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 Author Topic: Opamp feedack: series RC  (Read 1069 times) 0 Members and 1 Guest are viewing this topic.
qolpa
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 « on: May 24, 2010, 01:52:13 13:52 »

Hi all,

I have been wondering for a long time what is the purpose of series R2 C2?(see attached) The other part of circuit is not important.

I think it is some kind of filter but how can we calculate the corner freq, is it like basic low-pass or high pass RC? (1/2*pi*R*C ??)

Any help would be appreciated..
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when everthing else fails, read the instructions
gopi_sonsivri
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 « Reply #1 on: May 24, 2010, 02:16:46 14:16 »

it is circuit for integrator

i think the order of filter is fixed by the R2,C2 (second order)

Just read some book on Linear Integrated Circuits
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hate
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 « Reply #2 on: May 25, 2010, 11:45:30 11:45 »

The impedance of the feedback circuit consisting of C1,C2,R2 is Z=(R2*C2*s+1)/[R2*C1*C2*s*s+(C1+C2)*s] which looks like a bandpass filter. And the input output relationship is Vo=[5*(R1+Z)/R1]-Vi*Z/R1. If the non-inverting input should be grounded instead of being connected to 5v, the transfer function would consist of only the 2nd term and this would look like a bandpass filter to me. With the non-inverting input connected to 5v it looks like a mixer with filtering capabilities. Try to Bode plot the transfer function!

Regards...
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