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-   -   iXYS linear power mosfet (http://www.diyaudio.com/forums/solid-state/184787-ixys-linear-power-mosfet.html)

Avlin 9th March 2011 10:35 PM

iXYS linear power mosfet
 
Hi ! :)

I'm new on this forum

I want to now if IXYS linear 2 mosfet series are good rated for audio amplification since they are designed for "linear amplifier".

IXYS Product Portfolio | Power Devices

How could we now if a lateral structure mosfet is good ?

what are the main criteria ?

Is the 2sk1058 the best ? mosfet are evolving all months, but only in switching applications (trench fet gen 2 - hexfet - GaN ...) :headbash:

I'll eventually build a class a single ended preamp this month :cool:

thanks.

abraxalito 9th March 2011 10:48 PM

Those FETs might make great output stages (very high power handling and excellent low thermal resistance) but would not be a great choice for preamp duty - capacitances look very high. No P-channel parts listed either.

As to whether 2SK1058 is best, it depends what your evaluation criteria are - ruggedness (for example) or value for money? Its switching that has the volumes these days, which explains why the 2SK has been around unchanged for decades.

<edit> ooops, forgot to say - welcome to diya! :p

Avlin 9th March 2011 11:34 PM

oops I wanted to say amp and not preamp, and in single ended class A there is no need for P channel.

so as I understand, since there is no evolution in lateral structure mosfet, the 2sk remains a good choice ?

maybe i could build an experimental amp with 2sk1058 and try another mosfet later

so i should search linear mosfet with low capacitance ?

thanks for your quick response.

woody 10th March 2011 12:07 AM

You might also want to look at the power jfets from Simisouth they have a lot less
distortion but are expensive.

abraxalito 10th March 2011 12:52 AM

Quote:

Originally Posted by Avlin (Post 2498255)
so as I understand, since there is no evolution in lateral structure mosfet, the 2sk remains a good choice ?

A good choice amongst laterals yes. But then you're really looking at such a narrow range of available parts that its almost Hobson's. You've decided that laterals suit your application best? In a class A application where the quiescents are huge (relatively) I think the relative disadvantages of verticals are much reduced. Temperature stability for one hardly matters as the amp actually gets cooler when playing :D

Quote:

so i should search linear mosfet with low capacitance ?
Lower capacitance is easier to drive, all other things being equal. MOSFETs usually have 3 capacitances specified on the datasheet, which ones are important depends on whether you're using it common-drain or common-source.

Quote:

Originally Posted by woody
You might also want to look at the power jfets from Simisouth they have a lot less distortion but are expensive.

Well if we're really in price-no-object territory, how about this Cree one?

CREE | SiC MOSFET

ANADIGIT 10th March 2011 01:27 AM

I known SOT-227 MOSFET
 
1 Attachment(s)
Used in Gamut D200I SOT-227 case manufactued from Microsemi but I think it's look like IXYS, too

http://www.diyaudio.com/forums/solid...ht-name-5.html

Thanks
Anadigit

Avlin 10th March 2011 02:22 AM

Quote:

Originally Posted by abraxalito (Post 2498327)
You've decided that laterals suit your application best? In a class A application where the quiescents are huge (relatively) I think the relative disadvantages of verticals are much reduced.

may vertical structure mosfet be a good choice for a single ended class A amp ?

Quote:

Originally Posted by abraxalito (Post 2498327)
Temperature stability for one hardly matters as the amp actually gets cooler when playing :D

hmm it is easier to find a very good mosfet with better thermal stability than a lateral structure.

Quote:

Originally Posted by abraxalito (Post 2498327)
Well if we're really in price-no-object territory, how about this Cree one?
CREE | SiC MOSFET

according what you says GaN mosfet may be better (or actually trenchfet Gen 3) : (page 3)

http://www.irf.com/product-info/ganpowir/GaNGeneral.pdf

@ ANADIGIT : seems the SOT 227 good for thermal stability :D

very interesting and nice forum

but 4:00 am for me (france), i'll go to sleep

ps : what about mosfet package parasite inductance ? :p

abraxalito 10th March 2011 02:41 AM

Quote:

Originally Posted by Avlin (Post 2498392)
may vertical structure mosfet be a good choice for a single ended class A amp ?

Yeah, I tend to think so. Better because its cheaper and there are more sources out there. I would guess that Nelson Pass thinks so too. Why not go ask him as he's the man with the most experience in this department?

Quote:

according what you says GaN mosfet may be better (or actually trenchfet Gen 3) : (page 3)
GaN FETs are new to me. Just from a quick read it seems their FOM (figure of merit) is based on Rds(ON) which is of zero consequence in linear applications. So for now, I recommend sticking with the traditional silicon based FETs for audio. If I was investing, I'd go with IR's Si-substrate approach rather than Cree's as it looks more cost effective.

Quote:

ps : what about mosfet package parasite inductance ? :p
Not really an issue at audio frequencies with a linear amp. Big concern for switching amps though.

ANADIGIT 10th March 2011 03:53 AM

Why didn't Class-A amplifier havn't use SOT-227 in their product ?

WuYit 10th March 2011 07:23 AM

Hi,
on what basis is the entire product family entitled "linear"?


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