Architecture of neural processing unit for deep neural networks

Deep Neural Networks (DNNs) have become a promising solution to inject AI in our daily lives from self-driving cars, smartphones, games, drones, etc. In most cases, DNNs were accelerated by server equipped with numerous computing engines, e.g., GPU, but recent technology advance requires energy-efficient acceleration of DNNs as the modern applications moved down to mobile computing nodes. Therefore, Neural Processing Unit (NPU) architectures dedicated to energy-efficient DNN acceleration became essential. Despite the fact that training phase of DNN requires precise number representations, many researchers proved that utilizing smaller bit-precision is enough for inference with low-power consumption. This led hardware architects to investigate energy-efficient NPU architectures with diverse HW-SW co-optimization schemes for inference. This chapter provides a review of several design examples of latest NPU architecture for DNN, mainly about inference engines. It also provides a discussion on the new architectural researches of neuromorphic computers and processing-in-memory architecture, and provides perspectives on the future research directions.