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-   -   Lateral MOSFET thermal vs others (http://www.diyaudio.com/forums/solid-state/140715-lateral-mosfet-thermal-vs-others.html)

jackinnj 19th March 2009 01:13 AM

Lateral MOSFET thermal vs others
 
I ran this test today --

http://www.tech-diy.com/Amplifiers/T...OSFET_Bias.gif

Bob Cordell 19th March 2009 01:59 AM

This is quite a good result, and shows how stable lateral MOSFETs tend to be with temperature stability. Their Temperature coefficient of Id goes through zero at typically between 100mA and 200mA.

Was this a lone device that you put in an oven, or was it a lateral MOSFET power amplifier?

Cheers,
Bob

jackinnj 19th March 2009 02:01 PM

It was a lone device on a heat sink inside an old amplifier. I used a Tektronix temperature probe as close to the device as possible. The kink in the curve is "operator error", perhaps too much coffee.

SpittinLLama 20th March 2009 08:05 PM

When I did AN-1645 and work for AN-1850 (although not shown in the note) I found that the Renesas devices are really stable on bias with temperature. I like these devices for that reason but wish they had more current and power capability. I think I used devices I got from your online store along with the IR devices.

Funny side note, the reason the Magnatec devices are not shown in AN-1850 was because they refused to send me a set for free so I could test them with the LME49830. I had to pay out of my own pocket for the devices used in AN-1645. You'd think a company would like such advertising for less than $50. Bone heads.

-TH

jackinnj 20th March 2009 10:26 PM

Quote:

Originally posted by SpittinLLama
When I did AN-1645 and work for AN-1850 (although not shown in the note) I found that the Renesas devices are really stable on bias with temperature. I like these devices for that reason but wish they had more current and power capability. I think I used devices I got from your online store along with the IR devices.

Funny side note, the reason the Magnatec devices are not shown in AN-1850 was because they refused to send me a set for free so I could test them with the LME49830. I had to pay out of my own pocket for the devices used in AN-1645. You'd think a company would like such advertising for less than $50. Bone heads.

-TH

You ran it in seconds, to 600 secs, I ran it in minutes.

Right now I have an LM4702 and lateral MOSFET amplifier transmitting at 1.1 MHz -- if I were in Cleveland I could knock Trivasano off the air.

fab 21st March 2009 01:59 PM

Quote:

Originally posted by SpittinLLama
When I did AN-1645 and work for AN-1850 (although not shown in the note) I found that the Renesas devices are really stable on bias with temperature. I like these devices for that reason but wish they had more current and power capability. ....
-TH

Of course one can use parallel matched devices....but the cost
:xeye:

jackinnj 21st March 2009 02:20 PM

Quote:

Originally posted by fab


Of course one can use parallel matched devices....but the cost

It's peculiar, but I have found that paralleled matched devices are more stable in operation than singles. I have no "good" idea why this should be the case, but I do have my suspicions.


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