Design Method for FIR Filter with Variable Multiple Elements of Stopband Using Genetic Algorithm

In general, a design of digital filters is used computers having relatively long bit length. On the other hand, filter coefficients could be rounded to the specified number of bit length, when digital filters are implemented embedded equipment. Then, filter characteristics may become degradation. It is difficult to realize high accuracy measurement. In this paper, we propose a finite bit length design method of variable digital filters with variable multiple elements of stopband. Proposed variable filter's coefficients are approximated by polynomial using variable parameters, and the polynomial coefficients are composed by finite bit length. The design problem is multiple objective optimization due to variable multiple elements. Then, we propose individual evaluation method for design variable digital filters using a genetic algorithm. Finally, effectiveness of the proposed method is shown by a design example.