1415-s2 - hd on thi lt

HD n thi-VLBD-AY1415-S2Trang 1/14

HBK TP HCMKHOA IN-IN T B MN IN T GV: H Trung M

Hng dn n thi LT mn Vt l bn dn HK 2 Nm hc: 2014-2015

Ch : thi trc nghim khong 50 cu S : 4 n 8 thi khng cho s dng ti liu

Trng tm n thi ca cc chng nh sau: Chng 4. Chuyn tip PN Chuyn tip PN

o K tn 4 bc chnh trong qu trnh planar ch to chuyn tip PN. Tc dng ca lp SiO2 l g? o nh ngha ca chuyn tip PN loi bc (step), loi bin i u (graded) o S to thnh chuyn tip PN:

Hnh 4.1 (a) Cc bn dn (c pha tp cht u) loi P v N trc khi to thnh chuyn tip. (b) in trng trong min ngho (depletion region) v gin di nng lng ca chuyn tip p-n iu kin cn bng nhit

Chuyn tip PN cha c phn cc (vi chuyn tip bc) (chuyn tip PN iu kin cn bng) o s hnh thnh min ngho-chuyn ng ca ht dn? o min ngho, min trung ha.

Th ni khuch tn Vbi (hay B ) hay ro th 0 0

20 0

ln ln lnD A n pbi T Tp ni

kT N N n pV V Vq n pn

Ch : Em l in trng cc i ti giao tip ca P v N, W l b rng min ngho ca chuyn tip PN, WP (cn gi l xp) l b rng min ngho bn bn dn P v WN (cn gi l xn) l b rng min ngho bn bn dn N, v s l hng s in mi ca bn dn.

Min in tch khng gian (min ngho) A P D NN W N W

12bi m

V E W 2 1 1S bi

P NA D

VW W Wq N N

D N A Pm

S S

qN W qN WE

Cc phn cc c th c chuyn tip PN

Lm sao nhn bit chuyn tip PN ang tnh trng: khng phn cc, phn cc thun, hay phn cc ngc? Chuyn tip PN c phn cc thun (forward bias) (vi chuyn tip bc)

o Phn cc thun? (th ti P > th ti N). o Khi phn cc thun tng th : min ngho gim v in tr min ngho gim.


2 ( ) 1 1S bi FA D

V VWq N N

vi Vbi > VF > 0 l in p thun trn diode o Dng in thun do cc thnh phn ht dn no to thnh, a s hay thiu s? o Phng trnh dng in qua chuyn tip PN c phn cc thun: 0 / 1A TF V VI I e vi I0 (cn c gi l IS) l dng in bo ha ngc v khi nhit tng th I0 tng.

(a) Chuyn tip PN vi phn cc thun (b) Chuyn tip PN vi phn cc ngc

Chuyn tip PN phn cc ngc (reverse bias) (vi chuyn tip bc)

o Phn cc ngc? (th ti P < th ti N). o Dng in ngc: IR I0 (khi nhit tng th I0 tng) o B rng min ngho tng ln

(vi in p ngcVR: VBR (in p nh thng) > VR > 0, in p t vo diode l VA= VR) 2 ( ) 1 1S bi R

A D

V VWq N N

Dng in sinh ti hp

Dng in ti hp thng th phn cc thun thp v dng in khuch tn thng th phn cc thun cao hn. 0 / 1A TF V VI I e

vi l h s l tng (h s pht x) c tr t 1 n 2 ty theo vt liu ch to, th d vi Ge l 1, vi Si l 1.1 hoc t 1.2 n 2

o xem hnh 4.4 cc dc khc nhau do ci g nh hng? o tc ng ca n c tuyn I-V nh th no?

Hnh 4.4 Dng diode dng semilog ( ln I = f(V) ) phn cc thun (Vi e=in tch in t; kB=hng s Boltzmann; rS= in tr khi)).

in tr vt liu khi RS 0 ( )/ 1A F S TF V I R VI I e tc ng ca RS n c tuyn I-V nh th no?


in dung min ngho ca chuyn tip PN

Xt chuyn tip PN vi phn cc ngc (VA= VR < 0): hnh thnh in dung min ngho. in dung min ngho trn mt n v din tch mt ct ngang Cdep (F/cm2) (cn gi l Cj):

SdepC W

vi 2 ( ) 1 1S bi RA D

V VWq N N

khi p ngc VR tng th Cdep gim v ngc li. Ngi ta ng dng hiu ng ny ch to diode bin dung (varicap hay varactor).

