PROTEUS: A 40 nm Programmable General-Purpose Digital Compute-In-Memory Accelerator With eNVM and Hierarchical ISA for Versatile Edge AI
We present PROTEUS, an 18 mm2 programmable general-purpose digital compute-in-memory (GP-DCIM) accelerator integrating 4 Mb resistive random access memory (RRAM) and 2.6 Mb tensor static random access memory (SRAM) with a 32-bit hierarchical DCIM instruction set architecture (ISA). PROTEUS features fine-grained 1-D matrix tiling and a reconfigurable DCIM datapath/pipeline for near-100% memory utilization, supporting INT8/INT16/FP8/FP16 DCIM computations. PROTEUS unifies SRAM/RRAM dataflows and embeds nonvolatile micro-programs in RRAM to enable rapid switching among prestored kernels without incurring off-chip instruction feeds or RRAM rewrites. Fabricated in 40 nm ultra-low power (ULP) CMOS with foundry RRAM, PROTEUS delivers 702 GOPS throughput, 6.4 TOPS/W energy efficiency, and 0.039 TOPS/mm2 compute density. It is validated on ResNet-20, BERT-Tiny, MobileViT, GraphSAGE, and Vision Mamba, demonstrating versatility across CNN, Transformer, hybrid CNN-Transformer, graph neural network (GNN), and state-space model (SSM) workloads.