Noise Margin for CMOS

Discussion in 'Homework Help' started by zulfi100, Apr 1, 2013.

  1. zulfi100

    Thread Starter Member

    Jun 7, 2012
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    Hi,
    Can some body plz guide me with the following question:
    I dont know whether i have to use a foprmula to solve this question or its just a fixed value which i have to remember. I have found some values in the following link:
    http://www.interfacebus.com/Logic_Family_Noise_Margin.html

    but it doesnt say about series or parallel.

    Kindly guide me.

    Zulfi.
     
  2. WBahn

    Moderator

    Mar 31, 2012
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    The HI level noise margin is basically the difference between the lowest HI value that an output is guaranteed to produce and the lowest HI value that an input is guaranteed to recognize.
     
  3. zulfi100

    Thread Starter Member

    Jun 7, 2012
    320
    0
    Hi,
    Thanks for your reply. Using the values on the site:
    Noise Margine High=4.9-3.985=0.915v
    Plz reply me.

    Zulfi.
     
  4. WBahn

    Moderator

    Mar 31, 2012
    17,748
    4,796
    Plz reply you what?

    I don't know where you are getting those numbers from. It isn't from the table on the page you linked to.

    That page tells you exactly how to calculate the noise margin and tabulates the results for many different families. What, exactly, are you asking about that is not clear from that page?
     
  5. zulfi100

    Thread Starter Member

    Jun 7, 2012
    320
    0
    Hi,
    Sorry for not clarifying you.
    My question is:
    This is the question. I dont have any other data other than CMOS 5v series circuit. Is it possible to calculatye high level noise margin?

    From the site i got following for CMOS 5v:
    Based upon your definition
    I calculated noise margin by subtracting VOH & VIH i.e (4.9-3.85)
    Thanks for your interest in my problem.

    Zulfi.
     
    Last edited: Apr 2, 2013
  6. WBahn

    Moderator

    Mar 31, 2012
    17,748
    4,796
    But look at your post #3:

    That you got a value different from the 1050mV given in that same table should have set off warning bells.

    But it's clear you understand the concept, which is what is important.
     
  7. zulfi100

    Thread Starter Member

    Jun 7, 2012
    320
    0
    Okay thanks for your response.

    Zulfi.
     
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