General SPICE Models for Memristor and Application to Circuit Simulation of Memristor-Based Synapses and Memory Cells

Memristor had been ̄rst theorized nearly 40 years ago by Prof. Chua, as the fourth fundamental circuit element beside the three existing elements (Resistor, Capacitor and Inductor) but because no one has succeeded in building a memristor, it has long remained a theoretical element. Some months ago, Hewlett-Packard (hp) announced it created a memristor using a TiO2=TiO2 X structure. In this paper, the characteristics, structures and relations for the invented hp's memristor are brie°y reviewed and then two general SPICE models for the charge-controlled and °ux-controlled memristors are introduced for the ̄rst time. By adjusting the model parameters to the hp's memristor characteristics some circuit properties of the device are studied and then two important memristor applications as the memory cell in a nonvolatileRAM structure and as the synapse in an arti ̄cial neural network are studied. By utilizing the introduced models and designing the appropriate circuits for two most important applications; a nonvolatile memory structure and a programmable logic gate, circuit simulations are done and the results are presented.