Non Inverting Operational Amplifier | Non Inverting Op AmpPublished on 24/2/2012 and last updated on 5/9/2018
Let us explain the thing by constructing the op amp circuit with the feedback loop as shown below, Here, in the above circuit, we connect an external resistance R1 and feedback resistance Rf at inverting input. Now, by applying Kirchhoff Current Law, we get, Let us assume the input voltage applied to the non inverting terminal is vi.
The closed loop gain of the circuit is, This term does not contain any negative part. Hence, it proves that the input signal to the circuit gets amplified without changing its polarity at the output.
From the expression of voltage gain of an non inverting op amp, it is clear that, the gain will be unity when Rf = 0 or R1 → ∝. So, if we short circuit the feedback path and/or open the external resistance of the inverting pin, the gain of the circuit becomes 1.