A complementary symmetry all-cascode power amplifier design with no overall feedback. Local error correction for the output stage which uses low-voltage high-current MOSFETs in a cascode configuration with power darlington bipolars. Simple signal path but with elaborate support circuitry for current sources, etc.
Question: Will the output stage be stable? I never built this design but am curious to know if it would work as planned. I am self-taught with no degree in EE, so please be gentle with comments. Thanks!
Notes:
1) The active current-source load for the input differential pairs was borrowed from a Burr-Brown linear op amp applications book, the purpose of which is to reduce DC drift in the front end and improve common-mode rejection.
2) The idea for the error-correction circuit in the output stage was borrowed from an article (circa 1976 IIRC) in the Journal of the Audio Engineering Society written by a British audio engineer (I can't remember his name) and was described as "feedforward" error correction.
Question: Will the output stage be stable? I never built this design but am curious to know if it would work as planned. I am self-taught with no degree in EE, so please be gentle with comments. Thanks!
Notes:
1) The active current-source load for the input differential pairs was borrowed from a Burr-Brown linear op amp applications book, the purpose of which is to reduce DC drift in the front end and improve common-mode rejection.
2) The idea for the error-correction circuit in the output stage was borrowed from an article (circa 1976 IIRC) in the Journal of the Audio Engineering Society written by a British audio engineer (I can't remember his name) and was described as "feedforward" error correction.
Malcolm Hawksford was his name.
He has written a few papers on error correction. The first one I saw is this one from 1980: https://www.semanticscholar.org/pap...b6b54ba291ea6936ec558080733cbeae#paper-header
This one you can download uses an approach that seems more popular: https://www.researchgate.net/profil...n-switching-power-amplifier-output-stages.pdf
There's been a long (and sometimes rowdy😀) discussion of the approach elsewhere on this site.
He has written a few papers on error correction. The first one I saw is this one from 1980: https://www.semanticscholar.org/pap...b6b54ba291ea6936ec558080733cbeae#paper-header
This one you can download uses an approach that seems more popular: https://www.researchgate.net/profil...n-switching-power-amplifier-output-stages.pdf
There's been a long (and sometimes rowdy😀) discussion of the approach elsewhere on this site.
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Hawksford error correction is also used by Bob Cordell in his famous 1984 amp design. Hawksford e.c. is feedback error correction.
Feedforward e.c. is for instance made famous by Giovanni Stochino.
Articles should be available online, or check the Linear Audio .nl website.
Jan
Feedforward e.c. is for instance made famous by Giovanni Stochino.
Articles should be available online, or check the Linear Audio .nl website.
Jan
I think one weekend I am going to run this on NI Electronic workbench and see what I would come up with. It is absolutely interesting design.