Tempus Core: Area-Power Efficient Temporal-Unary Convolution Core for Low-Precision Edge DLAs

TL;DR

Tempus Core introduces a scalable unary-based convolution core that significantly reduces area and power consumption in deep learning accelerators, enabling efficient edge AI inference with minimal hardware overhead.

Contribution

This work presents Tempus Core, a novel unary-based PE array design that integrates seamlessly with existing DLAs, offering substantial improvements in area, power, and throughput for low-precision neural network inference.

Findings

Achieves 59.3% area and 15.3% power reduction over NVDLA's CMAC at 45nm CMOS.

Delivers 5x and 4x throughput improvements for INT8 and INT4 precisions respectively.

Requires only 0.017 mm^2 die area and 6.2mW power for a 16x4 PE array at INT4 precision.

Abstract

The increasing complexity of deep neural networks (DNNs) poses significant challenges for edge inference deployment due to resource and power constraints of edge devices. Recent works on unary-based matrix multiplication hardware aim to leverage data sparsity and low-precision values to enhance hardware efficiency. However, the adoption and integration of such unary hardware into commercial deep learning accelerators (DLA) remain limited due to processing element (PE) array dataflow differences. This work presents Tempus Core, a convolution core with highly scalable unary-based PE array comprising of tub (temporal-unary-binary) multipliers that seamlessly integrates with the NVDLA (NVIDIA's open-source DLA for accelerating CNNs) while maintaining dataflow compliance and boosting hardware efficiency. Analysis across various datapath granularities shows that for INT8 precision in 45nm CMOS, Tempus Core's PE cell unit (PCU) yields 59.3% and 15.3% reductions in area and power consumption, respectively, over NVDLA's CMAC unit. Considering a 16x16 PE array in Tempus Core, area and power improves by 75% and 62%, respectively, while delivering 5x and 4x iso-area throughput improvements for INT8 and INT4 precisions. Post-place and route analysis of Tempus Core's PCU shows that the 16x4 PE array for INT4 precision in 45nm CMOS requires only 0.017 mm^2 die area and consumes only 6.2mW of total power. We demonstrate that area-power efficient unary-based hardware can be seamlessly integrated into conventional DLAs, paving the path for efficient unary hardware for edge AI inference.