Design of selective linear phase filters using classical filter transfer functions

This paper reviews the exact and approximate linear phase IIR filter designs based on the classical approximating functions (elliptic, Butterworth and Chebyshev type functions) and the use of various processing techniques. Using all-pass IIR subfilters obtained from the minimal phase solution, it is possible to implement a causal filter which exhibits simultaneously approximate constant amplitude response and exact or approximate linear phase response.