Applications of Operational amplifier

Operational Amplifier, high gain differential amplifier, used to perform the operations like addition, subraction, integration, differentiation and amplifies AC as well as AC. It is versatile device. The circuit schematic of op-amp is a triangle.

It has two input terminals and one output terminal with negative sign called inverting input terminal. The terminal with positive sign called the non-inverting input terminal.

operational amplifier

Open-loop op-amp configurations

The term open-loop indicates in any form, given to the input from the output. When connected in open-loop, the op-amps functions as a very high gain amplifier. There are three open-loop configurations of a op-amp:

  1. Differential amplifier
  2. Inverting amplifier
  3. Non-inverting amplifier

Open loop differential amplifier

In this configuration, the inputs applied to the inverting and non inverting input terminals of the op-amp and the device amplifies the difference between the input voltages.

The input voltages are diagrammatically by Vin1 and Vin2. The source resistance are negligible and high input resistance of the op-amp.tge voltage drop across these source resistance are trimmed to zero.


Where A is large signal voltage gain.

Inverting amplifier

In this configuration, the input signal applied to the inverting input terminal of the op-amp and the non inverting input terminal connected to the ground.

The output voltage is 180 degree out of phase w.r.t input. Hence, the output voltage Vo given by Vo=-AVin

Non-inverting amplifier

The open-loop non inverting amplifier. The input signal applied to the non-inverting input terminal of the op-amp. And the input terminal connected to the ground.

The signal is amplified by the open gain A and therefore the output is in section with signal.



  1. Clipping of the output wave form occurs when output voltage exceeds the saturation levels.
  2. Because of very high open loop gain of the op-amp and due to this fact only the smaller signals having very low frequency can be amplified accurately without distortion.
  3. The information measure of most open-loop op amps is negligibly little.

Closed-loop op-amp configuration

The op-amp can be effectively utilized in linear applications from output to input either directly or indirectly.

If the signal fed back out of phase by 180degrees with respect to input, then op-amp that uses feedback called as a closed loop amplifier.

  1. Inverting amplifier
  2. Non-inverting amplifier

Inverting amplifier

Inverting electronic equipment a similar inverting electronic equipment redrawn in several methods thus on illustrate however voltage shunt feedback provided. The input signal drives the inverting input of the op-amp through resistors.

Non-inverting amplifier

The non-inverting amplifier with negative feedback of the input drives the non-inverting input at the operational amplifier.

The op-amp provides an internal gain. The external resistors RL and Rf from the voltage divider circuit.

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