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How to define DC Gain of Operational Amplifier or OTA ?

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girih192002

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Hi,

I have very basic question in mind. How do we decide DC Gain of OPAMP or OTA irrespective of application ? Does it decide on basis of settling error voltage or it has some other relation.

If you have any good and basic refernce for it. then, please share it.
 

How to define DC Gain
How do we decide DC Gain

What do you mean?
Are you going to design an amplifier?
Or do you ask for measurement techniques?
 

File:Operational_amplifier_noninverting.svg


DC gain is determined by feedback ratio Rf/Rin for inverting and for non-inverting input DC gain = { 1+ Rf/Rin }ratio

Details
https://en.wikipedia.org/wiki/Operational_amplifier
 

Hi LvW,

My question is What are factor we consider while deciding Gain as specifications ? Does Settling Error has relation with it ? then how ?

- - - Updated - - -

Hi LvW,

My question is What are factor we consider while deciding Gain as specifications ? Does Settling Error has relation with it ? then how ?

- - - Updated - - -

Hi LvW,

My question is What are factor we consider while deciding Gain as specifications ? Does Settling Error has relation with it ? then how ?
 

The desired gain is determined by the application. For example if you have a 0-100mV peak signal from a sensor that you want to expand to the 0-5V range of an A/D converter than you need a gain of 5/0.1 = 50.

The settling time can be affected by the gain. You have to look at the gain-bandwidth and settling time specs for the particular op amp you are using to determine what that is.

Edit: Deleted double post.
 
Last edited:

You have already answered your own question.
The main consideration is the error that you will see at the output when non-ideal circuits are used.
This error has various components
1. Input common-mode variation
2. Input-referred offset
3. Gain error, which is derived from feedback network accuracy and opamp open loop gain
 

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