While I was reading about filter design, and going through the schematics, the following 2 questions popped up in my mind and I could not find a satisfactory answer to them:
1) A first order low pass butterworth filter may be designed as shown below:
and a basic second order low pass butterworth filter as :
But if we are to design a higher order filter, we don't just put another RC segment in the non-inverting terminal, instead, we cascade a combination of first and second order filters. Why is it so, I mean, why don't we just add another RC segment? Closed loop stability issues?
2) A band pass filter can be constructed by cascading a low pass filter to a high pass filter with the frequency cut-off constraints. Does it make any difference which segment is added first, like 1st Order High-Pass Butterworth and then 1st order Low-Pass Butterworth, would it be any different from 1st Order Low-Pass Butterworth and the 1st order High-Pass Butterworth Filter?