HR³AM: A Heat Resilient Design for RRAM-based Neuromorphic Computing

RRAM based accelerators have been widely adopted in many neuromorphic designs. However, RRAM cells are sensitive to temperature, which changes RRAM’s conductance. Such heat-induced interference can significantly decrease the computational accuracy because values are functions of RRAM conductance. In this paper, we propose HR ³ AM, a heat resilience design, which improves accuracy and optimizes the thermal distribution of RRAM based neural network accelerators. HR ³ AM consists of two key mechanisms: bitwidth downgrading and tile pairing. Bitwidth downgrading re-represents weights by shifting the conductance to improve the network inference accuracy. Tile pairing matches hot crossbar units with pre-defined idle units to mitigate high-temperature issues. We evaluated HR ³ AM on four real world neural network models. Results show that HR ³ AM improves classification accuracy by up to 41.8% compared with current state-of-the-art designs. For thermal optimization, HR ³ AM effectively decreases the maximum temperature by 6.2K and average temperature by 6K.