Maximum operating frequency

Discussion in 'General Electronics Chat' started by rameshrowthu@gmail.com, Aug 20, 2009.

  1. rameshrowthu@gmail.com

    Thread Starter New Member

    Aug 20, 2009
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    Hello,
    I would like to know how to find maximum operating frequency of a Digital circuit?
     
  2. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
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    98
    It varies from part to part. It'll be in the datasheet.
     
  3. rspuzio

    Active Member

    Jan 19, 2009
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    You can make a ballpark estimate based on the
    way the logic is implemented (RTL, DTL, TTL,
    ECL, CMOS). Basically, the limiting factor is the
    parasitic capacitance of a transistor --- closing a
    digital switch is limited by the time it takes to
    charge the capacitance. To make faster logic,
    one either figures out a way of making charging
    faster (e.g. use a diode rather than a resistor) or
    by not charging up the capacitor all the way
    (e.g. not driving transistors to saturation in
    common emitter logic).

    As for the numbers, I remember off the top of
    my head that CMOS goes up to a few
    MegaHertz, but don't recall what the numbers
    are for the other logic families.
     
  4. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
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    It boils down to "how fast do you need"
     
  5. rameshrowthu@gmail.com

    Thread Starter New Member

    Aug 20, 2009
    2
    0
    Thank you........
     
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