So I have been having trouble understanding the difference of Rc filters that have the capacitor in series with the resistance and Rc filters that have the capacitor parallel to the resistance .
To make this more specific , why are both low pass filters? Can all filters be made in parallel and in series?
Best Answer
They are not both low pass filters. The upper circuit is a high-pass filter.
But the fact the capacitor is labelled \$\rm C_f\$ suggests this filter might be used in the feed back path of an op-amp circuit.
In that case, the overall op-amp circuit might very well be a low-pass filter. Because using a high-pass filter to increase the negative feedback at high frequencies will result in reducing the response of the overall op-amp circuit at those frequencies.