Basic Electrical & Electro . .
ntcs Engineering (MU - Sem 1) . ) Page no. (6-2)
(Introduction to Transistors · · ·
- 6.1 BIPOLAR JUN
CTION ftANs1noa <•JT>
6.1.1 Transistor
(1) A transistor is a three t .
en111n,\l de-vi,, • . • and consequently
• . cc \\ 11tl'li 1t11n~tc1!l II signal hum II low w~1s111m:c to high res1stnnce
name transistor is give ._ . .
' n '') trnn~fN ➔• 1', s1st111
•• • •
"" 111111sistm , I r ,111si s1111 hus II very 1m~1rlanl proper ' 1t can ra1,;e or
ty th·it
•
increase the strength of a weak s, , .
· gnuI, 1 hts p1npc1 ty is c1,llcrl umpllncutlon.
(2) Transistors Clas.-.lficatlon :
(i) Unipolar Junction Trunslst 1 . llJ'f . h ton involves either
· · ( rs ( • ) : Umpolm transistors nre i;o numcd hccau!'.C t cir opera 1
electrons or holes. In UJT cut1. . . d to rna•onty carriers.
. . • cm co11duct1011 ts only clue to one type of charge camcf!I a.c. ue ~
Field effect transistors arc unipolar. t·
June ton truns1st01s.
(ii) Bipolar Junction Transistors (BJT) : A BJT is a three terminal electronic device constructed of doped
semiconductor material and may be used in amplifying or switching applications. Bipolar trans1stors are w named
because their operation involves both electrons and holes. In BJT, current conduction is due to both the type of charge
earners i.e. due to both majority and minority carriers.
"B. 6.1.2 Transistor Junctions
(1) The transistor has two p-n junctions JE and Jc as shown in below figure. The junction JE is a junction between enutter
and base regions. Thus, it is known as emitter-base junction. Similarly, the junction Jc is a junction between collector
and base regions. Thus, it is known as collector-base junction.
(2) Thus, a transistor is like two p-n junction diodes connected back to back as shown in Fig. 6.1.1.
J J
1~
Emitter Collector Emitte~ Collector
•
E I •
C
•
E
I<] C
•
B Base B Base
n-p-n transistor n-p-n transistor
Fig.6.1.1
~ 6.1.3 Transistor Symbols
I
NPN P~'P
Sr. Parameter
No.
(i) Symbol
8-<: 8-<CE
(1CD) t1~
I
(New Syllabus w.e.f Academic Year 24-25)(Ml-03)
, no (fi-3)
PNI
'
/J"lf-1' 1111 I r
n · 11111,,htt,,
C I
fl fJ
p-n-p Iran t r
I lg (d.J
Fk,ll\'11~ 1lok
f----------------1
C'nm·nt Ill'"$ ft\'lll tlw ,·111lt'l'lo1 ln Currrn1 flo~ from the Em t r t
f11llltt'r !t'flllllhll. l'11lh:, lor.
1\ 1..~,,1\:,·r,,r-Enuttt'r, ,,11.,gt' rl,siti, t' Nq:Jll\.C
,Y.:-E'
Rardy ti-cd
~ 6.2 PNP AND NJ>N TRANSISTOlt
3.. 6.2.1 Constructi on of PNP Transistor
Emitter Base Col,ector
• :\ hp,..1!:rr jun,tion transistor (BIT) hns three regions known ns
,
E II C
I
p p
Emitter. Base Jnd CoUeclor. Three regions are provided with I
N
"
•
:ermmlls.. n.:undy Emmer. base. collei:tor.
In P).1' tr:UI.Sistor shown in Fig. 6.2.1. Emitter terminal is
;' -..
Emitter-base Collector-base
.:-...,::ne.:-;eo 10 P-type mJterial. base temlinn.l is connected to N-type ·unction J unction J
B
ra:iren:il :md collector temtinal is connected to P-1ype material.
(1c1)Fig. 6.1.1 : Com.1ruetion of PNP tran..,;i,tor
Emitter Base Collector
s) It i~ a region in one side of (a) It is a middle region thnl forms (a) lt is ,, region in l,ther side l,f
tr:i.nslSlor. ,,hich supplies charge two P-N junctions in the tmnsistor. \\hich Cl,llccts ,hargc
car!"er-. to other mo region$. Lransistor. carriers
(b) Errutter 1~ a heuvil) doped lb) This region is thin ns compare to lb) Collector ure.1 of tr:ms1st,1r ts
region. emitter regions. l,u·gcr rh:111 Emitll'r anJ Base of
(c) The Emmer 1s al\\,J):. fomard (c) Base is lightly doped region the trans1s1,u
bi:i_-.ed \\.r.t co base ,o that 1l can (ti) Electrons arc present. (c) <\,llcclllr is modc1,11el) Ul)IJCd
,uppl~ a large number of region. Ct11lccll,r is ah, ays
[llaJOfll) l'arrier., rt·Wrsl' tirns.·J conditwn.
