Memristors for energy-efficient new computing paradigms

In this Review, memristors are examined from the frameworks of both von Neumann and neuromorphic computing architectures. For the former, a new logic computational process based on the material implication is discussed. It consists of several memristors which play roles of combined logic processor and memory, called stateful logic circuit. In this circuit configuration, the logic process flows primarily along a time dimension, whereas in current von Neumann computers it occurs along a spatial dimension. In the stateful logic computation scheme, the energy required for the data transfer between the logic and memory chips can be saved. The non-volatile memory in this circuit also saves the energy required for the data refresh. Neuromorphic (cognitive) computing refers to a computing paradigm that mimics the human brain. Currently, the neuromorphic or cognitive computing mainly relies on the software emulation of several brain functionalities, such as image and voice recognition utilizing the recently highlighted deep learning algorithm. However, the human brain typically consumes approximate to 10-20 Watts for selected human-like tasks, which can be currently mimicked by a supercomputer with power consumption of several tens of kilo- to megawatts. Therefore, hardware implementation of such brain functionality must be eventually sought for power-efficient computation. Several fundamental ideas for utilizing the memristors and their recent progresses in these regards are reviewed. Finally, material and processing issues are dealt with, which is followed by the conclusion and outlook of the field. These technical improvements will substantially decrease the energy consumption for futuristic information technology.D.S.J. and K.M.K. contributed equally to this work. CSH acknowledges support from the Global Research Laboratory Program (No. NRF-2012K1A1A2040157) of the Ministry of Science, ICT, and Future Planning, and the National Research Foundation of Korea (NRF) grant (No. NRF-2014R1A2A1A10052979) from the Republic of Korea