Cc m hnh diode: (cha k n vng nh thng)

M hnh diode tn hiu nh vi tn s thp: Phn cc vi VDQ < VON VDQ VON

Mch tng ng

rr in tr ngc > 10 M

vi rd l in tr AC ca diode

Ch vi tn s cao th c thm in dung song song. in tr ng rD v in tr tnh RD ca diode

o in tr ng rD hay rd (cn gi l in tr AC) D T TD

D D Q Q

dV V V kTrdI I I qI

( T=300oK th rD 0.025V/ID) vi VD, ID l p v dng qua diode, IQ l ID im lm vic Q.

o in tr tnh RD (cn gi l in tr DC): RD=VD/ID=VQ/IQ in dung chuyn tip PN

o vi phn cc ngc: c in dung chuyn tip CJ [F] (J=junction=chuyn tip) ) . SJ dep

AC AC W

vi A: din tch mt ct ngang; S hng s in mi bn dn; W: b rng min ngho.


o vi phn cc thun: c in dung khuch tn CD [F]: D TDT

ICV

vi T l thi gian i qua diode (cn gi l thi gian chuyn tip [T=transit])

Hnh 4.6 in dung ca diode chuyn tip PN vi phn cc ngc VA = VR ( ch : V0=Vbi)

Cc loi diode khc

o Diode chnh lu: diode tip xc PN thng thng - chnh lu: cho dng in i qua 1 chiu (t anode sang cathode) - thng th c in p nh thng ln.

o Diode n p (cn gi l diode Zener) - S dng hiu ng nh thng Zener v/hoc hiu ng nh thng thc l. - Xem li nh hng ca nhit ? Vi in p nh thng VBR= VZ (vi VZ>0) th TCVZ < 0 vi nh thng Zener v TCVZ >0 vi nh thng thc l.

o Diode bin dung (varicap hay varactor) - ng dng in dung tip xc CJ = f(VR), khi VR tng th CJ gim (phn cc ngc VA = VR < 0) (xem hnh 4.6).

Hnh 4.7 M hnh diode Zener vi phn cc ngc VR > VZ0 o Diode Schottky

- to t tip xc M-S (M=Metal=kim loi v S=Semiconductor=bn dn), th d M l platinum v S l bn dn loi N hnh thnh diode Schottky vi Anode bn M v cathode bn S. - Hy k thm cc kim loi khc ngoi Platinum? - c ro th nh ( ~ t 0.2V n 0.3V) - hot ng tt/dn tc chuyn mch cao.

Cc ng dng ca diode o Mch chnh lu: bn k, ton sng, v chnh lu. S v cc cng thc o Mch lc sng gn bng t. Cch tnh t vi cc mch chnh lu i vi mch lc. o Mch xn dng diode thng v Zener. o Mch n p dng diode Zener. o . . .

Chng 5. BJT (TRANSISTOR TIP XC LNG CC) Ti sao c tn gi lng cc? tip xc (hay chuyn tip hay mi ni)? Cu to BJT loi NPN v loi PNP.K hiu jE, jC. Nng tp cht ca cc min?


Hnh 5.1 K hiu ca hai loi BJT: (a) PNP v (b) NPN.

k hiu BJT th mi tn cc E c ngha g? Cc dng in trong BJT ch tch cc [thun]:

Dng in r (r) ICBO (dng t C n B vi E h mch) v ICEO (dng t C n E vi B h mch) trong BJT (nhit tng dn n dng r tng)

o cu hnh CB: IC = IE + ICBO o cu hnh CE: IC = IB + ICEO vi ICEO = ICBO/(1-)

H s vn chuyn min nn B, hiu sut cc pht E? Chng ph thuc nh th no vi cc tham s ca BJT (nng tp cht, b rng min nn)? BJT tt c B, E tin gn ti 1.

o Hiu sut cc pht E

vi pe0 = ni2/NDE ; nb0 = ni2/NAB; WB = b rng min nn DE = h s khuch tn ca ht dn thiu s ti E = Dp DB = h s khuch tn ca ht dn thiu s ti B = Dn

