Noise reduction in Digital IIR Filters by finding optimum arrangement of second-order sections

This paper proposed a new method to obtain an optimum arrangement of the second-order sections in digital IIR filters in order to reduce the steady-state output noise variance when the model of filter is considered as the cascade connections of second-order sections. The proposed method is based on minimizing the external normalization coefficients in each section. According to the computational complexity of obtaining the output noise variance, our method can reach to an optimal arrangement recursively, without computing the output noise variance. Experimental results show the accuracy and simplicity of our new method when it is compared with MATLAB filter design toolbox (FDT).