Arny Krueger wrote:
"Eeyore" wrote in
Arny Krueger wrote:
I notice that Self makes some heavy claims about a
proprietary implemention of class G.
I haven't heard that. I'd be curious to know how it can
be made proprietary !
http://www.dself.dsl.pipex.com/ampins/classg/g.htm
"Class-G is now out and about. So what has changed? This would be easier to
answer if there had been more published on the technology; as it is I have
to rely pretty much on my own research. I found that Schottky power diodes
have eliminated the commutation-diode glitching. Having peeled this skin
from the distortion onion, linearity was still signficantly poorer than a
Blameless Class-B design. This proved to be due to Early effect in the
output stage devices, stemming from the sudden changes in collector voltage
they experience in Class-G operation. I had my own ideas about how to deal
with this, and you can read all in Electronics World for Dec 2001 and Jan,
Feb 2002. There is a fully worked-out design, and even a PCB available to
ease building it."
The "Early Effect" amounts to being an increase in beta with increased VCE.
The happens in a class-G amp when the power supply voltage is switched to a
higher voltage.
I notice that his ideas on the matter can only apparently be read in the copies
of EW mentioned.
His does pontificate a heck of alot !
Graham