Proposes an extension of the differential correction algorithm for simultaneous design of real and imaginary parts of IIR (infinite impulse response) transfer functions in minimax norm. The implementation of the proposed algorithm requires the iterative solution of a minimization problem having linear objective and quadratic constraints. The method is globally convergent and it can be proven to deliver stable IIR filters. Practical implementations of the algorithm compare very favorably with existing design tools. Actual operation is examined by means of filter design examples.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>