Notes on Digital Signal Processing: Practical Recipes for Design, Analysis and Implementation

Note 42. Elliptic Filters

Elliptic filters have ripples in both the passband and the stopband, and generally have better selectivity than Chebyshev filters of comparable orders. Determining the transfer function is somewhat more complicated for an elliptical filter than it is for Butterworth or Chebyshev filters. The process begins with the specification of four parameters, which are depicted in Figure 42.1.

A_p = maximum passband loss, dB

A_s = minimum stopband loss, dB

ω_p = passband cutoff frequency

ω_s = stopband cutoff frequency

Figure 42.1. Magnitude response showing parameters used to specify an elliptical filter.

The minimum filter order ...