
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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