Synthesis of Multivalued Multithreshold Functions for CCD Implementation

Basic multivalued building blocks constructed using CCD (charge-coupled devices) technology are presented. They are used to realize simple threshold functions. Existing techniques for decomposition of multivalued multithreshold functions into simpler subfunctions are reviewed. Usage of the CCD technology in implementation of these subfunctions is discussed. Two new decomposition techniques are proposed. Their aim is to obtain realizations that are better suited to CCD technology in terms of the maximum number of thresholds per element and the generation of negative weights. Synthesis techniques based on the proposed decompositions are presented and compared. Although 4-valued logic functions are stressed, the techniques are, in principle, applicable to functions of any radix.