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Old 10th May 2013, 10:57 AM   #111
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Quote:
Originally Posted by sajti View Post
I don't agree with You. I used triple EF in many amplifiers, without any problem. And the distortion is decreased to 1/10 of the original double EF version.
Especially the triple EF gives lower output impedance before feedback.

Sajti
It is all in the implementation. Most of the output stage distortion is voltage distortion, not drive distortion, so no matter how much you buffer it, miller and Early leakage will conduct its distortion directly into the signal path.
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Old 10th May 2013, 12:52 PM   #112
sajti is online now sajti  Hungary
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Originally Posted by kgrlee View Post
Sajti, have you a link to your circuits? Are these distortion figures 'real life' or SPICE?

Toni, thanks for the models.
Yes I have, so I will put it to this forum.
Both simulation, and measurement.

Sajti
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Old 10th May 2013, 01:00 PM   #113
sajti is online now sajti  Hungary
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Quote:
Originally Posted by keantoken View Post
It is all in the implementation. Most of the output stage distortion is voltage distortion, not drive distortion, so no matter how much you buffer it, miller and Early leakage will conduct its distortion directly into the signal path.
Yes, but the loop gain is increasing, and the higher feedback results lower distortion.

Sajti
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Old 10th May 2013, 01:01 PM   #114
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Default 2stageEF_MOSFET_class_AB_power_amplifier.asc

proudly present a pre alpha untuned MOSFET version.

But not yet ready for production test!

BR, Toni
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File Type: asc 2stageEF_MOSFET_class_AB_power_amplifier.asc (37.3 KB, 151 views)
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Old 10th May 2013, 01:44 PM   #115
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Originally Posted by astx View Post
Dear Harry

thank you for answering. There is so many to learn how to measure amplifier stability correctly. The Tianprobe in the NFB loop is only one test. If you have some hints where to find the error in the minor loop which is only visible in real world design and not reproducable in simulation? Where to set which probe type in simulation would be helpful.
You should consult page 8 and the addendum in my paper and the references therein.

Quote:
Originally Posted by astx View Post
THX. Attached a new PSRR test. Hopefully now correct.
Don't forget that here you have only measured +ve rail PSRR. You will need to repeat the test but with the AC source in series with the negative-rail voltage source.

Last edited by HarryDymond; 10th May 2013 at 01:47 PM.
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Old 10th May 2013, 01:56 PM   #116
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Originally Posted by sajti View Post
Yes, but the loop gain is increasing, and the higher feedback results lower distortion.

Sajti
I never said an EF3 wouldn't decrease distortion if properly applied. I'm only pointing out that it takes skill to do this.
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Old 10th May 2013, 02:06 PM   #117
sajti is online now sajti  Hungary
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Quote:
Originally Posted by keantoken View Post
I never said an EF3 wouldn't decrease distortion if properly applied. I'm only pointing out that it takes skill to do this.
Sorry, it was a misunderstanding.

Sajti
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Old 10th May 2013, 02:17 PM   #118
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Originally Posted by HarryDymond View Post
You should consult page 8 and the addendum in my paper and the references therein.



Don't forget that here you have only measured +ve rail PSRR. You will need to repeat the test but with the AC source in series with the negative-rail voltage source.
Dear Harry,

thanks for hints. Attached a PSRR check also from negative rail - better as from positive rail.

BR, Toni
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File Type: png pssr.png (101.5 KB, 541 views)

Last edited by astx; 10th May 2013 at 02:18 PM. Reason: fast mouse finger ...
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Old 10th May 2013, 02:30 PM   #119
astx is offline astx  Austria
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Default New driver BJT's ...

New driver bjt's (2SC4793/2SA1837 and MJE15032/MJE15033) arrived today! Need matched bjt's.
Will this do with this homebrew "breadboard hellmachine". Can measure 10 pieces of BJT's/JFET's/MOSFET's automatically.
Needs up to 3 USB-controlled multimeters.

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Old 10th May 2013, 03:45 PM   #120
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Originally Posted by astx View Post
Can measure 10 pieces of BJT's/JFET's/MOSFET's automatically.
Needs up to 3 USB-controlled multimeters.

Lol very nice, I like it
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