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Virtual Short in Op-amps

Ankit Sahay
Prodigy 100 points

Can anyone explain how virtual short of the two input terminals of op-amp works?

We say that the voltage at two terminals are assumed to be the same, ie V1=V2 and then that output is A(V2-V1).

If V1=V2, then how do we get any gain at all?

  • 0
    TI__Guru 64895 points

    Hello Ankit,

    We explain negative feedback, loop-gain, and closed loop gain in both the bandwidth and stability videos of the TI Precision Labs videos (links below). 

    Basically the resistive feedback network in a non-inverting or inverting amplifier forms a voltage divider from the output to the inverting input.  The voltage divider results in an attenuation (β) of the output voltage at the inverting input. The output must therefore equal a voltage higher than the input voltage by the inverse of the attenuation (1/β).  This is how the feedback network forms a controlled closed-loop gain.   

  • 0
    Prodigy 10 points
    This is very easy . We want gain to be high ,as gain=Vout/V1-V2. Therefore for gain to be infinite V1=V2=0.