Simulating CMRR of an opamp.........?

[malli_1729]

Hi!

i am in the process of learning about opamps...in that i want simulate and see CMRR so, that i will get some interpretation of this parameter..theoritically i know what it is..i need to see practically...

i took TINA from TI as a simulator. i took OPA130 as the opamp for which min CMRR = 90dB.
so, i want to see this practically by simulating....
thing is i don't know how to proceed to this...i mean to how to simulate it...

anybodies help will be very grateful to me....

 

[narenderbalguri]

you know what is cmrr then just find the common mode gain and differential gain by applying some input signal.....

CMRR=it is the ratio of above two gains.

 

[malli_1729]

Hi!

thank you..very nice of you ...it really helped.

i have used TINA from TI and OPA130 opamp. which has 90dB min CMRR from datasheet.

i just connected 2 sources to 2 inputs checked gain for common and differential mode configurations and calculated CMRR it is coming around 110dB.....

i am just attaching the circuit for others reference......
thank you very much again.... i will come back if any issues comes.....
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for ex if CMRR = 90dB as in this case 10^ 4.5 = 31623(approx) what it means is opamp can differentiate 10uV when around 10uV * 31623 = 3.623V common signal is added to the inputs ...
i think it is correct...is it OK...