A new approach to the design of QMF banks

New L₂ objective functions for the design of quadrature-mirror-filter (QMF) banks are proposed. They are based on the derivative information of the reconstruction error. Simple and explicit matrix-form expressions for the proposed objective functions are derived. An efficient design method is proposed by incorporating a separability technique into the derived optimality conditions on prototype filters. The proposed method only needs to solve linear equations iteratively without nonlinear optimization. Design examples demonstrate that good low-delay QMF banks and linear-phase QMF banks can be obtained after a few iterations. Compared to the conventional approach, the new approach leads to QMF banks with larger stopband attenuation and smaller reconstruction errors