AD Vs BD Modulation in Class-D

[Workhorse]

Hi Andy,

Then Stay Tuned..........

K a n w a r

[Iyremenko]

@Workhorse

I think Ecler is making Class-BD amps.....

www.ecler.com

[Workhorse]

Originally posted by Iyremenko
@Workhorse

I think Ecler is making Class-BD amps.....

www.ecler.com

Thanks for the link i have just read there white paper on Tri-level amazing facts.....

[ravaz]

This document may helps you:

http://focus.ti.com/lit/an/sloa119a/sloa119a.pdf

As for my understanding BD requires smaller components and has better EMI, having the only drawback of being more dificult to calculate.




Regards,

Ravaz

[savu]

to Ravaz:

Thanks a milion for sloa199a

best regards,

[Workhorse]

Originally Posted by ravaz

This document may helps you:

http://focus.ti.com/lit/an/sloa119a/sloa119a.pdf

As for my understanding BD requires smaller components and has better EMI, having the only drawback of being more dificult to calculate.




Regards,

Ravaz

BD requires more components than AD modulation.

[81bas]

About EMI and AB/AD modulation:
http://www.hypex.nl/docs/AES124_Masterclass_Putzeys.pdf, pages 81, 82, 83

[Eva]

Who would trade overall EMI performance for eliminating carrier residual only when there is no signal?

Carrier residual applied to speakers is completely harmless. EMI can potentially disturb any piece of electronics around.

Class BD means "wrong design goals". Low EMI should be the first goal.

[ericbrooking]

The reason people are interested in BD comes from Delta-Sigma convertors. If you can use a three level output you can decrease quantization noise by 6dB. You also get to utilize the dead time instead of it being your enemy. One problem with BD though is that you lose the inherent linearity of a two level system. The distance between high and low level in a two level is what it is but in a three level the distance (magnitude) from "zero" to high level will be different than from "zero" to low level or negative. This introduces nonlinearity. Otherwise, the BD is kinda neat when you are trying to do a more advanced noise shaped amp, especially if it's a true digital amp.

Cheers

[phase_accurate]

I think Kanwar is talking about what is described in Bruno's paper (which was mentioned some posts before) and not some three-state amp that is using an "open" state.

This has one advantage: The apparent switching frequency and also the actual sampling frequency is twice as high for a given carrier frequency when you use a carrier-based amp. Therefore you can use more loop gain.

Regards

Charles