0

0

1 1 eEP E BeEN b B E

pI D WI n D L


LE = chiu di khuch tn ca ht dn thiu s ti E= Lp Thay cc biu thc trn vo e , ta c dng biu din khc ca e nh sau:

1 pAB BeDE n p

DN WN D L

o H s vn chuyn min nn B

2112

Bn

B

WBL

vi WBn= b rng min nn phn trung ha WB LB = chiu di khuch tn ca ht dn thiu s ti B = Ln

li dng in cc nn chung = B.E = IC/IE li dng in cc pht chung = / (1 ) = IC/IB

o cao cn: tc ti hp thp min nn v thi gian chuyn tip (i qua) ngn min nn o ph thuc vo IC v nhit . o DC : dc = IC/IB vi IC, IB l dng DC o AC: ac = IC/IB vi IC, IB l s thay i ca IC, IB do dng tn hiu AC

Cc ch lm vic (ch hot ng) ca BJT v c im ca chng:

Ch :

o Vi BJT NPN Si th VON = 0.7V, VBEsat = 0.70.8V, v VCEsat 0.2V. o R l ch tch cc ngc. o SV t suy ra cch nhn bit vi BJT PNP.

M hnh tn hiu ln ca BJT (TD: xt BJT Si loi NPN)

a) Tch cc (hay Tch cc thun)

b) Bo ha (VBE,sat=0.7V 0.8V)

c) Tt Hnh 5.2 M hnh tn hiu ln ca BJT SI loi NPN trong cc ch hot ng khc nhau


Cc cu hnh mc BJT: (Nh 1 mng 4 cc vi: Bn tri l mch vo v Bn phi l mch ra)

a) CB = Common Base =B chung b) CE=Common Emitter=E chung c) CC=Common collector=C chung

Hnh 5.3 Cc cch mc BJT NPN trong mch Hy nu c im ca cc cch mc vi ng dng kha in t v mch khuch i?

Phng trnh cc dng in trong BJT NPN ch tch cc thun: Dng [in cc] thu IC Dng [in cc] nn IB Dng [in cc] pht IE

1BE BE

T T

V VV V

C S S B EI I e I e I I

1

BE

T

VVC S E

BI I II e 1

BE

T

VVC S

E BI II e I

vi IS l dng bo ha: 2

E n iS

A Bn

qA D nIN W

trong AE l din tch mt ct ngang ti min pht, NA l nng tp cht Acceptor ti min nn v WBn l b rng phn trung ha trong min nn. Cc c tuyn Volt-Ampere ca BJT (cn gi l cc c tuyn I-V)

a) c tuyn vo b) c tuyn ra

Hnh 5.4 Cc c tuyn vo v ra ca BJT NPN mc CE

nh hng ca nhit n cc c tuyn ca BJT (TD vi BJT NPN)

iu ch min nn: Xt BJT NPN phn cc ch tch cc [thun] (khuch i), nu VCE tng b

rng hiu dng ca min nn gim dng IC tng. Ngha l b rng min nn b thay i (iu ch) khi in p VCE thay i.


in p Early VA: gi tr in p ti im nm trn trc honh m mi ng cong IC theo VCE ( phn khuch i) u i qua im ny. dc ti im lm vic Q:

C CQ CQ

CE CEQ A A

dI I IdV V V V

(nu VA >> VCEQ) Khi dng IC:

1BE

T

VV CE

C SA

VI I eV

in p nh thng BVCBO , BVCEO o CB: BVCBO khng b nh hng bi IE. o CE: BVCEO b nh hng bi IB (IB tng th BVCEO gim)

Hnh 5.5 Mt th d v nh thng BJT

Kha in t dng BJT : Kha m vi BJT tt (OFF) Kha ng vi BJT bo ha (ON)

a) Kha in t dng BJT NPN b) Kha in t dng BJT PNP Do in tch cha ti JC khi bo ha nn gim tc chuyn mch ca BJT khi chuyn t bo ha

sang tt. VP Transistor Schottky:

Cu to Mch tng ng K hiu c im

Gim in tch cha ti JC khi BJT bo ha v diode Schottky c VON nh hn VON ca chuyn tip PN. Tng tc chuyn mch


M hnh tn hiu nh ca BJT (tn s trung bnh)

(a) M hnh (mc CE)

(b) M hnh T (nu khng b qua ro c th s c in tr ro ni t C n E)

