Menene aikin ƙananan wutar lantarki MOSFETs?

Akwai da yawa iri naMOSFETs, galibi an raba su zuwa junction MOSFETs da ƙofar MOSFETs da aka keɓe, kuma duk suna da tashoshin N-channel da maki P-channel.

 

Metal-Oxide-Semiconductor Field-Effect Transistor, wanda ake kira MOSFET, an raba shi zuwa nau'in ragewa MOSFET da nau'in haɓakawa MOSFET.

 

MOSFETs kuma an raba su zuwa bututu mai-ɗaya da kofa biyu. MOSFET mai dual-gate yana da kofa masu zaman kansu guda biyu G1 da G2, daga ginin kwatankwacin MOSFET mai kofa guda biyu da aka haɗa a jeri, kuma fitowar ta na yanzu tana canzawa ta hanyar sarrafa wutar lantarki ta ƙofar biyu. Wannan sifa ta MOSFETs mai-kofa biyu tana kawo dacewa mai girma lokacin amfani da ita azaman amplifiers masu girma, samin amplifiers, masu haɗawa da masu haɓakawa.

 

1, MOSFETnau'i da tsari

MOSFET wani nau'in FET ne (wani nau'in shine JFET), ana iya ƙera shi zuwa nau'in haɓakawa ko raguwa, P-tashar ko tashar N-tashar duka nau'ikan nau'ikan huɗu ne, amma aikace-aikacen ka'idar kawai ingantaccen tashar N-tashar MOSFET da haɓaka P- tashar MOSFET, wanda yawanci ake kira NMOS, ko PMOS yana nufin waɗannan nau'ikan guda biyu. Amma don me yasa ba a yi amfani da nau'in ragewa MOSFETs ba, kar a ba da shawarar binciken tushen dalilin. Dangane da MOSFET guda biyu da aka haɓaka, mafi yawan amfani da su shine NMOS, dalilin shine cewa juriya kaɗan ne, kuma mai sauƙin ƙira. Don haka canza wutar lantarki da aikace-aikacen tuƙi, gabaɗaya amfani da NMOS. zance mai zuwa, amma kuma ƙarin tushen NMOS. fil uku na MOSFET m capacitance yana wanzu tsakanin fil uku, wanda ba buƙatunmu bane, amma saboda iyakokin tsarin masana'antu. Kasancewar parasitic capacitance a cikin ƙira ko zaɓi na da'irar tuƙi don adana ɗan lokaci, amma babu wata hanyar gujewa, sannan cikakken gabatarwar. A cikin zane-zane na MOSFET ana iya gani, magudanar ruwa da tushen tsakanin diode parasitic. Wannan shi ake kira jiki diode, a cikin tuki na hankali lodi, wannan diode yana da matukar muhimmanci. Af, diode jiki yana wanzuwa a cikin MOSFET guda ɗaya kawai, yawanci ba a cikin guntun da'ira ba.

 

2, MOSFET halayen gudanarwa

Muhimmancin gudanarwa shine mai sauyawa, daidai da ƙulli mai canzawa.Halayen NMOS, Vgs mafi girma fiye da wani ƙima za su gudanar, dace da amfani a cikin yanayin lokacin da tushen ya kasance ƙasa (ƙananan motsi), kawai ƙarfin wutar lantarki ya isa. a 4V ko 10V.PMOS halaye, Vgs kasa da wani ƙima za su gudanar, dace da amfani a cikin yanayin lokacin da aka haɗa tushen zuwa VCC (high-end drive).

Duk da haka, ba shakka, PMOS na iya zama mai sauƙi don amfani da shi azaman babban direba, amma saboda juriya, tsada, ƙananan nau'in musayar da wasu dalilai, a cikin babban direba, yawanci har yanzu suna amfani da NMOS.

 

3, MOSFETcanza hasara

Ko NMOS ne ko PMOS, bayan da ake juriya ya wanzu, ta yadda na yanzu zai cinye makamashi a cikin wannan juriya, wannan bangare na makamashin da ake cinyewa ana kiransa hasara a kan juriya. Zaɓin MOSFET tare da ƙaramin juriya zai rage asarar juriya. MOSFET mai ƙarancin ƙarfi na yau da kullun akan juriya yawanci yana cikin dubun milliohms, ƴan milliohms a can. MOS a cikin lokaci-lokaci da yanke-kashe, dole ne ba a cikin saurin kammala ƙarfin lantarki a cikin MOS akwai tsarin faɗuwa, halin yanzu yana gudana ta hanyar haɓakawa, a wannan lokacin, asarar MOSFET shine. samfurin ƙarfin lantarki da na yanzu ana kiransa hasara mai canzawa. Yawanci asarar sauyawa ya fi girma fiye da asarar gudanarwa, kuma da sauri saurin sauyawa, mafi girma asarar. Babban samfuri na ƙarfin lantarki da na yanzu a nan take na gudanarwa ya ƙunshi babban hasara. Rage lokacin sauyawa yana rage asarar a kowace gudanarwa; rage mitar sauyawa yana rage adadin masu sauyawa kowane lokaci naúrar. Duk hanyoyin biyu na iya rage asarar sauyawa.

