Design and implementation of Closed Loop Control of Three Phase Interleaved PFC AC-DC Converter

37 International Journal for Modern Trends in Science and Technology
Volume: 2 | Issue: 08 | August 2016 | ISSN: 2455-3778IJMTST
Report on Ripple Carry Adder Power
Delay using Brent Kung (BK) Adder
Mr. M. Mahaboob Basha1
| Jhansi Pabbathi2
1Associate Professor, Department of ECE, SVR Engineering College, Nandyal.
2PG Scholar, Department of ECE, SVR Engineering College, Nandyal.
In this paper, Carry Select Adder (CSA)architecture are proposed using parallel prefix adder. Instead of
using 4-bit Ripple Carry Adder (RCA), parallel prefix adder i.e.,4-bit Brent Kung (BK) adder is used to design
CSA. Adders are key element in digital design, performing not only addition operation, but also many other
function such as subtraction, multiplication and division. Ripple Carry Adder (RCA) gives the most
complicated design as-well-as longer computation time. The time critical application use Brent Kung parallel
prefix adder to drive fast results but they lead to increase in area. Carry Select Adder understands between
RCA and BK in term of area and delay. Delay of RCA is larger therefore we have replaced it with Brent Kung
parallel prefix adder which gives fast result. Power and delay of 4-bit RCA and 4-bit BK adder architecture
are calculated at different input voltage. This paper describes comparative performance of 4-bit RCA and
4-Bit BK parallel prefix adder designed using TANNER EDA tool.
KEYWORDS: Brent Kung (BK) Adder, Ripple Carry Adder, Power, Delay.
Copyright © 2016 International Journal for Modern Trends in Science and Technology
All rights reserved.
I. INTRODUCTION
In this paper, describe demand for high-speed
arithmetic units in digital image processing units,
DSP and other processor chips has superimpose
the path for develop of high speed adders as
addition is an essential operation in almost every
arithmetic unit, also the basic building block for
combination of all other arithmetic logical
computations .To increase portability of systems
and battery life, delay and power are the ensuring
the success of concern. Even in servers and
personal computers (PC), power efficient is a vital
design parameter. In now day’s scenario, Design of
power-efficient high-speed logic systems in VLSI
design techniques. In digital adders, the speed of
addition is limited time required by the carry to
generate through the adder. In present scenario,
where Computations need to be performed using
low-power circuit that must operate at high speed
which is achievable with lesser delay that’s why
this paper describes comparative performance of
4-bit RCA and 4-Bit BK parallel prefix adder
designed using TANNER EDA tool. Finally delay,
power for the design adder presented and compare.
A. Drawbacks of Ripple Carry Adder
Multiple full adder circuits can be rapidly
cascaded in parallel to addition of N-bit number.
For an N- bit cascaded parallel adder, there must
be N number of full adder circuits[1]. A ripple carry
adder is a logic circuit in which the carry out of
each full adder parameter is the carry in of the
following next most significant full adder. It is
called a ripple carry adder because each and every
carry bit gets wind up into the next stage of adder.
In figure1, the first sum bit should wait up until
input carry is given; the second sum bit should
wait up until previously carry is propagated and so
on. Finally the output sum should wait up until all
previous carries are generated. So it results in
delay.
Fig 1. 4-bit ripple carry adder.
ABSTRACT

Report on Ripple Carry Adder Power Delay using Brent Kung (BK) Adder
II. RELATED WORK
A. Parallel Prefix Adders
These are used to take the binary additions
because of their flexibility. Carry Look Ahead
Adder’s (CLA) structure is utilized in order to get
the parallel prefix adders. Tree structures
algorithm are used to increase the speed high
performance of arithmetic operation. Parallel prefix
adders are used for high performance arithmetic
circuits in industries as they increase the speed of
operation. The construction of parallel prefix
Adder involves three stages:
1. Pre- processing stage
2. Carry generation Process
3. Post processing stage
Pre-possessing stage:-
Generate and propagate signals to each pair of the
inputs A and B are computed in this stage. These
signals are given by the,
Following equations:
Pi=Ai xor Bi (1)
Gi=Ai and Bi (2)
Carry generation network:-
In this stage, carries equivalent to each bit is
calculated. All these operations are implemented
and carried out in parallel. Carries in parallel are
segmented into smaller pieces after the
implementation of the stage. Carry propagate and
generate are used as intermediate signals which
are given by the logic equations3& 4:
CPi:j=Pi:k+l and Pk:j (3)
CGi:j=Gi:k+l or (Pi:k+l and Gk:j) (4)
The operations involved in fig. 1 are given as:
CPO=Pi and Pj (3(i))
CGO=(Pi and Gj) or Gi (3(ii))
Fig 2. Carry Network.
Post processing Stage:-
This is the concluding step to compute the
summation of input bits. It is similar for all the
adders and then sum bits are computed by logic
operation equation 4& 5:
Ci-1= (Pi and Cin ) or (4)
Si=Pi xor Ci-1 (5)
Brent-Kung Adder:-
Brent-Kung adder is a very popular and widely
used adder. It actually gives an excellent number of
stages from input to all outputs but with
asymmetric loading of Intermediate stages. It is one
of the parallel prefix adders. It is one of the parallel
prefix adders where these adders are the ultimate
class of adders that are based on the use of
generate and propagate signals. In case of Brent
Kung adders along with the cost, the wiring
complexity is also less. But the gate level depth of
Brent-Kung adders is 0 (log2 (n)), so the speed is
lower. The block diagram of 4-bit Brent-Kung
adder is shown in Fig. 3.
Fig 3. Tree Diagram of 4-bit Brent Kung Adder.
III. IMPLEMENTATION
A. 4-Bit Ripple Carry Adder
This fig. 4 has CMOS Ripple-carry select adders
are the simplest and most compact full adders, but
their concert is limited by a carry that must
propagate from the least -significant bit to the
most- significant bit Ripple Carry Adder(RCA) gives
the most compact design as-well-as longer
computation time.
Fig 4. 4-BIT RCA Schematic.

