Understanding Common Mode Rejection Ratio (CMRR) in Op-Amps

[lkari]

So if we have a Opamp component, do we have to give the input as sine wave or as a dc supply? I think it has to be at a DC voltage. please correct me.
Thanks in Advance
Lakshmi

 

[Topher925]

Most opamps will amplify a sinusoidal or dc signal.

 

[lkari]

So I can get a constant OUTPUT DC current with this opamp rt?

 

[lkari]

Reading a datasheet

Hi I need to understand few things about the Datasheet. I want to know what the input voltages for the pins vIN+ and VIN-could be. Please find teh enclosed datasheet for reference. I need it very urgently for a project.
Thank you in advance
Kari

 

[uart]

Look at the item marked "common mode voltage range" in the datasheet.

 

[lkari]

I reffered to it but, what do they mean by saying the following there? (V+) –3

 

[berkeman]

(I merged the two related threads into one -- both were about the opamp datasheet)

 

[Redbelly98]

So if we have a Opamp component, do we have to give the input as sine wave or as a dc supply? I think it has to be at a DC voltage. please correct me.
Thanks in Advance
Lakshmi

If you mean V+ or V-, those should be DC voltage supplies.

If you mean V⁺_IN and V^-_IN, it could be either AC or DC ... depends on the application.

(Refering to figure on p. 1 of the datasheet:
https://www.physicsforums.com/attachment.php?attachmentid=17873&d=1236355902 )

 

[lkari]

i really don't understand why they are on the same subject. one is about the circuit the other is about reading the data sheet for the component.

<< post edited by berkeman to clean up txt speak >>

 

[Proton Soup]

I reffered to it but, what do they mean by saying the following there? (V+) –3

ideally, you want an op-amp to amplify only the difference between Vin+ and Vin-, not to amplify the average of Vin+ and Vin-. the higher the common mode rejection ratio, the closer you are to this ideal. to get the best rated performance for this op-amp, keep the inputs between (V-) - 0.1, and (V+) -3V.