Diseño óptimo de transformadores de Hilbert sin multiplicadores con base en el uso de un subfiltro simple

Very sharp Hilbert transformers can be efficiently designed by using the Frequency Transformation (FT) method, where a basic building block, formed with two identical subfilters, is repeatedly implemented. The number of the building blocks used is obtained from the length of a prototype filter. Recently, the Pipelining-Interleaving (PI) technique has been applied to avoid the repetitive use of the basic building block, reducing the number of required coefficients. However, the design of the subfilter and the prototype filter is based on a heuristic search. In this paper, we present an optimal method to design the subfilter and prototype filter minimizing the number of coefficients. Additionally, an alternative structure, which permits to use a unique subfilter inside the basic building block, is presented. As a result, the total number of coefficients is decreased. Two examples show that the proposed design method is optimal, simple, and efficient.