diyAudio

diyAudio (http://www.diyaudio.com/forums/)
-   Parts (http://www.diyaudio.com/forums/parts/)
-   -   AD797 Fet Inputs ? (http://www.diyaudio.com/forums/parts/200406-ad797-fet-inputs.html)

gk7 13th November 2011 01:28 PM

AD797 Fet Inputs ?
 
In a review of Resonessence Labs Invicta on 6mmons ( 6moons audio reviews: Resonessence Invicta ) is stated:

"In the user manual we do mention that the analog output stage uses jfets. We do however not use discrete jfets but instead the AD797 op-amp as a jfet input amplifier with a DC-bootstrapped compensation capacitor and additional AC-coupled feedback path. While ADI's circuit diagram indicates bipolar input devices, those are not conventional bipolars as can be inferred from the data sheet where collector current and base current are mentioned in a ratio higher than any any reasonable bipolar device can do. We know this through a personal relationship with the AD797's designer. Hence we refer to jfets in the input stage of the AD797."

Why would the datasheet have wrong information on the input stage ?
Confusing...

QSerraTico_Tico 13th November 2011 02:08 PM

Wrong
 
They are simply wrong. Look at the input bias current in the data sheet and you will see that it's not a JFET input stage.
:cool:

Mooly 13th November 2011 02:17 PM

Quote:

Originally Posted by QSerraTico_Tico (Post 2779957)
They are simply wrong. Look at the input bias current in the data sheet and you will see that it's not a JFET input stage.
:cool:

And theres more :)

the data sheet mentions a 25ma max input current... so again not FET.

gk7 13th November 2011 04:33 PM

Yes thatīs exactly what I thought, Iīm pretty sure itīs bipolar. But because they say "We know this through a personal relationship with the AD797's designer" I hoped for a comment by Scott Wurcer.


All times are GMT. The time now is 01:48 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright Đ1999-2014 diyAudio


Content Relevant URLs by vBSEO 3.3.2