Matched n-channel JFET

Smidoid · 9th January 2012, 03:09 AM

No doubt this comes up from time to time, but what the heck happened to JFETs while I was sleeping? One minute they're cheap and easily available, the next, only the 2n3819 and similar seem left.

I'm searching for a monolithic matched pair for my own design, preferably one that I can get this time next year! Low noise is they key here, so mos won't do... I could use bipolar but jfet gets that sound you don't get with bipolar.

Any suggestions gratefully received - preferably ones that won't require the sale of internal organs...

len_scanlan · 9th January 2012, 03:56 AM

Linear Systems LSK389 comes to mind.

Toshiba have discontinued almost everything of interest from their discretes catalog. Slim pickings ahead it seems..

-Len.

Smidoid · 9th January 2012, 01:47 PM

Yes... Very slim. At this rate I'll have to go any buy a box of MPF102s and sort some matched pairs myself. I know FETs have their problems, but it's a shame that they're being abandoned in preference for single chip solutions like Op Amps.

The circuit I had in mind was suggested by Horowitz and Hill and only needs 2 pairs. The same thing with Op Amps needs at least three amps and would be better with more. Now that's a pain because all the extra silicon adds noise and isn't optimised for what I need.

juma · 9th January 2012, 07:19 PM

BF862

Smidoid · 11th January 2012, 12:08 AM

Thanks juma, but that's a single. I need two on the same bit of silicone.

Cheers anyway,

Marc

SemperFi · 11th January 2012, 08:46 AM

I also worry a bit about the low interest for matched transistors among manufacturers. This is not a JFET, but a depletion mode MOSFET, kinda similar. Advanced Linear Devices makes some interesting matched transistors, duals and quads. Mostly low voltage devices, but that just gives us a good excuse for a cascode.
http://www.aldinc.com/pdf/ALD114804.pdf

9th January 2012, 03:09 AM	#1
Smidoid diyAudio Member Join Date: Jan 2012	Matched n-channel JFET No doubt this comes up from time to time, but what the heck happened to JFETs while I was sleeping? One minute they're cheap and easily available, the next, only the 2n3819 and similar seem left. I'm searching for a monolithic matched pair for my own design, preferably one that I can get this time next year! Low noise is they key here, so mos won't do... I could use bipolar but jfet gets that sound you don't get with bipolar. Any suggestions gratefully received - preferably ones that won't require the sale of internal organs...

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9th January 2012, 03:56 AM	#2
len_scanlan diyAudio Member Join Date: Dec 2004 Location: Auckland, NZ	Linear Systems LSK389 comes to mind. Toshiba have discontinued almost everything of interest from their discretes catalog. Slim pickings ahead it seems.. -Len.

9th January 2012, 01:47 PM	#3
Smidoid diyAudio Member Join Date: Jan 2012	Yes... Very slim. At this rate I'll have to go any buy a box of MPF102s and sort some matched pairs myself. I know FETs have their problems, but it's a shame that they're being abandoned in preference for single chip solutions like Op Amps. The circuit I had in mind was suggested by Horowitz and Hill and only needs 2 pairs. The same thing with Op Amps needs at least three amps and would be better with more. Now that's a pain because all the extra silicon adds noise and isn't optimised for what I need.

9th January 2012, 07:19 PM	#4
juma diyAudio Member Join Date: Nov 2005 Location: Zemun	BF862

11th January 2012, 12:08 AM	#5
Smidoid diyAudio Member Join Date: Jan 2012	Thanks juma, but that's a single. I need two on the same bit of silicone. Cheers anyway, Marc

11th January 2012, 08:46 AM	#6
SemperFi diyAudio Member Join Date: Jan 2002 Location: nowhere	I also worry a bit about the low interest for matched transistors among manufacturers. This is not a JFET, but a depletion mode MOSFET, kinda similar. Advanced Linear Devices makes some interesting matched transistors, duals and quads. Mostly low voltage devices, but that just gives us a good excuse for a cascode. http://www.aldinc.com/pdf/ALD114804.pdf

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