Differential amplifier with op-amps

[eem2am]

Hello,

A differential amplifier using op-amps cancels out common mode noise which appears at its inputs.

However, does a differential mode amplfier actually AMPLIFY differential mode noise appearing at its inputs ?

If so, how do you deal with both types of noise with op-amp amplifiers ?

 

[FvM]

It not clear to me, if you are talking about common mode signal rejection of a differential amplifier or amplifier noise?

 

[Kral]

eem2am,
A differential amplifier does amplify differential mode noise appearing on its inputs. If you know the nature of the noise, you can somewtimes filter it at the amplifier output. However, if the amplitude of the differential input noise is large, the amplifier may saturate, and filtering the output will not be effective. It is possible to filter each of the differential inputs, however, you run the risk of converting common mode noise to differential noise if the filters are not exactly matched. Also, if the noise is pseudo-random, it is very difficult to design an effective filter.
Regards,
Kral

 

[xulfee]

it just take difference of voltages at both ends,n multiply it with its gainin factor