I work with ADAU 1701minz to implement IIR filter on audio signal.
We doing it using few Bi-quads in the filter module.
No we need to add gain to the system... but we don't want it to change the transfer function (except constant gain of course ).
what happens is the transfer function change when adding gain module after the filter....
now I wand to define few things -as I understand it:
1. each Bi-quad_n is function of of xn and yn
2. xn is the output of last bi-quad (for the first one is system input) and yn is the in input for next level.
now here is my question- the last bi-quad output - yn - how does it define? system output?
(you can see my attached diagram....)