Nonlinear-phase maximally-flat lowpass FIR filter design

This paper reports a new analytic technique for the design of nonlinear-phase maximally-flat lowpass FIR filters. By subjecting the response magnitude and the group delay (individually) to differing numbers of flatness constraints, a new family of filters is obtained. With these filters, the delay can be reduced while maintaining relatively constant group delay in the passband, without significantly altering the response magnitude