M hnh tn s cao ca BJT ch tch cc: (C=Cbe, C=Cbc)

Tn s ct fT (khi ac =1)

01

2 2m

Tec

gf f fC C

Vi ec l thi gian in t i t E n C vi BJT NPN mc CB ch tch cc, f v f l cc tn s m ac v ac gim i 2 so vi tr s tn s thp, v 0 (dc=hFE) l gi tr ca ac tn s thp. M hnh tham s h. Cc tham s h cho BJT cu hnh CE:

'

0

BE

BCE

be T Tie be ac e

CE b EQ CQ

v V Vvh r r ri i I IV v

0

C

BCE

cfe ac m ie

CE b

iih g hi iV v

'

1CQm

T e

Ig

V r

0

1 CEC

B

A CEQce Ac O

Boe c CQ CQ

V Vv Vvr rh i i I II i

(nu VA >> VCEQ) Ch : dc = hFE = IC/IB ; ac = hfe = ic/ib ( tn s thp v trung bnh: ac dc=)


Gng dng in (Current mirror) Mch iu kin l ngun dng Phng trnh

1. Q1 v Q2 c c tnh ging nhau 2. Q1 (c mc nh diode) v Q2

lun ch tch cc thun (dn n c gii hn vi in tr ti RL)

Ch : VCC v VEE > 0

Dng hng qua ti:

21R

OUTII

vi dng chun IR: CC EE BE

RV V VI

R

Gii hn ca ti RL l ,0 CC EE CE satL

OUT

V V VR

I

Thyristor: l dng c cng sut quan trng, c thit k x l in p cao v dng in ln.

o Diode 4 lp p-n-p-n Cu to c tuyn dng-p ca diode p-n-p-n

o SCR (Silicon Controlled Rectifier)

Cu to ca SCR K hiu c tuyn dng-p ca SCR


Chng 7. MOSFET MOSFET c cch l gia cng v knh dn bng lp cch in, thnh phn c bn l kim loi (M=Metal), lp cch in SiO2 (O=Oxide), v bn dn (S=semiconductor). Cc tn gi khc ca MOSFET l MISFET (Metal-Insulator-Semiconductor), IGFET (Insulated Gate FET). Nguyn tc hot ng ca FET l dng ht dn t ngun in mng c iu khin bng in p cng hay in trng cng. in trng ny lm cm ng in tch trong bn dn giao tip bn dn-oxide. Cu trc ca MOSFET

MOSFET loi giu (cn gi l MOSFET knh dn cha lp sn)

MOSFET loi ngho (cn gi l MOSFET knh dn lp sn)

K hiu ca EMOS:

N-EMOS P-EMOS

M t nh tnh hot ng ca N-EMOS


Cc ch phn cc cho t MOS trong N-EMOS C 3 ch phn cc quan trng cho t MOS:

o Tch ly l (Hole Accumulation): khi phn cc m gia kim loi v bn dn (VGS < VFB < 0, VFB l in p di phng), ti giao tip gia bn dn v cch in s c tch ly l. o Ngho (Depletion): khi phn cc dng gia kim loi v bn dn (VFB < VGS < VTN, VTN > 0), ti giao tip gia bn dn v cch in s cc l b y xung di hnh thnh min ngho. o o ngc (Inversion): khi phn cc dng gi tr ln gia kim loi v bn dn (VGS > VTN), cc in t c ht vo min gn giao tip gia bn dn v cht cch in, do hnh thnh nn knh dn in t (knh N) trong bn dn P.

Cu trc N-EMOS

Vt liu dng cho bn cc dn in thng dng Silicon a tinh th c pha tp cht rt nhiu (cn c gi l polysilicon hay polySi hay poly). Vt liu cch in thng thng l SiO2. ti thiu ha dng in gia min thn v min S(source)/D(drain) ngi ta thng ni min thn vi cc ngun. S to thnh knh dn trong N-EMOS

S to thnh knh dn N S nh hng ca chiu di knh dn L v chiu rng knh dn W

MOSFET c gi l MOSFET knh ngn khi L < 1m, trong IC ngi ta thng dng MOSFET knh ngn.

