  Rational approximation of fractional order (FO) differ-integrators via
Continued Fraction Expansion (CFE) is a well known technique. In this paper,
the nominal structures of various generating functions are optimized using
Genetic Algorithm (GA) to minimize the deviation in magnitude and phase
response between the original FO element and the rationalized discrete time
filter in Infinite Impulse Response (IIR) structure. The optimized filter based
realizations show better approximation of the FO elements in comparison with
the existing methods and is demonstrated by the frequency response of the IIR
filters.
