ISSN 2394-3777 (Print)
ISSN 2394-3785 (Online)
Available online at www.ijartet.com
International Journal of Advanced Research Trends in Engineering and Technology (IJARTET)
Vol. II, Special Issue XXIII, March 2015 in association with
FRANCIS XAVIER ENGINEERING COLLEGE, TIRUNELVELI
DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING
INTERNATIONAL CONFERENCE ON RECENT ADVANCES IN COMMUNICATION SYSTEMS AND
TECHNOLOGIES
(ICRACST’15)
TH
25 MARCH 2015
ADAPTIVE DELTA SIGMA MODULATOR WITH FIFTH ORDER SCHEME
SUITABLE FOR SDR SYSTEMS
H Dhivya
ME-Applied Electronics
Shri Andal Alagar College of Engineering
Abstract- This Paper, First shows the first order scheme of an
delta sigma modulator The simulation of an first order delta
sigma modulation reveals the average low pass filtered bit
stream never exactly represents the input signal. It is always
superimposed by some kind of noise. One way to reduce this
noise is to increase the order because of its instability
conditions so higher order modulation techniques is used. In
delta sigma modulation technique upto Nth order values can
be used. so here we using fifth order scheme through which
achieves a low noise compare to the previous order noise
values in it. The simulation of an fifth order delta sigma
modulation also reveals even though the high order scheme
used in DSM it provide less efficiency so we go for an fifth
order adaptive delta sigma modulation The purpose of
adaptive ΔΣ techniques is to enhance the stability and the
dynamic range of the ΔΣ modulators. To be used for SDR
(software defined radio) systems wireless transmitters This
system is employed in order to provide an increased dynamic
range and reduced quantization noise .
The Delta-Sigma Modulator and uses. integration or summing
(the sigma) is over the difference (the delta) In the 70’s,
because of the initially limited performance of Sigma-Delta
Modulators, their main use was in encoding low frequency
audio signals (analog-to-digital conversion) using a 1-bit
quantizer and a first or a second order loop filter. Where
Sigma-Delta noise-shaping techniques were used (digital-todigital conversion). Since then a lot of research on improving
SDM performance has been performed and great
improvements have been realized. It is also used to transfer
higher-resolution digital signals into lower-resolution digital
Mr.P Saravankumar
Assitant Professor Department/ECE
Shri Andal Alagar College of Engineering
signals as part of the process to convert digital signals into
analog.
Index Terms— modulation, delta sigma modulation adaptive
delta sigma modulation
I. INTRODUCTION
Though our world has an analog nature, nowadays information
is very often stored, transferred, and processed digitally. The
advantage is obvious: 1. digital signals are much more immune
to noise than their analog counterparts. Noise and distortion
will accumulate during the transfer or copy of an analog signal,
while a digital signal can be lossless copied or transferred as
long as the noise and distortion are lower than the threshold
which changes the digital value. 2. signal processing circuits
can be implemented more easily, accurately and economically
in digital domain thanks to the fast and continuous
development of CMOS process. According to ITRS roadmap
(International Technology Roadmap for Semiconductors), the
mainstream CMOS process feature size will be scaled down to
32nm in the next 10 years, which is about one third of the
current technology level (100nm, year 2003)
It is a DSP method for encoding analog signals into digital
signals as found in an ADC. It is also used to transfer higherresolution digital signals into lower-resolution digital signals
as part of the process to convert digital signals into analog. In
a conventional ADC, an analog signal is integrated, or
sampled, with a sampling frequency and subsequently
quantized in a multi-level quantizer into a digital signal. This
process introduces quantization error noise. The first step in a
delta-sigma modulation is delta modulation. In delta
43
All Rights Reserved © 2015 IJARTET
ISSN 2394-3777 (Print)
ISSN 2394-3785 (Online)
Available online at www.ijartet.com
International Journal of Advanced Research Trends in Engineering and Technology (IJARTET)
Vol. II, Special Issue XXIII, March 2015 in association with
FRANCIS XAVIER ENGINEERING COLLEGE, TIRUNELVELI
DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING
INTERNATIONAL CONFERENCE ON RECENT ADVANCES IN COMMUNICATION SYSTEMS AND
TECHNOLOGIES
(ICRACST’15)
TH
25 MARCH 2015
modulation the change in the signal (its delta) is encoded,
rather than the absolute value. The result is a stream of pulses,
as opposed to a stream of numbers as is the case with PCM. In
delta-sigma modulation, the accuracy of the modulation is
improved by passing the digital output through a 1bit DAC and adding (sigma) the resulting analog signal to the
input signal, thereby reducing the error introduced by the
delta-modulation. The quality and stability of noise shaping is
a concern in the design of higher-order delta-sigma
modulators for high-resolution, high-speed oversampled
digital -to-digital conversion.
