This document discusses various methods of transistor biasing: 1. Fixed bias circuit - Applies a fixed voltage at the base through a resistor to establish a quiescent operating point. 2. Emitter-stabilized bias - Uses feedback from the emitter leg to stabilize the operating point. A resistor between the emitter and ground provides feedback. 3. Voltage divider bias - Applies bias through a resistor voltage divider network. The transistor draws current which drops the voltage at the emitter, keeping the operating point stable.

1. Transistor Biasing

2. (Transistor Biasing)
1.
2.
3.
1.
2.
3.
1

3. 1.
Biasing)
2.
(Transistor Biasing)
2

4. 3.
4
1. Fixed Bias Circuit)
2. Emitter-Stabilized
3. Voltage Divider
4. DC DC Bias with
(Transistor Biasing)
3

5. (Transistor Biasing)
3.1 Fixed Bias Circuit)
3.2 Emitter-Stabilized Bi
IB RB
-
-
-
(ß)
RE
(ß)
-
-
4

6. (Transistor Biasing)
3.3 Voltage Divider Bia
3.4 DC DC Bias with Volt
-
–
Input
-
IC, VCE
-
210ER R
5

7. 4.
4.1 Fixed Bias Circuit)
(Transistor Biasing)
4.1 Fixed Bias Circuit)
(a) (b)
1. Input Output 4.1 (b
2. Capacitor
Capacitor
6

8. 0.7 ( )
= 0.3 ( )
,
( 1)
BE
BE
C
FE
B
C B
E C B
E B B
E B C
V V Silicon
V V Germanium
I
h
I
I I
I I I
I I I
I I I
(Transistor Biasing)(
3.
………………………………………
……………………….... 4-6
4. (Kirchhoff's
Voltage Law, KVL)
……………………… 4-1
…………………………………… 4
…………………………………....
……………………………….... 4
7

9. BCC R BE
CC B B BE
CC BE B B
CC BE
B
B
V V V
V I R V
V V I R
V V
I
R
(Kirchhoff's Voltage Law, KVL)
“
(Transistor Biasing)
4.1 (c) Input
4.1 (b)
Input
BR B BV I R
…………....
4-7 …………....
…………....
…………....
8

10. 0
CCC R CE
CC C C CE
CE CC C C
C CE
B BE
E
V V V
V I R V
V V I R
V V
V V
V
(Kirchhoff's Voltage Law, KVL)
(Transistor Biasing)
4.1 (d) Output
4.1 (b)
Output
……….... 4
CR C CV I R 4-11 …….... 4
…….... 4
…………..……....
4-14…………..……....
4-15…………..……....
4-16
9

11. 12 V 0.7 V
47.08 uA
240 kΩ
(50)(47.08 uA ) 2.35 mA
= 12 V (2.35 mA)(2.2 kΩ )
= 6.83 V
0.7 V
6.83 V
CC BE
B
B
C B
CE CC C C
B BE
C CE
V V
I
R
I I
V V I R
V V
V V
1. 4.1 (e) IB, IC, V(Transistor Biasing)
4.1 (e)
* *
2.35 mA 47.08 uA
2.397 mA
E C B
E C
I I I
I I
…….... 4-4
4-3
4-13
4-15
4-14
4-10
10

12. (Transistor Biasing)
4.1

13. (Transistor Biasing)4.2 Emitter-Stabilized
4.2 Emitter-Stabilize
(a) (b)
11

14. 0
( 1)
( 1) 0
( 1)
[ ( 1) ]
-
( 1)
CC B B BE E E
E B
CC BE B B B E
CC BE B B B E
CC BE B B E
CC BE
B
B E
V I R V I R
I I
V V I R I R
V V I R I R
V V I R R
V V
I
R R
0
0
( ) 0
( )
CC C C CE E E
E C
CC C C CE C E
CC CE C C E
CE CC C C E
V I R V I R
I I
V I R V I R
V V I R R
V V I R R
(Transistor Biasing)
4.2 (c) Input 4.2 (d) O
…. 4-6 …. 4-6
…....
4-17
….
4-18
12

15. (Transistor Biasing)4.3 Voltage Divider
4.3 Voltage Divi
(a) (b)
4.3 (a)
13

16. 1 2ThR R R
1 2
2
1 2
2
1 2
1 2
1
2
2
( )
[ ]
CC R R
CC
CC
Th R
CC
Th
V V V IR IR
V I R R
V
I
R R
E V IR
V
E R
R R
(Transistor Biasing)
4.3 (c) 4.3 (d)
4.3 (e) VR2
…..…..….
4-19
...…..….
4-20
14

17. 0
( 1)
( 1) 0
( 1)
[ ( 1) ]
-
( 1)
Th B Th BE E E
E B
Th BE B Th B E
Th BE B Th B E
Th BE B Th E
Th BE
B
Th E
E I R V I R
I I
E V I R I R
E V I R I R
E V I R R
E V
I
R R
(Transistor Biasing)
4.3 (f) ...…..….
4-21
Output
15

18. ' 0
'
' ,
0
0
= ( )
[ ( )]
CC C C B B BE E E
C B C
C C E C
CC C C B B BE C E
C B
CC B C B B BE B E
CC BE B C B B B E
B C B E
CC BE B B C E
V I R I R V I R
I I I
I I I I
V I R I R V I R
I I
V I R I R V I R
V V I R I R I R
I R R R
V V I R R R
I
-
( )
CC BE
B
B C E
V V
R R R
(Transistor Biasing)4.4 DC DC Bias
with Voltage Feedback)
4.4 DC
...…..….
4-22
(a)
(b)
16

19. ' 0
'
' ,
0
( ) 0
( )
CC C C CE E E
C B C
C C E C
CC C C CE C E
CC CE C C E
CE CC C C E
V I R V I R
I I I
I I I I
V I R V I R
V V I R R
V V I R R
(Transistor Biasing)
4.4 (c)
Output
17

20. (Transistor Biasing)