Bipolar vs. cmos

Discussion in 'General Electronics Chat' started by new2circuits, May 5, 2009.

  1. new2circuits

    Thread Starter Member

    Apr 22, 2009
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    HI:

    I'm trying to understand the difference between bipolar and cmos signals and why one would be chosen over the other in certain applications.

    Also, do bipolar input signals always requirea dual supply ?
    And if so, why?
    Any reference material is welcome.

    Thanks in advance.
     
  2. bertus

    Administrator

    Apr 5, 2008
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  3. Wendy

    Moderator

    Mar 24, 2008
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    Both refer to transistors, or logic. Dual power supply is a non-sequitur, since both also use single power supplies.
     
  4. mik3

    Senior Member

    Feb 4, 2008
    4,846
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    The chose depends upon the application. In switch mode power supplies they usually use MOS because you can control large amount of current by applying only voltage to the MOS gate.

    BJT's require a significant base current to switch high currents but they switch faster than MOS due to their higher transconductance.

    Also, MOS have a positive temperature coefficient whereas BJTs negative. This prevent thermal runaway of which BJTs suffer. This allows MOS to be paralleled too.

    Search google and you will learn more.
     
  5. new2circuits

    Thread Starter Member

    Apr 22, 2009
    21
    0
    Thanks for your inputs. Much appreciated.
     
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