Modeling of the Memristor in SPICE

IntroductionIntroductionIn 1971, professor Chua predicted the existence of the fourth circuit element – memristor [3]. The memristor is an element that connects magnetic flux to electric charge in the same way that resistor connects voltage to current, capacitor connects voltage to charge, and inductor connects flux to current [4].

ObjectiveObjectiveIn this paper, we explore different aspects of memristor modeling and present a new simulation program with integrated circuit of the recently physically implemented memristor.

DESIGN OF THE MEMRISTOR CIRCUITDESIGN OF THE MEMRISTOR CIRCUIT EXISTING MODELS: COMPARISON EXISTING MODELS: COMPARISON AND SUMMARYAND SUMMARY

ConclusionConclusion

Design EquationsDesign Equations

We presented a new SPICE model of the memristor. This proposed model could be a powerful tool for researchers and electrical engineers to design and experiment new circuits with memristors. In this work, we also analyzed linear and non-linear memristor device models. From our study, we observed that the non-linear model offer closer dynamic device characteristic representations when compared to the limited physical published results as opposed to the linear model.

ReferenceReference [1] A. Rak, G. Cserey, “Macromodeling of the Memristor in SPICE,” IEEE Trans. on Computer-Aided Design of Integrated Circuits and Systems, vol.29, no.4, April 2010. [2] Z. Biolek, D. Biolek, and V. Biolkov´a, “SPICE model of memristor with nonlinear dopant drift,” Radioengineering, vol. 18, no. 2, pp. 210–214, 2009. [3] L. Chua, “Memristor: The missing circuit element,” IEEE Trans. Circuit Theory, vol. 18, no. 5, pp. 507–519, Sep. 1971.

Abylay Satybaldy

In this section we present our nonlinear model of the memristor and design equations (formulas) which are given in order to deduce model parameters from physical parameters.

Figure 4. A) V-I hysteresis behavior B) Current versus time C) State variable as a function of time

The memristor (M1) used in circuit (Figure 2) was created as a new library and added to design. The memristor has three pins: 1(+), 2(-), and the 3 (state) We create an external input to be able to monitor the state as well. It consists of an DC voltage source (V=0.5V) and the resistance R2=1MΩ The circuit consist of a sine wave signal source with the frequency of 500Hz and the output resistance R1=1kΩ.

Figure 3. I−V hysteresis loop time for a proposed memristor model driven by ac SIN source signal

SIMULATION MEASUREMENTSSIMULATION MEASUREMENTSThe memristor based test circuit consisting of a sinusoidal voltage source was used for testing the simulation speed in PSPICE OrCAD 16.6 (OrCAD Capture, PSpice A/D). The key parameters of the memristor model were: Rset = 100Ω, Cmem= 90nF, Rstep = 1k Ω and Ron=100 Ω, Roff = 1 k Ω. The simulation step-size was 10us. We measured 10ms average computation time of a simulation step.

Figure1. Linear dopant drift model of the thin-film memristor [1]

Figure 2. Schematic diagram of our SPICE model

From the results, we observe that the I-V plot of non-linear model exhibit a more pointed signature compared to the linear model [2] Moreover , I(t) plot of non-linear model is sharper because of the usage of the window function. It is important to notice the state variable (1 – w/D) plots remain quite similar for both linear and non-linear models