[M.Vijayan 4(2): February,2015] ISSN: 2277-9655
Scientific Journal Impact Factor: 3.449
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IJESRT
INTERNATIONAL JOURNAL OF ENGINEERING SCIENCES & RESEARCH
TECHNOLOGY
RECENT TREND BASED WALLACE TREE MULTIPLIER AIMING TO LOW
LEAKAGE POWER
M.Vijayan*, T.Jayachandran, D.Arulanantham
*
ECE Department,Velalar College of Engineering and technology,India
ECE Department,Nandha Engineering College,India
ECE Department,Nandha Engineering College,India
ABSTRACT
A new domino circuit is proposed with low leakage and high noise immunity which decreases the parasitic
capacitance on the dynamic node, yielding a smaller keeper for wide fan-in gates to implement fast and robust
circuits. The technique utilized is based on comparison of mirrored current of the pull-up network with its worst case
leakage current. Thus, the power consumption and delay are reduced. A 4*4 Wallace tree multiplier is designed
based on CCD (Current Comparison Domino) which uses low leakage high speed full adders. These full adders
uses current comparison based domino logic to achieve low leakage and high speed. The proposed 4*4 Wallace tree
multiplier using current comparison based domino logic full adders was simulated using 180nm CMOS technology
which shows a relative power reduction when compared to the 4*4 Wallace tree multiplier using standard full
adders.
KEYWORDS: Domino logic, Leakage-tolerant, Noise immunity, Wallace Multiplier, Wide fan-in.
INTRODUCTION
Dynamic logic is distinguished from so-called static
logic in that dynamic logic uses a clock signal in its
implementation of combinational logic circuits. The
usual use of a clock signal is to synchronize
transitions in sequential logic circuits. For most
implementations of combinational logic, a clock
signal is not even needed. In contrast, in dynamic
logic, there is not always a mechanism driving the
output high or low. Dynamic logic requires a
minimum clock rate fast enough that the output state
of each dynamic gate is used or refreshed before the
charge in the output capacitance leaks out enough to
cause the digital state of the output to change, during
the part of the clock cycle that the output is not being
actively driven. Dynamic logic, when properly
designed, can be over twice as fast as static logic. It
uses only the faster N transistors, which improve
transistor sizing optimizations. Static logic is slower
because it has twice the capacitive loading,
higher thresholds, and uses slow P transistors for
logic. Dynamic logic can be harder to work with, but
it may be the only choice when increased processing
speed is needed. In Dynamic logic, problem arises
when cascading one gate to the next. In order to
cascade dynamic logic gates, one solution is Domino
Logic, which inserts an ordinary static inverter
between stages. While this might seem to defeat the
point of dynamic logic, since the inverter has a pFET,
there are two reasons it works well. First, there is no
fanout to multiple pFETs. The dynamic gate connects
to exactly one inverter, so the gate is still very fast.
And since the inverter connects to only nFETs in
dynamic logic gates, it too is very fast. Second, the
pFET in an inverter can be made smaller than in
some types of logic gates.
In this paper, a new current-comparison-based
domino (CCD) [1] circuit for wide fan-in applications
in ultradeep submicrometer technologies is proposed.
The novelty of the proposed circuit is that our work
simultaneously increases performance and decreases
leakage power consumption. With this, a low leakage
Wallace tree multiplier [2] is designed to show its
minimum power consumption.
The rest of this paper is arranged as follows. After the
existing system in Section II, the proposed circuit is
described in Section III. Section IV includes
simulation results for the proposed circuit using
180nm CMOS tool compared with other
conventional circuits. Section V concludes the
results.