Self Oscillating Class D

jony · 25th January 2009, 11:01 PM

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

itsmrdavid · 17th February 2009, 04:33 AM

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

hreith · 18th February 2009, 03:56 PM

It's a SODA from Bruno Putzeys.

tiki · 18th February 2009, 09:53 PM

Hallo Hubert,
immer schön am Ball bleiben!

Beste Grüße, Timo

Eva · 19th February 2009, 04:13 AM

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

GGEC · 23rd February 2009, 10:56 AM

"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!

Ouroboros · 23rd February 2009, 11:03 AM

I've just emailed you a copy of the first document. (It's the Mueta paper).

jony · 23rd February 2009, 02:27 PM

Thanks for help
Now I "understudy" that this circuit work as a simple opamp oscillator

Here is the link to
"A Novel Audio Power Amplifier Topology with High Efficiency and State of the Art Performance"
http://www.icepower.bang-olufsen.com...ntion/5197.pdf

scott wurcer · 23rd February 2009, 02:33 PM

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).

GGEC · 24th February 2009, 01:44 AM

Thank you Ouroboros & jony!

18th February 2009, 09:53 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, 04:13 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, 10:56 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, 02:33 PM	#9
scott wurcer diyAudio Member Join Date: Jan 2004 Location: cambridge 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). __________________ Pain is never permanent

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17th February 2009, 04:33 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, 03:56 PM	#3
hreith diyAudio Member Join Date: Jun 2004 Location: Heidelberg	It's a SODA from Bruno Putzeys.

23rd February 2009, 11:03 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).

24th February 2009, 01:44 AM	#10
GGEC diyAudio Member Join Date: Jun 2007	Thank you Ouroboros & jony!

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