Compute-in-Memory Chips for Deep Learning: Recent Trends and Prospects

Compute-in-memory (CIM) is a new computing paradigm that addresses the memory-wall problem in hardware accelerator design for deep learning. The input vector and weight matrix multiplication, i.e., the multiply-and-accumulate (MAC) operation, could be performed in the analog domain within memory sub-array, leading to significant improvements in throughput and energy efficiency. Static random access memory (SRAM) and emerging non-volatile memories such as resistive random access memory (RRAM) are promising candidates to store the weights of deep neural network (DNN) models. In this review, firstly we survey the recent progresses in SRAM and RRAM based CIM macros that have been demonstrated in silicon. Then we discuss general design challenges of the CIM chips including analog-to-digital conversion (ADC) bottleneck, variations in analog compute, and device non-idealities. Next we introduce the DNN+NeuroSim benchmark framework that is capable of evaluating versatile device technologies for CIM inference and training performance from software/hardware co-design's perspective.