Progress in Signals and Telecommunication Engineering Ivan Krstic, Miloš Zivkovic, Ivana Kostic and Goran Stancic 9 2 2020 http://www.dline.info/pste/fulltext/v9n2/pstev9n2_3.pdf In this work we have outlined the method for modelling the software realization of infinite impulse response (IIR) digital filter with one notch frequency. We observed that the introduced a configuration which has parallel nature with a pure delay in one path and third order all-pass phase corrector in another. The final filter completes all predefined specifications which is for arbitrary given maximal pass-band attenuation, band-stop boundary frequencies are symmetrical about notch frequency. With the help of illustrations, we have demonstrated the effectiveness, particularly by employing the Matlab system.