Question

Why are the Op-amps with open loop configuration not used in linear applications?
A. High risk of distortion
B. High risk of clipping of output
C. Both a & b
D. Works as an attenuator

Answer 1

Hint: In open loop configuration of the operational amplifier, no feedback is given to the input of Op-amp from the output. The Op-amp in open loop configuration works as a very high gain amplifier. When the output voltage exceeds the saturation level of Op-amp, the clipping of the output waveform occurs.

Complete answer:
Let us understand the open loop configuration of Op-amp.We know that in closed loop configuration of the operational amplifier, some fraction of the output is fed to the input which is known as feedback. In open loop configuration of the operational amplifier, no feedback is given to the input of Op-amp from the output. When we connect the Op-amp in open loop configuration, it works as a very high gain amplifier.

The following figure shows the open loop configuration of the Op-amp of an inverting amplifier.

In the above figure, is the input resistance and is the load resistance.
There are limitations of the open loop configuration of Op-amp. When the output voltage exceeds the saturation level of Op-amp, the clipping of the output waveform occurs. This usually happens due to high gain of the operational amplifier. Due to the high gain of the open loop configuration of the Op-amp, the distortion occurs at high frequency. For the above stated limitations, the open loop configuration of the Op-amp is not used in linear circuits. Therefore, both options A and B are true.

So, the correct answer is option C.

Note:Open loop configuration of Op-amp cannot be used in linear circuits but it is used in non-linear circuits such as comparators, square wave generators and astable multivibrators. The open loop configuration of the Op-amp does not work as a frequency attenuator.