Compute-in-Memory with Emerging Nonvolatile-Memories: Challenges and Prospects

This invited paper surveys the recent progresses of compute-in-memory (CIM) prototype chip designs with emerging nonvolatile memories (eNVMs) such as resistive random access memory (RRAM) technology. 8kb to 4Mb CIM mixed-signal macros (with analog computation within the memory array) have been demonstrated by academia and industry, showing promising energy efficiency and throughput for machine learning inference acceleration. However, grand challenges exist for large-scale system design including the following: 1) substantial analog-to-digital (ADC) overhead; 2) scalability to advanced logic node limited by high write voltage of eNVMs; 3) process variations (e.g. ADC offset) that degrade the inference accuracy. Mitigation strategies and possible future research directions are discussed.