电(dian)(dian)放(fang)电(dian)(dian)过程长，加之器件跨(kua)导(dao)(dao)小(xiao)，所以工(gong)(gong)作速度更(geng)低，在NMOS电(dian)(dian)路（见(jian)N沟(gou)道金(jin)属—氧化物—半(ban)导(dao)(dao)体(ti)集成电(dian)(dian)路）出现之后，多数(shu)已为NMOS电(dian)(dian)路所取(qu)代(dai)。只是，因(yin)PMOS电(dian)(dian)路工(gong)(gong)艺简(jian)单(dan)，价格便宜，有(you)些中规模和小(xiao)规模数(shu)字控制电(dian)(dian)路仍采用PMOS电(dian)(dian)路技术。
NMOS英文全称(cheng)为(wei)N-Metal-Oxide-Semiconductor。意思为(wei)N型(xing)金属-氧化物-半导体，而拥有(you)这(zhei)种结构的晶(jing)体管(guan)(guan)(guan)我(wo)们称(cheng)之(zhi)为(wei)NMOS晶(jing)体管(guan)(guan)(guan)。MOS晶(jing)体管(guan)(guan)(guan)有(you)P型(xing)MOS管(guan)(guan)(guan)和N型(xing)MOS管(guan)(guan)(guan)之(zhi)分(fen)。由(you)MOS管(guan)(guan)(guan)构成(cheng)(cheng)的集(ji)成(cheng)(cheng)电(dian)(dian)路(lu)称(cheng)为(wei)MOS集(ji)成(cheng)(cheng)电(dian)(dian)路(lu)，由(you)NMOS组成(cheng)(cheng)的电(dian)(dian)路(lu)就(jiu)(jiu)是(shi)NMOS集(ji)成(cheng)(cheng)电(dian)(dian)路(lu)，由(you)PMOS管(guan)(guan)(guan)组成(cheng)(cheng)的电(dian)(dian)路(lu)就(jiu)(jiu)是(shi)PMOS集(ji)成(cheng)(cheng)电(dian)(dian)路(lu)，由(you)NMOS和PMOS两种管(guan)(guan)(guan)子组成(cheng)(cheng)的互补MOS电(dian)(dian)路(lu)，即CMOS电(dian)(dian)路(lu)。
制造工艺比(bi)较(jiao)(jiao)简(jian)单、成(cheng)品率较(jiao)(jiao)高、功耗低(di)、组(zu)成(cheng)的(de)(de)逻辑电(dian)(dian)(dian)(dian)路比(bi)较(jiao)(jiao)简(jian)单，集(ji)成(cheng)度高、抗(kang)干扰(rao)能力强(qiang)，特别(bie)适合于大(da)规模(mo)集(ji)成(cheng)电(dian)(dian)(dian)(dian)路。N沟(gou)道(dao)(dao)(dao)MOS管组(zu)成(cheng)的(de)(de)NMOS电(dian)(dian)(dian)(dian)路、P沟(gou)道(dao)(dao)(dao)MOS管组(zu)成(cheng)的(de)(de)PMOS电(dian)(dian)(dian)(dian)路及由N沟(gou)道(dao)(dao)(dao)MOS和(he)P沟(gou)道(dao)(dao)(dao)MOS两种管子组(zu)成(cheng)的(de)(de)互补(bu)MOS电(dian)(dian)(dian)(dian)路，即CMOS电(dian)(dian)(dian)(dian)路。P沟(gou)道(dao)(dao)(dao)MOS门电(dian)(dian)(dian)(dian)路与N沟(gou)道(dao)(dao)(dao)MOS电(dian)(dian)(dian)(dian)路的(de)(de)原理完全相(xiang)同，只是电(dian)(dian)(dian)(dian)源极性相(xiang)反而(er)已。数字(zi)电(dian)(dian)(dian)(dian)路中(zhong)MOS集(ji)成(cheng)电(dian)(dian)(dian)(dian)路所使用的(de)(de)MOS管均为增强(qiang)型管子，负载常(chang)用MOS管作为有源负载，这样不仅节省了硅片(pian)面积，而(er)且简(jian)化了工艺利于大(da)规模(mo)集(ji)成(cheng)。
