Discussion in 'Homework Help' started by icyzero, Jan 26, 2007.

  1. icyzero

    Thread Starter New Member

    Jan 26, 2007
    its required for me to do an amplifier circuit using a common emitter BJT...
    and in the evaluation i think they will ask two question that yet i codnt get an answer for em...

    why its better to use a common emitter rather than common base?
    and if we changed the saturation current Is without changing the doping of the material... wat will be the effect?

    i really need those answers... the evaluation is on next monday...

    SOS !!!!!
  2. beenthere

    Retired Moderator

    Apr 20, 2004

    We look to you to do the work. If you come here with some work to show, we can probably help. Otherwise, it is like you are asking us to do your work, and we don't get the grade/recognition.
  3. thingmaker3

    Retired Moderator

    May 16, 2005
    Better for what exactly? I can think of two or three applications where a common base amplifier would be more useful.

    Change the saturation current?!? Change the doping material?!? I would love to see a demonstration of this.
  4. extremeads1

    Active Member

    Feb 10, 2007
    As you are using the BJT as an amplier device the gain provided By the BJT must be maximum .
    When The BJT is operated in CB configuration the gain factor ;
    a= Ie/Ic & Ic=Ie apprx. hence the gain is 1
    It simply means that o/p is same as i/p.
    However in CE configuration gain =Ic/Ib where Ib is in microamps and Ic is in milliamps calculate it its found that the ratio is high which means amplification takes place max in CE configuration.