Quote:
Originally posted by forr
[B]Having received so little returns about the subject of Common Mode Feedback puzzles me. I wonder if the concept is not that much known or if there is some kind of drawback when if used inside an amplifying circuit (someone should have told us).
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Hi forr
I once had the same question as I was doodling circuits one day with a pencil and eraser, but there was no interest in the idea here. So I slapped together a mock up circuit, and actually was surprised to see that it did work and quite well considering the simple miller feedback and compensation used. Way out-performs the CCS loaded single VAS type circuit I played with before, with the same output stage. DC bias is very stable and it has been working for months, both channels so it's not just a fluke, spread out on a small table.  Now I am less doubtful. I too am kinda puzzled at the lack of interest on this in the forum. As for the CMFF...interesting. I will have to digest it a while. Thanks for the links. 
BTW, I am going to use the THAT340 descrete quad BJT IC in my next design.
http://www.thatcorp.com/datashts/300data.pdf
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All the trouble I've ever been in started out as fun......
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2nd June 2007, 01:37 AM
Now I am less doubtful. I too am kinda puzzled at the lack of interest on this in the forum. As for the CMFF...interesting. I will have to digest it a while. Thanks for the links.
