Confusion in connecting two op amps

Discussion in 'Homework Help' started by Rheegeaux, May 15, 2016.

  1. Rheegeaux

    Thread Starter New Member

    May 15, 2016
    Shouldn't v1 = -4 v since Vout1 of the first op amp is Vs(3+1) = 4 and Vout1 + V1 - VnOf2ndOpAmp = 0
    and shouldn't Vo = -16 V since it is an inverting amplifier? Am I missing something here?

    Thank you for your help :)
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  2. DGElder


    Apr 3, 2016
    "Shouldn't v1 = -4 v"

    Yes, the first "KVL" eq. has a sign error on V1. Perhaps because of a miss application of KVL as you do not have a closed continuous current loop with those elements. Anyway the KVL approach is overkill here. One of the advantages of op amps is their very high input impedances and low output impedances. So you can analyze the first amp in isolation from the second stage. So V1 and it's resistor and everything after it can be ignored to analyze the first stage. Then you do the second stage with the known Vo of the first stage.
    Last edited: May 15, 2016