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OPAMP

sudeep e
Intellectual 525 points


HI,

i have an inverting amplifier shown below

if the R3 is shorted, is it correct that the gain of the opamp becomes infinite, and the voltage will saturate...

is it my understanding is correct

  • 0
    TI__Intellectual 1095 points

    Hi Sudeep,

    your assumption is right, the output will saturate.
    In this configuration you are forcing the inverting terminal to ground. However, a short at R3 causes that the negative terminal is set at the level of your source. Consequently the difference of V+ and V- will be amplified by an infinite gain. A real opamp has a finite open loop gain and you will see a voltage close to your supply depending on the voltage swing of the opamp.
    A way to avoid saturation is to source the non-inverting terminal. When R3 is shorted you'll have a buffer configuration with an infinite high resistance to ground and consequently the output voltage follows the input voltage with a gain of 1.

    Best,
    Miriam