DESIGN OF DIGITAL ALLPASS FUNCTIONS WITH SPECIFIED PHASE TOLERANCES

In this paper, a new method is introduced for designing IIR digital al lpass functions with specified phase tolerances. Since the phase error characteristics subject to the desired phase response have been speci fied in the interest bands, the phase design of digital allpass functi ons in the form of a linear programming problem can be formulated by u sing the Remez exchange algorithm. Then the linear equations are solve d to obtain a set of filter coefficients and the optimal coefficients in the Chebyshev sense can easily be obtained through a few iterations . By appropriately selecting the initial extremal frequencies, the pro posed design algorithm always converges, and the phase error character istics can be arbitrarily specified. Finally, some design examples are presented to demonstrate the effectiveness of the proposed method.