Chin. Phys. B Vol. 22, No. 8 (2013) 088501
The design and simulation of a titanium oxide memristor-based
programmable analog filter in a simulation program with
integrated circuit emphasis
∗
Tian Xiao-Bo(田晓波)
†
and Xu Hui(徐 晖)
Embedded System and Solid-State Engineering Technology Center, School of Electronic Science and Engineering,
National University of Defense and Technology, Changsha 410073, China
(Received 31 October 2012; revised manuscript received 22 December 2012)
In many communication and signal routing applications, it is desirable to have a programmable analog filter. Ac-
cording to this practical demand, we consider the titanium oxide memristor, which is a kind of nano-scale electron device
with low power dissipation and nonvolatile memory. Such characteristics could be suitable for designing the desired filter.
However, both the non-analytical relation between the memristance and the charges that pass through it, and the changeable
V –I characteristics in physical tests make it difficult to accurately set the memristance to the target value. In this paper, the
conductive mechanism of the memristor is analyzed, a method of continuously programming the memristance is proposed
and simulated in a simulation program with integrated circuit emphasis, and its feasibility and compatibility, both in simu-
lations and physical realizations, are demonstrated. This method is then utilized in a first-order active filter as an example to
show its applications in programmable filters. This work also provides a practical tool for utilizing memristors as resistance
programmable devices.
Keywords: memristor, programmable filter, dopant drift, SPICE
PACS: 85.35.–p, 84.30.Vn, 87.85.Qr, 89.20.Ff DOI: 10.1088/1674-1056/22/8/088501
1. Introduction
Since the research and development of traditional elec-
tronic devices are gradually moving towards maturity, there
is an urgent need for new techniques and materials for the
higher performances of modern circuits, in terms of faster
speed, lower power dissipation and cost, smaller geometric
size, higher accuracy and reliability, etc. To realize these re-
quirements, nano-electronics is the best option.
[1]
The tita-
nium oxide memristor is a kind of typical nano-scale electron
device with great proven potential in areas such as resistive
random access memory (RRAM),
[2]
cellular neural networks
(CNNs),
[3]
digital logical operation,
[4]
programmable analog
applications,
[5]
and chaotic circuit analysis,
[6,7]
and will be
widely utilized in the near future.
The memristor was first predicted as a basic circuit el-
ement by Chua in 1971.
[8]
It is defined by the relation be-
tween the charge quantity q(t) and magnetic flux φ (t), and
one of its theoretical characteristics is that it can remember
the last state after the outer electrical bias has been cut off.
Chua and Kang
[9]
later extended the memristor concept to a
broader memristive system. In 2008 the first nano-scale tita-
nium oxide memristor with a metal/oxide/metal structure was
fabricated in a HP laboratory.
[10]
Since then, research around
the characteristics, simulations, and applications of memris-
tors have become hot issues in circuit research. Song et al.
[11]
studied the basic properties and applications of the memristor
circuit. Zhang et al.
[12]
looked at the mathematical model and
the properties of memristors with border constraint, whereas
Bao et al.
[13]
investigated the initial state-dependent dynami-
cal behaviors of the memristor-based chaotic circuit and tran-
sient chaos in a smooth memristor oscillator.
[14]
In many communication and signal routing applications,
such as material identification, it is desirable to have an ana-
log filter. This should be composed of more than one sin-
gle filter that only signals in a certain frequency range may
pass through.
[15]
Moreover, the analog filter should have a
small geometric size, dissipate a low amount of power, and
be easily programmable. The nano-scale memristor has non-
volatile memory, and works at low current and low voltage,
thus consuming a small amount of energy. Moreover, for
memristive memory cells, the switching time can be in the sub-
nanosecond range.
[16]
All the characteristics mentioned above
make the memristor a potential candidate for realizing the de-
sired programmable analog filter. However, there has been no
detailed realization of such circuits in the existing research.
Moreover, the nonlinear relations between the model variables
and changeable conductive characteristics in real experimental
tests block the simulations and applications of the memristor
as a resistance-programmable device.
By using the memristive properties of vanadium dioxide,
Driscoll et al.
[17]
experimentally demonstrated an adaptive fil-
ter by placing a memristor into an LC contour. They found that
this circuit reacts to the application of select frequency signals
∗
Project supported by the National Natural Science Foundation of China (Grant Nos. 61171017 and F010505).
†
Corresponding author. E-mail: txiaobo1985@gmail.com
© 2013 Chinese Physical Society and IOP Publishing Ltd http://iopscience.iop.org/cpb http://cpb.iphy.ac.cn
088501-1