CNG N TP

MN HC: CU KIN IN T

Phn I: L THUYT

Cu 1: Bn dn thun (Si): Khi nim, cc c trng c bn. Phn bit s khc nhau v

mt bn cht gia vt liu dn in, vt liu cch in v vt liu bn dn.

Cu 2: Bn dn tp loi N v bn dn tp loi P: Khi nim, cc c trng c bn. S ph

thuc ca in tr sut (in dn sut) ca vt liu bn dn vo nhit c gii thch nh

th no?

Cu 3: V sao gi qu trnh ch to bn dn tp l qu trnh pha tp c iu khin, khi

nim tp cht phi c hiu nh th no? M t hin tng cn bng ng xy ra trong

bn dn, ngha vt l ca n.

Cu 4: Trnh by qu trnh hnh thnh v nhng c trng c bn ca mt ghp PN trng

thi cn bng. V sao gi min gii hn bi mt ghp PN l min ngho ng t?

Cu 5: M t mt ghp PN trng thi phn cc thun v phn cc ngc. Nu cc hiu

ng nh thng mt ghp PN.

Cu 6: Cu to v c tuyn Volt Amperre ca Diode bn dn (Diode chnh lu). Da

vo c tuyn V-A ch ra cc tham s c bn ca Diode (in tr tnh, in tr ng,

dng in, in p v cng sut gii hn, in p nh thng).

Cu 7: Trnh by phng php phn tch ch tnh c ti ca Diode. T ch ra tnh

cht dn in mt chiu ca n.

Cu 8: Trnh by phng php phn tch ch ng c ti ca Diode trong trng hp

ch c tn hiu xoay chiu tc ng ln Diode. V s , phn tch hot ng v v gin

thi gian ca mch chnh lu 2 na chu k (hoc chnh lu cu).

Cu 9: Trnh by phng php phn tch ch ng c ti ca Diode trong trng hp c

c ngun 1 chiu v tn hiu xoay chiu tc ng. ngha vt l ca qu trnh ny?

Cu 10: K tn v v k hiu ca mt s loi Diode thng dng. Dng c tuyn Volt

Amperr chng minh tnh cht n p ca Diode Zerner trong s n p c bn.

Cu 11: Trnh by cu to, nguyn tc hot ng v c tuyn ca Diode xuyn hm

(Tunnelling Diode).

Cu 12: Trnh by cu to ca Transistor lng cc. Da vo cu to ca Transistor lng

cc hy cho bit: C th dng Transistor nh mt Diode c khng? Nu c th phi

mc Transistor nh th no? C th dng hai Diode mc thnh mt Transistor c

khng? V sao?

Cu 13: Nu phng php phn cc v nguyn tc hot ng ca Transistor lng cc

trong ch khuch i. Vit cc phng trnh dng in m t mi quan h dng in trn

cc cc.

Cu 14: V s kho st, trnh by phung php xy dng h c tuyn u vo v u

ra ca BJT trong cch mc B chung.

Cu 15: V s kho st, trnh by phng php xy dng h c tuyn u vo u ra

ca BJT trong cch mc E chung. Phn tch h c tuyn u ra.

Cu 16: Phng php xy dng cc h thng tham s vi phn ca BJT. Phng trnh m t

cc h thng tham s vi phn. Mi quan h gia cc h thng tham s vi phn (trong cng

mt cch mc).

Cu 17: Trnh by phng php phn tch ch hot ng c ti ca BJT loi PNP mc

theo s E chung, thin p bng ngun c nh. T ch ra cc tham s gii hn ca

BJT.

Cu 18: Trnh by cu to v nguyn tc hot ng ca JFET (mt loi bt k no ).

Cu 19: Trnh by cu to v nguyn tc hot ng ca MOSFET (mt loi bt k no ).

Cu 20: Trnh by cu to, nguyn tc hot ng v c tuyn Volt Amperre ca

Dinhistor v Thiristor. ng dng ca chng trong thc t.

Cu 21: C s vt l, cu to, nguyn tc hot ng v ng dng ca quang tr (nu v d

c th v ng dng).

Cu 22: C s vt l, cu to, nguyn tc hot ng v ng dng ca Photo Diode.

