Iyini indima yama-MOSFETs amancane kagesi?

Kunezinhlobo eziningi zeAma-MOSFET, ngokuyinhloko ihlukaniswe yaba ama-MOSFET ahlanganayo kanye nama-MOSFET avale isango izigaba ezimbili, futhi wonke anamaphuzu esiteshi esingu-N kanye nesiteshi se-P.

I-Metal-Oxide-Semiconductor Field-Effect Transistor, ebizwa ngokuthi i-MOSFET, ihlukaniswe yaba uhlobo lokuqeda i-MOSFET kanye nohlobo lokuthuthukisa i-MOSFET.

Ama-MOSFET nawo ahlukaniswe abe amashubhu anesango elilodwa namabili. I-MOSFET enamasango amabili inamasango amabili azimele i-G1 ne-G2, kusukela ekwakhiweni kwesilinganiso sama-MOSFET amabili esango elilodwa axhunywe ochungechungeni, kanye noshintsho lwamanje oluphumayo ngokulawulwa kwamandla kagesi wamasango amabili. Lesi sici sama-MOSFET anamasango amabili siletha ukunethezeka okuhle uma sisetshenziswa njengezikhulisi zemvamisa ephezulu, ama-amplifiers azuzayo okulawula, izihlanganisi nama-demodulators.

1, I-MOSFETuhlobo kanye nesakhiwo

I-MOSFET iwuhlobo lwe-FET (olunye uhlobo i-JFET), ingakhiqizwa ibe uhlobo oluthuthukisiwe noma oluncishayo, i-P-channel noma i-N-channel ingqikithi yezinhlobo ezine, kodwa ukusetshenziswa kwethiyori kwe-N-channel MOSFET ethuthukisiwe kanye ne-P- ethuthukisiwe isiteshi i-MOSFET, esivame ukubizwa ngokuthi i-NMOS, noma i-PMOS ibhekisela kulezi zinhlobo ezimbili. Mayelana nokuthi kungani ungasebenzisi ama-MOSFET ohlobo lokuphelelwa amandla, ungancomi ukusesha umsuka. Mayelana nama-MOSFET amabili athuthukisiwe, asetshenziswa kakhulu yi-NMOS, isizathu siwukuthi ukumelana nokumelana kuncane, futhi kulula ukuwenza. Ngakho-ke ukushintsha ukunikezwa kwamandla kanye nezinhlelo zokusebenza zokushayela imoto, ngokuvamile zisebenzisa i-NMOS. lesisho esilandelayo, kodwa futhi esekwe ku-NMOS. izikhonkwane ezintathu ze-MOSFET i-parasitic capacitance ikhona phakathi kwezikhonkwane ezintathu, okungezona izidingo zethu, kodwa ngenxa yemikhawulo yenqubo yokukhiqiza. Ukuba khona kwe-parasitic capacitance ekwakhiweni noma ekukhethweni kwesekethe yedrayivu ukuze konge isikhathi esithile, kodwa ayikho indlela yokugwema, bese kuba nesingeniso esinemininingwane. Kumdwebo wohlelo we-MOSFET ungabonakala, ukudonsa kanye nomthombo phakathi kwe-parasitic diode. Lokhu kubizwa ngokuthi i-diode yomzimba, ekushayeleni imithwalo enengqondo, le diode ibaluleke kakhulu. Ngendlela, i-diode yomzimba ikhona kuphela ku-MOSFET eyodwa, ngokuvamile ayikho ngaphakathi kwe-chip yesekethe ehlanganisiwe.

2, izici zokuqhuba ze-MOSFET

Ukubaluleka kokuqhuba kunjengokushintshana, okulingana nokuvalwa kweswishi.Izici ze-NMOS, ama-Vgs amakhulu kunevelu ethile azoqhuba, alungele ukusetshenziswa esimweni lapho umthombo usekelwe (idrayivu esezingeni eliphansi), i-voltage yesango kuphela efikayo. kuzici ze-4V noma ze-10V.PMOS, ama-Vgs angaphansi kwenani elithile azoqhuba, afanele ukusetshenziswa esimweni lapho umthombo uxhunywe ku-VCC (i-high-end drive).

