Quaternary universal-literal CAM for cellular logic image processing

A new quaternary content-addressable memory (CAM) is proposed for cellular logic image processing. A universal literal in CAM cell is used to compare a quaternary input value with various template patterns simultaneously. The universal-literal cell circuit with quaternary data storage capability can be implemented by just four floating-gate MOS transistors, since the cell function is performed by simple threshold operations together with logic-value conversion. As a result, the effective cell area in the proposed CAM array is reduced to 32 percent in comparison with that in a corresponding binary CAM-based implementation.