(d) Hole, are pn:~nt. (d) Holl·s arl' present.
{New Syllabus w.e.f Academic Year 24-25)(Ml-03)
==-=====-
,, ~
6 2.2 o,, lftl!nottl1H
'rt IUlllltlt I
f•
1
r 1
f, l1I 1 •
1
V \J 't.i (l z 3
Ill) OjKI
•
(3
(ll) •
I rr11t1, r
([ )
Cl1J Sywhol
11c-.1)l<iJ'. t,.l.J.
(J) ! I (> 2 2 ~liows 1111• w,,1 ► 1r1v ,,f J> N I' tr.111s1111,,, .
(2) V, luage ,.., 1pplild ,,, 11111111, b:t"' ;,11<11 <,IJC(!ll,1 tia:e
JUnctiorr 111 tram,h.tcJJ.
(3) The t 1rnttct hil~t: pm1 fl<J11 qf tr;111 , t1,r , f1,1w,,1d (1C,CJl- lg 6.2.3
biai,cd
(4) I >Ul lo tfu o; fwwa1d 1,r:is 1111 lic,lc •, J11 tfi, J• IYJJ' c1111trcr
lo flow 1owc11d the 1,a<., c•
(5) ·1111s u,nq1f11H , 1111111, (; Ill,, rit 11 •
t.:mllttr
(I)) It IS ,I JI pJIIJI Ill
.,,,, ,d, ,,, (II J fl I
l1t1ll'- l 1111 , wf111 fi 'uppf11 • ( 1,,,,,,1
CO IIJI I to t,lfw, 1#1111 I'"'"
(h} f 1111th I ,J 1,,
,1v1fy 111,pc d (I) J
1y 1,,,w,1111 (I )
(<..;)
() lf1<1I ti C Ill /dJ
'"11pply w,111
fl t1lllfll J1 I ol
(NPw •,yll,11>1,s w" f IV .11J1 11111 Yt II L'1 l',JCl.11 '' 1)
ntcs Engineering (MU - Sem 1) . ) Page no. (6-2)
(Introduction to Transistors · · ·
- 6.1 BIPOLAR JUN
CTION ftANs1noa <•JT>
6.1.1 Transistor
(1) A transistor is a three t .
en111n,\l de-vi,, • . • and consequently
• . cc \\ 11tl'li 1t11n~tc1!l II signal hum II low w~1s111m:c to high res1stnnce
name transistor is give ._ . .
' n '') trnn~fN ➔• 1', s1st111
•• • •
"" 111111sistm , I r ,111si s1111 hus II very 1m~1rlanl proper ' 1t can ra1,;e or
ty th·it
•
increase the strength of a weak s, , .
· gnuI, 1 hts p1npc1 ty is c1,llcrl umpllncutlon.
(2) Transistors Clas.-.lficatlon :
(i) Unipolar Junction Trunslst 1 . llJ'f . h ton involves either
· · ( rs ( • ) : Umpolm transistors nre i;o numcd hccau!'.C t cir opera 1
electrons or holes. In UJT cut1. . . d to rna•onty carriers.
. . • cm co11duct1011 ts only clue to one type of charge camcf!I a.c. ue ~
Field effect transistors arc unipolar. t·
June ton truns1st01s.
(ii) Bipolar Junction Transistors (BJT) : A BJT is a three terminal electronic device constructed of doped
semiconductor material and may be used in amplifying or switching applications. Bipolar trans1stors are w named
because their operation involves both electrons and holes. In BJT, current conduction is due to both the type of charge
earners i.e. due to both majority and minority carriers.
"B. 6.1.2 Transistor Junctions
(1) The transistor has two p-n junctions JE and Jc as shown in below figure. The junction JE is a junction between enutter
and base regions. Thus, it is known as emitter-base junction. Similarly, the junction Jc is a junction between collector
and base regions. Thus, it is known as collector-base junction.
(2) Thus, a transistor is like two p-n junction diodes connected back to back as shown in Fig. 6.1.1.
J J
1~
Emitter Collector Emitte~ Collector
•
E I •
C
•
E
I<] C
•
B Base B Base
n-p-n transistor n-p-n transistor
Fig.6.1.1
~ 6.1.3 Transistor Symbols
I
NPN P~'P
Sr. Parameter
No.
