A Scalable and Energy-Efficient Processing-in-Memory Architecture for Gen-AI

Large language models (LLMs) have achieved high accuracy in diverse NLP and computer vision tasks due to self-attention mechanisms relying on GEMM and GEMV operations. However, scaling LLMs poses significant computational and energy challenges, particularly for traditional Von-Neumann architectures (CPUs/GPUs), which incur high latency and energy consumption from frequent data movement. These issues are even more pronounced in energy-constrained edge environments. While DRAM-based near-memory architectures offer improved energy efficiency and throughput, their processing elements are limited by strict area, power, and timing constraints. This work introduces CIDAN-3D, a novel Processing-in-Memory (PIM) architecture tailored for LLMs. It features an ultra-low-power Neuron Processing Element (NPE) with high compute density (#Operations/Area), enabling efficient in-situ execution of LLM operations by leveraging high parallelism within DRAM. CIDAN-3D reduces data movement, improves locality, and achieves substantial gains in performance and energy efficiency—showing up to $1.3\times $ higher throughput and $21.9\times $ better energy efficiency for smaller models, and $3\times $ throughput and $71\times $ energy improvement for large decoder-only models compared to prior near-memory designs. As a result, CIDAN-3D offers a scalable, energy-efficient platform for LLM-driven Gen-AI applications.