Ijett v7p222

International Journal of Engineering Trends and Technology (IJETT) – Volume 7 Number 1- Jan 2014

Design of Low Power Basic 2x1Multiplexer Using Various Gates S. Ahmed Basha#1, K.Prasad Babu*2,H.Devanna #3, B.Venkatesh*4 #

E.C.E. Department, Assistant Professor Assistant Professor Associate Professor, Assistant Professor, JNTU Anantapur.

University India St.John’s College of Engineering & Technology, Yemmiganur, 518360, Kurnool, Andhra Pradesh,India.

Abstract—Power dissipation is one of the important factor in VLSI design. All the systems with high performance have constraints regarding power consumption per chip. Low power consumption is generally done by careful design. In this paper we are designing the basic 2x1 multiplexer using various gates.

We represent the low power dissipated multiplexer among them.

Table 2.When S=1

Inputs

Output

x1

x2

t

0

0

0

0

1

1

Keywords—MUX ;Complex Gates;PASS Transistor;

1

0

0

Transmission Gates;Power;

1

1

1

I. INTRODUCTION Multiplexer: It is the device that has 2n inputs and number of select lines by which the input line is send to the output line. Multiplexers in short are called as MUX. Mux’s are used for incrementing the information that has to be sent over the channel/network within the duration of time, with allotted bandwidth. Data selector is the other name of Mux. It is used for multiple inputs with one output at atime.

The basic operation of 2x1 Mux is mentioned below table Basic Operation of 2x1 MUX: Table 1.When S=0

Inputs

Output

x1

x2

t

0

0

0

0

1

0

1

0

1

1

1

1

ISSN: 2231-5381

Basic operation of Transmission gates: Transmission gate is the one that momentarily allow or stop a voltage level from input side to output side. Transmission gate is composed of both pMOS and nMOS transistors. The operation of control gate is in such a way that complementary output is observed, i.e. When Logic 1 is applied at node A Logic 0 is seen at node active low A. Thus both transistors conduct and pass the voltage level at IN to OUT. And when Logic 0 on node active-low A is applied the complementary Logic 1 is applied to node A, thus both transistors are off and which gives us a highimpedance state at both the IN and OUT nodes. Thus we have 3 states high, low and high-impedance.

The Schematic, Circuit, Layout symbols are shown below

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International Journal of Engineering Trends and Technology (IJETT) – Volume 7 Number 1- Jan 2014 Basic operation Pass transistor: The logic of pass transistor has an input to the gate, which acts as the control input and this value of control variable, at the source end of transistor appears at the drain end, i.e. the control variable value controls a pass transistor to which passing variables are applied. This logic represents logic families that are used in Integrated circuits. The main advantage of pass transistor is, it reduces the no transistors which are repeated. Pass transistor as the name, pass only logic levels between nodes and this causes the reduction in active devices..

MUX Circuit operation using Gates:

II. IMPLEMENTATION & SIMULATION Implementation using Transmission gates:

Analog Simulation:

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International Journal of Engineering Trends and Technology (IJETT) – Volume 7 Number 1- Jan 2014

Layout:

Implementation using Or & And gates:

ISSN: 2231-5381

Analog Simulation:

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International Journal of Engineering Trends and Technology (IJETT) – Volume 7 Number 1- Jan 2014

Layout:

Implementation using Pass transistors: Analog Simulation:

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International Journal of Engineering Trends and Technology (IJETT) – Volume 7 Number 1- Jan 2014 Mux is used in many digital applications, If we reduce the power dissipation of a Mux, then power dissipation of entire system using Mux will also be reduced.

From above result table, we can conclude that Pass Transistor implemented 2x1Mux has low power, when compared with other implemented circuits.

REFERENCES

Layout:

[1]

Debashis, De (2010). Basic Electronics. Dorling Kindersley. p. 557.

[2]

http://www.maximintegrated.com/app-notes/index.mvp/id/4243

[3]

Essentials of VLSI CIRCUITS and systems- A.Pucknell PHI 2005.

[4]

Principles of CMOS VLSI design- Weste and Eshranghian, Pearson edition1999.

[5]

Simulation based Power estimation for Digital CMOS Technologies

by Jins David Alexander http://en.wikipedia.org/wiki/Multiplexer

[6]

III. RESULT TECHNOLOGY 0.12µm 0.12µm

No. OF METALS 6 6

0.12µm

6

TECNIQUE Gates Transmission gates Pass Transistor

POWER DISSIPATION 6.277µW 6.037 µW 1.27µW

IV. CONCLUSIONS & FUTURE SCOPE Power dissipation or the Total power dissipation is the sum of the Static & Dynamic power dissipation. Dynamic power dissipation is far greater than Static power dissipation when systems are active & hence static power is ignored.

Dynamic dissipation is due to charging and discharging of load capacitances, “short-circuit” current while both pMOS & nMOS networks are partially ON. Static dissipation is due to sub-threshold conduction through OFF transistors, tunneling current through gate oxide, leakage through reverse-biased diodes, contention current in rationed circuits.

We propose the use of Pass transistor.

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