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How to plot CMRR for an op-amp?

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chinito

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about CMRR of an op-amp

I have designed opamp with Av ~ 80dB, PSRR+ = 87dB etc. I don't know how to plot CMRR. Could someone explain the setup. Thanks.
 

Re: about CMRR of an op-amp

Pls refer the book of CMOS Analog Circuit Design by Allen. with an amplifier with unity-gain form, you could get the CMRR.
 
Re: about CMRR of an op-amp


This will help I think
If I have helped you..could you please click the helped me button and help me.
thank you
:-D
 
Re: about CMRR of an op-amp

short the inputs and apply an ac source at 1V then see the output. it gives the common mode gain.Avcm

CMRR=Av/Avcm
 

Re: about CMRR of an op-amp

I don't know how to plot CMRR
Click to expand...

When you say "plot", you refer to plot the signal with a simulation program (like PSpice)....

Or just want parameters to "calculate" the Avcm by yourself, so to do the formula: CMRR=Avd/Avcm


Regards.
 

Re: about CMRR of an op-amp

Read Design of Analog Integrated Circuits by
Paul R Gray and Rober Mayor.

Analog IC Design by Allan and Holberg also
helps.
 
Re: about CMRR of an op-amp

Acmrr=Avd/Acm
All books on integrated circuit has talked about it.
Please refer to one text.
 
about CMRR of an op-amp

Can anyone tell me how to get CMRR, PSRR from xf analysis in cadence?

thanks in advance!
 

Re: about CMRR of an op-amp

just short the inputs and perform ac analysis.you get common mode gai at the output.subtract this common mode gain with Ad.you get cmrr.don't forget you short the input with proper input offset voltage apllied at -ve input
 

Re: about CMRR of an op-amp

Construct your opamp as a unity gain buffer and you can easily get the CMRR simulation result. Check P. Allen's book
 

Re: about CMRR of an op-amp

Hi,

You just connect both the terminals of OP-AMP and connect the AC voltage source of 1Vp-p, do the AC analysis.

It will give you the CMRR.

Rahul
 

Re: about CMRR of an op-amp

Check the book: Op Amps for everyone
 

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