 
4, MOSFET tuki

Idan aka kwatanta da transistors na bipolar, yawanci ana ɗauka cewa babu wani halin yanzu da ake buƙata don yin halin MOSFET, kawai ƙarfin GS yana sama da wani ƙima. Wannan yana da sauƙi don yin, duk da haka, muna kuma buƙatar gudu. A cikin tsarin MOSFET zaka iya ganin cewa akwai ƙarfin ƙarfin parasitic tsakanin GS, GD, kuma tuƙin MOSFET shine, a ka'idar, caji da fitarwa na capacitance. Yin cajin capacitor yana buƙatar halin yanzu, kuma tunda ana cajin capacitor nan take ana iya kallon shi azaman ɗan gajeren kewayawa, yanzun nan take zai yi girma. Zaɓin / ƙira na MOSFET tuƙi abu na farko da za a kula da shi shine girman gajeriyar kewayawa na yanzu za a iya ba da ita. Abu na biyu da ya kamata a kula da shi shine, gabaɗaya ana amfani dashi a cikin babban tuƙi na NMOS, akan buƙata shine ƙarfin ƙofa ya fi ƙarfin tushen. High-karshen drive MOS tube conduction tushen ƙarfin lantarki da lambatu irin ƙarfin lantarki (VCC) guda, don haka ƙofar ƙarfin lantarki fiye da VCC 4V ko 10V. muna ɗauka cewa a cikin wannan tsarin, don samun ƙarfin lantarki mafi girma fiye da VCC, muna buƙatar na'urar haɓakawa ta musamman. Yawancin direbobin motoci suna haɗa fam ɗin cajin, don kula da shi shine yakamata ya zaɓi madaidaicin capacitor na waje, don samun isasshen ɗan gajeren lokaci don fitar da MOSFET. 4V ko 10V da aka fada a sama ana amfani da MOSFET akan ƙarfin lantarki, ƙirar ba shakka, buƙatar samun takamaiman gefe. Mafi girman ƙarfin wutar lantarki, saurin kan-jihar gudun kuma ƙananan juriya na kan-jihar. Yawancin lokaci akwai ƙananan MOSFET na wutar lantarki a cikin jihar da ake amfani da su a cikin nau'ikan daban-daban, amma a cikin tsarin lantarki na motoci na 12V, talakawan 4V akan-jihar ya isa.

 

 

Babban sigogi na MOSFET sune kamar haka:

 

1. Gate source breakdown voltage BVGS - a cikin tsari na ƙara ƙarfin wutar lantarki na gate, ta yadda kofa na yanzu IG daga sifili don fara karuwa mai girma a cikin VGS, wanda aka sani da Ƙofar Ƙofar Ƙofar Ƙofar BVGS.

 

2. kunna wutar lantarki VT - kunna wutar lantarki (wanda kuma aka sani da ƙarfin wuta): sanya tushen S da magudanar ruwa D tsakanin farkon tashar tashar ta ƙunshi ƙarfin wutar lantarki da ake buƙata; - daidaitaccen N-tashar MOSFET, VT kusan 3 ~ 6V; - bayan aiwatar da haɓakawa, na iya yin ƙimar MOSFET VT zuwa 2 ~ 3V.

 

3. Drain breakdown voltage BVDS - ƙarƙashin yanayin VGS = 0 (ƙarfafawa) , yayin da ake ƙara ƙarfin wutar lantarki ta yadda ID ɗin ya fara karuwa sosai lokacin da ake kira VDS mai lalata wutar lantarki BVDS - ID ya karu sosai saboda wadannan abubuwa guda biyu:

 

(1) rugujewar dusar ƙanƙara na raƙuman ruwa kusa da magudanar lantarki

 

(2) magudanar ruwa-source inter-pole rushewar - wasu kananan ƙarfin lantarki MOSFET, ta tashar tsawon shi ne takaice, daga lokaci zuwa lokaci don ƙara VDS zai sa magudana yankin na depletion Layer daga lokaci zuwa lokaci don fadada zuwa tushen yankin. , don haka da cewa tashar tsawon sifili, wato, tsakanin magudanar ruwa-source shigar azzakari cikin farji, shigar azzakari cikin farji, tushen yankin na mafi yawan dillalai, tushen yankin, zai zama madaidaiciya don tsayayya da depletion Layer na sha na lantarki filin. don isa yankin da aka zubar, yana haifar da babban ID.

 

4. DC shigar da juriya RGS-watau rabo daga irin ƙarfin lantarki da aka kara tsakanin ƙofar tushen da ƙofar halin yanzu, wannan halayyar wani lokacin ana bayyana a cikin sharuddan ƙofar halin yanzu gudana ta cikin ƙofar MOSFET ta RGS iya sauƙi wuce 1010Ω. 5.

 

5. ƙananan mitar transconductance gm a cikin VDS don ƙayyadaddun ƙimar yanayi, microvariance na magudanar ruwa da kuma ƙaramar wutar lantarki ta ƙofar kofa ta hanyar wannan canji ana kiranta transconductance gm, yana nuna ikon sarrafa wutar lantarki ta ƙofar ƙofar akan magudanar ruwa a halin yanzu shine ya nuna cewa haɓakar MOSFET na wani muhimmin siga, gabaɗaya a cikin kewayon ƴan zuwa ƴan mA / V. MOSFET na iya wuce 1010Ω cikin sauƙi.