Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Class D Switching Power Amplifiers and Power D/A conversion

Power Transistor Choices (New to Class D Design)
Power Transistor Choices (New to Class D Design)
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
Thread Tools Search this Thread
Old 7th February 2012, 06:03 AM   #1
PabloPhoenix is offline PabloPhoenix  United States
diyAudio Member
Join Date: Feb 2012
Default Power Transistor Choices (New to Class D Design)

Hi all. I'm not at all new to electronics, but I'm new to the design of audio amplifiers. I've gotten it into my head that I'd like to attempt to design a class D amp. And by "design" I mean without the use of someone else's class D chip. The more I read on this topic, the more I think that it may be wrong-headed to think that this is a good starting point in trying amplifier design. But I haven't changed my mind quite yet.

I've come to the conclusion that a good starting point in choosing components might be to narrow down my choice of power transistors, since this will ultimately determine the timing and voltages required from the previous stage. I'm currently considering a full bridge design that would use some specific Infineon transistors I've selected, primarily based on their rise and fall times, input capacitances, low cost, and some other specs. The two options I'm currently considering are as follows:

1. 4 of IPP034N03L (N channel)
2. 2 of IPP034N03L (N channel) and 2 of IPD50P03P4L-11 (P channel)

If I were considering a half-bridge design, I'd probably be unsure if these transistors were matched closely enough. Given that it would be a full-bridge design, I believe they probably are, but my worst concern about pairing them up is that the PMOSFETs might sort of drag down the quality of the whole system.

So my questions are:
1. Do any of you have any experience using Infineon's offerings in the OptiMOS line? If so, are they very good in the power stage of a class D amp?

2. Given the rise and fall times of these transistors, am I correct in assuming that shoot-through would be less of a risk in a design based on them, as long as timing is done in a reasonably good way?

3. Is it reasonable to think that these two specific transistors would work pretty well together in a full bridge, so long as I'm not trying to push them harder than what the PMOSFETs can do?

4. Supposing I'm completely wrong about this, what are some better options and (if it won't be obvious) why?
  Reply With Quote
Old 7th February 2012, 05:46 PM   #2
darkfenriz is offline darkfenriz  Poland
diyAudio Member
darkfenriz's Avatar
Join Date: Jun 2004
Location: Warsaw
1. These are reasonable transistors, however logic level is a bit of a problem. Low 'logic' Vgs threshold favours fast switch on and slow switch off, opposite of what you'd like to have in a class D amplifier. Miller capacitance can also pose some issues although this is not a big issue at 30V. P channel is much worse in every aspect, but the worst is very limited Vgs swing, +5V/-16V of Vgs can get induced over internal inductances when switching fast and kaboom for no apparent reason.

2. You can get no shoot through with either slow or fast ones, it' more a matter of tweaking rise/fall times vs. dead time. BTW charges are more informative compared to switching times.

3. Yes, aside from the possible exceeding of Vgs of a Pmos.

4. You're not, generally. I suggest you went for all N channel though.

  Reply With Quote
Old 7th February 2012, 08:44 PM   #3
PabloPhoenix is offline PabloPhoenix  United States
diyAudio Member
Join Date: Feb 2012

Thanks for your input.

At the moment, I think I'm leaning toward using four NMOSFETs. The ease of generating the signals for well-matched NMOS and PMOS is still very appealing and it seems like generating the signals for 4 NMOSFETs would be kind of a pain, but finding a really good NMOS/PMOS pair seems difficult.

Do you have any specific recommendations for transistors that work well on the output stage of a class D?
  Reply With Quote
Old 8th February 2012, 12:46 AM   #4
MOER is offline MOER  United States
diyAudio Member
Join Date: Aug 2003
Default Infineon

Dear Pablo,

We use the Infineon IPP200N15NG3 with rail voltages up to +/-65v in a totem output configuration.

These are the best 150v N channel MOSFETs available for class D. Low Qg, high current, low RDs.

We have used tens of thousands and they are super reliable. We run our class D amplifiers at between 400-500KHz.

No matter what MOSFET you use, dead time is a must.

Other parts we use are IRFB4212 (100v), IRFB4227 (200v), FDP2572 (150v), FDP3682 (100v) FDP42AN15Ao (150v)


Zed Audio
  Reply With Quote


Power Transistor Choices (New to Class D Design)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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
CCS transistor choices hirafu_boarder Tubes / Valves 38 9th August 2013 03:16 PM
Mute transistor choices? JuKu Parts 17 16th November 2011 08:58 PM
Power transistor for class A amp MrJimBeam Parts 3 9th January 2010 05:30 PM
Portable Class D Power! Choices? Andres83 Class D 16 28th November 2005 05:32 AM
Choices for Vas transistor Shaun Solid State 38 17th May 2005 07:59 AM

New To Site? Need Help?

All times are GMT. The time now is 04:03 AM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio