On the Sensitivity of Two-Channel IIR Filter Banks with Variable Crossover Frequency

In this paper, we investigate the sensitivities of the magnitude responses for the two classes of two-channel IIR filter banks. The term class I denotes the IIR filter pair implemented as a parallel connection of two all-pass filters, whereas class II stays for the tapped cascaded interconnection of two identical all-pass filters. A simple tuning scheme that shifts the crossover frequency of the start-up IIR half-band filter pair to the desired location has been introduced recently. In this paper, we concentrate on the effects, which appear when the finite-precision arithmetic is used to implement the tuning formulae. For the two classes of two-channel IIR filter banks, we demonstrate by means of examples the sensitivities of the magnitude frequency characteristics, and show the effects of those sensitivities to the accuracy of the tuning procedure.