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
    R1oad = 33 kΩ
    Rsource = 600Ω

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

    Honestly i dont know where to start
    Your help is greatly appreciated
     
  2. Jony130

    AAC Fanatic!

    Feb 17, 2009
    3,961
    1,097
    hmm, you can start with this:
    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.
     
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