Stateful Logic Using Phase Change Memory

Stateful logic is a digital processing-in-memory (PIM) technique that could address von Neumann memory bottleneck challenges while maintaining backward compatibility with standard von Neumann architectures. In stateful logic, memory cells are used to perform the logic operations without reading or moving any data outside the memory array. Stateful logic has been previously demonstrated using several resistive memory types, mostly resistive RAM (RRAM). Here, we present a new method to design stateful logic using a different resistive memory-phase change memory (PCM). We propose and experimentally demonstrate four logic gate types (NOR, IMPLY, OR, NIMP) using commonly used PCM materials. Our stateful logic circuits are different than previously proposed circuits due to the different switching mechanisms and functionality of PCM compared to RRAM. Since the proposed stateful logic forms a functionally complete set, these gates enable the sequential execution of any logic function within the memory, paving the way to PCM-based digital PIM systems.