This technique has found increasing use in modern electronic
component such converters, synthesizers, switched and motor
controllers, primarily because of its cost efficiency and
reduced circuit complexity. A delta-sigma ADC first encodes
an analog signal using high-frequency delta-sigma
modulation, and then applies a digital filter to form a higherresolution but lower sample-frequency digital output. On the
other hand, a delta-sigma DAC encodes a high-resolution
digital input signal into a lower-resolution but higher samplefrequency signal that is mapped to voltages, and then
smoothed with an analog filter. In both cases, the temporary
use of a lower-resolution signal simplifies circuit design and
improves efficiency. The coarsely-quantized output of a deltasigma modulator is occasionally used directly in signal
processing or as a representation for signal storage. For
example, the Super Audio CD (SACD) stores the output of a
delta-sigma modulator directly on a disk.
Figure 1: First order delta sigma modulator
An adaptive sigma delta modulator is provided. The adaptive
sigma delta modulator includes an input stage, a sigma delta
modulator, an adaptation stage, and an output stage. The input
stage produces a difference signal representing the difference
between an analog input signal in a first amplitude range and
an adaptive feedback signal. The sigma delta modulator
produces an intermediate digital output sequence in a reduced
second amplitude range representative of the difference signal.
The adaptation stage produces the adaptive feedback signal
such that the amplitude of the adaptive signal keeps the
difference signal within the reduced second range. The output
stage produces a final digital output sequence which is the
sum of the intermediate digital output sequence and a delayed
adaptive feedback signal. The final digital output sequence has
an amplitude in the first range and is a digital representation of
the analog input. clock period. The adaptive feedback signal
may include an estimate of an signals.
II. PROPOSED SYSTEM:
The proposed which uses the different types of ordering
scheme a first order system shows the performance of uses
position information in order to design a strong self-pruning
condition. The drawbacks of first order DSM is that they are
sensitive to frequency synchronization problems and provides
44
All Rights Reserved © 2015 IJARTET
ISSN 2394-3777 (Print)
ISSN 2394-3785 (Online)
Available online at www.ijartet.com
International Journal of Advanced Research Trends in Engineering and Technology (IJARTET)
Vol. II, Special Issue XXIII, March 2015 in association with
FRANCIS XAVIER ENGINEERING COLLEGE, TIRUNELVELI
DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING
INTERNATIONAL CONFERENCE ON RECENT ADVANCES IN COMMUNICATION SYSTEMS AND
TECHNOLOGIES
(ICRACST’15)
TH
25 MARCH 2015
loss of efficiency that is caused by its noise sources of its so
we implement an higher order scheme in it that is the fifth
order schemes it also has some drawbacks such as its stability
of the system doesn’t achieved. Adaptive delta sigma
modulation is used to overcome all the drawbacks of an delta
sigma modulation for analysis purpose we use an same fifth
seen in first-order delta sigma modulators is pattern noise.To
overcome these issues we have to go for an higher order delta
sigma modulator through which we can achieve a low noise
compare to the previous order noise values in it.
order scheme it should adapt the amplitude of the ∆∑ output
signal to the amplitude of the input signal it is achieved based
on the variations in input signal power/magnitude
.
Figure 2: Block diagram of fifth Order delta sigma
modulation
III. SYSTEM ANALYSIS
1.
Existing system
2.
Delta sigma modulation
A requirement of analog-to-digital (A/D) interfaces is
compatibility with VLSI technology, in order to provide for
monolithic integration of both the analog and digital sections
on a single die. Since the Σ−∆ A/Converters are based on
digital filtering techniques, almost 90% of the die is
implemented in digital circuitry which enhances the prospect
of compatibility. The modulator will be implemented with
digital technology if you have a digital signal source and in
analogue technique in case of an analogue signal source. The
same applies to the low pass filter: You will use an analogue
low pass filter if you need an analogue signal output. A digital
low pass filter will be implemented if you want a digital
output. The digital low pass filter will probably be realized by
a digital circuit or by an algorithm within a signal processor.
The delta sigma modulator is the core of delta sigma
converters. Additional advantages of such an approach include
higher reliability, increased functionality, and reduced chip
cost. Those characteristics are commonly required in the
digital signal processing environment of today. Consequently,
the development of digital signal processing technology in
general has been an important force in the development
of high precision A/D converters which can be integrated on
the same die as the digital signal processor itself
The better way to reduce the noise is to use a higher order
sigma delta Modulator. Bit streams produced by higher order
modulators produce less noise at the low pass filter outputs.