金(jin)属-氧化(hua)物-半导体(ti)(ti)(Metal-Oxide-SemIConductor)结构的晶体(ti)(ti)管(guan)(guan)(guan)(guan)简称MOS晶体(ti)(ti)管(guan)(guan)(guan)(guan)，有P型(xing)(xing)MOS管(guan)(guan)(guan)(guan)和N型(xing)(xing)MOS管(guan)(guan)(guan)(guan)之(zhi)分。MOS管(guan)(guan)(guan)(guan)构成的集(ji)成电(dian)(dian)路(lu)(lu)(lu)(lu)称为MOS集(ji)成电(dian)(dian)路(lu)(lu)(lu)(lu)，而PMOS管(guan)(guan)(guan)(guan)和NMOS管(guan)(guan)(guan)(guan)共同构成的互补型(xing)(xing)MOS集(ji)成电(dian)(dian)路(lu)(lu)(lu)(lu)即为CMOS集(ji)成电(dian)(dian)路(lu)(lu)(lu)(lu)。由p型(xing)(xing)衬底(di)和两个高(gao)浓(nong)度n扩(kuo)散区构成的MOS管(guan)(guan)(guan)(guan)叫作n沟(gou)(gou)道(dao)(dao)(dao)(dao)(dao)MOS管(guan)(guan)(guan)(guan)，该管(guan)(guan)(guan)(guan)导通时(shi)在(zai)(zai)两个高(gao)浓(nong)度n扩(kuo)散区间形成n型(xing)(xing)导电(dian)(dian)沟(gou)(gou)道(dao)(dao)(dao)(dao)(dao)。n沟(gou)(gou)道(dao)(dao)(dao)(dao)(dao)增强型(xing)(xing)MOS管(guan)(guan)(guan)(guan)必须(xu)在(zai)(zai)栅(zha)极(ji)上施加正向偏压(ya)，且只有栅(zha)源电(dian)(dian)压(ya)大于(yu)阈值电(dian)(dian)压(ya)时(shi)才有导电(dian)(dian)沟(gou)(gou)道(dao)(dao)(dao)(dao)(dao)产生的n沟(gou)(gou)道(dao)(dao)(dao)(dao)(dao)MOS管(guan)(guan)(guan)(guan)。n沟(gou)(gou)道(dao)(dao)(dao)(dao)(dao)耗尽型(xing)(xing)MOS管(guan)(guan)(guan)(guan)是(shi)指在(zai)(zai)不加栅(zha)压(ya)（栅(zha)源电(dian)(dian)压(ya)为零(ling)）时(shi)，就(jiu)有导电(dian)(dian)沟(gou)(gou)道(dao)(dao)(dao)(dao)(dao)产生的n沟(gou)(gou)道(dao)(dao)(dao)(dao)(dao)MOS管(guan)(guan)(guan)(guan)。
N沟(gou)道MOS集(ji)(ji)(ji)成(cheng)(cheng)(cheng)电(dian)(dian)路(lu)是N沟(gou)道MOS电(dian)(dian)路(lu)，NMOS集(ji)(ji)(ji)成(cheng)(cheng)(cheng)电(dian)(dian)路(lu)的输(shu)入(ru)阻抗(kang)很(hen)高，基本上(shang)不需要(yao)吸(xi)收电(dian)(dian)流，因此，CMOS与NMOS集(ji)(ji)(ji)成(cheng)(cheng)(cheng)电(dian)(dian)路(lu)连接时不必考虑电(dian)(dian)流的负载(zai)问题。N沟(gou)道MOS集(ji)(ji)(ji)成(cheng)(cheng)(cheng)电(dian)(dian)路(lu)大多采(cai)用(yong)单组正电(dian)(dian)源供(gong)电(dian)(dian)，并(bing)且以5V为多。