5 CONCLUSIONS
In this paper, two well known approaches have been
used to develop a new first order s-to-z mapping
function. The proposed operator was found to be
stable for various sampling frequencies and the
magnitude results matched with the ideal
differentiator upto
%78 of the Nyquist frequency.
The phase of the proposed operator also
approximates a linear phase of half a sample of
delay with a maximum error of
°24.8 at 55.0 of
the Nyquist frequency.
The half differentiator models obtained by
discretization of the proposed operator using
continued fraction expansion exhibit better
performance in terms of magnitude and phase as
compared to those obtained by Taylor series
expansion. The above mentioned results of half
differentiator validate the effectiveness of the
proposed operator. Such modeling finds application
in discrete realization of fractional order circuits.
In this paper, z-domain stable models of fractional
order differentiators (
r
s ) have been presented for
r=0.5. This method can be further extended to
obtain z-domain stable models based on the
proposed operator for different
r.
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NOVEL DIGITAL DIFFERENTIATOR AND CORRESPONDING FRACTIONAL ORDER DIFFERENTIATOR
MODELS
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