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Old 1st December 2011, 09:27 PM   #3241
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Elantec, they made good buffers. OK, you are working on a balanced input. Have you seen my JOSI Opamp ?
I thought about how the wheel was invented. I think it came by watching trees rolling.
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Old 1st December 2011, 09:29 PM   #3242
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Maybe the second stage of your design should be a folded cascode with current mirror.
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Old 1st December 2011, 09:37 PM   #3243
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Something like that works very nice ( AD797, LT1468 ) and gives very low distortion and high bandwidth.
Of cause you have a Fet input.
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Old 3rd December 2011, 02:04 AM   #3244
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Yes, this ones are pretty cool to cascode low Ugs N channel J-Fets:
PN4391 Datasheet pdf - Leaded JFET General Purpose - Central Semiconductor
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Old 3rd December 2011, 02:11 AM   #3245
EUVL is offline EUVL  Europe
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Guten Morgen Joachim,

Jan sends his regards.
We had an enjoyable evening on a bottle of Bordeaux.




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Old 3rd December 2011, 02:15 AM   #3246
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Only one bottle (:
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Old 3rd December 2011, 02:21 AM   #3247
EUVL is offline EUVL  Europe
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Ich habe Gicht. Muß leider aufpassen.




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Old 3rd December 2011, 11:07 AM   #3248
sampler is offline sampler  Lithuania
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Quote:
Originally Posted by Joachim Gerhard View Post
Something like that works very nice ( AD797, LT1468 ) and gives very low distortion and high bandwidth.
Of cause you have a Fet input.
Yep, classics. Even without bootstrapping it's already very good, and I'm not fancying 0.000.... thd games. Something like this (attached) should do it. Servoing ccs IME has always worked better then injection to gain nodes. What I still don't like is that non inverting servo and current through mirrors could be higher, but upper left bjt is already at 300mW dissipation. I've done some noise and thd sims vs. original starless as now I take it as benchmark point (because I like it so much). Other parameters should be on pair.
What do you think Joachim ? Should I give it a try or something needs further improvement ?
I'm still playing with this circuit only to try balanced in, that's something I haven't tried yet. I don't expect much, but want to try it for myself.
I didn't had a chance to listen to SE version, still have to build second channel, maybe this weekend.
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File Type: png bal_in_foldet.PNG (36.7 KB, 219 views)
File Type: png bal_in_vs_starless_noise.PNG (33.7 KB, 208 views)
File Type: png fft.PNG (28.0 KB, 199 views)
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Old 3rd December 2011, 11:20 AM   #3249
MiiB is offline MiiB  Denmark
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Another way of folding the cascode....
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Old 3rd December 2011, 11:34 AM   #3250
sampler is offline sampler  Lithuania
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Quote:
Originally Posted by MiiB View Post
Another way of folding the cascode....
And looks even simpler. Have you actually build it ?
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