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PNP Transistor voltage calculation

  1. Apr 1, 2017 #1
    sJWddht.jpg

    For the B) part, I don't get why is it that for calculating voltage between collector an the emitter (Vce) I take into account diode on base (0.7V), whereas for part A) it's ignored?

    Why is Vce in part A and part B are calculated differently? Why is it that in part A voltage of 0.7V isn't taken into account? I get that if βf = infinite, and βf = ic/ib ib -> 0
     
  2. jcsd
  3. Apr 2, 2017 #2

    Baluncore

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    The thread title refers to PNP but the diagram shows NPN. What gives?

    What is the origin of the image you inserted? How reliable is it?

    In the first circuit base bias comes from the collector voltage so it limits the lowest voltage on the collector with Vc > Vb.
    In the second case the transistor is being modelled on the edge of saturation with Vc = Vb.
     
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