PERFORMANCE EVALUATION OF REVERSIBLE LOGIC BASED CNTFET DEMULTIPLEXER-2

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PERFORMANCE EVALUATION OF REVERSIBLE LOGIC BASED CNTFET DEMULTIPLEXER-2 Powered By Docstoc
					 International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –
INTERNATIONAL JOURNAL OF ELECTRICAL ENGINEERING
 6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 3, May - June (2013), © IAEME
                           & TECHNOLOGY (IJEET)

ISSN 0976 – 6545(Print)
ISSN 0976 – 6553(Online)                                                  IJEET
Volume 4, Issue 3, May - June (2013), pp. 53-62
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     PERFORMANCE EVALUATION OF REVERSIBLE LOGIC BASED
                  CNTFET DEMULTIPLEXER


                                 Y.Varthamanan1, V.Kannan2
        1
        Research scholar, Sathyabama University, Chennai, Tamilnadu, India - 600119
       2
        Principal, Jeppiaar Institute of Technology, Kunnam, Tamilnadu, India -631604



  ABSTRACT

         This paper discuss about the design and analysis of a demultiplexer that is realized
  using carbon nano tube transistor using reversible logic. Reversible logic realization of
  the digital circuits offers numerous advantages then the conventional circuit design.
  Power analysis has been performed using HSPICE simulation software and the results are
  obtained for the 1:2 and 1:4 demultiplexer transient behavior and the power consumption
  obtained is 0.8 and 1.6 nano watts respectively. Comparative analysis has been performed
  with the conventional demultiplexer design to validate the proposed design performance.

  Keywords: CNTFET, Demultiplexer, Power, Reversible Logic

  I. INTRODUCTION

         The nano electronic is one of the greatest emerging fields of Nano Technology for
  developing such kinds of computer systems and other electronic gadgets. The Nano
  technology is being introducing in every fields of the Science and Technology such as in
  Bio technology, Bio Medical Science, Medical Science, Research, Aerospace and
  education etc. Nanotechnology is increasingly being used in consumer products across the
  globe. Nanoelectronics encompass nanoscale circuits and devices including (but not
  limited to) ultra-scaled FETs, quantum SETs, RTDs, spin devices, super lattice arrays,
  quantum coherent devices, molecular electronic devices, and carbon nanotubes.


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International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –
6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 3, May - June (2013), © IAEME

        In designing of computer depends upon the fundamental components as AND,
NAND, OR, NOR, NOT and XOR gates. The designing of combinational circuits,
memory and registers also depends upon these basic gates. To develop these logic gates at
nano scale (10-9), the whole computer can be developed with nano electronics
components. [8].
        CNT as a channel in the Field Effect Transistors (FET) of both n-CNFET and p-
CNFET types that are used. Because of its very small size, it has been s that a CNT-based
FET switches reliably using much less power than a silicon-based device, and thus the
new device will consume less power than traditional t-gate multiplexer. CNT device uses
the fundamental Lorentz magnetic force from the basic laws of Electromagnetic as a
switching mechanism between two conducting CNTs. Since a demultiplexer is a
fundamental logic block, the new devices can have a wide range of applications in a wide
variety of nano circuits.
The most desirable future work involved in CNTFETs will be the transistor with higher
reliability, cheap production cost, or the one with more enhanced performances.

II. CARBON NANO TUBE FET

        Carbon nano tube structures are prominent in reducing the packaging density of
the very large scale integrated circuits. The exceptional electrical properties of carbon
nanotubes arise from the unique electronic structure of graphene itself that can roll up and
form a hollow cylinder. The circumference of such carbon nanotube can be expressed in
terms of a chiral vector: Ĉh=nâ1+mâ2 which connects two crystallographically equivalent
sites of the two-dimensional graphene sheet. Here n and m are integers and â1 and â2 are
the unit vectors of the hexagonal honeycomb lattice. Therefore, the structure of any
carbon nanotube can be described by an index with a pair of integers (n,m) that define its
chiral vector.
        A carbon Nanotube’s band gap is directly affected by its chirality and diameter. If
those properties can be controlled, CNTs would be a promising candidate for future nano-
scale transistor devices. Moreover, because of the lack of boundaries in the perfect and
hollow cylinder structure of CNTs, there is no boundary scattering. CNTs are also quasi-
1D materials in which only forward scattering and back scattering are allowed, and elastic
scattering mean free paths in carbon nanotubes are long, typically on the order of
micrometers. As a result, quasi-ballistic transport can be observed in nanotubes at
relatively long lengths and low fields.[1].
        Multi walled carbon nanotubes (MWCNTs) have huge potential for applications in
electronics because of both their metallic and semiconducting properties and their ability
to carry high current. CNTs can carry current density of the order 10 µA/nm2, while
standard metal wires have a current carrying capability of the order 10 nA/nm2.
Semiconducting CNTs have been used to fabricate CNTFETs, which show promise due
to their superior electrical characteristics over silicon based MOSFETs.[7].




