Ultra low noise dual jfet

Pjotr · 25th November 2003, 07:51 PM

Djeez, this dual jfet has 0.3 nV/sqrt(Hz) at 100 Hz. Great for a MC amp isn’t it:

http://www.interfet.com/pdf/DS_IF3602.pdf at

http://www.interfet.com/

Only problem is minimum order is $500

Cheers

Onvinyl · 6th December 2003, 10:46 AM

...and it has a gm of 750 !!! This would be really worth a try!?
input capacitance is not low. Doesn't it count?
Someone found a source for purchasing say 20 items or so?
Rüdiger

Petter · 6th December 2003, 12:07 PM

GM=750mS=0.75

Other potential problem is low power dissipation of 300mW for entire device.

Petter

Christer · 6th December 2003, 12:14 PM

Quote:

Originally posted by Petter
Other potential problem is low power dissipation of 300mW for entire device.

Petter

Do you usually need more for typical low-noise applications
like MC input stages? Seems quite sufficient IMHO.

Onvinyl · 6th December 2003, 12:24 PM

Quote:

GM=750mS=0.75

Sorry, this definitly can't be true. You'll end up with a damper instead with an amplifier...
Rüdiger

Pjotr · 6th December 2003, 01:45 PM

Hi,

A Gm of 750 mS looks a bit high indeed. Here is a bit more about the chip:

http://www.interfet.com/pdf/P_NJ3600L.pdf

No need to e-mail Interfet, they simply will give you not more info than what is on the WEB-site.

Note that this is simply a very large area jfet-chip that acts like many smaller jfet-chips in parallel. The large input capacitance is not an issue IMHO regarding the 50-100 ohms resistance involved with MC amps.

I got this hint from an old colleague at the University of Delft. For that 500 bucks you get app 25 fets. It is excluding VAT and duties. Interfet does not keep them them in stock, they produce on order. He measured a real 0.7 nV/sqrt(Hz) at 10 Hz and room temperature. He has still a lot in his drawer but refuses to sell me a pair

At the moment I use the 2SK389’s but these become rare and expensive nowadays. Also these are not well tailored to low source resistances regarding noise.

Cheers

Onvinyl · 6th December 2003, 01:54 PM

Quote:

For that 500 bucks you get app 25 fets

At that price it is a theoretical discussion at all...
There seem to be just a few fets suitable for audio (that are obtainable), if one searches the archives here.
Rüdiger

Pjotr · 6th December 2003, 02:10 PM

Quote:

At that price it is a theoretical discussion at all...

Dunno, but if cost is no objective... It is the lowest noise dual jfet I came across, especially with low source impedances and at low frequencies.

25th November 2003, 07:51 PM	#1
Pjotr diyAudio Member Join Date: Nov 2002 Location: Netherlands	Ultra low noise dual jfet Djeez, this dual jfet has 0.3 nV/sqrt(Hz) at 100 Hz. Great for a MC amp isn’t it: http://www.interfet.com/pdf/DS_IF3602.pdf at http://www.interfet.com/ Only problem is minimum order is $500 Cheers

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
JFET Ultra Wideband Preamp PCBs for Sale	juajuara	Solid State	44	29th December 2006 09:40 PM
Low noise dual JFET pair	rtarbell	Parts	4	17th March 2006 10:11 PM
Ultra low noise JFET voltage regulator	Kochkurov Maxim	Digital Source	6	25th January 2004 11:33 AM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	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

6th December 2003, 10:46 AM	#2
Onvinyl diyAudio Member Join Date: Aug 2002 Location: Germany	...and it has a gm of 750 !!! This would be really worth a try!? input capacitance is not low. Doesn't it count? Someone found a source for purchasing say 20 items or so? Rüdiger

6th December 2003, 12:07 PM	#3
Petter diyAudio Member Join Date: Jan 2001 Location: Scandinavia	GM=750mS=0.75 Other potential problem is low power dissipation of 300mW for entire device. Petter

6th December 2003, 01:45 PM	#6
Pjotr diyAudio Member Join Date: Nov 2002 Location: Netherlands	Hi, A Gm of 750 mS looks a bit high indeed. Here is a bit more about the chip: http://www.interfet.com/pdf/P_NJ3600L.pdf No need to e-mail Interfet, they simply will give you not more info than what is on the WEB-site. Note that this is simply a very large area jfet-chip that acts like many smaller jfet-chips in parallel. The large input capacitance is not an issue IMHO regarding the 50-100 ohms resistance involved with MC amps. I got this hint from an old colleague at the University of Delft. For that 500 bucks you get app 25 fets. It is excluding VAT and duties. Interfet does not keep them them in stock, they produce on order. He measured a real 0.7 nV/sqrt(Hz) at 10 Hz and room temperature. He has still a lot in his drawer but refuses to sell me a pair At the moment I use the 2SK389’s but these become rare and expensive nowadays. Also these are not well tailored to low source resistances regarding noise. Cheers

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)