Distortion issues

[Snickers-is]

Hopefully I have not missed an older thread about this. I believe we could make some kind of listing of the majour types of distortion in a class D construction, and the cause of their nature.

I know there is a lot of people here with a lot of knowledge so this thread could actually be almost complete!

Please do not be afraid of writing anything wrong. It will probably be commented and corrected.

[BWRX]

You can't just generalize for class d because there are different types of distortion inherent to different modulation schemes. For example, the accuracy of the traingular or sawtooth waveform will effect the distortion performance of a fixed frequency PWM amp.

[Snickers-is]

Off course. That is what this thread is for!

[classd4sure]

There is a fairly old thread on distortions in class d.. someplace.

[Snickers-is]

Do you remember the title?

[classd4sure]

I don't recall actually. I thought it was distortions in class d... searching for that turned up nothing.

[Baldin]

Like the idea a lot, to get one place to find "all" distortion causes and ways to minimize these in class-d amps.

Classd4sure; I can't seem to find a thread which is dealing with this in depth!

Maybe we should try to also draw up the different topologies and descripe distortion causes for each, as BWRX pointed out you can't gereralize, but some issues will be common though.

I have at the moment problems with 3. harmonics in a full bridge self osc. design ..... the source of the distortion .... unknown!
2. harmonic is quite low, where 3. is about 1% at 10 W out. .... a thread like the suggested would help

[analogspiceman]

Originally posted by Baldin
I can't seem to find a thread which is dealing with this in depth!

Google is your friend.

Go to Google, click on Advanced Search then (this is important) search only in the domain diyaudio.com for the following terms:

"class d" distortion (the parentheses must be used as shown)

There are a ton of hits - about half are pertinent.

Among the hits is a recent thread that was on dead time distortion. Perhaps this is the one Chris was thinking of?

Regards -- analogspiceman

[classd4sure]

It isnt' the one I was thinking of, but I think this supercedes it!

You can append this to your search too site:www.diyaudio.com saves you a few clicks

It doesn't seem to bring up the old ones though?

[Snickers-is]

Originally posted by Baldin
Like the idea a lot, to get one place to find "all" distortion causes and ways to minimize these in class-d amps.

Classd4sure; I can't seem to find a thread which is dealing with this in depth!

Maybe we should try to also draw up the different topologies and descripe distortion causes for each, as BWRX pointed out you can't gereralize, but some issues will be common though.

I have at the moment problems with 3. harmonics in a full bridge self osc. design ..... the source of the distortion .... unknown!
2. harmonic is quite low, where 3. is about 1% at 10 W out. .... a thread like the suggested would help

-What kind of oscillation do you use?
-What kind of feedback do you use?
-Could it simply be some kind of 2. harmonic dist that adds up to 3. harm dist when bridged?