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Comparison of Trans-Conductance Ratio (β) for a High-Speed Inverter Design
-- Abhijit Asatiand Chandra Shekhar
In Complementary Metal Oxide Semiconductor (CMOS) circuit designs, the low mobility
(mp) P-channel Metal Oxide Semiconductor (PMOS) devices are sized up to attain the same conduction performance as
the high mobility (mn) N-channel Metal Oxide Semiconductor (NMOS) devices. The PMOS/NMOS width
ratio (β) is an important ratio in the design of digital circuits using conventional CMOS logic. The
conventional method of estimating β excludes the effect of several technology parameters in estimation of
PMOS/NMOS width ratio. This paper discusses a more accurate estimation of PMOS/NMOS width ratio, using
relevant technology parameters like tox, Vtn,
Vtp, Cj0n, Cj0p, Cj0swn, Cj0swp and built-in potential of PN junction
(PB). β ratio is computed for 0.5 mm technology and compared to their values computed using the
conventional method. The β ratio, taking into consideration many other technology parameters increases the
inverter threshold (switching threshold) voltage Vth by 5% and average propagation delay by 0.6%.
© 2009 IUP. All Rights Reserved.
Reliability of OCDMA MAN System Using
Wavelength-Time Matrix Encoding and
Decoding Technique
-- Gurjit Kaur, Divyesh Mohan Saxena and Neena Gupta
Of late, Optical Code Division Multiple Access
(OCDMA) has attracted much attention because of its
vast bandwidth availability and for allowing simultaneous users to access the same optical channel with less
delay. The construction of codes with good auto and cross correlation properties with low Multiple Access
Interference (MAI) is a big challenge in OCDMA system. Hence, there is increasing research in this area. In this paper,
we propose a reliable simulated model for OCDMA system with improved performance as compared to
previous designs. The system has been designed for a Metropolitan Area Network (MAN) with optical fiber length
of 60 km. In this paper, the optical CDMA system has been designed and simulated by using redesigned W/T matrix code and WDM-type components for high data rates, i.e., 1 Gbps, 1.25 Gbps, 2.5 Gbps and 5
Gbps. A comparative Bit Error Rate (BER) and eye diagram analysis of high speed OCDMA system for
asynchronous concurrent communication of multiple users at the above-mentioned data rate has been carried out.
Results show that this proposed system can accommodate 16 simultaneous users for 2.5 Gbps for BER
e-10. Previous designs have been on a bit rate of 1.25 Gbps for 16 users with BER
e-9 (Mendez et al., 2004). With -19
db received power, 16 simultaneous users can be accommodated at the BER of
e-16, e-13, e-10 and
e-4 for 1 Gbps, 1.25 Gbps, 2.5 Gbps and 5 Gbps respectively. Hence, the system designed in the present work is
well-suited for 16 simultaneous users for the data rates, i.e., 1 Gbps, 1.25 Gbps and 2.5 Gbps, and can accommodate
up to eight numbers of simultaneous users for data rate 5 Gbps.
© 2009 IUP. All Rights Reserved.
Shorted Parasitic Rectangular Microstrip Antenna
for Compact Operation
-- N M Sameena, R B Konda,
S N Mulgi and P V Hunagund
A simple design of rectangular microstrip antenna with shorted parasitic strip is presented for compact
and wideband operation. The antenna consists of a parasitic strip which was looped around the rectangular
microstrip patch, and a shorting strip was placed at the optimum point between the parasitic strip and radiating
patch. From the experimental results, it was observed that 73.97% of large effective reduction of antenna size
was achieved and -10 dB return loss impedance bandwidth was 1.83 times more than that of conventional
rectangular microstrip antenna without change in broadside radiation characteristics. This antenna may find application
in Secondary Surveillance Radar (SSR) systems (1.03-1.09 GHz). Design concepts of proposed antennas
are given and experimental results are discussed.
© 2009 IUP. All Rights Reserved.
Simulation, Design and Development
of a Wideband Printed Linearly Tapered
Slot Antenna
-- Ved Vyas Dwivedi and Y P Kosta
A printed, Linearly Tapered Slot Antenna for 11.0 GHz was theoretically designed using the
Stepped Approximation Method (SAM). The designed and calculated values have been optimized for wide
band performance using the Computer Simulation Technology (CST) Microwave Studio. This microstrip
antenna was fabricated on polytetra fluoroethylene (PTFE) and finally tested for its RF wideband performance.
Various antenna parameters such as Voltage Standing Wave Ration (VSWR), radiation pattern, energy loss and
1:2 VSWR bandwidth were measured and the same recorded in the plots. The performance of this
antenna system indicated its multi-frequency operation as a wideband Traveling Wave Antenna in the end fire
mode. Also, the dielectric constant performance variation with frequency was tested in RF lab to confirm
the effectiveness of its wideband multi-frequency operation.
© 2009 IUP. All Rights Reserved.
Performance Comparison of a Six-Phase
VSI for Symmetrical and Quasi Six-Phase Configurations
-- Shaikh Moinuddin and Atif Iqbal
The proposal for multi-phase motor drive system was at first presented in 1969 (Ward and Härer, 1969).
An upsurge in the research on multi-phase motor drive is seen in recent years due to the advent of cheap
and reliable semiconductor devices such as IGBTs and MOSFETs. This paper takes up the issue of control of
a six-phase voltage source inverter. Two configurations of a six-phase inverter are investigated leading
to symmetrical six-phase supply and quasi six-phase supply. Simple square wave control is considered,
instead of Pulse Width Modulation (PWM) mode.The existing 180° conduction mode of operation is elaborated and
a novel 150° conduction mode is proposed in this paper. Phase-to-neutral voltages are investigated and
their harmonic analysis is done. A comparison of two configurations is provided based on the quality of
output voltages. A prototype six-phase inverter is built in the laboratory and simple analog circuit based gate
control is developed. The experimental setup and results are elaborated in detail.
© 2009 IUP. All Rights Reserved.
Dynamic Performance Improvement
of Variable Speed Induction Motor Drives
Using Particle Swarm Optimizer
-- K Naga Sujatha, K Vaisakh and K Srihari
In this paper, selection of the state feedback gains by Particle Swarm Optimization (PSO) technique is
presented in opposition to the selection of the feedback gains reported in literature. The proposed design has been
applied to the variable speed induction motor drive system. The system performance has been simulated and
compared with some previous methods such as Variable Structure Controller (VSC) method and Genetic Algorithm
(GA) approach. Simulation results show improved dynamic system performance. The results bring out
the effectiveness of the proposed technique.
© 2009 IUP. All Rights Reserved.
Optimal Power Flow Using Differential Evolution
Under Deregulated Environment
-- Rathinasamy Rajathy, Gnanadass Ramachandran,
K
Manivannan and Harish Kumar
To meet the growing load demand, power industries throughout the world are undergoing a
restructuring process. The Independent Power Producers (IPP) must respond quickly to those load changes with
respect to time. This paper describes the solution for Optimal Power Flow (OPF) in a deregulated environment
using Differential Evolution (DE) technique. The proposed approach is capable of obtaining minimum
solution irrespective of the nature of the objective function. The effectiveness of the approach is compared with
the performance of Particle Swarm Optimization (PSO) technique. The algorithm has been demonstrated
on IEEE-14, 30 systems.
© 2009 IUP. All Rights Reserved.
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