Offset autozeroing in cascaded two stage operational amplifiers

[Junus2012]

Hello

For the reason to extend the amplifier bandwidth at high cloased loop gain, I have cascaded two op-amps (regular non-inverting ampliifer).

In case of offset voltage correction, do I need offset correction for each amplifier individually, or one offset correction scheme should be enough from the output of the first amplifier to the input of the first amplifier stage.

Thank you

Regards

 

[Dominik Przyborowski]

If they are dc coupled then you can consider both cases (as they has pros and cons).
For example, in multistage limiting amplifiers dc offset is cancelled by low bandwidth loop covering all stages.

 

[sutapanaki]

I would say, it depends. If you care about the input referred offset, than correcting the first amplifier and not the second is probably ok. However, if the offset of the second amplifier is high and causes saturation of its output, then this will break the circuit and you will have to also correct for that one.