Hardware implementation of a 15-channel filter bank

The filter bank concept is a frequently used method of spectral analysis in speech processing systems. This paper describes a concept and an implementation of a digital filter bank with only one multiplier/accumulator circuit. It contains 15 bandpass filters, five of which covering two octaves at the time. All filters are of FIR type with constant relative bandwidth and equal number of coefficients. Real time operation at a sampling rate of 12.3 kHz is achieved by taking advantage of the decimation technique. Using two banks of scratch pad memory, the coefficient´s symmetry is exploited to speed up the internal processing.