Common-mode signal - Electronic Circuits Projects Diagrams Free

alphacat · 30th October 2009, 10:14 AM

Hello.

I though that a common mode signal is an unwanted signal that adds directly to both input signals, and therefore will be eliminated when the differential amplifier processes the difference of the input signals.

So why is it said that the common mode signal is the half-sum of the input voltages?
Vcm = ½(V1 + V2)

Thanks.

ericgibbs · 30th October 2009, 10:24 AM

Quote:

Originally Posted by alphacat

Hello.

I though that a common mode signal is an unwanted signal that adds directly to both input signals, and therefore will be eliminated when the differential amplifier processes the difference of the input signals.

So why is it said that the common mode signal is the half-sum of the input voltages?
Vcm = ½(V1 + V2)

Thanks.

hi,
This explains it.
The Art of Electronics Design : The Differential Amplifier Common-Mode Error ? Part 2

alphacat · 30th October 2009, 11:04 AM

Thank you very much!

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30th October 2009, 10:14 AM	#1
alphacat	Common-mode signal Hello. I though that a common mode signal is an unwanted signal that adds directly to both input signals, and therefore will be eliminated when the differential amplifier processes the difference of the input signals. So why is it said that the common mode signal is the half-sum of the input voltages? Vcm = ½(V1 + V2) Thanks.