Hello
I am trying to model a bireciprocal Cauer filter in LTspice but I don't get the expected results. More precisely, using ?=(re(s)?1)/(re(s)+1)
where re(s) is the realpart of the pole, gives this result:
Among the few references I have, one that gives a numerical example is a th esis, "Design and Realization Methods for IIR Multiple Notch Filters and Hi gh Speed Narrow-band and Wide-band Filters, L. Barbara Dai" and, simply by looking at the numbers and comparing them with what I had, it seemd as if t he poles need to be "normalized" to the single real pole, s[(N+1)/2]. That' s what I did:
?=(re(s)/s[(N+1)/2]?1)/(re(s)/s[(N+1)2]+1)
so, even if the numerical values still differed, but a not as before, I got this result:
The example used here is not the one used in the thesis, but I seem to get good results (I cannot verify them) with either stop-band, or transition-ba nd optimizations and for any (odd) order.
So, my question is: is this the way to do it, "normalize" poles by dividing each to the single, real pole?