Computationally efficient uniform single rate FIR DFT filter banks
G. T. Sundar Rajan, SK Mitra, P. Vaidyanathan, Yrjo A. Neuvo · 1st IASTED International Symposium on Signal Processing and its Applications · 1987
Most uniform filter bank structures proposed in the literature (see [3]) have so far utilized multirate techniques. The basic complex modulator model [3] of the filter bank structure involves the replication of the prototype lowpass filter in the N paths. In each path, the input signal is modulated to the appropriate frequency before being lowpass-filtered. This is equivalent to bandpass filtering the original input signal. The complex modulator model leads to the complex bandpass filter interpretation where the modulation is incorporated into the lowpass filters. Now, the same input signal is filtered by a bank of N bandpass filters of equal bandwidth and with complex coefficients. In the polyphase decomposition of the complex bandpass interpretation, the coefficients of the polyphase filters are derived from the prototype lowpass filter. Sampling rate changes are utilized to effect the necessary modulation and demodulation of the signals in the different channels. The modulation of the frequency response in each branch can also be provided by the DFT bank, leading to the DFT filter bank realization. Due to the aliasing in the analysis filters, separate synthesis filters have to be designed to remove this aliasing in the reconstruction stage. For a total or error-free reconstruction of the original wideband input signal, i.e., for no magnitude and phase errors, the overall analysis-synthesis transfer function has to be equal to a delay.