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Old 1st March 2003, 03:43 AM   #1
jcarr is offline jcarr  United States
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Default Duplicate opamp inside feedback loop?

On July 22 2002, Mirlo mentioned:

>there is an interesting app note on the Analog Devices website about improving opamp circuit phase response by putting a replica opamp in the NFB loop.<

http://www.diyaudio.com/forums/showt...4998#post44998

Does anyone have an idea what application note this is, and/or the URL?

Many thanks in advance, jonathan carr
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Old 1st March 2003, 06:29 AM   #2
mirlo is offline mirlo  United States
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Hmmm.

This will teach me not to refer to something vaguely, and then never be able to find it again.

I can't find it easily, and I can't remember exactly what they were doing.

The vague picture in my mind of what I think I saw looks like it would create a stability nightmare, so I am assuming I don't remember it well.

Sorry about that!
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Old 1st March 2003, 09:55 AM   #3
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Lightbulb An-107

Hi Jonathan,
That must be Application Note 107:
Active Feedback Improves Amplifier Phase Accuracy by James Wong.
I couldn't find it on the AD website. I have it on CD-ROM. Can send you the PDF file.

elso/not into opamps anymore
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Old 1st March 2003, 11:13 AM   #4
banana is offline banana  Hong Kong
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Default are u talking about composite opamp??

Composite Opamp: the use of high speed CFB opamp to boost the bandwidth of a precision VFB opamp. See link below:

http://www-s.ti.com/sc/psheets/sboa002/sboa002.pdf

or page 13 on te AD797 data sheet:

http://www.analog.com/UploadedFiles/...d.pdf:bigeyes:
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Old 1st March 2003, 12:39 PM   #5
halojoy is offline halojoy  Sweden
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Question Elso or jcarr - is this really good?

Quote:
Originally posted by Elso Kwak
Hi Jonathan,
That must be Application Note 107:
Active Feedback Improves Amplifier Phase Accuracy by James Wong.
I couldn't find it on the AD website. I have it on CD-ROM. Can send you the PDF file.

elso/not into opamps anymore
Elso or jcarr - is this really good?

In what applications should this sort of configuration
be good?
Not for notmal LF-audio, I would imagine.

/halo - has his doubts- wants to KISS - Keep It SSimple
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Old 10th March 2003, 11:01 AM   #6
Werner is offline Werner  Europe
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Join Date: Jan 2002
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Default Re: An-107

Quote:
Originally posted by Elso Kwak

That must be Application Note 107:
I have it on CD-ROM. Can send you the PDF file.

Hi Elso,

I have a gut feeling about which circuit this will turn out to be ...

Could you please send me the PDF?

ogiers @ fillfactory.com

Many thanks,

Werner
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