Input offset voltage

Discussion in 'Analog & Mixed-Signal Design' started by hp1729, Aug 16, 2016.

  1. hp1729

    Thread Starter Well-Known Member

    Nov 23, 2015
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    Let's say we have a non-inverting op amp circuit with a gain of 100 and an input offset voltage of 5 mV. A ground at the input would result in an output of 5 mV x 100 or 500 mV. Is that right?
    An input pulse 1 mV high would still result in an increase at the output of 100 mV, right?
     
  2. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Depending on the polarity of the offset the output could be +500mV or -500mV.
    Right.
     
  3. #12

    Expert

    Nov 30, 2010
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    Now, try it as a comparator running with the gain at open loop.
    Set the input offset voltage at + 5 mv for the first test and - 5 mv for the second test.

    Then try some scenarios for different input bias current, input bias current offset, input resistors, different noise levels, and different frequencies.
     
  4. crutschow

    Expert

    Mar 14, 2008
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    Just to be clear to the OP, the offset polarity and magnitude for a particular op amp device is generally random with a voltage limit as given in the data sheet.
     
  5. hp1729

    Thread Starter Well-Known Member

    Nov 23, 2015
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    True. I can see your point on a voltage comparator.
     
  6. ramancini8

    Member

    Jul 18, 2012
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    hp1729---What happens if the gain is 1000 on a 5V supply?
     
  7. hp1729

    Thread Starter Well-Known Member

    Nov 23, 2015
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    Good point there.
     
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