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บทที่ 11 การไบอัสทรานซิสเตอร์ในกระแสตรง(DC Biasing BIPOLAR JUNCTION TRANSISTORS )
Collector-Feedback Bias
-Emitter-Follower Bias-Common-Base Bias
Collector-Feedback Configuration
วธีิการปรับเสถียรภาพของการไบอสัวงจร อีกวธีินึง คือ การใชก้ารป้อนกลบัของกระแสที่ขาคอลเลคเตอร์
ในการไบอสัวงจรน้ี Q-point มีผลกระทบเพียงเลก็นอ้ย จะถึงอยู่กบัอตัราขยายของทรานซิสเตอร์หรือ beta, .
CBC III
BCCECC IIIIII ,,
Collector-Feedback Configuration
Ba
se-E
mit
ter
Lo
op
0 EEBEBBCCCC RIVRIRIV
)( ECB
BECCB
RRR
VVI
0))(( ECBBBECC RRRIVV
CECC IIII ,
Collector-Feedback Configuration
( )CE CC C C EV V I R R= - +
( ) 0C C E CE CCI R R V V- + - + =
offCE CCV V=
sat
CCC
C E
VI
R R=
+
Co
llec
tor-
Em
itte
r L
oo
p
0 CCCCCEEE VRIVRI
mA
A
II BCQ
07.1
) 91.11)(90(
A
kk
V
RRR
VVI
ECB
BECCB
91.11
)2.17.4(90250
)7.010(
)(
Example
Determine ICQ and VCEQ of the following network and repeat ICQ for = 135
mA
A
II BCQ
2.1
) 89.8)(135(
A
kk
V
RRR
VVI
ECB
BECCB
89.8
)2.17.4(135250
)7.010(
)(
V
kmAV
RRIVV ECCQCCCEQ
69.3
)2.17.4)(07.1(10
)(
For = 135 which is 50% increased
Only 12% increased
VkmAV
RIVV CCCCC
22.9)3.3)(66.2(18
mA
A
II BCQ
66.2
) 5.35)(75(
A
kk
V
RRR
VVI
ECB
BECCB
5.35
)51.03.3(75201
)7.018(
)(
Example
Determine IB and VC of the network
R1 + R2 = RB
VC
Emitter-Follower Configuration
( ) 0B B BE E E EEI R V I R V+ + + - =
Base-Emitter Loop
Collector-Emitter Loop
( ) 0CE E E EEV I R V+ + - =
CE EE E EV V I R= -
+
++-
-
-VBE
IE
IB
+
-VCE
+
-IE
BE II )1(
0)())1(( EEBEEBB VVRRI
EB
BEEEB
RR
VVI
)1(
Common-Base Configuration
EE BEE
E
V VI
R
-=
0EE E E BEV I R V- - =
Base-Emitter Loop
Common-Base Configuration
Collector-Emitter Loop
( ) 0CC C C CE E E EEV I R V I R V- + + + + - =
( )CE EE CC E C EV V V I R R= + - +
AmAI
I EB
08.45
61
75.2
1
mAk
VV
R
VVI
E
BEEEE 75.2
2.1
7.04
Example
Determine IE, IB, VCE and VCB of the network
V
kAV
RIVV CCCCCB
5.3
)24)(08.45(6010
V
kmAVV
RRIVVV ECECCEECE
1.4
)6.3)(75.2(104
)(
QuiZ
1. Determine the level of VE and IE and for the network
2. Determine the range of VC for the network
GooD LuCk
mA
RR
VVVI
VRIVRIV
EB
BEEECCB
EEEEBEBBCC
78.23
)1(
0)(
QuiZ
1. Determine the level of VE and IE and for the network
Base-Emitter Loop
2.55
E E E EEV I R V
V
= -
= -
mAII BE 87.2)1(
V
VRIVV CCCCC
31.8
99.5
mAIkRmA
mAIkRmA
kR
V
RRR
VVI
CB
CB
B
ECB
BECCB
785.0 1150;36.4
278.1 150;1.7
)7.43.3(180
)7.012(
)(
QuiZ
2. Determine the range of VC for the network
VVV C 31.899.5
V
kmAV
RIVV EEEECE
68.11
)2)(16.4(20
mA
mA
II BEQ
16.4
)73.45)(91(
)1(
mA
kk
VV
RR
VVI
EB
BEEEB
73.45
)2(91240
7.020
)1(
Example
Determine VCEQ and ICQ of the network
