Operational Amplifier: Inverting Op Amp and The Concept of Virtual Ground in Op Amp
In this video, the inverting Op-Amp configuration and the concept of virtual ground in Op-Amp has been discussed.
Why do we require feedback in Op-Amp?
Op-Amp is a very high gain differential amplifier. So, in open loop configuration, even a small differential input (in micro volts) is applied between the two terminal of the Op-amp, then also the output will be get saturated. And we can not use it as an amplifier.
Because in the amplifier the relation between and the output is linear.
So, to control the gain of the op-amp and to use it as an amplifier, negative feedback is required in op-amp.
Inverting Op-Amp configuration:
In this configuration, the input is applied at the inverting end of the opamp and the output voltage is 180 degrees out of phase with the input. that is why it is known as the Inverting Op amp configuration.
What is virtual Ground (Virtual Short)?
This concept is applicable during the negative feedback only.
Because of a very high gain of Op-amp, the differential input voltage signal used to be very small and almost negligible.
So, the voltage difference between the inverting and non-inverting input terminal will be approximately equal to zero.
Or we can say that both the terminals are at the same potential.
It means that there is virtual short between the two terminals.
So, if one terminal is at ground potential then another terminal will appear to be at ground potential, (Although physically it is not grounded).
This concept is known as the virtual Ground Concept.
Time stamps for the different topics covered in the video:
0:34 Why do we need the feedback in Op-Amp (Negative Feedback)
3:08 Inverting Op-Amp configuration
3:47 Concept of Virtual Ground in Op-Amp (What is virtual Short)
6:38 Derivation of Inverting Op-Amp Configuration
Why do we require feedback in Op-Amp?
Op-Amp is a very high gain differential amplifier. So, in open loop configuration, even a small differential input (in micro volts) is applied between the two terminal of the Op-amp, then also the output will be get saturated. And we can not use it as an amplifier.
Because in the amplifier the relation between and the output is linear.
So, to control the gain of the op-amp and to use it as an amplifier, negative feedback is required in op-amp.
Inverting Op-Amp configuration:
In this configuration, the input is applied at the inverting end of the opamp and the output voltage is 180 degrees out of phase with the input. that is why it is known as the Inverting Op amp configuration.
What is virtual Ground (Virtual Short)?
This concept is applicable during the negative feedback only.
Because of a very high gain of Op-amp, the differential input voltage signal used to be very small and almost negligible.
So, the voltage difference between the inverting and non-inverting input terminal will be approximately equal to zero.
Or we can say that both the terminals are at the same potential.
It means that there is virtual short between the two terminals.
So, if one terminal is at ground potential then another terminal will appear to be at ground potential, (Although physically it is not grounded).
This concept is known as the virtual Ground Concept.
Time stamps for the different topics covered in the video:
0:34 Why do we need the feedback in Op-Amp (Negative Feedback)
3:08 Inverting Op-Amp configuration
3:47 Concept of Virtual Ground in Op-Amp (What is virtual Short)
6:38 Derivation of Inverting Op-Amp Configuration
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