NbO2-Based Frequency Storable Coupled Oscillators for Associative Memory Application

Oscillatory neural networks with nano-oscillators and synapse devices are a promising alternative to implement neuromorphic systems owing to its fast recognition speed and low power consumption. In this paper, we demonstrate a compact frequency storable oscillator using nanoscale two-terminal NbO
₂
insulator-metal-transition devices along with TaO
_x
-based resistive switching memory (RRAM) devices. By controlling RRAM resistance, we realized a wide range of analog oscillation frequencies. The synchronization window of two coupled oscillators, which is a key parameter for determining pattern recognition, increases with the increasing coupling capacitance and decreasing RRAM resistance of the reference oscillator. The simple device structure (metal-NbO
₂
-metal-TaO
_x
-metal), small device area (4F
²
), and frequency storability of NbO
₂
-based coupled oscillator device show a strong potential for future integrated neuromorphic device application.