Construction of 2‐D digital filters using all‐pass networks with complex coefficients
久道 豊嶋, Shinichi Takahashi · Electronics and Communications in Japan (Part III Fundamental Electronic Science) · 1991
Abstract Several methods have been presented recently for constructing the one‐dimensional IIR digital filter by combining all‐pass networks. It is known that the filter composed of the all‐pass networks has a better computational efficiency and also low coefficient sensitivity due to the structural boundaries. In addition to the one‐dimensional filters, a construction of the two‐dimensional filter based on the all‐pass network has also been proposed. A problem in that method, however, is the restriction on the realizable characteristics. This paper attempts to overcome that problem, and proposes a new construction of the two‐dimensional digital filter using the all‐pass network. The new approach employs the complex coefficient all‐pass network instead of the conventional real‐coefficient all‐pass network. By this approach, the degree of freedom in the design is enhanced, and the characteristics which have been difficult or impossible to realize in the case of the real coefficient filters, are now made realizable.