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Class D Switching Power Amplifiers and Power D/A conversion

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Old 10th March 2008, 06:40 AM   #1
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Default ClassA, how does it work?

http://www.google.com/patents?id=tUu...udio+amplifier

How does it work? Why the example use only +/-14V, and the selfoscilating frequency only 100khz?

Won't work for +/-50V at 400khz?
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Old 10th March 2008, 12:49 PM   #2
TheMG is offline TheMG  Canada
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All it is is a Class D amplifier driving a Class A amplifier output stage. Doesn't make any practical sense, since you're losing nearly all the benefits of the high efficiency of Class D and end up with a VERY inefficient amplifier.
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Old 10th March 2008, 01:37 PM   #3
fredos is offline fredos  Canada
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I think that MG didnt read carefully...The class d just lift the low voltage psu of the class a amplifier to provide high voltage output swing. Since it lift the power supply form the middle point, no power supply perturbation will affect the class A stage. Funny that this is very close to the labgruppen patent...
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Old 10th March 2008, 03:56 PM   #4
Pafi is offline Pafi  Hungary
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I'm almost sure I have seen the first figure (I mean: an equivalent schematic) earlier than 2006. I don't think this is an invention. It's sooo trivial!
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Old 10th March 2008, 04:39 PM   #5
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Peter Walker back in the 1970s spoke about the possibility of a Quad405-like current dumping arcitecture but using a class-D amp as the beefy 'current dumping' source.
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Old 10th March 2008, 08:33 PM   #6
Tim__x is offline Tim__x  Canada
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Current dumping is a different concept.
This is class-H/tracking supplies, it's not all that unique, it's not new, and it's not that great of an idea.
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Old 11th March 2008, 10:33 AM   #7
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I can only guess, this schottky+1000uF is a clever way to make use of the residual of IRAUDAMP system. IRAUDAMP use pre-filter feedback point.
Fredos, I think it is a bit different than labgruppen patent, since the sources of final mosfets are only connected to schottky+cap bank floating supply. I also don't know how can we adjust the margin (VDS) of this scheme. Maybe adjusting the cap value?
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