Cu 23: C s vt l, cu to, nguyn tc hot ng v ng dng ca Photo BJT.

PHN 2: BI TP

Tt c cc dng bi tp ra trn lp.

Ch thm cc cu sau:

Cu 1:

Cu hi: Cho mch in nh hnh v: hy cho bit cch to im cng tc (cch thin p)

l loi no?

Chng minh rng, nu h s truyn t dng in cc gc ca BJT tha mn >>1, th

dng Ic c xc nh gn ng 0.

.

C c B

c

B T

E I RI

R R

.

Gi tr li:

y l mch to thin p v n nh im lm vic cho BJT mc E chung bng phn hi

m in p mt chiu t cc gp (HS t ch ra tnh cht n nh ca mch ny).

xc nh Ic ta da vo h phng trnh:

. .

.

.

c T b B

c b

c T CE

b c

E I R I R

I I

E I R U

I I I

, vi ch v >> 1 +1 , gii h phng trnh, ta

thu c pcm.

Cu 2:

Cu hi: Cho mch in nh hnh v, hy lp cng thc gn ng xc nh tr khng u

vo Zvo v h s khuch i dng in KI (dng in u ra ly trn in tr RE).

RT

RB

EC

Gi tr li:

S dng h phng trnh dng in v in p cho mch mc phi hp cc BJT vi ch

: Ube1, Ube2, Ube3 0, 1, 2, 3 >> 1, b qua Ic0 ca cc BJT ta c:

1 2 1 1 1

2 3 2 2 1 2

3 3 3 1 2 3

e b b v

e b b v

e ra b v

v ra E

I I I I

I I I I

I I I I

U I R

, t ta xc nh c:

1 2 3

o 1 2 3

raI

v

vv E

v

IK

I

UZ R

I

Cu 3:

Cu hi: Cho mch in nh hnh v, cho c tuyn ca transistor. Hy xc nh im

cng tc trn h c tuyn.

T1,1 T2,2 T3,3

Zvo

+ EC

RE

Gi tr li:

Trc ht, p dng nh l my pht in ng tr, a s v dng c phn

tch vi cc tham s ca ngun in ng tr u vo nh sau:

2

1 2

c BB

B B

E RU

R R

;

1 2

1 2

B BB

B B

R RR

R R

; Sau , xy dng h phng trnh cho mch:

(1)

(2)

(3)

B b B e E

c c C ce e E

e b c

U I R I R

E I R U I R

I I I

. xc nh im cng tc ca BJT trn c tuyn,

ta xc nh 2 mi quan h:

- Mi quan h th nht (ng ti tnh ca mch) c xc nh gn ng khi coi Ic

xp x Ie, t (2) ta c:

0 5 10 15 20 Uce(V)

IC 6

4

2

25a

50a

75a

100a

125a

ma

RB1=88k

RB2=17,2 k

RC=3,2k

EC=20v

RE=780

IB

c ce

c

C E

E UI

R R

, ng ti ny i qua 2 im:

A: khi Ic = 0 th Uce = Ec

B: khi Uce = 0 th Ic = Ec/(RC + RE)

- Mi quan h th hai (ng ti ng) c xc nh bng cch bin i h phng

trnh tm quy lut ph thuc tuyn tnh ca Uce vo Ib, sau khi bin i, mi quan h

c xc lp:

21

C E B EC Ece c B b E

E E

R R R RR RU E U I R

R R

Mi quan h trn xc nh ng thng i qua 2 im:

M1: Chn Ib = Ib1 Uce = Uce1;

M2: Chn Ib = Ib2 Uce = Uce2;

T xc nh c im lm vic M l giao ca 2 ng ti ni trn, t v tr ca

M, ta xc nh cc gi tr Ib, Ic v Uce tng ng.

Cu 4:

Cu hi: Cho s mch in nh hnh v sau:

Bit Transistor c = 0,98, Ico = 10A, Ec = +24V, Rb1 = 1M, Rb2 = 500K, Rc =

5K.

Uce

Ec

K

Rc

T,

Rb1

Rb2

Hy tnh gi tr in p Uce v dng in cc gp Ic trong hai trng hp ng vi

kho K ng vo hai v tr khc nhau.

