Operational Amplifier: Op-Amp as Differential Amplifier or Op-Amp as subtractor (With Examples)

In this video, how to use the op-amp as the differential amplifier (Difference amplifier) or as subtractor has been discussed with solved examples.

Op-amp as Differential Amplifier:
The differential amplifier is the op-amp configuration in which the difference between the inputs is amplified by some gain factor.
An Op-amp itself is a differential amplifier in open loop configuration but it has very high open loop gain. So, we can not use the opamp as the differential amplifier in the true sense in the open-loop configuration. And we require some sort of feedback to use this op-amp as a differential amplifier in the true sense.

Application of Op-Amp as differential Amplifier:

Apart from performing the mathematical functions, this differential amplifier configuration is used along with sensors. (e.g RTD)
The only disadvantage of this differential amplifier is that its input impedance is relatively low and depends on the series resistance used with the inputs. And in some case, it might affect the source voltage because of the loading effect.

The loading effect of the source can be avoided by using the buffer before applying the input voltages. And this method can be used for general purpose applications. For more sophisticated applications with sensors, instrumentation amplifier is used instead of the differential amplifier.

The timestamps for the different topics covered in the video is given below:

1:00 Op-amp as Differential Amplifier
6:30 Application of Differential Amplifier
9:35 Example 1
11:30 Example 2 (Effect of Biasing Voltages on output)
13:31 Example 3 (For practice )

This video will be helpful to all students of science and engineering in understanding how to use an op-amp as the differential amplifier.

The link to the related videos on the op-amp:

Introduction to Operational Amplifier:
   • Introduction to Operational Amplifier: Cha...  

Inverting Op-Amp:
   • Operational Amplifier: Inverting Op Amp an...  

Non-Inverting Op-Amp:
   • Operational Amplifier: Non-Inverting Op-Am...  

This video will be helpful to all the students of science and engineering in understanding the inverting and non-inverting summing amplifier.


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