The Elliptic Filter

A filter when a sharp roll-off is all that matters.. Superimpose a Chebychev Type 1 and a Chebychev type 2 and this is what you get. In reality the Butterworth, Chebychev type 1 and Chebychev type 11 are subsets of the Elliptic (Cauer, Zolotrov) filter, as the table shows