Self Oscillating Class D
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 Class D Switching Power Amplifiers and Power D/A conversion

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jony
diyAudio Member

Join Date: Jun 2004
Location: wroclaw
Self Oscillating Class D

Here is the simplified schema of a self-oscillating class D amplifier.

Can anyone explain it to me how this circuit work.
Maybe some intuitive approach help me understand this circuit.

PS I attach "full" circuit
Attached Images
 78_1232569987.png (27.8 KB, 1250 views)

 17th February 2009, 03:33 AM #2 itsmrdavid   diyAudio Member   Join Date: Sep 2005 That looks interesting enough to try on a bread-board... Here's my take on your question: take a look at the theory for a "buck converter" power supply circuit... It's a pretty simple thing. Hysteretic control style has a coil, just like this circuit. I was looking at buck converter designs a while back, and thought to myself: "what if I modulated the control for the output voltage?" I think that's pretty much what's happening here. The only trouble - audio wise - is when you load the output, the oscillation frequency changes, and it probably changes gain, etc... ~David
 18th February 2009, 02:56 PM #3 hreith   diyAudio Member     Join Date: Jun 2004 Location: Heidelberg It's a SODA from Bruno Putzeys.
 18th February 2009, 08:53 PM #4 tiki   diyAudio Member     Join Date: Feb 2004 Location: Dresden Hallo Hubert, immer schön am Ball bleiben! Beste Grüße, Timo __________________ tiki
 19th February 2009, 03:13 AM #5 Eva   diyAudio Member     Join Date: Oct 2003 Location: Near the sea It looks like a mix of hysteresis and phase shift oscillator. Read this paper, it gives a brief explanation of both approaches: http://www.ciaudio.com/ucd_aes.pdf __________________ I use to feel like the small child in The Emperor's New Clothes tale
 23rd February 2009, 09:56 AM #6 GGEC   diyAudio Member   Join Date: Jun 2007 I want to see something PDF file. "An Asynchronous switching High-end Power Amplifier" Presented at the 112th AES Convention Preprint 5503. "A Novel Audio Power Amplifier Topology with High Efficiency and State of the Art Performance" Presented at the 109th AES Convention Preprint 5197. My E-mail: hrz709@163.com Thank you!
 23rd February 2009, 10:03 AM #7 Ouroboros   diyAudio Member     Join Date: Dec 2003 Location: Nottingham UK I've just emailed you a copy of the first document. (It's the Mueta paper).
jony
diyAudio Member

Join Date: Jun 2004
Location: wroclaw
Thanks for help
Now I "understudy" that this circuit work as a simple opamp oscillator

"A Novel Audio Power Amplifier Topology with High Efficiency and State of the Art Performance"
http://www.icepower.bang-olufsen.com...ntion/5197.pdf
Attached Images
 97_1233105218.png (13.3 KB, 642 views)

 23rd February 2009, 01:33 PM #9 scott wurcer   diyAudio Member     Join Date: Jan 2004 Location: dorchester ma Google SOPA or self oscillating power amplifier. There's a group of industry/university folks in Europe that have been trying for years to convert ADSL over to a CMOS SOPA architecture. They have lots of good theoretical papers dating back 8-9 years. The best was a differential one with lots of harmonic cancellation (almost magical). __________________ "The question of who is right and who is wrong has seemed to me always too small to be worth a moment's thought, while the question of what is right and what is wrong has seemed all-important."
 24th February 2009, 12:44 AM #10 GGEC   diyAudio Member   Join Date: Jun 2007 Thank you Ouroboros & jony!

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