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                                                                  (IJEET),
International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –
6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 3, May - June (2013), © IAEME




                          Fig..1 Multi-Walled Nanotube Transistor

        Ballistic model of CNTFET has numerous advantages over other models. Carbon
                                                                  hirality
nano tube is embedded between the insulator and the sio2 layers. Chirality plays an important
role in deciding the electrical characteristics.




                 Fig. 2. Ballistic Carbon Nano Tube Field Effect Transistor

        The valence and conduction bands of the carbon nanotube are symmetric, which
                                      applications.
allows complementary structures in applications. The nearly ballistic transport at low bias
implies the possibility of deriving carbon nanotube transistors. Both the metallic and semi
                                                                                      active
conducting nanotubes can be exploited in integrated circuits as interconnection and act
devices respectively [3-6].
        Carbon nanotubes have shown reliability issues when operated under high electric
                               [7].
field or temperature gradients.[7].

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                                                                  (IJEET),
International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –
6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 3, May - June (2013), © IAEME

III. REVERSIBLE LOGIC IN DIGITAL CIRCUITS

        A Reversible circuit has the facility to generate a unique output vector from each
  put
input vector, and vice versa .The gate/ circuit does not loose information is called reversible.
Number of inputs is equal to the number of outputs. Every gate output that is not used as
                                                                          lized
input to other gate or as a primary output is called garbage. The unutilized outputs from a
gate are called “garbage”. Fig.3 represents reversible logic gate with garbage. Fig.4
represents typical Feynman gate. Table I represents the truth table of 2X2 Feynman Gate.




                         Fig. 3. A typical reversible logic component




                                     Fig. 4. Feynman gate

                           Table I: 2 x 2 Feynman Gate truth table




Use as many outputs of every gate as possible, and thus minimize the garbage outputs. Do not
create more constant inputs to gates that are absolutely necessary. Use as less number of
               s
reversible gates as possible to achieve the goal.


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International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –
6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 3, May - June (2013), © IAEME




                                    Fig. 5. Fredkin gate


Table II is the truth table of the 4X4 Feynman gate.


                          Table II: 4x 4 Feynman Gate truth table




IV. REVERSIBLE LOGIC IMPLEMENTATION IN CNTFET

                                                            be
        Logically reversible process is that the output can be obtained by knowing the binary
input of a logic gate, and the converse is true. A one to one mapping exists between the input
string and output string. Mathematically speaking the function is bijective. An example of the
logically reversible gate is NOT gate.
        Realization of the reversible logic using CNTFET is shown in the Fig.6 and Fig.7 for
the proposed 1X2 and 1X4 demultiplexer circuits respectively.



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International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –
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                              DEM UX                          S
                              1 :2
                                                                  2


                                                         M2
                                  1 Vdd            4
                                               A

                                  M1                     M7           6
                                          S'                              S'A
                          S
                          2               3
                                  M6
                                                         M3
                                                   B=0
                                                   5
                                                         M8

                                                                  S
                                                                  2


                                                         M4
                                               B=0
                                               5
                                                         M9
                                                                              SA
                                                         S'       3
                                                                          7
                                               4              M5
                                               A

                                                         M 10

                                                                  S
                                                         2

                                Fig. 6. 1:2 DEMUX Realization

        Demultiplexer realization using ballistic model of CNTFET is a novel approach in the
digital circuit designing. This model has electrical and physical properties that are superior to
other models.




                                Fig. 7. 1:4 DEMUX Realization

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International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –
6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 3, May - June (2013), © IAEME

V. RESULTS AND CONCLUSION

        Fig. 8 and Fig.9 represents the 1X2 and 1X4 demultiplexer transient response using
reversible logic respectively.




            Fig.8 Transient Response of Reversible Logic 1:2 Demultiplexer




            Fig.9 Transient Response of Reversible Logic 1:4 Demultiplexer

Fig.10 and Fig.11 represents the 1X2 and 1X4 CNTFET demultiplexer transient response
using reversible logic respectively.


