August 26, 2016 8:51 WSPC/S0218-1274 1650145
A New Simple Chaotic Cir c uit Based on Memristor
the above proposed chaotic systems based on HP
memristor only made computer verification and
did not make experimental verification. Besides,
chaotic circuits based on piecewise-linear memris-
tor were proposed [Muthuswamy & Kokate, 2009;
McCullough et al., 2013; Li et al., 2009; Wang
et al., 2009]. For example, Muthuswamy and Kokate
[2009] proposed memristor-based chaotic circuits
with the memductance mathematically defined as
piecewise-linear discontinuous function W (ϕ)=
dq(ϕ)/dϕ. These memristor-based chaotic circuits
can generate various chaotic attractors. However,
the constitutive relations of these memristors are
nonsmooth piecewise-linear functions, resulting in
discontinuous nonlinear characteristics of the mem-
ristance M (ϕ) and memductance W (ϕ), which
makes the physical realization of such nonsmooth
memristors impossible [Bao et al., 2011a]. Chaotic
circuits based on smooth continuous nonlinear-
ity memristor were proposed [Bao et al., 2011a;
Muthuswamy, 2010; Bao et al., 2011b; Hrubos,
2012; Muthuswamy & Chua, 2010]. For example,
Bao designed a simple memristor-based chaotic cir-
cuit using a negative inductor, a negative resistor
and a negative capacitor in series with a parallel
combination of a memristor and a capacitor [Bao
et al., 2011a].
By using the memristor proposed in this paper,
we designed a new simple memristor-based chaotic
circuit. The memristor-based chaotic circuit con-
sists of an inductor and a negative resistor in series
with a parallel combination of a memristor and
a capacitor, which is simpler compared to those
memristor-based chaotic circuits reported in the
abovementioned papers. Compared to circuit in
paper [Bao et al., 2011a], our proposed memristor-
based chaotic circuit requires only one negative ele-
ment, which is advantageous because it reduces the
number of active elements and reduces power con-
sumption accordingly.
This paper is organized as follows. In Sec. 2,
some fundamentals of memristor are illustrated, a
new memristor is proposed, and an emulator built
from off-the-shelf solid state components which imi-
tates the behavior of the proposed memristor is
presented. In Sec. 3, the memristor-based chaotic
circuit topology, system equations are described and
then the dynamics of chaos are confirmed by numer-
ical computation. In Sec. 4, an electronic circuit is
designed to implement the chaotic system. Finally,
conclusions are given in Sec. 5.
2. The Memristor and Emulator
According to Chua and Kang [1976], a generalized
memristor is defined by
y = g(z, u)u
˙z = f (z,u)
(1)
where u and y denote the input and output of
the system respectively, z denotes the state of the
system. The g is a continuous n-dimensional vec-
tor function and f is a continuous scalar function.
The output y is zero whenever the input u is zero,
regardless of the state z which incorporates the
memory effect. This property manifests that the
pinched hysteresis loop always passes through
the origin. A generalized current-controlled mem-
ristor is defined by
v = M(z
1
,z
2
,...,z
n
)i
˙z
k
= f
k
(z
1
,z
2
,...,z
n
; i),k=1, 2,...,n
(2)
where the memristance M is a continuous func-
tion of z
1
,z
1
,...,z
n
,andz
1
,z
1
,...,z
n
are the state
variables defined by n-order system of differen-
tial equations. Alternatively, a generalized voltage-
controlled memristor is defined by
i = W (z
1
,z
2
,...,z
n
)v
˙z
k
= f
k
(z
1
,z
2
,...,z
n
; v),k=1, 2,...,n
(3)
where the memductance W is a continuous function
of the state variables z
1
,z
1
,...,z
n
.
Now, we define a generalized voltage-controlled
memristor as
i = αz
2
v
˙z = − βv − λz + κvz
(4)
where α, β, λ, κ are parameters and α>0 (the
intention for this choice is to keep the memristor
a passive one). z is the internal state of the memris-
tor. Compared with those memristors proposed by
Muthuswamy [2010]andBao[Bao et al., 2011a], the
proposed memristor’s memductance W = αz
2
only
contains a quadratic nonlinearity term and does not
contain constant term. The intention is to make the
mathematical model simpler and its emulator easier
to be implemented.
Now, an emulator built from off-the-shelf solid
state components which imitates the behavior of the
above proposed memristor is designed, as shown in
Fig. 1.
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