(i) Symbol
8-<: 8-<CE
(1CD) t1~
I
(New Syllabus w.e.f Academic Year 24-25)(Ml-03)
, no (fi-3)
PNI
'
/J"lf-1' 1111 I r
n · 11111,,htt,,
C I
fl fJ
p-n-p Iran t r
I lg (d.J
Fk,ll\'11~ 1lok
f----------------1
C'nm·nt Ill'"$ ft\'lll tlw ,·111lt'l'lo1 ln Currrn1 flo~ from the Em t r t
f11llltt'r !t'flllllhll. l'11lh:, lor.
1\ 1..~,,1\:,·r,,r-Enuttt'r, ,,11.,gt' rl,siti, t' Nq:Jll\.C
,Y.:-E'
Rardy ti-cd
~ 6.2 PNP AND NJ>N TRANSISTOlt
3.. 6.2.1 Constructi on of PNP Transistor
Emitter Base Col,ector
• :\ hp,..1!:rr jun,tion transistor (BIT) hns three regions known ns
,
E II C
I
p p
Emitter. Base Jnd CoUeclor. Three regions are provided with I
N
"
•
:ermmlls.. n.:undy Emmer. base. collei:tor.
In P).1' tr:UI.Sistor shown in Fig. 6.2.1. Emitter terminal is
;' -..
Emitter-base Collector-base
.:-...,::ne.:-;eo 10 P-type mJterial. base temlinn.l is connected to N-type ·unction J unction J
B
ra:iren:il :md collector temtinal is connected to P-1ype material.
(1c1)Fig. 6.1.1 : Com.1ruetion of PNP tran..,;i,tor
Emitter Base Collector
s) It i~ a region in one side of (a) It is a middle region thnl forms (a) lt is ,, region in l,ther side l,f
tr:i.nslSlor. ,,hich supplies charge two P-N junctions in the tmnsistor. \\hich Cl,llccts ,hargc
car!"er-. to other mo region$. Lransistor. carriers
(b) Errutter 1~ a heuvil) doped lb) This region is thin ns compare to lb) Collector ure.1 of tr:ms1st,1r ts
region. emitter regions. l,u·gcr rh:111 Emitll'r anJ Base of
(c) The Emmer 1s al\\,J):. fomard (c) Base is lightly doped region the trans1s1,u
bi:i_-.ed \\.r.t co base ,o that 1l can (ti) Electrons arc present. (c) <\,llcclllr is modc1,11el) Ul)IJCd
,uppl~ a large number of region. Ct11lccll,r is ah, ays
[llaJOfll) l'arrier., rt·Wrsl' tirns.·J conditwn.
(d) Hole, are pn:~nt. (d) Holl·s arl' present.
{New Syllabus w.e.f Academic Year 24-25)(Ml-03)
==-=====-
,, ~
6 2.2 o,, lftl!nottl1H
'rt IUlllltlt I
f•
1
r 1
f, l1I 1 •
1
V \J 't.i (l z 3
Ill) OjKI
•
(3
(ll) •
I rr11t1, r
([ )
Cl1J Sywhol
11c-.1)l<iJ'. t,.l.J.
(J) ! I (> 2 2 ~liows 1111• w,,1 ► 1r1v ,,f J> N I' tr.111s1111,,, .
(2) V, luage ,.., 1pplild ,,, 11111111, b:t"' ;,11<11 <,IJC(!ll,1 tia:e
JUnctiorr 111 tram,h.tcJJ.
(3) The t 1rnttct hil~t: pm1 fl<J11 qf tr;111 , t1,r , f1,1w,,1d (1C,CJl- lg 6.2.3
biai,cd
(4) I >Ul lo tfu o; fwwa1d 1,r:is 1111 lic,lc •, J11 tfi, J• IYJJ' c1111trcr
lo flow 1owc11d the 1,a<., c•
(5) ·1111s u,nq1f11H , 1111111, (; Ill,, rit 11 •
t.:mllttr
(I)) It IS ,I JI pJIIJI Ill
.,,,, ,d, ,,, (II J fl I
l1t1ll'- l 1111 , wf111 fi 'uppf11 • ( 1,,,,,,1
CO IIJI I to t,lfw, 1#1111 I'"'"
(h} f 1111th I ,J 1,,
,1v1fy 111,pc d (I) J
1y 1,,,w,1111 (I )
(<..;)
() lf1<1I ti C Ill /dJ
'"11pply w,111
fl t1lllfll J1 I ol
(NPw •,yll,11>1,s w" f IV .11J1 11111 Yt II L'1 l',JCl.11 '' 1)
