Operational Amplifier

Discussion in 'Homework Help' started by ds_164, Nov 8, 2004.

  1. ds_164

    Thread Starter New Member

    Nov 6, 2004
    Hi, I got the following problem for homework (attached), I solved it but wanted to double check the answer.

    Please give it a try. Thanks.

  2. vineethbs

    Well-Known Member

    Nov 14, 2004
    i think the noninverting input is A

    apply a + vol to A and B grnd

    as it is pnp the collector current prop to exp(vbe/vt) decreases say by dI
    I biasing so , current thru B inc by dI

    3A current source so current thru o/p trans of the second stage decreases by dI

    VB-Vbe=constant at emitter of the o/p transistor of the second trans
    so as current decreases Vce increases and o/p amp gain = +1 so o/p increases

    + at A => + at o/p
    so A is non inverting