Minimax Design of Two-Channel Nonuniform-Division Filterbanks Using IIR Allpass Filters.

The design of two-channel linear-phase nonuniform-division filter (NDF) banks' constructed by infinite impulse response (IIR) digital allpass filters (DAFS) in the sense of L_∞ error criteria is considered. First, the theory of two-channel NDF bank structures using two IIR DAFs is developed. Then, the design problem is appropriately formulated to result in a simple optimization problem. Utilizing a variant of Karmarkar's algorithm, we can efficiently solve the optimization problem through a frequency sampling and Iterative approximation method to find the coefficients for the HR DAFs. The resulting two-channel NDF banks can possess approximately linear-phase response without magnitude distortion. The effectiveness of the proposed technique is achieved by forming an appropriate Chebyshev approximation of a desired phase response and then to find Its solution from a linear subspace in a few Iterations. Several simulation examples are presented foi illustration and comparison. [ABSTRACT FROM AUTHOR]