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Inverting op-amp with too much gain ? More options
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| Trying to build a multi-stage 120kHz bandpass filter... decided to
use multi-feedback topology...
Seems that it amplifies the desired signal alright, but ends up full-
swing output (after just one stage) and since it's inverted, the
full-
swing output feedback ends up cancelling out the input and it
collapses back on itself.
I'm no op-amp expert but am ernestly trying to learn.... and I'm
stumped on how to procceed...
thanks!
...dane
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| dane wrote:
> Trying to build a multi-stage 120kHz bandpass filter... decided to
> use multi-feedback topology...
>
>
> Seems that it amplifies the desired signal alright, but ends up full-
> swing output (after just one stage) and since it's inverted, the
> full-
> swing output feedback ends up cancelling out the input and it
> collapses back on itself.
>
>
> I'm no op-amp expert but am ernestly trying to learn.... and I'm
> stumped on how to procceed...
Post a schematic.
Ed
>
>
> thanks!
> ..dane
>
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| Salmon Egg 2007-03-07, 8:25 pm |
| On 3/7/07 7:30 AM, in article
1173281406.627786.192600@n33g2000cwc.googlegroups.com, "dane"
<REMOVE_dane_walther@hotmail.com> wrote:
> Trying to build a multi-stage 120kHz bandpass filter... decided to
> use multi-feedback topology...
>
>
> Seems that it amplifies the desired signal alright, but ends up full-
> swing output (after just one stage) and since it's inverted, the
> full-
> swing output feedback ends up cancelling out the input and it
> collapses back on itself.
>
>
> I'm no op-amp expert but am ernestly trying to learn.... and I'm
> stumped on how to procceed...
>
>
> thanks!
> ..dane
>
Write in English or at least say what language you are using.
Bill
-- Fermez le Bush--about two years to go.
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> Post a schematic.
> Ed
How do I post a schematic?
Anyway, I used some filter design tool the first time around (can't
remember which), but I think I may have 'tweaked' it too much and
broke it... Going back to FilterPro helped a lot and I'm now back-on-
track.
thanks!
...dane
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| dane wrote:
>
>
> How do I post a schematic?
>
"Draw" it here in ascii or put it on your website with
a link to it posted here, or post it on abse
(abse = alt.binaries.schematics.electronic)
Ed
> Anyway, I used some filter design tool the first time around (can't
> remember which), but I think I may have 'tweaked' it too much and
> broke it... Going back to FilterPro helped a lot and I'm now back-on-
> track.
>
> thanks!
> ..dane
>
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