MOSFET c gi l MOSFET knh di khi L > 1m

Cc min hot ng ca N-EMOS vi VGS > VTN

Min tuyn tnh (min Ohm hay min triode) (VDS < VDS,sat=VGSVTN)

Min bo ha (hay min tch cc) (VDS VDS,sat=VGSVTN)

cnh min bo ha VDS=VDS,sat

min bo ha VDS VDS,sat


Khi VDS nh (c th hon i D v S) th c th xem nh in tr c iu khin bng p (VGS3> VGS2> VGS1>VTN)

Khi VDS tng, im nght di chuyn v pha cc ngun

c tuyn truyn t v c tuyn ra ca N-EMOS

c tuyn truyn t c tuyn ra

BVDSS= in p nh thng gia DS khi ngn mch cng

Cc phng trnh dng in mng ID trong N-EMOS VGS VTN : min tt ID=0 VGS > VTN : (VDS,sat = VGS VTN )

o 0 < VDS < VDS,sat : min tuyn tnh (cn gi l min Ohm, min in tr hay min triode) 2

2DS

D n ox GS TN DSVWI C V V V

L

vi n l linh ng in t v Cox l in dung lp cch in trn 1 n v din tch. Nu 2DS GS TNV V V th ID l hm tuyn tnh theo VDS: (c th hon i D v S)

D n ox GS TN DSWI C V V VL Khi MOSFET tng ng vi in tr RDS (RON hay RDS,ON):

1DS

n ox GS TN

R WC V VL

o VDS VDS,sat = VGS VTN : min bo ha (cn gi l min tch cc) vi 212D n ox GS TN

WI C V VL

Ngi ta thng ng dng min tt v tuyn tnh cho MOSFET lm kha in t, v min bo ha cho MOSFET lm phn t khuch i tn hiu hoc lm ngun dng. Mt s c tnh khng l tng ca MOSFET (Xt N-EMOS min bo ha)

o iu ch chiu di knh dn: tng t hiu ng Early trong BJT, khi tng VDS th im nght dch chuyn v min ngun, dn n chiu di knh dn hiu dng nh hn hay dng ID tng ln. Khi phng trnh dng in mng c dng

21 12D n ox GS TN DS

WI C V V VL

vi 1AV

v VA l in p Early o Hiu ng thn: khi tng VSB lm in p ngng VTN tng nh hng c tuyn I-V.


o nh hng ca nhit : khi T tng VTN v linh ng gim dng ID gim o S bo ha vn tc: khi kch thc transistor gim, dy lm oxide mng hn vn tc in t

bo ha v lc phng trnh dng ID: 12D n ox GS TN

WI C V VL

vi =1 2, ty theo cng ngh. M hnh tn hiu ln ca N-EMOS (dng phn tch tng qut hay tnh im tnh)

M hnh tn hiu nh ca N-EMOS (khi N-EMOS lm vic min bo ha v 0.2gs GS TNv V V )

M hnh M hnh T Tn s cao

H dn gm:

dDm n ox GS TNGS gsQ

idI Wg C V VdV v L

in tr ra ro:

A DSQDS ds Ao

D d DQ DQQ

V VV v VrI i I I

Tn s ct 2 mT gs gdgf

C C

o Cc cch mc MOSFET: CS, CD v CG. o Cc ng dng tiu biu ca MOSFET l kha analog, in tr c iu khin bng p, ngun dng

v phn t khuch i tn hiu trong mch khuch i. Tm tt quan h dng-p ca MOSFET

NMOS PMOS Min tt (VGS VTN): ID = 0 Min triode (VGS > VTN v 0 VDS < VDS,sat)

22DS

D n GS TN DSVI K V V V

vi n n ox WK C L

Min bo ha (VGS > VTN v VDS VDS,sat) 2

2n

D GS TNKI V V

2m n GSQ TN n DQg K V V K I im chuyn tip VDS,sat = VGS VTN Loi giu: VTN > 0 Loi ngho: VTN < 0

Min tt (VGS VTP): ID = 0 Min triode (VGS < VTP v 0 VDS > VDS,sat)

22DS

D p GS TP DSVI K V V V

vi p p ox WK C L

Min bo ha (VGS < VTP v VDS VDS,sat) 2

2p

D GS TP

KI V V

2m p GSQ TP p DQg K V V K I im chuyn tip VDS,sat = VGS VTP Loi giu: VTP < 0 Loi ngho: VTP > 0

1415-s2 - hd on thi lt

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