Gi tr li:

Khi K ng vo v tr trn: y l s thin p bng dng c nh, ta c h phng trnh:

0

(1)

(2)

1 (3)

c b b

c c c ce

c b c

E I R

E I R U

I I I

, gii h phng trnh, ta thu c:

0; . 1 ;c c

b c c ce c c c

b b

E EI I I U E I R

R R

* Khi K ng vo v tr di: y l s thin p bng phn hi m in p, ta c h

phng trnh:

0

(4)

(5)

1 (6)

c b b b c c

c b c c ce

c b c

E I R I I R

E I I R U

I I I

, gii h phng trnh ta thu c:

01 .

; . 1 ;c co c

b c b c ce c c b c b b

b c

E I RI I I I U E I I R I R

R R

Cu 5:

Cu hi: Cho s mch in v c tuyn l tng ho ca cc diode nh hnh v sau:

Bit hai diode c cc tham s: D1: Eth1 = 0,2V; rth1 = 20 ; D2: Eth2 = 0,6V; rth2 = 16. Hy tnh dng in chy qua tng diode khi R = 1K v 10K. Bit E = 200V.

p s:

R

D1 D2 E

+

- rth = 1/tg = Ri

Ith (mA)

Uth (V) 0 Eth

Trng hp R = 1K ta c: ID1 = 53,8mA, ID2 = 45mA

Trng hp R = 10K ta c: ID1 = 10mA, ID2 = 0.

Cu 6:

Cu hi: Cho mch in nh hnh v : Bit rng : RHC=10k, EXC= 5v, E= = 20v; I0 =

10A; tnh nhit trong phng, cho hng s Bolzmahn K = 1,38.10-23 (J/oK).

Hy xc nh in p u ra URA1 v URA2 bit rng 3 Diode c tham s ging

ht nhau.

Gi tr li:

S dng phng php tnh gn ng: c 3 diode u phn cc thun nn RD=RD1 + RD2 +

RD3

+ 3 diode c tham s ging ht nhau.

Cu 7:

Cu hi: Cho mch in nh hnh v: Hy xc nh dng in chy qua tng Diode. Bit

rng: Khi dng kiu mu mt chiu tuyn tnh ha c tuyn ca cc Diode th ta c:

D1 c cc tham s :Rth1= 10, Eth1=0,2v

D2 c cc tham s : Rth2=15, Eth2=0,3v

D3 c cc tham s : Rth3=20 , Eth3= 0,5v

E0=70v, RHC= 5k

Gi tr li:

Nhn xt: D1 lun lun thng (v nu D1 tt th c 3 Diode u tt v l do E0 >>

Eth3).

Gi s c 3 Diode u thng iu kin Ura = UD > Eth3. Phng trnh nh lut

Ohm vit cho ton mch nh sau:

0 . HC DE I R U trong :

1 2 3

, 1, 2,3D thiithi

I I I I

U EI i

R

(I) Thay cc biu thc dng

in v cc tham s vo phng trnh, ta tnh c:

1 2 30

1 2 3

1 3 3

1

th th thHC

th th th

DHC HC HC

th th th

E E EE R

R R RU

R R R

R R R

, thay s vo ta tnh c UD, so snh vi iu

RHC

E0 D1 D2

D3

kin:

- Nu iu kin tha mn, ta tnh I1, I2, I3 theo h phng trnh (I).

- Nu iu kin khng tha mn D3 tt I3 = 0, tip tc gi s D2 thng UD >

Eth2, tnh ton tng t ta c:

1 20

1 2

1 2

1

th thHC

th th

DHC HC

th th

E EE R

R RU

R R

R R

li so snh vi iu kin:

+ Nu iu kin tha mn, tnh I1, I2 theo (I).

+ Nu iu kin khng tha mn D2 cng tt I2 = 0 v ch cn D1 thng, khi

:

10

1

1

1

thHC

th

DHC

th

EE R

RU

R

R

v I1 cng c xc nh theo (I).

Cu 8:

Cu hi: Cho mch in nh hnh v. Hy xc nh in p UCE, URE khi ng v m kha

K. Bit rng EC=20V, RC=2k, RE=500

EB=2V, RB= 10k ; = 0,92; IC0 = 10A.

