Designing IIR filters with variable stopbands using SP method

In this paper, we propose a design method for variable IIR digital filters with changeable multifactors in the stopband using the successive projection (SP) method. The SP method uses less computer memory to design digital filters than semidefinite programming. The proposed variable IIR filter has piecewise high stopband attenuation in the stopband, and the filter varies stopband edge frequency, and both the frequency and its magnitude in the piecewise high attenuation. The filter coefficients are composed polynomial expression using variable parameters to vary the filter characteristics. Finally, we demonstrate effectiveness of the proposed method.