In this paper, an improved method for the design of two-channel quadrature mirror filter (QMF) bank with linear phase characteristics is presented. A prototype low-pass filter of the QMF bank is implemented using polyphase components. The design technique optimizes the value of the prototype filter coefficients to match the ideal transfer function of the filter bank using Eigenvalue-Eigenvector approach without any matrix inversion. The optimization is carried out to minimize an objective function which is a linear combination of pass-band error and stop-band residual energy of the low-pass analysis filter of the filter bank, and square error of the distortion transfer function of the QMF bank at the quadrature frequency. The simulation results show that the proposed method requires less computational time and number of iterations with similar performance of Peak Reconstruction Error (PRE) in comparison to already existing methods.

Quadrature Mirror Filter (QMF) banks are comprehensively used for sub-band coding, where the signal is split into two or more sub-bands in the frequency domain, so that each sub-band signal can be processed in an independent manner and sufficient compression may be achieved (Vaidyanathan, 1993). Two-channel QMF bank finds applications in various signal processing fields, such as design of wavelet bases (Chan et al., 2004), image coding (Smith and Eddins, 1990; and Xia and Jiang, 1995), digital trans-multiplexers (Bellanger and Daguet, 1974), discrete multi-tone modulation systems (Vetterli, 1984), ECG signal compression (Afonso et al., 1999), antenna systems (Chandran, 2003), digital audio industry (Painter and Spanias, 2000), biomedical signal processing (Kumar et al., 2010) and wireless personal communication (Vaidyanathan, 1990; and Liu et al., 2000). Efficient design of two-channel QMF bank, while keeping minimum dimensions, is an important task in the field of multirate signal processing. Therefore, various unconstrained and constrained optimization techniques (Johnston, 1980; Jain and Crochiere, 1984; Chen and Lee,

Electrical and Electronics Engineering Journal, Eigen design, Polyphase structure, Number of iterations, Sub-band coding