CMOS集(ji)(ji)(ji)成(cheng)(cheng)(cheng)电(dian)(dian)路(lu)只要(yao)选用(yong)与N沟(gou)道MOS集(ji)(ji)(ji)成(cheng)(cheng)(cheng)电(dian)(dian)路(lu)相同的电(dian)(dian)源，就可与N沟(gou)道MOS集(ji)(ji)(ji)成(cheng)(cheng)(cheng)电(dian)(dian)路(lu)直接连接。不过(guo)，从N沟(gou)道MOS到CMOS直接连接时，由于N沟(gou)道MOS输(shu)出的高电(dian)(dian)平低于CMOS集(ji)(ji)(ji)成(cheng)(cheng)(cheng)电(dian)(dian)路(lu)的输(shu)入(ru)高电(dian)(dian)平，因而需要(yao)使(shi)用(yong)一(yi)个（电(dian)(dian)位）上(shang)拉电(dian)(dian)阻R，R的取(qu)值一(yi)般(ban)选用(yong)2～100KΩ。
在一(yi)块掺(chan)杂(za)浓(nong)度较低(di)的(de)P型(xing)(xing)硅(gui)衬(chen)底(di)上，制作两个(ge)(ge)高掺(chan)杂(za)浓(nong)度的(de)N+区，并用(yong)金属铝引出(chu)两个(ge)(ge)电极(ji)(ji)(ji)，分别作漏极(ji)(ji)(ji)d和源(yuan)极(ji)(ji)(ji)s。然后在半导体表(biao)(biao)面(mian)覆盖(gai)一(yi)层很薄的(de)二氧化硅(gui)(SiO2)绝缘层，在漏——源(yuan)极(ji)(ji)(ji)间(jian)的(de)绝缘层上再装上一(yi)个(ge)(ge)铝电极(ji)(ji)(ji),作为栅极(ji)(ji)(ji)g。在衬(chen)底(di)上也引出(chu)一(yi)个(ge)(ge)电极(ji)(ji)(ji)B，这就构成了一(yi)个(ge)(ge)N沟道增强型(xing)(xing)MOS管。MOS管的(de)源(yuan)极(ji)(ji)(ji)和衬(chen)底(di)通常(chang)是(shi)接(jie)在一(yi)起的(de)(大多数管子(zi)在出(chu)厂(chang)前(qian)已(yi)连接(jie)好)。它(ta)(ta)的(de)栅极(ji)(ji)(ji)与(yu)其它(ta)(ta)电极(ji)(ji)(ji)间(jian)是(shi)绝缘的(de)。图(tu)(tu)(a)、(b)分别是(shi)它(ta)(ta)的(de)结(jie)构示(shi)意(yi)图(tu)(tu)和代(dai)表(biao)(biao)符号。代(dai)表(biao)(biao)符号中的(de)箭头方向(xiang)表(biao)(biao)示(shi)由P(衬(chen)底(di))指(zhi)向(xiang)N(沟道)。P沟道增强型(xing)(xing)MOS管的(de)箭头方向(xiang)与(yu)上述(shu)相反，如图(tu)(tu)(c)所示(shi)。
（1）vGS对iD及(ji)沟道的控制作(zuo)用
① vGS=0 的情况(kuang)
从图(tu)1(a)可(ke)以看出，增强(qiang)型MOS管的(de)漏(lou)极(ji)d和源(yuan)极(ji)s之间(jian)有(you)两(liang)个(ge)背靠背的(de)PN结。当栅——源(yuan)电(dian)压(ya)(ya)vGS=0时(shi)，即使加上漏(lou)——源(yuan)电(dian)压(ya)(ya)vDS，而且不论vDS的(de)极(ji)性如何(he)，总(zong)有(you)一个(ge)PN结处(chu)于反偏状(zhuang)态，漏(lou)——源(yuan)极(ji)间(jian)没有(you)导电(dian)沟道(dao)，所以这(zhei)时(shi)漏(lou)极(ji)电(dian)流iD≈0。
② vGS>0 的情况(kuang)
