Looking for chipamp with J-FET in input stage.

Progg70 · 28th January 2009, 10:06 AM

Is there any nice chipamp with J-FET in the input stage, the signal path?

Regard

Progg70

Nuuk · 28th January 2009, 10:37 AM

Do you mean with a Jfet input buffer?

AndrewT · 28th January 2009, 10:52 AM

the chipamps are generally specified with a very low input offset current.
This suggests that these low input offset chipamps use a FET input LTP as the input stage.
I doubt they are using mosFETs that just leaves jFETs.

Progg70 · 28th January 2009, 10:53 AM

Yes something like that or the amp. differential bridge with J-fet.

Progg70 · 28th January 2009, 10:56 AM

If you look at the schematics for ex. LM3876 they have the ordinary bipolar transistor input.

Nuuk · 28th January 2009, 11:01 AM

Have a look at OPA541/OPA549.

Progg70 · 29th January 2009, 07:55 AM

Thanks

28th January 2009, 10:06 AM	#1
Progg70 diyAudio Member Join Date: Jul 2004 Location: Sweden	Looking for chipamp with J-FET in input stage. Is there any nice chipamp with J-FET in the input stage, the signal path? Regard Progg70

28th January 2009, 10:37 AM	#2
Nuuk diyAudio Member Join Date: Feb 2003 Location: Somerset, SW England	Do you mean with a Jfet input buffer? __________________ The truth need not be veiled, for it veils itself from the eyes of the ignorant.

28th January 2009, 10:52 AM	#3
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	the chipamps are generally specified with a very low input offset current. This suggests that these low input offset chipamps use a FET input LTP as the input stage. I doubt they are using mosFETs that just leaves jFETs. __________________ regards Andrew T.

28th January 2009, 11:01 AM	#6
Nuuk diyAudio Member Join Date: Feb 2003 Location: Somerset, SW England	Have a look at OPA541/OPA549. __________________ The truth need not be veiled, for it veils itself from the eyes of the ignorant.

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28th January 2009, 10:53 AM	#4
Progg70 diyAudio Member Join Date: Jul 2004 Location: Sweden	Yes something like that or the amp. differential bridge with J-fet.

28th January 2009, 10:56 AM	#5
Progg70 diyAudio Member Join Date: Jul 2004 Location: Sweden	If you look at the schematics for ex. LM3876 they have the ordinary bipolar transistor input.

29th January 2009, 07:55 AM	#7
Progg70 diyAudio Member Join Date: Jul 2004 Location: Sweden	Thanks

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