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Design >> Analog Design >> Chopper amplifier with ripple suppression feedback
https://designers-guide.org/forum/YaBB.pl?num=1341930243

Message started by tzg6sa on Jul 10^th, 2012, 7:24am

Title: Chopper amplifier with ripple suppression feedback
Post by tzg6sa on Jul 10^th, 2012, 7:24am

Hi Guys,

I've just wondered about the attached architecture what I found in a paper. It looks so much simpler for me to connect the input of the feedback loop - input of Gm3 - before CHOP2, since the reason to have CHOP3 is to modulate the ripple down to DC and modulate the signal up for easier removal.
It uses one chopper more and Gm3's bandwidth must be higher than the chopper clock.

So the question is why is the attached architecture superior?

The paper was: Auto Correction Feedback for Ripple Suppression in a Chopper Amplifier by Y. Kusuda, JSSC Aug. 2010

Title: Re: Chopper amplifier with ripple suppression feedback
Post by tzg6sa on Jul 27^th, 2012, 1:18am

Well, to be honest, I don't understand the feedback chopper topologies, because according to my understanding
-they does not ease the filter requirements
The feedback loop will reduce the upmodulated signal if it has bandwidth at that frequency. Therefore the same filter is needed in the feedback loop as in the classical scheme, since the signal/chopper frequency ratio is the same.
-they does not increase the amplifier bandwidth (like in the feedforward architectures)
Due to the mentioned reasons they don't make lower chopper frequencies possible compared to the classical scheme.

So I am puzzled here. I would like to understand what are the benefits of the feedback configurations. I would love to hear your opinion about it.