Instrumentation Amplifier

Discussion in 'Homework Help' started by ac_dc_1, Jan 27, 2013.

  1. ac_dc_1

    Thread Starter Member

    Jan 27, 2013
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    0
    Hi.

    I have this instrumentation amplifier and i am trying to prove that every expressions(written in blue in the circuit),in order to understan it better...So far i have only managed to prove two of them...Is there anybody who can give a little help on this?

    Thanks
     
  2. WBahn

    Moderator

    Mar 31, 2012
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    4,795
    Which two?

    You need to show what you've done so that we can go off of that and either point out where you are making a mistake or offer a hint on how to get a little further.
     
  3. ac_dc_1

    Thread Starter Member

    Jan 27, 2013
    74
    0
    I have assumed that there is a differential voltage vid between the output of the two amplifiers and therefore its easy to prove that the current in the feedback resistors is vid/2R1 and vid/2R2..but can not prove the rest...
    The circuit is made by two non-inverting amplifiers and by a subtractor montage right?

    Thanks
     
  4. WBahn

    Moderator

    Mar 31, 2012
    17,743
    4,795
    If you are assuming that vid is the voltage difference between the output of the two amps, then why are the currents in the feedback resistors vid/2R1 and vid/2R2.

    SHOW YOUR WORK!!!

    Since R1 and R2 may be different values, you are claiming that the currents in the two feeback resistors may be different. If that is the case, then where does the difference current go?
     
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