High Frequency Response of Non-Volatile Memristors

Recent Advances and Future Prospects for Memristive Materials, Devices, and Systems

“…It can be observed that the memristor state experiences an insignificant net change Δ x n over the course of each cycle n of a high-frequency excitation signal during the transient phase of its oscillation. According to the mathematical analyses introduced in ref and ref , which were supported by the afore-described behavioral observations, the value of x̅ over each input cycle of a purely-AC periodic high-frequency voltage stimulus v ( t ), characterized by a very small period T , can be related to the value of Δ x over the same cycle through the following analytical equation: The functions g (+) (·) and g (−) (·) ( g (+) (·) ≠ g (−) (·)) are sign-invariant functions with opposite signs, modeling the device switching kinetics in the positive and negative stimulation cases, respectively. The moment at which transients decay to zero, the time-waveform of x becomes periodic, oscillating about x̅ s with a negligible peak-to-peak amplitude (see the inset in Figure b).…”

“…Finally, it should be noted that the methodologies described in this manuscript are not restricted to the specific TaO x memristor mathematical description, which represents the object of investigation here, but can be applied to any first-order sign-invariant nonvolatile memristor DAE set model, irrespective of the expression for its state evolution function, as explained thoroughly in refs − . Concluding, even though the results discussed in ref and ref are based solely on theoretical studies, it is anticipated that they shall inspire the development of programming algorithms and/or methods for real-world nonvolatile memristors in the years to come.…”

“…Depending on its switching sensitivity to input level and polarity, as well as its memory state(s), a highly nonlinear dynamical process determines the input-induced response of a real-world nonvolatile memristor. The recent research works in ref and ref , demonstrated how a system- and circuit-theoretic analysis of a nonlinear system, such as the memristor, enables to draw a comprehensive picture for its response to input/initial condition combinations of interest to the application at hand. In particular, the mechanisms underlying the resistance switching phenomenon that occur in a TaO x -based nanodevice, manufactured and modeled in Hewlett-Packard (HP) Laboratories, when stimulated with high-frequency AC periodic inputs, were elucidated on the basis of deep circuit-theoretic study.…”

“…But what does a high frequency periodic input mean in terms of the memristor response? Quoting the definition provided in ref : “ A high-frequency periodic input induces a solution waveform of the device state, which, after some finite time, becomes periodic with such a small peak-to-peak amplitude that the resulting device current–voltage locus exhibits no apparent hysteresis. ”…”

“…Importantly, eq describes the condition for the emergence of the fading memory phenomenon in memristors, − based on which the steady-state time-response of the state variable x ( t ), depends on the characteristics of the voltage input v ( t ), but not on the initial memristor state x 0 (see Figure d, e). Through eq , the theoretical investigation performed in ref and ref provided a mathematical proof for the fading memory phenomenon in resistive switches that exhibit asymmetric switching kinetics with respect to the input polarity. The predictive power of eqs and was validated through a series of simulation experiments, utilizing periodic inputs with square-wave, sinusoidal, and triangle shapes.…”