Optimizing ADC Utilization through Value-Aware Bypass in ReRAM-based DNN Accelerator

ReRAM-based Processing-In-Memory (PIM) has been widely studied as a promising approach for Deep Neural Networks (DNN) accelerator with its energy-efficient analog operations. However, the domain conversion process for the analog operation requires frequent accesses to power-hungry Analog-to-Digital Converter (ADC), hindering the overall energy efficiency. Although previous research has been suggested to address this problem, the ADC cost has not been sufficiently reduced because of its unsuitable approach for ReRAM. In this paper, we propose mixed-signal-based value-aware bypass techniques to optimize the ADC utilization of the ReRAM-based PIM. By utilizing the property of bit-line (BL) level value distribution, the proposed work bypasses the redundant ADC operations depending on the magnitude of value. Evaluation results show that our techniques successfully reduce ADC access and improve overall energy efficiency by 2.48 × -3.07 × compared to ISAAC.