若vGS＞0，则(ze)栅极(ji)和衬(chen)底(di)之间的(de)(de)(de)SiO2绝缘层中(zhong)(zhong)便产生一(yi)个电场(chang)(chang)。电场(chang)(chang)方向垂直(zhi)于(yu)半导体表面的(de)(de)(de)由栅极(ji)指向衬(chen)底(di)的(de)(de)(de)电场(chang)(chang)。这(zhei)个电场(chang)(chang)能(neng)排斥空穴而吸(xi)引电子(zi)(zi)。排斥空穴：使栅极(ji)附近的(de)(de)(de)P型衬(chen)底(di)中(zhong)(zhong)的(de)(de)(de)空穴被排斥，剩下不(bu)能(neng)移动的(de)(de)(de)受(shou)主离子(zi)(zi)(负离子(zi)(zi))，形(xing)成耗(hao)尽层。吸(xi)引电子(zi)(zi)：将 P型衬(chen)底(di)中(zhong)(zhong)的(de)(de)(de)电子(zi)(zi)（少子(zi)(zi)）被吸(xi)引到(dao)衬(chen)底(di)表面。
（2）导电(dian)沟道的(de)形成
当(dang)vGS数值(zhi)较小(xiao)，吸(xi)引(yin)(yin)电(dian)(dian)子(zi)的(de)能力不(bu)强(qiang)时(shi)，漏——源极之(zhi)间(jian)仍无导电(dian)(dian)沟道出现(xian)，如(ru)(ru)图(b)所示(shi)。vGS增加时(shi)，吸(xi)引(yin)(yin)到(dao)P衬底(di)表面层的(de)电(dian)(dian)子(zi)就增多(duo)(duo)，当(dang)vGS达到(dao)某一数值(zhi)时(shi)，这些(xie)电(dian)(dian)子(zi)在(zai)栅(zha)极附(fu)近的(de)P衬底(di)表面便形(xing)成一个N型薄(bo)层，且与两个N+区相(xiang)连通，在(zai)漏——源极间(jian)形(xing)成N型导电(dian)(dian)沟道，其导电(dian)(dian)类型与P衬底(di)相(xiang)反，故又称为(wei)反型层，如(ru)(ru)图(c)所示(shi)。vGS越大，作(zuo)用于(yu)半导体表面的(de)电(dian)(dian)场就越强(qiang)，吸(xi)引(yin)(yin)到(dao)P衬底(di)表面的(de)电(dian)(dian)子(zi)就越多(duo)(duo)，导电(dian)(dian)沟道越厚，沟道电(dian)(dian)阻越小(xiao)。
开始形(xing)成沟道时的(de)栅(zha)——源极电压称(cheng)为开启(qi)电压，用VT表示。
上(shang)面(mian)讨论的(de)N沟(gou)道(dao)MOS管在vGS＜VT时(shi)，不(bu)能形成导电(dian)沟(gou)道(dao)，管子处(chu)于截止状态。只有当vGS≥VT时(shi)，才(cai)有沟(gou)道(dao)形成。这(zhei)种必须(xu)在vGS≥VT时(shi)才(cai)能形成导电(dian)沟(gou)道(dao)的(de)MOS管称为增(zeng)强型MOS管。沟(gou)道(dao)形成以后，在漏——源极(ji)间加上(shang)正向电(dian)压vDS，就有漏极(ji)电(dian)流产生(sheng)。
vDS对iD的影响
如(ru)(ru)图(tu)(a)所示，当(dang)(dang)vGS>VT且(qie)为一确定值(zhi)时，漏(lou)(lou)——源电(dian)压(ya)vDS对(dui)导电(dian)沟(gou)道(dao)(dao)(dao)及(ji)电(dian)流(liu)iD的(de)(de)影响与(yu)结型(xing)场效应(ying)管相(xiang)似。漏(lou)(lou)极(ji)(ji)电(dian)流(liu)iD沿沟(gou)道(dao)(dao)(dao)产生的(de)(de)电(dian)压(ya)降使沟(gou)道(dao)(dao)(dao)内(nei)各点与(yu)栅极(ji)(ji)间的(de)(de)电(dian)压(ya)不再相(xiang)等，靠(kao)近源极(ji)(ji)一端(duan)的(de)(de)电(dian)压(ya)最(zui)大(da)(da)，这里(li)沟(gou)道(dao)(dao)(dao)最(zui)厚，而(er)漏(lou)(lou)极(ji)(ji)一端(duan)电(dian)压(ya)最(zui)小，其(qi)值(zhi)为VGD=vGS－vDS，因而(er)这里(li)沟(gou)道(dao)(dao)(dao)最(zui)薄(bo)。