The sharpest possible transition for a given filter order
Optimal Transition: Elliptic filters achieve the sharpest possible transition between passband and stopband for a given filter order - no other filter can do better.
Equiripple Everywhere: Unlike Butterworth (flat) or Chebyshev (ripple in one band), elliptic filters have equiripple in BOTH the passband and stopband.
Trade-off: The price for the sharpest cutoff is ripple in both bands and significant phase distortion. Not suitable when linear phase is required.
| Filter Type | Passband | Stopband | Transition | Phase |
|---|---|---|---|---|
| Butterworth | Maximally Flat | Monotonic | Widest | Best |
| Chebyshev I | Equiripple | Monotonic | Medium | Medium |
| Chebyshev II | Monotonic | Equiripple | Medium | Medium |
| Elliptic | Equiripple | Equiripple | Narrowest | Worst |