A floating-gate-MOS-based multiple-valued associative memory

A digit-serial, multiple valued associative memory VLSI for high-speed information search is presented. Input and output data of a processing element (PE) in the VLSI are directly encoded by appropriate multiple-valued digits, respectively, so that search operations are efficiently described by the combination of a multiple-valued down literals and pass gates. Moreover, multiple-valued memory information is stored in each PE by programming the threshold of the down literal which can be easily implemented using special MOS transistors, called floating-gate MOS transistors. It is demonstrated that the number of interconnections and transistors in the 5-valued associative memory can be reduced to 25% and 53%, respectively, in comparison with the corresponding binary implementation.