但当(dang)(dang)vDS较小（vDS随着vDS的(de)(de)增大(da)(da)，靠(kao)近漏(lou)(lou)极(ji)(ji)的(de)(de)沟(gou)道(dao)(dao)(dao)越来越薄(bo)，当(dang)(dang)vDS增加(jia)到使VGD=vGS－vDS=VT(或vDS=vGS－VT)时，沟(gou)道(dao)(dao)(dao)在(zai)漏(lou)(lou)极(ji)(ji)一端(duan)出现(xian)预夹(jia)断，如(ru)(ru)图(tu)2(b)所示。再继续(xu)增大(da)(da)vDS，夹(jia)断点将(jiang)向源极(ji)(ji)方向移动，如(ru)(ru)图(tu)2(c)所示。由于vDS的(de)(de)增加(jia)部(bu)分几(ji)乎(hu)全部(bu)降落在(zai)夹(jia)断区(qu)，故iD几(ji)乎(hu)不随vDS增大(da)(da)而(er)增加(jia)，管子(zi)进(jin)入饱和区(qu)，iD几(ji)乎(hu)仅由vGS决定。
（1）特(te)性(xing)曲线(xian)和电流方程
1、输(shu)出特性曲线
N沟道增强型(xing)NMOS管(guan)的(de)输(shu)出(chu)特(te)性(xing)曲线如图1(a)所示。与结型(xing)场效应管(guan)一样(yang),其(qi)输(shu)出(chu)特(te)性(xing)曲线也可分为可变电阻(zu)区(qu)、饱和区(qu)、截止区(qu)和击穿(chuan)区(qu)几部分。
2、转移特(te)性曲(qu)线(xian)
转移特(te)(te)性曲(qu)线(xian)如图1(b)所(suo)(suo)示,由于场(chang)效应管作放大(da)器件使用时(shi)是(shi)工作在饱和(he)区(qu)(恒(heng)流区(qu)),此(ci)时(shi)iD几(ji)乎(hu)不随vDS而变化,即不同(tong)的(de)(de)vDS所(suo)(suo)对(dui)应的(de)(de)转移特(te)(te)性曲(qu)线(xian)几(ji)乎(hu)是(shi)重合的(de)(de),所(suo)(suo)以可用vDS大(da)于某一数值(vDS＞vGS-VT)后的(de)(de)一条(tiao)转移特(te)(te)性曲(qu)线(xian)代替(ti)饱和(he)区(qu)的(de)(de)所(suo)(suo)有转移特(te)(te)性曲(qu)线(xian)。
3、iD与vGS的近似关系
与结型场效(xiao)应管(guan)相类似。在(zai)饱和区内,iD与vGS的近似关(guan)系(xi)式为(wei)
式中IDO是vGS=2VT时的漏极电(dian)流iD。
（2）参数(shu)
MOS管的主要参数与结(jie)型场效(xiao)应管基本(ben)相同，只是增强型NMOS管中不用夹断电压(ya)VP ，而用开启(qi)电压(ya)VT表征管子(zi)的特性(xing)。
1、结构：
N沟道耗尽型(xing)NMOS管(guan)与N沟道增强型(xing)MOS管(guan)基本相似(si)。
2、区别(bie)：
耗尽型(xing)MOS管在vGS=0时(shi)，漏——源极(ji)间已有导电沟道(dao)产(chan)生，而增强型(xing)NMOS管要在vGS≥VT时(shi)才出现(xian)导电沟道(dao)。
3、原(yuan)因(yin)：
制造N沟道(dao)耗(hao)尽(jin)型(xing)MOS管(guan)时(shi)，在(zai)SiO2绝缘层中掺入了大量的(de)(de)碱(jian)金属正(zheng)(zheng)离子(zi)Na+或K+(制造P沟道(dao)耗(hao)尽(jin)型(xing)MOS管(guan)时(shi)掺入负离子(zi))，如(ru)图(tu)1(a)所示(shi)，因此即使vGS=0时(shi)，在(zai)这(zhei)些(xie)正(zheng)(zheng)离子(zi)产生的(de)(de)电(dian)(dian)(dian)场(chang)作用下，漏——源极间(jian)的(de)(de)P型(xing)衬底表(biao)面也(ye)能(neng)(neng)感应(ying)生成N沟道(dao)(称为(wei)初始(shi)沟道(dao))，只(zhi)要加(jia)上(shang)正(zheng)(zheng)向电(dian)(dian)(dian)压vDS，就有电(dian)(dian)(dian)流iD。