Two new two-pair structures for the realization of digital filters in the pure ladder form

Recently, Mitra, Kamat and Huey ("Cascaded lattice realization of digital filters," Int. J. Circuit meory Appl vol. 5, pp 3-11, 1977) have presented a new canonic realization method using the two-pair concept which leads to structures with pure ladder forms. This letter presents two new two-pair structures which allow one to synthesize digital transfer functions and which have identical properties to those proposed in that work.