1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Differential OP AMP Circuit Question

  1. Nov 5, 2014 #1
    1. The problem statement, all variables and given/known data
    Find Vin/Vout

    2. Relevant equations
    Vout = Rf/R1(Vb-Va) ???

    3. The attempt at a solution
    I think the answer is the first one.

    Answer choices:
    Vin/Vout = -2, Rin = 100

    Vin/Vout = -2, Rin = 200

    Vin/Vout = -2.5, Rin = 100

    Vin/Vout = -2.5, Rin = 200

    Vin/Vout = -3, Rin = 100

    Vin/Vout = 2, Rin = 100

    Vin/Vout = 2, Rin = 200

    Vin/Vout = 2.5, Rin = 100

    Vin/Vout = 2.5, Rin = 200

    None of the above
     

    Attached Files:

  2. jcsd
  3. Nov 5, 2014 #2

    gneill

    User Avatar

    Staff: Mentor

    Can you show us how you arrived at your conclusion? We won't confirm a guess...
     
  4. Nov 5, 2014 #3

    NascentOxygen

    User Avatar

    Staff: Mentor

    Hi joey5981. http://img96.imageshack.us/img96/5725/red5e5etimes5e5e45e5e25.gif [Broken]

    So you believe the 300 ohms resistor (and its 100 ohm companion) do nothing here? How can you prove this?

    The gain was given as this? Or did you mis-type what the book showed as Vout/Vin?
     
    Last edited by a moderator: May 7, 2017
  5. Nov 5, 2014 #4

    rude man

    User Avatar
    Homework Helper
    Gold Member

    Due to the unequal 200 and 300 ohm resistors this is not a differential amplifier in the accepted sense. In other words, it has a huge common-mode gain.

    If you accidentally labeled the 300 ohm resistors so it should have been 200 ohms, then you should come up with a computation as gneill asks for.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Differential OP AMP Circuit Question
  1. Op-Amp Circuit ANalysis (Replies: 16)

Loading...