Biorthogonal exponentially modulated filter bank

This paper explores modulated filter banks (MFBs) utilizing polyphase domain analysis. The MFB theory offers a variety of configuration alternatives and to narrow down the diversity our emphasis is on critically sampled perfect reconstruction systems in odd-stacked configuration. Into this MFB subclass, we introduce biorthogonal exponentially modulated filter bank (EMFB). The biorthogonal EMFB is suitable for subband processing of complex-valued signals and the analysis-synthesis reconstruction delay is an adjustable parameter. The EMFB is represented with its polyphase components and we develop a unified framework for analyzing different classes of complex-valued filter banks, covering perfect reconstruction conditions and metrics for residual distortion effects. In addition, it is shown how the EMFB can be converted into even-stacked configuration through frequency shifting. This provides a link with the modified discrete Fourier transform filter bank, but even-stacked EMFB solves the subsignal handling in a simplified manner.