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Op amp logarithmic & exponential amplifiers

  1. Mar 2, 2010 #1
    So I was playing around with logarithmic & exponential amplifiers in my lab class. I was looking at the following equations:
    http://upload.wikimedia.org/math/7/7/6/77663157d5b97ceb2e3edac5f587a620.png and
    http://upload.wikimedia.org/math/b/3/c/b3c569c85552561e41dec916f6e8ebe8.png

    Experimentally I found out that if I feed in 0V in both log. and exp. amplifiers I get 0V output.
    But according to the equations the log of zero is undefined and the power of any number is one, i.e. I should never get zero output voltage.
    I was wondering how to explain this observation, was it that my experiment was flawed or that real life op amps behave differently than those equations predict?
     
  2. jcsd
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