Flexible Structure for Oversampled Filter Banks
Luyun Wang, Ronggang Qi, Guoan Bi · 2017
Commonly used polyphase FFT based filter banks are a class of maximally decimated filter banks where the filter bank decimation factor is the same as the number of frequency channels. Many practical applications often needs non-maximally decimated filter banks, whose outputs are oversampled, where the decimation factor is smaller than the number of channels. Compared to the maximally decimated filter banks, the non-maximally decimated filter bank requires a prototype filter to possess a wide transitional bandwidth, which effectively reduces the computational complexity. This paper presents a polyphase FFT based structure of the non-maximally decimated filter bank. Similar to the one for maximally decimated filter bank, the proposed structure, composed of polyphaser filters and a FFT computation, is computationally efficient. Furthermore, the proposed structure can be also flexibly reconfigured to deal with other number of channels without the need to redesign the prototype filter used in the structure.