Elliptic filter design for a class of generalized halfband filters

Abstract

In multirate processing, symmetric finite impulse response halfband filters constitute an important class of filters that are useful for sampling rate alteration by a factor of two. Generalizing the notion of halfband filters to include infinite impulse response filters, a class of generalized halfband filters is examined and its properties are studied. The filters are efficient and have low roundoff noise. A filter design program has been developed to design a special class of elliptic filters taking into account restrictions due to the generalized halfband characteristics. The procedure adapts the results of elliptic filter design [10] to this special case. It is shown that if the passband and stopband edge frequencies are related, then these filters are computationally efficient even when no sampling rate change is needed.