LUT-LLM: Efficient Large Language Model Inference with Memory-based
  Computations on FPGAs
Authors: name: Zifan He; name: Shengyu Ye; name: Rui Ma; name: Yang Wang; name: Jason Cong
Published: 2025-11-09 01:17:08

Abstract: The rapid progress of large language models (LLMs) has advanced numerous
applications, yet efficient single-batch inference remains vital for on-device
intelligence. While FPGAs offer fine-grained data control and high energy
efficiency, recent GPU optimizations have narrowed their advantage, especially
under arithmetic-based computation. To overcome this, we leverage FPGAs'
abundant on-chip memory to shift LLM inference from arithmetic- to memory-based
computation through table lookups. We present LUT-LLM, the first FPGA
accelerator enabling 1B+ LLM inference via vector-quantized memory operations.
Our analysis identifies activation-weight co-quantization as the most effective
scheme, supported by (1) bandwidth-aware parallel centroid search, (2)
efficient 2D table lookups, and (3) a spatial-temporal hybrid design minimizing
data caching. Implemented on an AMD V80 FPGA for a customized Qwen 3 1.7B
model, LUT-LLM achieves 1.66x lower latency than AMD MI210 and 1.72x higher
energy efficiency than NVIDIA A100, scaling to 32B models with 2.16x efficiency
gain over A100.