the power amp class A,B,and AB

Discussion in 'Homework Help' started by flugman, May 30, 2008.

  1. flugman

    Thread Starter New Member

    May 21, 2008
    5
    0
    i am designing power amps of class A, B and AB.

    the specs
    Vcc=15V
    output range :from -10V to +10V
    load resistor : 100ohm

    now i'm composing the class A powe amp.

    at first i thought that i should decide the bias courret in Q2 and i

    used transistor to make it. so i used current mirror to get it.

    however i'm in trouble in making it because i can't make the current.

    i really want to solve this problem.plz help me to make this power amp.


    attatched some fig.
     
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  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    You biggest problem is in trying to use a 2N3904 biased for class A, but in a circuit where is has the signal coming off the emitter. That insures the gain will be less than one, which is not what you're looking for.

    Class A bias, nor present in your circuit, places the transistor in conduction during the full duration of the driving signal. It usually calls for a transistor capable of dissipating a fair amount of heat.

    Beside the lack of a bias network (what is the current source supposed to be doing?), there is no limiting resistor on the base. There are examples of transistor amplifiers all over, including our Ebook. You could benefit from some study time and experimentation before doing more designing.
     
  3. flugman

    Thread Starter New Member

    May 21, 2008
    5
    0
    the attatched circuit is what i wanto compose.

    i used the current mirror the diode as replacing the diode to get bias.

    but i faild to get it and this current mirror couldn't operate properly.

    i just want to exactly 100mA current in Q2 and output ranage -10V to +10V.

    i'm still in trouble because it is due day after 2 days. TT(this is crying emoticon. )
     
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  4. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
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