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A voltage divider in terms of a conductance

  1. Jun 29, 2009 #1
    I am looking at the following application note that goes into nodal analysis of op amps: http://www.maxim-ic.com/appnotes.cfm/an_pk/1939/ and down at the bottom where they're analyzing the Wien bridge oscillator the equation at the negative input of the op-amp taken from the output in terms of conductance is Gf/(Gi+Gf). I'm not sure how they got that - if expressed in terms of resistances that voltage divider is Ri/(Rf+Ri). How does one change the equation for a voltage divider in terms of resistance to terms of conductance?
  2. jcsd
  3. Jun 29, 2009 #2

    The Electrician

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    Gold Member

    In this expression, Ri/(Rf+Ri), substitute:

    1/Gf for Rf
    1/Gi for Ri

    then simplify and you should get the voltage divider formula in terms of conductance.
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