- Sa d6 mach:
~R, ' R,
R,
Hinh J .19. Cal) ngllljn clIO Transislor ngu(fc dung ngu6n am
- Phan tich each cap di~n:
+ Vi R, thuang nho han Rj ve tr! s6 nen UB < Uc (cu¢n day L2 co tr~ s6 tr6 khang kh6ng dang ke).
+ Vi R .. thuang nho han R2, nen UB > UE (di¢n ap UB am it han di~n ap UE). Nen dicu ki¢n cap di~n Uc > UB > UE van duqc thoa man.
4. Nguyen ~c chung vii phlf<!ng philp cap nguon cho Transistor trutlng D~ cap di~n m¢t chieu cho Transistor truong, chung ta cap di~n thea nguyen ule sau:
- Cap di9n cho Transistor JFET - kenh N:
UDS>O~ Uo > Us UGS < 0 ~ UG < Us
- Cap di~n cho Transistor JFET - kenh P:
UDS<O~ UD< Us
- Dip di¢n cho Transistor MOSFET - kcnh N:
UDS > 0 ('-? Uo > Us UGS < 0 ('-? UG < Us
- Cap di¢n cho Transistor MOSFET -kl~nh P:
UDS < 0 ('-? Uo < Us
UGS > 0 ('-? UG > Us .
- Cip di~n cho Transistor MOSFET cam ling - kenh N (gi6ng nhu Transistor luang qrc nguqc):
Uos > 0 ('-? Uu > Us UGs>O~ UG> Us
- Cap di~n cho Transistor MOSFET cam ling - kenh P (gi6ng nhu Transistor lLIang CI!C thu~n):
Uus < 0 ('-? lJl) < Us
Ucs < 0 ('-? Uc < Us
Cach dung cac linh ki¢n R, L, day dAn cip di9n cho cac CI!C eua Transistor tmong, cung Wang tI! nhu cach dung R, L, day dan d6 dip cho Transistor luang
cI!c. Ngoilj ra, cap di~n cho cI!C G Transistor truang con co m¢t phuong phap nfra duqc gQi HI. phuong phap cap di¢n tI! d¢ng hay con dUQ'c gQi li II! dan.
Vf dlr Cho m~ch di~n nhu sau:
-- - I i i - • - i . ! Trang do:
- QI lit Transistor truang JFET - kenh N.
- R21a di¢n tra dung de dan nguon cap cho cl!c D.
- R, la di~n tn; dung d€ (liin ngu6n cap cho CI!C S, day la each cap thea ki~u hoi tiep am dong di¢n mot chieu n6i tiep.
- R, IV. di~n tra cap di¢n cho cl!c G theo phuong phap tl! dan. Theo each cap
di~n cho Cl!C G kie'u nay thl di¢n ap t<;li cl!C G 1a di~n ap am.
VI. CHll DO C()NG TAc CVA PHAN nI KHUECH DAI
Transistor luang CI!C co ba tr~ng thai ho~t d¢ng: Tr~ng thai ngung dan, !r<;lng thai khu€ch d<;li va tr<;lng thaj bao hoa.
Khi tfnh to<in dc di¢n tra phan cl!c cho Transistor co nghia I;) ch9n diem ho,-~t dong tinh Q (di6m lam vi(:c) cho Transistor do. Khi co tin hi¢u xoay chieu tac d¢ng van ng6 van CciIa vao, dau vao) clla Transistor thl di~m ho~t d(mg Q se bj diYi cho va lam thuy d6i cac thong s6 khac cib m<ctch. Dl!a va~ die'm h0<ctt dong tinh Q nguai tu ehiu m~ch khuech d<cti fa cae che' dt) ho .... t d(mg hay con duqc gQi Hi chc d¢ cong taco Co cac che dO hO<;lt d¢ng cO ban sau; Che do ho~t d¢ng A, che d¢ hO<;lt dong B, che dO ho~lt d¢ng C va chc d¢ ho<ctt d¢og AB.
Ie
Vung buo hoa PMAX
Vung khuech dl;ii
a
Vung ngLIng dan
- Che d(> hO<;lt d(>ng A: Transistor duqc phan cl!c cho di~m hO':lt d¢ng tinh Q a gilta vung khuech d<.ti.
- Che d¢ hO':lt dc)ng B: Transistor duqc phan cl!c cho di~m h0<.tt d(>ng tinh Q
a trono vuno nuun u dan o 0 0 0 .
- Che d¢ hO':lt dOng C: Transistor duqc' phan cl!c cho di6m hO<;lt d¢ng tinh Q nam sau trong vung ngung dan.
- Che d¢ ho,.\( d¢ng AB: iii. h'.l-ng trung gian gifra che d(> hO':lt d(>ng A va ch€ d¢ hO<;lt d(>ng B. Transistor se duqc pM.n cl!c cho diem Q nam giua vung khucch d<;li va vung ngung dan.
