Date post: | 08-Jan-2017 |
Category: |
Technology |
Upload: | yong-heui-cho |
View: | 2,086 times |
Download: | 3 times |
BJT – Analysis of Bias
Yong Heui Cho @ Mokwon University
Some of slides are referred to:[1] A. S. Sedra & K. C. Smith, Microelectronic Circuits.
2
Electronic Circuits
8. BJT – Operational Principle
9. BJT – Model
10. BJT – Analysis of Bias
11. Analysis of CE Amplifier
3
CE Amplifier• CE (Common Emitter)• Input: Base, Output: Collector• Common: Emitter
4
CB Amplifier• CB (Common Base)• Input: Emitter, Output: Collector• Common: Base
5
CC Amplifier• CC (Common Collector)• Emitter Follower• Input: Base, Output: Emitter• Common: Collector
6
ComparisonType CE CB CCinput Base Emitter Base
output Collector Collector Emittercommon Emitter Base CollectorV gain large large noneI gain large none large
application first stage amplifier
high fre-quency am-
plifierbuffer
7
Bias Point• Quiescent point• Active mode
8
CE Amplifier• 4 R and 1 TR
9
Active Condition• Collector Current (IC) = about mA• CE Voltage (VCE) = VCC/2
10
Analysis of Bias (I)• Thevenin equivalent circuit
CCBB
BBB V
RRRV
21
2
21
2111 //
BB
BBBBB RR
RRRRR
VBB
RB
11
Analysis of Bias (II)• B-E loop: collector current (IC)
VBB
RB
VCC
RC
RE
BEBBE
EEBEBBBB
IRRVRIVRIV
)1(
BCBE IIII )1(
EB
BEBBB RR
VVI)1(
E
BEBB
EB
BEBBC
RVV
RRVVI
)1()(
12
Analysis of Bias (III)• C-E loop: CE voltage (VCE)
VBB
RB
VCC
RC
RE
BCBE IIII )1(
EECECCCC RIVRIV
)( ECCCC
EECCCCCE
RRIVRIRIVV
13
Selection of R
kRR BB 10, 21
BE RR
LC RR