Kodwa-ke, yiqiniso, i-PMOS ingaba lula kakhulu ukuyisebenzisa njengomshayeli ophezulu, kodwa ngenxa yokumelana, ezibizayo, izinhlobo ezincane zokuhwebelana nezinye izizathu, kumshayeli ophezulu, ngokuvamile usasebenzisa i-NMOS.

3, I-MOSFETukushintsha ukulahlekelwa

Kungakhathaliseki ukuthi i-NMOS noma i-PMOS, ngemva kokumelana nokukhona, ukuze i-current izodla amandla kulokhu kumelana, le ngxenye yamandla asetshenzisiwe ibizwa ngokuthi ukulahlekelwa kokuphikiswa. Ukukhetha i-MOSFET enokumelana okuncane kuzonciphisa ukulahleka kokumelana. Ukumelana okujwayelekile kwamandla aphansi kwe-MOSFET kuvamise ukuba kumashumi ama-milliohms, ama-miliohm ambalwa lapho. I-MOS ngesikhathi kanye nokunqanyulwa, akumele kube sekuqedweni ngokushesha kwe-voltage kuyo yonke i-MOS kunenqubo yokuwa, yamanje egeleza ngenqubo yokukhuphuka, ngalesi sikhathi, ukulahleka kwe-MOSFET umkhiqizo we-voltage kanye namanje ubizwa ngokuthi ukulahlekelwa kokushintsha. Ngokuvamile ukulahlekelwa kokushintsha kukhulu kakhulu kunokulahlekelwa kwe-conduction, futhi ngokushesha imvamisa yokushintsha, ukulahlekelwa kukhulu. Umkhiqizo omkhulu we-voltage kanye ne-current ngesikhathi sokwenziwa kwe-conducting wenza ukulahlekelwa okukhulu. Ukunciphisa isikhathi sokushintsha kunciphisa ukulahlekelwa ekuqhubeni ngakunye; ukunciphisa imvamisa yokushintsha kunciphisa inani lokushintshwa ngesikhathi seyunithi. Zombili izindlela zinganciphisa ukulahleka kokushintsha.

 
4, MOSFET drive

Uma kuqhathaniswa nama-bipolar transistors, ngokuvamile kucatshangwa ukuthi akukho okwamanje okudingekayo ukuze kwenziwe ukuziphatha kwe-MOSFET, kuphela ukuthi i-voltage ye-GS ingaphezu kwevelu ethile. Lokhu kulula ukukwenza, nokho, sidinga nesivinini. Ohlelweni lwe-MOSFET uyabona ukuthi kukhona i-parasitic capacitance phakathi kwe-GS, GD, kanye nokushayela kwe-MOSFET, ngokombono, ukushaja nokukhishwa kwe-capacitance. Ukushaja i-capacitor kudinga i-current, futhi njengoba ukushaja i-capacitor ngokushesha kungabhekwa njengesifunda esifushane, i-current instantaneous izoba phezulu. Ukukhethwa / ukuklama ukushayela kwe-MOSFET into yokuqala okufanele uyinake usayizi we-short-circuit current onganikezwa ngaso leso sikhathi. Into yesibili okufanele uyinake ukuthi, ngokuvamile esetshenziswa ku-NMOS yedrayivu ephezulu, lapho kudingeka khona i-voltage yesango inkulu kune-voltage yomthombo. I-high-end drive MOS tube conduction source voltage kanye ne-drain voltage (VCC) ngokufanayo, ngakho-ke i-voltage yesango kune-VCC 4V noma i-10V. sicabanga ukuthi ohlelweni olufanayo, ukuthola i-voltage enkulu kune-VCC, sidinga isifunda esikhethekile sokukhulisa. Abashayeli abaningi bezimoto bahlanganiswe iphampu yokushaja, ukunaka kufanele ukhethe i-capacitor yangaphandle efanele, ukuze uthole wamanje okwanele we-short circuit ukushayela i-MOSFET. I-4V noma i-10V eshiwo ngenhla ivame ukusetshenziswa i-MOSFET ku-voltage, umklamo weqiniso, isidingo sokuba nemajini ethile. Lapho i-voltage iphakeme, isivinini se-on-state sishesha kakhulu futhi sinciphisa ukumelana nesimo. Imvamisa kukhona nama-MOSFET ama-voltage amancane akusimo sezwe asetshenziswa ezigabeni ezihlukene, kodwa ezinhlelweni zikagesi zezimoto eziyi-12V, i-4V evamile esesimeni yanele.