Sau day ta se khao sat tung twang hqp Cl,l th~:
1. Che di? ho~t di?ng A
Q
v,
+
Hlllh 1.22. D(ic tuye'n van ache' de; hogt d(mg 1\
Tren d~c tuyen ng6 vao (elra vao) IJV BE ella Transistor, m<;lch khuech d<;li che d(> hO<;lt d(>ng A co di~m h0<.tt d¢ng tinh Q mlm giua duang d~c tuyen va co YSE ::::: O,65Y +- O,7Y eho Transistor iO,!-i Si va YBE ::::: O,2Y +- O,25Y cho Transistor IO':li Ge. Khi Transistor nh~n duqc tin hi~u xoay ehieu 6 Cl!C B thl dong di~n Is se b, thay d6i theo tin hi~u xoay chieu nay.
Ie Ji ..... . Ji ..... . o N·· .... , + ... - ---~ -.,- . . Q Duong 'ai r-----+--~I VeE + VeE
lIll/1l 1.23. D(ic tuyell ra (/ clu:' ell} harp d(mg;\
Tren d;)c tuyen ngo ra (elra fa) leN CE cUa Transistor, m~ch khuech d<.li che d() hO<;l1 d¢ng A c6 diem ho~t d¢ng tloh Q flam gifra duang liii va VeE::o: I/2Vec. Khi dong di~n If) bi thay d6i thea tfn hi¢u xoay chieu se lam cho dong di¢n Ie hi thay deli va keo thea di¢n ap VeE cung bj thay deli.
Ok d~c diem cua m<,tch khuech d<,ti che'd¢ hO<.lt d¢ng A Iii:
- Khuech d<.li trung thl!c tfn hi¢u xoay chitu (khuech d<,ti duqc d. hai ban chu ky cua tfn hi¢u xoay chieu hlnh sin),
- Dung cho cae m<;lch khuech d<,ti tfn hi¢u c6 bien d¢ nha. 2. Che d{> ho~t d{>ng B
Tren di!-c tuyen ngo va~ (elra vao) IJV BE thl m~ch khucch d~i che d¢ ho<,tt d¢ng B co diem ho~t d¢ng tinh Q a di~m VilE = OV va Ie = OA. Khi Transistor
nh~n duqc tfn hi¢u xoay chieu b qTc B thi chi co m¢t ban chu ky duqc khucch d~i
VI lam phan qTc tiep giap BE va IR tang len, con mQt ban chu ky lam giJm philn clfc tiep giap BE xu6ng vung ngung dan nen tfn hi¢u kh6ng duqc khuech d<;li.
Ie
o
Q
--/--<o'v"-----~1----'--..V BE
Y
Hinh 1.24. D~1c ttlyln voo d clut J(" J/O(Jt d(JIIg B
+
Hinh 1.25. D(ic lIlye'n ra ache' J¢ hoqt J(mg B
Tren d~c tuyen ng6 fa (elra fa) leN CE thl khuech d~i ehc d¢ ho~t dQng B co
di~m ho~t d¢ng tinh Q nam tren duemg bien giUa vung khuech d'.li va vung
nglffig dan, v C'E ~ V cc' Khi dong di~n If) tang len theo tin hi?u xoay chieu thl
dong di?n Ie cGng lang len va la.m eho di¢n lip V CE ghtffi xu6ng. 0 ng6 fa (ci'Ia
Oic d~c diem cua m~ch khue'ch d~i che d¢ hO<;lt d¢ng B Ui:
~ Khi khOng co tin hi¢u thl Transistor khOng da.n ( Is = 0, Ie = 0).
~ Transistor chi khuech d1.li duqc m¢t ban chu ky nen muon co du d. hai ban chu ky thl phiii dung hai Transistor de khuech d1.li lua.n phien eha hai ban chu kyo
~ Dung cho cac m1.lch khueeh d1.li co bien d¢ IOn.
~ Hi¢u suat cao do eOng suat tieu tan nhc.
- Tin hi¢u ra bi meo d1.lng (bien d<.tng) xuyen tfl,Ie.
Mea xuycn trl;lc (mea do chuycin tiep den)
Hillh 1.26. Meo do chuye'll tilp dhl
3. Che di? ho~t di?ng C
v, VUE
Tren d~c tuyen ng6 vao (ciia vao) IsfVBE clla Transistor, m~ch khuech d~i
che d¢ hO<;it d¢ng C co diem hO<;it d¢ng t'inh Q nam sAu trang vung ngung dan va co V BE ~ OV. Khi Transistor nMn dugc tin hi~u xoay chieu a clJc B, neu tin
hi~u xoay chieu co di~n ap dinh V p < v.( thi Transistor van chua dan di~n dugc ncn kh6ng co tin hi~u fa, neu tin hi¢u xoay chieu co di¢n ap dinh VI' > Vy thi chi co m¢t phan tin hi¢u ra dugc khuech d~i.
Tuang tlJ khi xet tfen d~c tuyen ng6 ra (cua fa) leN CE chi co m¢t phan ban chu ky duang duqc m~ch khuech d~i.
Cac d~c ditm cua m~ch khuech d<;ii che d¢ hO<;lt d¢ng C Iii.:
- Khi kh6ng co tin hi¢u vao thi Transistor kh6ng dun ( IB = 0, Ic = 0).