ηλεκτρονική1 7
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Transcript of ηλεκτρονική1 7
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5. (BJTs)
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1947 John Bardeen and Walter Brattain, William Shockley, @ Bell Labs () (Nobel prize 1956)
1954 Texas Instruments ().
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5.1
() ()
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To on, off,
on, off
. on, off
(wafers) ().
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5.2
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(interfacing) .
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p-n-p n-p-n. -- . .
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(Emitter)
(Base) (
) (Collector)
( ) ( )
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npn- Transistor pnp- Transistor
p pn
n np
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e- ( ) .
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5.3 Transistor
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( ) CB
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0,7V 0,3V
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(J) (Jc). . , , , .
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5.4 Transistor
( )
EB,CB
EB,CB
EB CB
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( e-
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p pnn np
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CE
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5.5
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CE
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CB
. npn: . pnp : .
(npn: e ) .
CB (e )
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q(V0+VCB)
q(V0-VBE)
BE
CB
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>0,7V
IB=IE-IC
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IB=IE-IC
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5.6
-pnp
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IE IpE ( ) InE ( ). IpE/ InE JE p n- .
. p-n-p . .
IE =IpE +InE, JE JC . IPC1 IpE IpE - IPC1 . .
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npn
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To JT
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JC Ic IC0. : InCo p n IpCo n p JC. :
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p-n-p IE IC0 IC.
n-p-n .
(2) IC0 (IE =0) :
pCOnCOC0 III
C CO pC1 C0 EI I I I I
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(large-signal current gain) . 0,9-0,995. IE, VCB .
(2) . . IC0 I-V . I0 IC0 V VC JC p n . :
VC VT (4) (2).
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C TV VC E COI I -I 1 e
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E
COC
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5.7 dc
DC
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adc = IC / O
, adc
adc .
' ( EB, BC). rb. (50-150)
() rb . , IBrb .
rb . rb .
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5.8 Early-
. . . , . , JE () Jc . WB WB WB =WB-W, W .
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Early.
VCB : VCB ( )
. |VCB| IpC1 ( 2).
H (pn) . pn 0 d V0. JE o IE |VCB|.
VCB WB . Punch-through.
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, -- . - VCB.
T : |VCB| IE Early VEB. |VCB|.
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(active region)
JC . IE =0. IC0 (mA nA Ge Si ). IE0 I IC (2). VCB IE. Early (. ) 0,5% |IC| |VCB|.
(saturation region)
VCB =0 IE =0 J , JC .
J C .
IC . pnp, JC .
I J JC (cutoff region).
active region
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5.11 Tran(sfer Re)sistor
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. Tran(sfer Re)sistor. .
:BE VBB BC VCC
IB , IC IE ( IC = IE 1)
rE = ac
IE = Vin/rE (Ohms Law)
Vout = ICRC IERC
out Vin
VA
V
E C C CV
E E E E
I R R RA
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RB
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VCC
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VCE
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ICE / IBE (TRANSFERCHARACTERISTIC). hfe
, . DC transistor, (dc CE) ,
dc = IC /
transistor 5% , , IB. , dc 20., dc 50 300. transistor dc 1000.
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5.13 dc
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. ( =50, C=10mA).
( Kirchhoff): IE=IC+IB ,
IC= IC0-IE : -1
I
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IB>>IC0 IC=IB. IC VCE. (. ). Early.
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IE=IC+IB IC :
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E B
C C dc dc
dcdc
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I I a
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IC = 100(10 ) = 1 mA
H VCE
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VBB IB= 20
IC = 100(20 ) = 2 mA
VCE
VCE , ;
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VCE= VCB + VBE = VCB + 0,7 V = 0 + 0,7V =0,7V. H VCB 0- ( )
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IB=0 IB= IE-IC IE= IC.
(.. 0,9 ) IC=10 IC0 . IB=0 JE.
JC JE
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( volt) VCE=VBE-VBC, VCE
IC VCE
VCE 0,7V
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IC : IC = dc
VCE ( ) .
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5.15 DC
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Maximum VCE=VCC Q ( )
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I(sat), ' , . RC VCC IC(sat) =IC(max)
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CE satV : CC CE sat CC
C sat
C C
c CC CE
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B sat
V V VI
R R
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1mV peak
R110k
RL2.2k
RC3.6k
RE1k
VCC+10V
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dc , . (=200)
To IB . ,
transistor. :
ac , ac. (-1800) ac :
2
1 2
1 8.TH B CCR
V V V VR R
1 8 1 8. .ac dcV V
T acV V V
1 1.BE B E EV V V V V 6 04.C CC C CV V I R V
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JE Jc . .
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L :
+1. n-p-n Ic-VCE . B. B0. c B.
IC=(+1)(C0+IL)
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VB . VB .
5.19
VB 0.7V ( < VC), VE = VB0.7 V.
: VB + VB; VE VE + VE = VB + VB 0.7 V. VE = VB, VE/VB= 1. ( ) , .
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IE/IB=
(100), . . buffer . ;
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VBE 0.6 Volts . , , .
VBE 0.7 Volts , - . , VBE=0.7 Volts .
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VBE(Volts) VCE (Volts)
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0.7 VCB>0 (npn) IC=hFEIB 0.7 VCE=0 IB ICSat / hFE
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1. VBE 0,7 Volts , . 2. VCE .3. VBE, .
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dc . :
=(VBB-VBE)/RB= (10V-0.7V)/1.5M=6.2
To dc dc :
To transistor 2N3904 dc =125. dc ;
C dc BI I 125 6 2 A 0 775mA. .
CE CC C CV V I R 20 0 775mA 5k 16 1V, ,
dc - :
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To transistor 2N4401 dc = 80. dc
:
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dc transistor.
20 mA - - 30 V, RB.
CC
C
V 30V20mA
R 1 5k.
CCV 30V
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IC VCE Q RB = 390 k dc = 80;
CE CC C CV V I R 30V 6mA 1 5k 21V.
CC BEB
B
V V 30V 0 7VI 75 1 A
R 390k
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C dc BI I 80 75 1 6mA. :
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Q 6mA 21 V
RB Q ' dc . RB Q .
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, LED, transistor ; dc = 150, Vin transistor ; LED 2 V.
transistor , , VCE . ' 1 k LED. transistor
To dc , transistor ,
, transistor ,
CC LED
LED C sat C
C
V V 20V 2VI I 18mA
R 1k
in B B BEV I R V 0 12mA 47k 0 7V 6 34V. . .
C sat
B sat
dc
I 18mAI 0 12mA
150.
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(=100, IC0=20nA=2*10
-15mA).
VBB npn . .
. Kirchoff : -5+200IB+VBE=0.
( ) VBE=0,7V :
: IC00. :
IB IC RC . 3K VCB .
mA0215.0200
7,05IB
V85,27,01015,23V 0VVI310
CB
BECBC
5.5
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R=50K. =100 IB IC.
Kirchoff : -5+50IB+0,8=0 IB=4.2/50=0,084mA
: -10+3IC+0,2=0 IC=9,8/3=3,27mA
IB :
IB=0,084> IBmin= 0,033mA .
CB minI 3,27
I 0,033mA100
5.6
