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Output voltage vs output current

  1. Nov 15, 2009 #1
    In the output charecteristics of a transistor in CE mode, according to the eqation
    VCE = VCC - IC RC it comes as when VCE increases IC
    decreases and vice versa. But it is only because of the reverse collector-emitter voltage, the charge carriers are attracted to the collector side from the emitter side. Hence when the collector-emitter voltage increases collector current should also proportionally increase until it reaches the saturation value. Then why do we have a completly contradictory result in the above equation? According to this equation when collector-emitter voltage is maximum the collector current becomes zero and when the collector-emitter voltage is zero, the collector current becomes maximum! I need a logical explanation for it. My question is when the the collector-emitter voltage is zero how the collector current could become maximum as they can not reach the collector side at all as the accleration given to them by the collector-emitter voltage will also be zero?
  2. jcsd
  3. Nov 15, 2009 #2


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    Science Advisor

    The transistor does not have zero volts across it at saturation.
    It always has a small voltage between collector and emitter.

    I only has minimum voltage across it at that time because there is a series load resistor that drops most of the voltage reaching the transistor.
    Last edited: Nov 15, 2009
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