A practical method for designing FIR digital filters in the complex domain

A new method is presented for the design of FIR fillers in the complex domain. The method converts the complex approximation problem into an equivalent real nonlinear optimization problem, which is solved by successive linearization using an effective geometrical linearization technique. The method converges rapidly, and the solution has a guaranteed accuracy. It also has the flexibility of allowing addition of extra constraints such as constant group delay constraints and transition-band magnitude overshoot constraints. Numerical examples are presented to illustrate the performance of the method.