# Memristor

Ideal memristor with nonlinear dopant drift approach

**Libraries:**

Simscape /
Foundation Library /
Electrical /
Electrical Elements

## Description

This block allows you to model an ideal memristor with a nonlinear dopant drift approach. The behavior of memristor is similar to a resistor, except that its resistance (also called memristance) is a function of the current that has passed through the device. The memristance is defined by two states, A and B, with some fraction of the device in one of those states at a given time.

The nonlinear dopant drift model, [1], is described with the following equations:

*V* =
*M*·*I*

*M* =
*ξ**·R*_{A}+(1 –
*ξ*)*·R*_{B}

$$\frac{d\xi}{dt}=\frac{I}{{Q}_{0}}{F}_{p}\left(\xi \right)$$

where

*V*is the voltage across the memristor.*M*is the memristance.*I*is the current entering the + terminal.*R*_{A}and*R*_{B}are the resistances of the A and B states, respectively.*ξ*is the fraction of the memristor in state A. A positive current from the + terminal to the - terminal increases*ξ*. Similarly, a positive current from the - terminal to the + terminal decreases*ξ*. The value of*ξ*is bounded by 0 and 1.*t*is time.*Q*_{0}is the total charge required to make the memristor transition from being fully in one state to being fully in the other state.*F*is a "window" function, which keeps_{p}(ξ)*ξ*in the window between 1 and 0, and therefore gives zero drift at the boundaries of the device.

The window function is

*F*_{p}(*ξ*) = 1 –
(2*ξ* –
1)^{2p}

where *p* is a positive integer. This function is modified when
*ξ* is close to either 0 or 1, to improve numerical
stability.

### Variables

To set the priority and initial target values for the block variables prior to simulation, use
the **Initial Targets** section in the block dialog box or Property
Inspector. For more information, see Set Priority and Initial Target for Block Variables.

Nominal values provide a way to specify the expected magnitude of a variable in a model.
Using system scaling based on nominal values increases the simulation robustness. Nominal
values can come from different sources, one of which is the **Nominal
Values** section in the block dialog box or Property Inspector. For more
information, see Modify Nominal Values for a Block Variable.

## Ports

### Conserving

## Parameters

## References

[1] Joglekar, Y. N., and S. J. Wolf. "The elusive memristor:
properties of basic electrical circuits."* European Journal of
Physics*. 30, 2009, pp. 661–675.

## Extended Capabilities

## Version History

**Introduced in R2016b**