Normally this noise is random. First order modulators show
some strong frequencies in the power spectrum non-random
noise or residual tones, which is disadvantageous. If the input
signal is close to the limits of the input range this effect is
worst with first order modulators. Another problem usually
45
All Rights Reserved © 2015 IJARTET
ISSN 2394-3777 (Print)
ISSN 2394-3785 (Online)
Available online at www.ijartet.com
International Journal of Advanced Research Trends in Engineering and Technology (IJARTET)
Vol. II, Special Issue XXIII, March 2015 in association with
FRANCIS XAVIER ENGINEERING COLLEGE, TIRUNELVELI
DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING
INTERNATIONAL CONFERENCE ON RECENT ADVANCES IN COMMUNICATION SYSTEMS AND
TECHNOLOGIES
(ICRACST’15)
TH
25 MARCH 2015
Figure 3:Delta sigma modulation with digital to digital
converters
IV. METHODLOGY AND DESCRIPTION
Block Diagram
The stages involved in the process of fifth order adaptive
delta sigma modulator are discussed. It starts with a brief
review of the block diagram processes involved
Figure 4:Block diagram representation
1.
Adaptive delta sigma modulator with fifth order:
The adaptive ΔΣM presented here is a single-bit system and
uses instantaneous adaptation and backward estimation.The
adaptation algorithm is based on an exponential lawwhich
ensures that the adaptation properties are independent of the
average input power level over a particularinput amplitude
range. The feedback signal is generated by a digital-to-digital
converter (DAC). Possible levels ofthe feedback signal are
chosen from a finite set, which ensures a reproducible
reconstruction of the input signal from the binary data
sequence. The proposed adaptive modulator shows an
improved structre
46
All Rights Reserved © 2015 IJARTET
ISSN 2394-3777 (Print)
ISSN 2394-3785 (Online)
Available online at www.ijartet.com
International Journal of Advanced Research Trends in Engineering and Technology (IJARTET)
Vol. II, Special Issue XXIII, March 2015 in association with
FRANCIS XAVIER ENGINEERING COLLEGE, TIRUNELVELI
DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING
INTERNATIONAL CONFERENCE ON RECENT ADVANCES IN COMMUNICATION SYSTEMS AND
TECHNOLOGIES
(ICRACST’15)
TH
25 MARCH 2015
Figure 5 : Fifth order adaptive delta
Sigma modulator
V. RESULT ANALYSIS
1.
Result Evaluation
One of the major contributions of this work is the
design of a adaptive delta sigma modulator based on delta
sigma modulator approach that can achieve the Reduction of
quantization noise .the first order delta sigma modulation
shows the simple and best approach for small values of signals
To enhance the results we go for an Fifth order delta sigma
modulator which justify the higher order schemes capability
2.
Final simulation
The program coding has been written in Verilog
language and simulated in MODELSIM simulator
1) Simulation of first order delta sigma modulator
The figure shows that when the input data is given
into the system it performs the slow varying of signals in and
the ouput is with adding some noise in the simulated waveform
2) Simulation of fifth order delta sigma modulator
47
All Rights Reserved © 2015 IJARTET
ISSN 2394-3777 (Print)
ISSN 2394-3785 (Online)
Available online at www.ijartet.com
International Journal of Advanced Research Trends in Engineering and Technology (IJARTET)
Vol. II, Special Issue XXIII, March 2015 in association with
FRANCIS XAVIER ENGINEERING COLLEGE, TIRUNELVELI
DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING
INTERNATIONAL CONFERENCE ON RECENT ADVANCES IN COMMUNICATION SYSTEMS AND
TECHNOLOGIES
(ICRACST’15)
TH
25 MARCH 2015
The figure shows that the using an higher order
schemes the slow varying signals can overcome and the
stability of the system is increases
3) Simulation of fifth order adaptive delta sigma modulator
The figure shows that the noise made by an delta sigma
modulator is overcome by the usage of an adaptive delta
sigma modulator using the same order scheme and parameter
including in an adaptive delta sigma modulator is done
VI. CONCLUSION
Higher order schemes of an delta sigma modulator is used for
an comparison of the featured adaptive delta sigma modulator
in order to improve the stability of signals and also to reduce
the noise in delta sigma modulators which can be done using
the simulation techniques and these aspects are obtained in
digital signals which is used as an input to it modulation
where we use an digital source moment.
VII. REFERENCES
[1]Abdelghani Dendouga, Nour-Eddine Bouguechal, Souhil
Kouda, Samir Barra. (2010).Modeling of a Second Order
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48
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ISSN 2394-3777 (Print)
ISSN 2394-3785 (Online)
Available online at www.ijartet.com
International Journal of Advanced Research Trends in Engineering and Technology (IJARTET)
Vol. II, Special Issue XXIII, March 2015 in association with
FRANCIS XAVIER ENGINEERING COLLEGE, TIRUNELVELI
DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING
INTERNATIONAL CONFERENCE ON RECENT ADVANCES IN COMMUNICATION SYSTEMS AND
TECHNOLOGIES
(ICRACST’15)
TH
25 MARCH 2015
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