2. Objectives
2
At the end of the module the student would be
able to explain
Study Voltage Divider Bias
3. Voltage Divider Bias Circuit
3
Provides good Q-point stability
with a single polarity supply
voltage
1st step: Locate capacitors and
replace them with an open circuit
2nd step: Simplified circuit using
Thevenin Theorem
3rd step: Locate 2 main loops
which;
BE loop
CE loop
4. Voltage Divider Bias Circuit
4
1st step: Locate capacitors and replace them with
an open circuit
6. Voltage Divider Bias Circuit
6
■ 3rd step: : Locate 2 main loops.
BE Loop
2
CE Loop
2
1
7. Voltage Divider Bias Circuit
7
BE Loop Analysis
VTH − I B RTH − VBE − I E RE = 0
Recall; I E = ( β + 1) I B
1
Substitute for IE
VTH − I B RTH − VBE − ( β + 1) I B RE = 0
∴IB =
VTH − VBE
RRTH + ( β + 1) RE
8. Voltage Divider Bias Circuit
8
CE Loop Analysis
VCC − I C RC − VCE − I E RE = 0
2
Assume;
I E ≈ IC
Therefore;
∴VCE = VCC − I C ( RC + RE )
9. Voltage Divider Bias Circuit
9
Build the circuit as shown below and find out
the following parameters IC , IB , VB, VE and VC