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B I have a few questions about Vce(sat) and static resistance

  1. Aug 18, 2016 #1
    I think this is the place to ask these questions about static resistance of semiconductors:
    The static resistance in semiconductors is that kind of resistance that will decrease if the semiconductor is more heavily doped, right?

    In transistors, and especialy saturated transistors the usual 0,2V voltage drop between the emitter and the collector is the inevitable loss of energy duo to the static resistance of the semiconductor. Is that right?

    If so, that voltage drop will slightly increase with the increase of the collector current, right?
  2. jcsd
  3. Aug 18, 2016 #2


    Staff: Mentor

  4. Aug 18, 2016 #3
    Ah! And so because of this resistance, the transistor will drop some voltage between the emitter and the collector even though it is expected to act like a short circuit when saturated. My point is that it is that sheet resistance that causes that Vce(sat) right?
  5. Aug 18, 2016 #4
    This minimum voltage drop is not due to the resistance but to the need to forward polarize one of the junctions.
    I don't understand though where do you get the 0.2 V. For silicon transistors (junction type) is about 0.7 V.
    Maybe you are talking about a different type of transistor? What kind of transistor do you mean?
  6. Aug 18, 2016 #5
  7. Aug 18, 2016 #6
    I don't speak about the minimum turn on voltage you need to apply across a diode in a forward dirrection to turn it on. Im talking about the voltage difference between the emitter and the collector when a transistor is saturated: latest-topic-4-bipolarjunctiontransistors-21-638.jpg
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