Abstract

In this work, we have discussed design methodologies for generation of polynomial Butterworth, Papoulis and Filanovsky lowpass filters of different orders with arbitrary flatness, and also Thomson-Bessel lowpass filters, with monotonic amplitude-frequency response. We have shown how other monotonic responses can be obtained either by choosing lower order responses and/or by suitable combinations of these monotonic responses. We have proposed extraction of all possible lower order 1-D lowpass filters from the designed higher order lowpass filters, and segregate the filters with monotonic amplitude-frequency response. Furthermore, we cascaded the proposed extracted monotonic 1-D lowpass filters to realize higher order 1-D lowpass filters with monotonic characteristics, and studied combinations of the same. We have proposed 2-D fourth and fifth order Papoulis, Butterworth and Thomson-Bessel filters, and fifth order Filanovsky analog and digital lowpass filters, with monotonic amplitude-frequency response. Furthermore, by appropriately cascading lower order extracted 1-D lowpass filters from the above mentioned types, 2-D monotonic filters of different orders are realized. Also, a few combination 1-D lowpass filters having monotonic amplitude-frequency response are cascaded to realize 2-D monotonic lowpass filters of different orders