| JoeBob |
would this circuit work for a low-pass circuit? Or would the cap after the input impedance setting resistor screw things up?
I ask because if I use a "normal" style PLLXO with a resistor followed by the cap in front of the input impedance setting resistor than the two resistors would make a voltage devider, I would obviously like to avoid that. |
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| JoeBob |
Oh common, no one even looked at it...
:) |
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| Konrad |
| Put the capacitor in paralell with the feedback resistor!:nod: |
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| AndyM |
The -input works as a virtual ground in this configuration so there is no voltage swing there (at least with an ideal opamp). So the capacitor wonŽt contribute anything and could be left out.
As Konrad said, put the capacitor in parallel to the feedback resistor and youŽll be fine.
For calculating the capacitor use the feedback resistor value, not the input resitor value (unless you make them equal for a gain of 1)
Ciao
Andy |
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| JoeBob |
| Ah, I should have thought of that, thanks that helps alot. |
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| millwood |
| JoeBob, it is one of those "active filter" designs that you can find pretty much in any op amp cook book. |
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