Simplified procedures for quasi-equiripple IIR filter design

Simplified procedures for quasi-equiripple infinite-impulse response (IIR) filter design are proposed. The procedures can be applied in designs where the number of poles is low compared to the number of zeros. The design is initialized with an IIR filter optimizing a least squares criterion. In the simplified procedures, namely simplified iterative reweighting and fixed poles least pth design, the poles of the filter are kept fixed in the succeeding iterative optimization of the numerator. The simplified designs are compared to complete iterative reweighting, where complete IIR design is performed at each iteration. The simplified design is much faster with very small departure from optimality.