如(ru)果(guo)加(jia)上(shang)正(zheng)(zheng)的(de)(de)vGS，栅(zha)极与N沟道(dao)间(jian)的(de)(de)电(dian)(dian)(dian)场(chang)将在(zai)沟道(dao)中吸引来更多的(de)(de)电(dian)(dian)(dian)子(zi)，沟道(dao)加(jia)宽，沟道(dao)电(dian)(dian)(dian)阻变小，iD增大。反之vGS为(wei)负时(shi)，沟道(dao)中感应(ying)的(de)(de)电(dian)(dian)(dian)子(zi)减(jian)少，沟道(dao)变窄，沟道(dao)电(dian)(dian)(dian)阻变大，iD减(jian)小。当vGS负向增加(jia)到某一数值时(shi)，导电(dian)(dian)(dian)沟道(dao)消失，iD趋于(yu)零，管(guan)子(zi)截止，故称为(wei)耗(hao)尽(jin)型(xing)。沟道(dao)消失时(shi)的(de)(de)栅(zha)－源电(dian)(dian)(dian)压称为(wei)夹(jia)断电(dian)(dian)(dian)压，仍用VP表(biao)示(shi)。与N沟道(dao)结型(xing)场(chang)效应(ying)管(guan)相(xiang)同，N沟道(dao)耗(hao)尽(jin)型(xing)MOS管(guan)的(de)(de)夹(jia)断电(dian)(dian)(dian)压VP也(ye)为(wei)负值，但是，前者(zhe)只(zhi)能(neng)(neng)在(zai)vGS<0的(de)(de)情况下工(gong)作。而后(hou)者(zhe)在(zai)vGS=0，vGS>0，VP。
4、电流方(fang)程：
在饱和区内，耗尽型(xing)NMOS管(guan)的电流方程与结型(xing)场效应管(guan)的电流方程相(xiang)同，即：
各种场(chang)效应管特(te)性比较
金(jin)属氧(yang)化物半导体(ti)(ti)场(chang)(chang)效(xiao)应(ying)(MOS)晶(jing)(jing)体(ti)(ti)管(guan)(guan)(guan)(guan)可分为(wei)(wei)N沟(gou)(gou)道(dao)(dao)与P沟(gou)(gou)道(dao)(dao)两(liang)(liang)大(da)类(lei)，P沟(gou)(gou)道(dao)(dao)硅(gui)(gui)MOS场(chang)(chang)效(xiao)应(ying)晶(jing)(jing)体(ti)(ti)管(guan)(guan)(guan)(guan)在N型(xing)(xing)硅(gui)(gui)衬(chen)底上(shang)有两(liang)(liang)个P+区，分别叫做(zuo)源(yuan)极和漏(lou)极，两(liang)(liang)极之间(jian)不通导，柵极上(shang)加有足够(gou)的(de)正电压(源(yuan)极接(jie)地)时，柵极下的(de)N型(xing)(xing)硅(gui)(gui)表(biao)面(mian)呈现P型(xing)(xing)反型(xing)(xing)层，成为(wei)(wei)连接(jie)源(yuan)极和漏(lou)极的(de)沟(gou)(gou)道(dao)(dao)。改(gai)变栅(zha)压可以改(gai)变沟(gou)(gou)道(dao)(dao)中(zhong)的(de)电子密度，从而改(gai)变沟(gou)(gou)道(dao)(dao)的(de)电阻。这(zhei)种MOS场(chang)(chang)效(xiao)应(ying)晶(jing)(jing)体(ti)(ti)管(guan)(guan)(guan)(guan)称为(wei)(wei)P沟(gou)(gou)道(dao)(dao)增(zeng)强(qiang)型(xing)(xing)场(chang)(chang)效(xiao)应(ying)晶(jing)(jing)体(ti)(ti)管(guan)(guan)(guan)(guan)。