phase shift in RC filters cascade

[riccardo manfrin]

Supposing I have a network filter of 3 RC filters connected in cascade configuration producing the filter H(w).

The single RC filter has a frequency response H_{RC}(w)

Is it correct the following?

phase(H(w)) = 3*phase(H_{RC}(w))

My doubt comes from the fact that the first and second filters when connected to form the cascade, exhibit a dependency from the network following them (the rest of the cascade).

Thanks in advance
R

 

[riccardo manfrin]

Il giorno sabato 14 giugno 2014 13:09:58 UTC+2, riccardo manfrin ha scritto:

Supposing I have a network filter of 3 RC filters connected in cascade configuration producing the filter H(w).



The single RC filter has a frequency response H_{RC}(w)



Is it correct the following?



phase(H(w)) = 3*phase(H_{RC}(w))



My doubt comes from the fact that the first and second filters when connected to form the cascade, exhibit a dependency from the network following them (the rest of the cascade).



Thanks in advance

R

Gotcha. basically the 10 factor used in each successive RC stage for the resistance has the task of "disconnecting" the following circuit from the previous RC filter (R_N looks like an open circuit to the R_{N-1}C_{N-1} filter), hence making the RC filters independent and therefore allowing their phase to be additive with good aproximation.