What are the characteristics of an elliptical filter?
Gradual passband rolloff with minimal stop-band ripple
Extremely flat response over its pass band with gradually rounded stop-band corners
Extremely sharp cutoff with one or more notches in the stop band✓Bonne réponse
Gradual passband rolloff with extreme stop-band ripple
Explication
The elliptic (Cauer) response places transmission zeros in the stop band, which show up as deep notches, and it gives the steepest possible cutoff for a given number of elements. The price is ripple in both the passband and the stop band.