Fig. 1. (Color online) (a) Schematic diagram of a typical artificial neural network. (b) Circuit implementation of the oscillation neuron with a TS device.

Fig. 2. (Color online) (a) TEM image of the Ag NDs TS device. (b) Schematic illustration of the threshold switching process in the device. (c) Typical current–voltage (I–V) curves for the Ag NDs TS device. (d) Cumulative probability of V_th and V_hold distributions for the Ag NDs TS device. (e) Endurance test of the Ag NDs TS device with over 10⁸ cycles. (f) Measured oscillation waveform of the oscillation neuron.

Fig. 3. (Color online) (a) Oscillation waveforms of the oscillation neuron with different V_in when R_L = 50 kΩ, C_L = 750 pF. (b) The oscillation frequency as a function of V_in. (c) Oscillation waveforms of the oscillation neuron with different R_L when V_in = 1.2 V, C_L = 750 pF. (d) The oscillation frequency as a function of R_L.

Fig. 4. (Color online) The oscillation frequency as a function of the RRAM crossbar array size under different on/off ratios of the TS device.

Fig. 5. (Color online) (a) The oscillation frequency distribution under different C_V. (b) The oscillation frequency distribution of different R_L when C_V = 7% (top panel) and C_V = 30% (bottom panel).

Fig. 6. (Color online) (a) The structure of MLP neural network. (b) Simulation results of the MNIST recognition accuracy loss as a function of the variability of the TS device.