Volume: 2 | Issue: 08 | August 2016 | ISSN: 2455-3778IJMTST
Figure 5 is the output waveform for 4 bit RSA
structure. Input is varied from 0000 to 1111 and
corresponding output is observed at each instant of
time. Waveform is seen in W-edit window of tanner
Fig 5. Output Waveform of 4-BIT RCA.
IV. EXPERIMENTAL WORK
Various adders were designed in Tanner EDA
version 13.0tool using CMOS technology. Power
consumption and delay of Ripple Carry Adder and
Brent Kung prefix adder 4-Bitword size. The
comparison of various adders for different
parameters like delay and power consumption is
shown in Table I. The result analysis shows that
Brent Kung Carry Select Adder shows better
results than the Ripple carry adder architectures in
terms transient analysis of delay and high speed at
different input voltages but with a small power
penalty. The graphical representation of
comparison of RCA and BK CSA for different input
voltages for power and delay consumption is shown
in fig. Results show BK CSA better results than
RCA.
Table I. Comparison of RCA and BK-CSA Adders for
transient Delay at Various Input Voltages.
Figure 8 is the graphical representation of
comparison of RCA and BK CSA at different input
voltages for transient Delay is shown in fig. Results
show that BK CSA strongly high speed results than
RCA.
Fig 8. Comparison of RCA and BK CSA Adders for Transient
Delay at Various Input Voltages.
Figure 9 is the graphical representation of
comparison of RCA and BK CSA at different input
voltages for power consumption is shown in fig.
Results show that RCA slightly better results than
BK CSA.
Fig 9. Comparison of RCA and BK CSA Adders for Power at
Various Input Voltages.
V. CONCLUSION
This work can be extended for higher number of
bits also. By using parallel prefix adder, delay and
power consumption of different adder
architectures is reduced. As, parallel prefix adders
derive fast results therefore Brent Kung adder is
used. The calculated results conclude that BK
Carry Select Adder is better in terms of power
consumption and high speed when compared with
RCA adder architectures and can be used
indifferent applications of adders like in
multipliers, to execute different algorithms of
Digital Signal Processing like Finite Impulse
Response, Infinite Impulse Response etc.
REFERENCES
[1] Sudheer Kumar Yezerla, B RajendraNaik. “Design
and Estimation ofdelay, power and area for Parallel
prefix adders” Proceedings of 2014RAECS UIET
Panjab University Chandigarh, 06 - 08 March, 2014.

Report on Ripple Carry Adder Power Delay using Brent Kung (BK) Adder
[2] N. H. E. Weste and D. Harris, CMOS VLSI Design,
4thedition,Pearson–Addison-Wesley, 2011.
[3] R. P. Brent and H. T. Kung, “A regular layout for
parallel adders,” IEEETrans. Comput., vol. C-31, pp.
260-264, 1982.
[4] Y. Choi, "Parallel Prefix Adder Design", Proc. 17th
IEEE Symposiumon Computer Arithmetic, pp.
90-98, 27th June 2005.
[5] Basant Kumar Mohanty and Sujit Kumar Patel
“Area–Delay–PowerEfficient Carry-Select Adder,”
IEEE transaction on circuits and systemsII:Express
briefs, VOL. NO. 6, JUNE 2014.
[6] L. Mugilvannan and S. Ramasamy “Low-Power and
Area-EfficientCarry Select Adder Using Modified
BEC-1 Converter” IEEE-31661. 4thICCCNT2013
July 4-6, 2013, Tiruchengode, India.
[7] T. Lynch and E. E. Swartzlander, “A Spanning Tree
Carry Look aheadAdder,” IEEE Trans. On
Computers, vol. 41, no. 8, pp. 931-939,Aug.1992.

Design and implementation of Closed Loop Control of Three Phase Interleaved PFC AC-DC Converter

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