N型局部有源忆阻器的神经形态行为

Neuromorphic behaviors of N-type locally-active memristor

局部有源忆阻器(locally-active memristor,LAM)凭借其高集成度、低功耗和局部有源特性等优点,在神经形态计算领域显示出巨大的潜力.本文提出了一种简单的N型LAM数学模型,通过揭示其非线性动力特性,设计了N型LAM神经元电路.采用Hopf分岔、数值分析等方法定量研究了该电路的动力学行为,成功模拟了多种神经形态行为,包括全或无行为、尖峰、簇发、周期振荡等.并利用该神经元电路结构模拟了生物触觉神经元的频率特性.仿真结果表明:当输入信号幅值低于阈值时,神经元电路输出信号的振荡频率与输入信号强度呈正相关(即兴奋状态),并在阈值处达到最大值.随后,继续增大激励强度,振荡频率则逐渐降低(即保护性抑制状态).最后,设计了N型LAM硬件仿真器,并完成了人工神经元电路的硬件实现,实验结果与仿真结果、理论分析相一致,验证了该N型LAM具备的神经形态行为.

Owing to the advantages of high integration,low power consumption and locally active characteristics,locally-active memristor(LAM)has shown great potential applications in neuromorphic computing.To further investigate the neuromorphic dynamics of LAMs,a simple N-type LAM mathematical model is proposed in this work.By analyzing its voltage-current characteristic and small-signal equivalent circuit,a neuron circuit based on the N-type LAM is designed,where a variety of neuromorphic behaviors are successfully simulated,such as“all-or-nothing”behavior,spikes,bursting,periodic oscillation,etc.Moreover,Hopf bifurcation theory and numerical analysis method are used to study the dynamics of the circuit quantitatively.Then,an artificial tactile neuron and its frequency characteristics are presented by using the proposed neuron circuit topology.The simulation results show that when the amplitude of the input signal is lower than the threshold,the oscillation frequency of the output signal of the artificial neuron circuit is positively correlated with the intensity of the input signal,and reaches a maximum value at the threshold.The above frequency characteristics are consistent with those of the exciting state of biological sensory system.Subsequently,if the incentive intensity continues to increase,the oscillation frequency will gradually decrease,corresponding to the protective inhibition behavior.Finally,the physical circuit of the N-type LAM,and artificialneuron circuit are realized.The experimental results accord well with the simulation results and theoreticalanalyses,manifesting the practicability of the N-type LAM model and the feasibility of artificial neuron circuit.