1.6. TRANZITOR TRNG (FET)1.6.1. Gii thiu chung1.6.2. Cu to v c tnh ca JFET1.6.3 MOSFET

1.6.1. Gii thiu chungKhc vi tranzitor lng cc m c im ch yu l dng in trong chng do c hai loi ht dn (in t v l trng) to nn, tranzitor trng (Field Effect Tranzitor - FET), hot ng da trn nguyn l hiu ng trng, dn in ca n tinh th bn dn c iu khin nh tc dng ca mt in trng ngoi. Dng in trong FET ch do mt loi ht dn to nn.

Tranzitor hiu ng trng FET gm c hai loi chnh:FET iu khin bng cc ca tip xc p-n (vit tt l JFET).FET c cc ca cch ly: Thng thng lp cch in l lp xt nn gi l Metal oxide Semiconductor FET (MOSFET hay MOS). Trong loi tranzitor trng c cc ca cch in li c chia lm hai loi l MOS c knh lin tc (knh t sn) v MOS c knh gin on (knh cm ng).

1.6.2. Cu to v c tnh ca JFET1. Cu to v k hiu

a.pnpDGSVng nghoUDSIDSppNDGSVng nghoUDSIDSppNDGSVng nghoUGSb.c.

2. Hot ngXt JFET knh N c cc D ni vi dng ngun, S ni vi m ngun nh hnh 1.22b.a. Khi cc G h (UGS = 0V)

Lc ny dng in s i qua knh theo chiu t cc dng ca ngun vo cc D v ra cc S tr v m ngun ca UDS, knh c tc dng nh mt in tr b. Khi cc G c in p m (UGS

1.4.3 MOSFETMOSFET c chia lm hai loi: MOSFET knh lin tc v MOSFET knh gin on. Mi loi knh lin tc hay gin on u c phn loi theo cht bn dn l knh N hay P. Ta xt cc loi MOSFET knh N v suy ra cu to ngc li cho knh P.

1. Cu to v k hiu ca MOSFET knh lin tcCu to

NNNnn Pcc mngDcc cngGcc ngunSSiO2knh NDSGDSGa.b.UDSUGS

c tnhID(mA)IDUGS=+1VUGS= 0VUGS= -1VUGS= -2VUGS= UP/2= -3VUDS10,98 4 IDSS/2 2 0 -2 -3 -6 UGS 0,3UP UP/2 UP IDSS/4 0 IDSS

2. Cu to v k hiu ca MOSFET knh gin onCu to

NNnn PSiO2knh NDSGDSGa)b)cc mngDcc cngGcc ngunSUDSUGSp

Hot ngKhi phn cc cho G c UGS>0V, cc in tch dng cc G s ht cc in t ca nn P v pha gia ca hai vng bn dn N v khi lc ht ln th s in t b ht nhiu hn, ni lin hai vng bn dn N v knh dn c hnh thnh. Khi c dng in ID i t D sang S, in p phn cc cho cc G cng tng th dng ID cng ln. in p UGS ln to thnh knh dn in gi l in p ngng UGS(T) hay UT. Khi UGS

c tnh