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International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –
6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 3, May - June (2013), © IAEME




   Fig. 10Transient Response of Reversible Logic based CNTFET 1:2 Demultiplexer




   Fig.11 Transient Response of Reversible Logic based CNTFET 1:4 Demultiplexer


Table III gives the details of the number of transistors that have been used for reversible
CNTFET and other models.
Table IV elaborates the power consumption of 1X2 and 1X4 demultiplexer circuits using
CNTFET reversible implementation and CMOS implementation.




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             Table III: No. of transistors for Different Demultiplexer design

                                            No. of Transistors
                     Description
                                                           Reversible
                                    CMOS Reversible
                                                           CNTFET
                    1:2 DEMUX         14           10         10
                    1:4 DEMUX         36           22         22


             Table 1V: Power Analysis of Different Demultiplexer Design

                                   Total Power Dissipation in nano watts
                 Description
                                                            Reversible
                                   CMOS     Reversible
                                                            CNTFET
                 1:2 DEMUX         6.473         3.176        0.860
                 1:4 DEMUX         9.782         6.353           1.765


Fig.12 represents the comprehensive analysis of power consumed by CMOS, Reversible and
Reversible realized CNTFET.




                  Fig. 12 Comparative analysis of Power Consumption


        Demultiplexer has been designed using CNTFET with reversible logic. Comparison
table of power dissipation shows a greatest amount of power reduction has been achieved
with the standard CNTFET model over a conventional CMOS. The dynamically
reconfigurable universal cells exhibit the possibility to realize dense, regular and highly
reconfigurable circuits in platform-based system on chip design. The unwanted growth of
metallic tubes during the fabrication of CNTs is a major challenge that will affect the
fabrication of robust CNT-based circuits.


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International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –
6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 3, May - June (2013), © IAEME

REFERENCES

[1] H. Dai, A. Javey, E. Pop, D. Mann, Y. Lu, "Electrical Properties and Field    Field-Effect
Transistors of Carbon Nanotubes," Nano: Brief Reports and Reviews 1, 1 (2006).
                                  Supriyo
[2] Anisur Rahman, Jing Guo, Supriyo Datta, and Mark S. Lundstrom. Theory of ballistic
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nanotransistors. Electron Devices, IEEE, 50(9):1853–1864, September 2003.
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[3] Dafeng Zhou, Tom J Kazmierski and Bashir M Al-Hashimi, VHDL-AMS implementation
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Specification and Design Languages 2008, Southampton, SO17 1BJ, UK, 2008.
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[4] I. O’Connor, J. Liu, F. Gaffiot. “CNTFET-based logic circuit design. IEEE-June 2006.
[5]                                              Okajima,
        Bipul C. Paul, Shinobu Fujita, Masaki Okajima, and Thomas Lee.Modeling and
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[6]www.siemens.com/innovation/en/about_fande/corp_technology/partnerships_experts/uc_b
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[7] www.wikipedia.org
[8] Comparative Study: MOSFET and CNTFET and the Effect of Length Modulation
Kuldeep Niranjan, Sanjay Srivastava, Jaikaran Singh, Mukesh Tiwari International Journal of
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AUTHORS

             Y.Varthamanan was born in Arani, Tamilnadu, India in 1967. He received
            Master Degree in Applied Electronics from Sathyabama University in the year
                                                                             working as
            2007. Currently he is doing PhD in Sathyabama University. He is work
            Assistant Professor in Department of ECE in Jeppiaar Engineering College,
                                                               Electronics,
            Chennai. His interested areas of research are Nano Electronics, VLSI Design
and Mixed Signal circuits.


             V.Kannan was born in Ariyalore, Tamilnadu, India in 1970. He received his
              Bachelor Degree in Electronics and Communication Engineering from Madurai
              Kamarajar University in the year1991, Masters Degree in Electronics and
                                                   ye                    .,
              control from BITS, Pilani in the year 1996 and Ph.D., from Sathyabama
              University, Chennai, in the year 2006. His interested areas of research are
Optoelectronic Devices, VLSI Design, Nano Electronics, Digital Signal Processing and
                                                                 nal
Image Processing. He has 170 Research publications in National / International Journals /
Conferences to his credit. He has 20 years of experience in teaching and presently working as
Principal, Jeppiaar Institute of Technology, Kunnam, Tamilnadu, India. He is a life member
of ISTE.



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