Analog–Digital Hybrid Memristive Devices for Image Pattern Recognition with Tunable Learning Accuracy and Speed
Ya Lin, Cong Wang, Yanyun Ren, Zhongqiang Wang, Haiyang Xu, Xiaoning Zhao, Jiangang Ma, Yichun Liu
Brain‐inspired memristive artificial neural networks (ANNs) have been identified as a promising technology for pattern recognition tasks. To optimize the performance of ANNs in various applications, a recognition system with tunable accuracy and speed is highly desirable. A single WO3−x‐based memristor is presented in which analog and digital resistive switching (A‐RS and D‐RS) coexist according to a selectively executed forming process. The A‐RS and D‐RS mechanisms can be attributed to the modulation of the Schottky barrier on the interface and the formation/rupture of conducting filaments inside the film, respectively. More importantly, a new analog–digital hybrid ANN is developed based on the coexistence of A‐RS and D‐RS in the WO3−x memristor, enabling tunable learning accuracy and speed in pattern recognition. The spike‐timing‐dependent plasticity learning rules, as a learning base for image pattern recognition, are demonstrated using A‐RS and D‐RS devices with obviously different fluctuations and rates of change. The learning accuracy/speed can be improved by increasing the proportion of A‐RS/D‐RS in the crossbar array. A convenient method is provided for selecting an optimized pattern recognition scheme to meet different application situations.