# Common Emitter Bias problem

Discussion in 'Homework Help' started by FutureEET, Nov 10, 2009.

1. ### FutureEET Thread Starter New Member

Nov 10, 2009
1
0
I have an extra Credit problem i need help on.
I have to design a common Emitter amp use voltage divider biasing
Here is the criteria:

Design a Single-Stage Common-Emitter Amplifier using voltage-divider biasing with a good stability factor to provide the following:
AvTotal = 40 dB
Zin(stage) > 1000Ω
Zout(stage) < 5000Ω

The transistor to be used in the design has the following characteristics:
hie = 650Ω
hfeMIN = 50
hfeMAX = 300

The following specifications are fixed:
Vcc = 18 V
Rsource = 600Ω

You can use the following approximations:
Vce ≈ 0.5 Vcc
Ve ≈ 0.1 Vcc

Honestly i dont know where to start

2. ### Jony130 AAC Fanatic!

Feb 17, 2009
3,990
1,115
VRc=Vcc-0.5Vce-0.1Ve=0.4*Vcc=7.2V
and Rc<Zout--->Rc=4.7K
Ic=7.2V/4.7K=1.5mA

3. ### thatoneguy AAC Fanatic!

Feb 19, 2009
6,357
718
Take a look through This Thread

Many formulas, calculations, and alternatives are there, which should get you going on the whole concept so you can solve this problem.

Once you get some work shown with a schematic and are having issues, we can help fine tune it or point you in the correct direction. Members here generally do not give a complete solution, but prefer to have the student understand how the entire system works.