Models of memristors for SPICE simulations

Memristors are novel devices which can be used in applications such as memory, logic, analog circuits, and neuromorphic systems. Several memristor technologies have been developed such as ReRAM (Resistive RAM), MRAM (Magnetoresistance RAM), and PCM (Phase Change Memory). To design circuits with memristors, the behavior of the memristor needs to be described by a mathematical model. While the model for memristors should be sufficiently accurate as compared to the behavior of physical devices, the model must also be computationally efficient. Several models for memristors have been proposed - the linear ion drift model, the nonlinear ion drift model, the Simmons tunnel barrier model, and the ThrEshold Adaptive Memristor (TEAM) model. In this paper, the different memristor models are described and a Verilog-A implementation for these models, including the relevant window functions, are presented. These models are suitable for EDA tools such as SPICE.