AD Vs BD Modulation in Class-D - diyAudio
Go Back   Home > Forums > Amplifiers > Class D

Class D Switching Power Amplifiers and Power D/A conversion

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 18th January 2006, 01:41 AM   #1
diyAudio Member
 
Workhorse's Avatar
 
Join Date: Dec 2004
Smile AD Vs BD Modulation in Class-D

Hi Everyone,

Whats your opinion regarding AD Vs BD Modulation in Class-D Bridged amps with External Clocked designs....Pros & Cons... 2 level & 3 Level PWM.......any helping great ideas.....

K a n w a r
  Reply With Quote
Old 19th January 2006, 12:51 AM   #2
diyAudio Member
 
Workhorse's Avatar
 
Join Date: Dec 2004
  Reply With Quote
Old 19th January 2006, 12:59 AM   #3
mirlo is offline mirlo  United States
diyAudio Member
 
Join Date: Jul 2002
Location: San Diego
Perhaps noone answered because they aren't familiar with the terms.

Here is a reference for anyone interested ...

http://www.iet.ntnu.no/~ivarlo/files...PCM_to_PWM.pdf

-- mirlo
  Reply With Quote
Old 19th January 2006, 01:27 AM   #4
diyAudio Member
 
Workhorse's Avatar
 
Join Date: Dec 2004
Thanks Mirlo...
  Reply With Quote
Old 29th January 2006, 05:50 AM   #5
diyAudio Member
 
vectorplane's Avatar
 
Join Date: Nov 2005
I remember having seen somewhere some description of commercial design which used 3-level ( BD ) modulation.

When the audio signal was positive, the PWM switched between positive polarity and ALL OFF switches, rather than between positive and negative. With zero input signal, the switches were all in high impedance state, instead of alternately hitting both rails at 50% DC. It seemed to make more sense, also maybe lower DC offset at no signal, but it may be more complex to implement.

I can't recall what manufacturer was providing this info. I'll look through my collection of bookmarks to see if I can find it.

Andy
  Reply With Quote
Old 29th January 2006, 11:38 PM   #6
Wiebel is offline Wiebel  Germany
diyAudio Member
 
Join Date: Feb 2005
Location: Bremen
As I have not been aware of the AD Modulation I am surprised about it in several ways.
I am used to the "normal" analog opamp based amps (building headphone amps), so the AD Modulation comes more "natural" to me. Some points that comes to my mind:
You can half the suply Voltage with BD due to the use of the H-bridges. Things like this simply have to come with some drawbacks, the H-bridge adds some extra pice of hardware in the signal path which I would consider as a subotimal,also I could imagine that the zero transits may cause some problems. As mentioned I like Headphones so another bad thing comes in mind, the common ground which is simply impossible with BD design.

As I want to build some active speakers (possibly with additional headphone out) this informations comes in very handy, thanks for this enlightenment.

I would prefer AD design, now that I know of it , if the dimensioning of the PS is not a big issue.

Then again I'm very much a newbie to audio diy and I may be completely wrong.
  Reply With Quote
Old 3rd February 2006, 10:10 AM   #7
diyAudio Member
 
Workhorse's Avatar
 
Join Date: Dec 2004
Default No one knows or there's some confusion

It seems that No one knows about my questionarrie....I just asked about Pros/Cons of 2 types of H-Bridge amp in which BD mode has Switching frequency in phase and AD mode has switching Frequency out of phase...thats all.

Hoping this time its little bit more simpler.....
K a n wa r
  Reply With Quote
Old 3rd February 2006, 01:18 PM   #8
diyAudio Member
 
vectorplane's Avatar
 
Join Date: Nov 2005
Sorry, Kanvar

I think your topic may be a little over the head of most members, and everyone reading this knows less than you do about it.

You might try asking Eva, by interjecting an off-topic post in one of the SMPS forums she monitors. (Class D is not too different from SMPS).

You might also try emailing tech guys at a semiconductor house like IRF.com, who actively promote class D design these days. Make sure to include a schematic or a mention that you use IR MOSFET part numbers in your design.
(make sure the diodes are IR part nrs also, not MUR...)

They're usually good with replying, and some of those guys feel so passionate about design, once you get them started, you can't stop them.

Andy
  Reply With Quote
Old 3rd February 2006, 01:28 PM   #9
diyAudio Member
 
Workhorse's Avatar
 
Join Date: Dec 2004
ThanX......Vectorplane,

Now I would Try these IRF babes...and get my chunk of info from them......

regards,
K a n w a r
  Reply With Quote
Old 4th February 2006, 04:48 AM   #10
diyAudio Member
 
vectorplane's Avatar
 
Join Date: Nov 2005
Quote:
Originally posted by Workhorse
ThanX......Vectorplane,

Now I would Try these IRF babes...and get my chunk of info from them......

regards,
K a n w a r

Hey, Kanwar, when you do get a reply, I'd be curious to know the answer too...

Andy
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Flux modulation 454Casull Multi-Way 71 2nd November 2011 11:21 PM
How many modulation methods in Class D amplifier ? xuhaoz Class D 20 5th December 2006 04:15 AM
Alternative modulation schemes for class d amps Nirav Desai Class D 6 10th January 2005 09:26 AM
Class D Modulation Scheme pokka Class D 7 15th December 2004 07:33 PM
new class D modulation method? sfx Class D 12 6th October 2004 07:02 AM


New To Site? Need Help?

All times are GMT. The time now is 11:05 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2