A new class of approximately linear phase filters

This paper presents a class of infinite impulse response (IIR) filters which have approximately linear phase response in their pass bands. The new filters provide better magnitude response although slightly worse phase linearity for a given order and transition bandwidth than previous designs. They can then be used as an alternative to those designs when we want some degree of phase linearity but the magnitude response and processing delay are more important. Some design examples are presented in which the new filters are compared with previous designs. Finally some structures for the efficient implementation of the filters are also discussed.