Different between the log circuits

Discussion in 'Homework Help' started by ali., Mar 16, 2012.

  1. ali.

    Thread Starter New Member

    Feb 23, 2012
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    0
    Hello Everyone,

    I’m looking for some help:

    What is the different between the log circuits using only diode with current source or using pomp with diode?
     
  2. crutschow

    Expert

    Mar 14, 2008
    12,991
    3,227
    The op amp converts input voltage to a current source of Vin/R through the diode and provides a low output impedance to drive a load. Otherwise the voltage versus diode current will be the same.
     
  3. ali.

    Thread Starter New Member

    Feb 23, 2012
    4
    0
    Thank crutschow for your quick reply so if the output of the log circuit connected to completer op amp there is no different between the 2 log circuits :)
     
    Last edited: Mar 16, 2012
  4. crutschow

    Expert

    Mar 14, 2008
    12,991
    3,227
    It's the same if you understand that the op amp circuit has a voltage input and the diode circuit has a current input. So the inputs are different but the outputs are the same (for the same equivalent diode current).
     
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