Perfect-Reconstruction Biorthogonal Cosine-Modulated Filter Banks with Fixed-Point Arithmetic

This paper describes the implementation of biorthogo-nal cosine-modulated filter banks on fixed-point arith-metic digital signal processors. The proposed imple-mentation has the property that the overall filter bank keeps the perfect reconstruction property despite coef-ficient quantization, overflow, and rounding of interme-diate results. The realization of the prototype filter is based on a factorization into zero-delay and maximum-delay matrices. We demonstrate how the frequency se-lectivity of the filter bank and the coding gain changes with the available wordlength of the fixed-point imple-mentation and the dynamic range of the input signal. For speech signals it turns out that overflow and round-ing errors hardly affect the frequency selectivity of the filters if the input signal uses only 75% of the available dynamic range.