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Conventional current?

  1. Jan 16, 2009 #1
    why do we still continue to use conventional current or the flow of positive charge? is there any benefits of using it? can someone explain or shed some light =]
  2. jcsd
  3. Jan 16, 2009 #2
    PNP bioloar transitors are more common than NPN. Somehow, it's easier to grasp PNP's with positive current.

    Other than convenience, does it matter what the sign of the current is?

    In Addition: PNP bipolar transitors preform better than NPN's, in general. The same is true of P channel FETS. With PNP bipolars and P channel FETS dominant, a convention of a single ended positive supply with a common ground is advantagous. These semiconductors are used extensively in digital integrated circuits, and so, the advantage persists. By far, the analysis is far simpler than it would be if the positive voltage souce were referenced as common ground and the negative source referenced as -5V.

    We have Ben Franklin, to thank for this fortuitous arrangement.
    Last edited: Jan 16, 2009
  4. Jan 16, 2009 #3


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    Staff: Mentor

    It would be too confusing to change this convention, because of all the books, articles, etc. that use it.
  5. Jan 16, 2009 #4
    I'm not quite sure where you read that pnp bjts & p-channel FETs are "better". The npn bjt & n-channel FET is the preferred polarity. N-channel semiconductor material is inherently better than the p-type counterpart. The IGBT is and has been since the '80's, an n-type device. The offering of p-channel IGBTs has been very limited.

  6. Jan 16, 2009 #5
    Good catch. You're right. I meant the N channel FET. In fact, I reversed everything, including the BJT didn't I? In any case some species have better gain than their counterparts.
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