如(ru)果N型(xing)(xing)硅(gui)(gui)衬(chen)底表(biao)面(mian)不加栅(zha)压就(jiu)已(yi)存在P型(xing)(xing)反型(xing)(xing)层沟(gou)(gou)道(dao)(dao)，加上(shang)适(shi)当(dang)的(de)偏(pian)压，可使沟(gou)(gou)道(dao)(dao)的(de)电阻增(zeng)大(da)或减小。这(zhei)样(yang)的(de)MOS场(chang)(chang)效(xiao)应(ying)晶(jing)(jing)体(ti)(ti)管(guan)(guan)(guan)(guan)称为(wei)(wei)P沟(gou)(gou)道(dao)(dao)耗尽型(xing)(xing)场(chang)(chang)效(xiao)应(ying)晶(jing)(jing)体(ti)(ti)管(guan)(guan)(guan)(guan)。统(tong)称为(wei)(wei)PMOS晶(jing)(jing)体(ti)(ti)管(guan)(guan)(guan)(guan)。
P沟(gou)(gou)道MOS晶体(ti)管(guan)的(de)空(kong)穴迁(qian)移率(lv)低,因(yin)而在(zai)MOS晶体(ti)管(guan)的(de)几何尺寸和工作(zuo)电(dian)(dian)压(ya)(ya)绝对值(zhi)相等的(de)情(qing)况下，PMOS晶体(ti)管(guan)的(de)跨(kua)(kua)导(dao)(dao)小于N沟(gou)(gou)道MOS晶体(ti)管(guan)。此(ci)外，P沟(gou)(gou)道MOS晶体(ti)管(guan)阈值(zhi)电(dian)(dian)压(ya)(ya)的(de)绝对值(zhi)一般偏高(gao)，要求有(you)较高(gao)的(de)工作(zuo)电(dian)(dian)压(ya)(ya)。它(ta)的(de)供电(dian)(dian)电(dian)(dian)源的(de)电(dian)(dian)压(ya)(ya)大小和极性,与双(shuang)极型晶体(ti)管(guan)——晶体(ti)管(guan)逻(luo)辑电(dian)(dian)路(lu)不兼容。PMOS因(yin)逻(luo)辑摆幅大，充电(dian)(dian)放(fang)电(dian)(dian)过程(cheng)长，加之器(qi)件跨(kua)(kua)导(dao)(dao)小，所以工作(zuo)速度更低，在(zai)NMOS电(dian)(dian)路(lu)(见N沟(gou)(gou)道金属(shu)—氧(yang)化物(wu)—半导(dao)(dao)体(ti)集(ji)成(cheng)电(dian)(dian)路(lu))出现之后，多数已为NMOS电(dian)(dian)路(lu)所取(qu)代(dai)。只是,因(yin)PMOS电(dian)(dian)路(lu)工艺简(jian)单,价格便宜，有(you)些中规(gui)模和小规(gui)模数字控制电(dian)(dian)路(lu)仍采用(yong)PMOS电(dian)(dian)路(lu)技术(shu)。
PMOS集成(cheng)(cheng)电(dian)路是一种适合在低速、低频领域内(nei)应用(yong)的(de)器件。PMOS集成(cheng)(cheng)电(dian)路采(cai)用(yong)-24V电(dian)压供(gong)电(dian)。如图5所示的(de)CMOS-PMOS接(jie)口(kou)电(dian)路采(cai)用(yong)两(liang)种电(dian)源(yuan)供(gong)电(dian)。采(cai)用(yong)直接(jie)接(jie)口(kou)方式，一般CMOS的(de)电(dian)源(yuan)电(dian)压选择在10～12V就能满足(zu)PMOS对输入电(dian)平的(de)要求。MOS场效应晶体管具(ju)有很高的(de)输入阻抗，在电(dian)路中便于直接(jie)耦合，容易制成(cheng)(cheng)规模大的(de)集成(cheng)(cheng)电(dian)路。
各种场(chang)效应管(guan)特性比较
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