David Báez-López E. Jimenez-Lopez A modified inverse-Chebyshev filter with an all positive elements ladder passive realization. 49-52 1999 conf/iscas/1999 ISCAS (6) http://doi.ieeecomputersociety.org/10.1109/ISCAS.1999.780092 db/conf/iscas/iscas1999-6.html#Baez-LopezJ99