Synthesis of digital filters by continued fractions is generally investigated. Several new canonic ladder realisations of a digital transfer function are presented, and the conditions for realisation are discussed. The new realisations are based on the applications of continued fraction expansions that proceed in terms ofAi+Bi2 andBjZ−1+Ajon an alternating basis. The resulting structures avoid the presence of delay-free loops and achieve a relatively small range of multiplier values. They are more versatile than the existing structures, allowing one to synthesise functions more readily. Furthermore, it will be shown that existing structures can be generated as special cases of the presented structures. Illustrative examples are provided.