Imingcele eyinhloko ye-MOSFET imi kanje:

1. I-voltage yomthombo wokuqhekeka kwesango i-BVGS - ohlelweni lokukhulisa amandla kagesi womthombo wesango, ukuze isango lamanje le-IG ukusuka ku-zero liqale ukwanda okubukhali ku-VGS, eyaziwa ngokuthi i-voltage yomthombo wokuqhekeka wesango i-BVGS.

2. I-voltage yokuvula i-VT - i-voltage yokuvula (eyaziwa nangokuthi i-threshold voltage): yenza umthombo ongu-S futhi ukhiphe u-D phakathi kokuqala kwesiteshi sokuhambisa kuhlanganisa i-voltage yesango edingekayo; - ejwayelekile N-channel MOSFET, VT cishe 3 ~ 6V; - ngemva kwenqubo yokuthuthukisa, ingenza inani le-MOSFET VT lehle liye ku-2 ~ 3V.

3. I-voltage ye-Drain breakdown BVDS - ngaphansi kwesimo se-VGS = 0 (eqinisiwe) , ohlelweni lokukhulisa amandla kagesi ukuze i-ID iqale ukwanda kakhulu lapho i-VDS ibizwa ngokuthi i-drain breakdown voltage BVDS - ID yanda kakhulu ngenxa izici ezimbili ezilandelayo:

(1) ukuwohloka kwe-avalanche kwesendlalelo sokuwohloka eduze kwe-electrode yokukhipha amanzi

(2) ukuwohloka kwe-drain-source inter-pole penetration - enye i-voltage encane i-MOSFET, ubude besiteshi sayo bufushane, ngezikhathi ezithile ukukhulisa i-VDS kuzokwenza indawo yokukhipha ungqimba lokuwohloka ngezikhathi ezithile inwebele endaweni yomthombo. , ukuze ubude besiteshi bukaziro, okungukuthi, phakathi kokungena komthombo wokukhipha amanzi, ukungena, indawo yomthombo yeningi labathwali, indawo yomthombo, buqonde ukumelana nongqimba lokuncipha lokumuncwa. wenkundla kagesi, ukufika endaweni yokuvuza, okuholela ku-ID enkulu.

4. Ukumelana nokufakwa kwe-DC RGS-okungukuthi, isilinganiso se-voltage engezwe phakathi komthombo wesango kanye nesango lamanje, lesi sici ngezinye izikhathi sivezwa ngokuya ngesango lamanje eligeleza esangweni le-RGS ye-MOSFET ingadlula kalula u-1010Ω. 5.

5. i-low-frequency transconductance gm ku-VDS yenani elingaguquki lezimo, i-microvariance ye-drain current kanye ne-voltage yomthombo wesango i-microvariance ebangelwa yilolu shintsho ibizwa ngokuthi i-transconductance gm, ebonisa ukulawulwa kwe-voltage yomthombo wesango I-drain current iwukukhombisa ukuthi ukukhuliswa kwe-MOSFET kwepharamitha ebalulekile, ngokuvamile ebangeni lama-mA / V ambalwa kuya kwambalwa. I-MOSFET ingadlula kalula 1010Ω.