+ EC

RC

RB kha K

EB

RE

UCE

URE

Gi tr li:

* Khi ng K: y l s thin p t phn cc s dng 2 ngun, ta c h phng

trnh:

(1)

(2)

1 (3)

( 1) 1 (4)

B b B e E

c c C ce e E

c b co

e b c b co

E I R I R

E I R U I R

I I I

I I I I I

, gii h phng trnh ta tm c:

1;

1

B co E

b

B E

E I RI

R R

thay vo (3) ta tm c Ic, t tm c Ie, thay vo (2) ta tm

c Uce. Sau xc nh URE = Ie.RE.

* Khi m K: Ib = 0, dng chy qua BJT lc ny l dng xuyn cc gp ban u

c xc nh:

;1

coc e ceo

II I I

T xc nh c Uce = Ec - (RC + RE).Iceo, URE = Iceo.RE.

Cu 9:

Cu hi: a) Cho h thng tham s h mch ca mt BJT no , hy tm h thng tham s ngn mch v tham s hn hp ca BJT . b) Cho s mc hn hp cc BJT nh hnh v sau:

Bit hai BJT c h s truyn t dng tnh cc pht l 1 v 2. Hy chng t rng s

T1,1

T2,2

trn tng ng vi mt BJT c h s truyn t dng tnh cc pht l *(1+2

1.2).

T h thng tham s h mch, xc nh h thng tham s ngn mch v h thng tham s

hn hp:

Y11 = Z22/Z; Y12 = -Z12/Z; Y21 = -Z21/Z; Y22 = Z11/Z H11 = Z/Z22; H12 = Z12/Z22; H21 = -Z21/Z22; H22 = 1/Z22; trong Z = Z11Z22 - Z21Z22. p dng cc cng thc m t quan h ca dng in trn cc cc BJT:

Ta c: * Ic / Ie trong Ie = Ie1, Ic = Ic1 + Ic2

ng thi: Ic1 1Ie1; Ic2 2Ie2 2Ib1 2(Ie1 Ic1)

T suy ra pcm.

Cu 10:

Cu hi: Cho mch in nh hnh v. Hy xc nh cch to im cng tc khi kha K ln

lt cc v tr 1, 2, 3. Tnh cc gi tr dng in v in p ng vi 3 trng hp khi

bit: =60; EC = 25v; EB = 2v; RC = 1k; RE = 200; RB1 = 100k; RB2 = 10k;

RB3=100k; RB4 =50 k.

RB3

RB1

RC

EC

Kha K 1

2

RB4 3

RB2

EB

RE

Gi tr li:

* Khi K ng vo v tr 1: y l mch thin p cho BJT bng dng c nh c phn

hi m dng in mt chiu t E v B. Khi ta c h phng trnh:

1 (1)

(2)

(3)

( 1) (4)

c b B e E

c c C ce e E

c b

e b c b

E I R I R

E I R U I R

I I

I I I I

Gii h 4 phng trnh ny, ta thu c cc

gi tr cn tm:

1 1c

b

B E

EI

R R

; 1 1

cc

B E

EI

R R

;

1

1 1

11 1

c B Ccce c c E

B E B E

E R REU E R R

R R R R

* Khi K ng vo v tr 2: y l s t phn cc s dng 1 ngun. tnh ton

s ny, ta p dng nh l My pht in ng tr chuyn v s tng ng ging

nh trng hp K ng vo v tr 3 nhng thay ngun EB bng ngun UB, thay in tr

RB2 bng RB vi:

4

3 4

c BB

B B

E RU

R R

;

3 4

3 4

B BB

B B

R RR

R R

Ta c h phng trnh:

(5)

(6)

(7)

( 1) (8)

B b B e E

c c C ce e E

c b

e b c b

U I R I R

E I R U I R

I I

I I I I

Gii h phng trnh ny, ta thu c:

1B

b

B E

UI

R R

; 1

Bc

B E

UI

R R

;

1

1

Bce c c E

B E

UU E R R

R R

* Khi K ng vo v tr 3: y l s t phn cc s dng 2 ngun. Tnh ton

hon ton tng t nh trng hp trn, thay UB bng EB, RB bng RB2 nh cho trong

bi.