Non inverting amplifier realized with op-amp is given in figure bellow.

**Simulate** Op-amp non inverting amplifier.

Input impedance is very high, since the overall input impedance of a closed-loop non inverting amplifier configuration is:

In here, **A _{OP-AMP}** is open loop gain of operational amplifier that is very high (usually higher then 10

^{6}),

**Î²**is feedback gain, and

**Z**is input impedance of op-amp that is also very high. Output voltage is in phase with input voltage. Since voltage amplification of operational amplifier is very high, inputs in operational amplifier can be treated as if there are on the same electrical potential, i.e. V

_{OP-AMP}_{+}=V

_{–}

Voltage gain can be calculated in two ways:

- By combining superposition theorem and node potential of input and output terminal.

Potential of inverting input can be calculated as voltage divider from output voltage:

On the other hand, due to V_{+}=V_{–}

Voltage gain is

- By equaling currents.

Since currents that flow from/to operational amplifier input can be neglected, current through **R _{2}** is equal to current through

**R**. Then, again

_{1}**V**, so

_{+}=V_{–}Final result for voltage gain is the same:

Go to op-amp non inverting amplifier simulation.

**External links:**

Non Inverting Op-amp Amplifier on All about circuits

Non Inverting Op-amp Amplifier on electronics-tutorials

Non Inverting Op-amp Amplifier on Hyperphysics

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