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Masters Design Projects

Masters Projects:


Tunable Active Filter For Distributed VCO
by :   Neeta Mehta
Advisor  :   Dr. Prasad Shastry
In Progress

ABSTRACT
   The project involves design, fabrication and tests and measurements of a varactor tuned active bandpass filter for a Distributed VCO. The VCO includes a distributed amplifier, a power divider, a varactor tune active bandpass filter and a amplifier in the feedback path. The active bandpass filter and the VCO will be designed to operate from 1.5 to 2.5 GHz.

 

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Distributed Architecture VCO-Design
by :   Zaheer A Shaik
Advisor  :   Dr. Prasad Shastry
In Progress

ABSTRACT
   This project involves design, fabrication, tests and measurements of a Voltage Controlled Oscillator (VCO) based on distributed amplifier technique. The VCO includes a distributed amplifier power divider, a tunable filter and an amplifier in the feedback path. The tunable filter and the amplifier in the feedback path provides the appropriate magnitude and the phase of loop gain necessary for oscillations. The VCO is desired to operate from 1.5 to 2.5 GHz.

 

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A 1.9 GHz Active Duplexer For Personal Communication System (PCS)
by :   Azrin Shah Mohd. Johari
Advisor  :   Dr. Prasad Shastry
May 2003

ABSTRACT
   Personal Communication System or PCS is one of the second generation mobile phone technologies, and duplexers are widely used in cellular phone and base station transceivers to enable simultaneous transmission and reception of signals through a single antenna. However, commercially available duplexers are designed as passive filter structures that have insertion loss and hence increase the noise figure of the receiver.
   In this project presentation, design, fabrication, test and measurements of an active duplexer will be presented. An active duplexer provides signal gain unlike a passive duplexer where the signal is attenuated. Also, filters will be designed and incorporated into the system at the transmitter and the receiver terminals in order to enhance isolation between transmitter and receiver.

 

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Electromagnetic Compatibility Studies
by :   Brian M.Harris
Advisor :   Dr. Prasad N.Shastry
May 2000

ABSTRACT
   This project focuses on electromagnetic compatibility, by developing emission and susceptibility testing procedures and presenting applicable limits in the United States and Europe. The testing procedures are put into practice with actual lab measurements on various electrical and electronic devices, and the test results are compared to applicable emission/susceptibility limits. Observations and conclusions on frequency versus emission and susceptibility characteristics for the various devices are presented.

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A Novel Proximity Coupled Active Integrated Antenna
by :   Sasidhar Vajha
Advisor :   Dr. Prasad N.Shastry
May 2000

ABSTRACT
   In this project, a novel design approach and measured results of a compact proximity coupled active integrated antenna (PCAIA) are presented. A new type of antenna feed structure is proposed. A single self-biased (through the RF port), two-stage low noise amplifier has been integrated with a proximity coupled patch antenna having a new feed structure. The proposed approach is useful in the design of compact PCAIA with good radiation characteristics for applications in microwave wireless systems.

 

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A CDMA Wireless Receiver Front-End
by :   Sameer Naik
Advisor  :   Dr. Prasad Shastry & Dr. In Soo Ahn
August 1999

ABSTRACT
   With cellular networks in the 800-900MHz band reaching capacity limits, PCS(1800-1900MHz) is proving to be the best alternative for cellular operators. Spread Spectrum, CDMA (Code Division Multiple Access) enables one to incorporate many users within a relatively wide bandwidth. The intent of the Phase I of the project was to design, construct and test the subsystems for CDMA Receiver Front-End in the PCS band. The goal of the project was to transmit a CDMA signal from a transmitter (base station) and retrieve the information at the receiver. Another goal for this project was to design a duplexer as a part of the subsystem, fabricate and test the duplexer for its performance in the PCS band.
   The CDMA signal was transmitted at 1.93 GHz from a transmitter, and received at the receiver end. The signal was then passed through a duplexer, and a low noise amplifier. The CDMA signal was then downconverted to an IF frequency of 210 MHz. Further, the signal was amplified (with an automatic gain control) and demodulated to a baseband signal. The design and performance characteristics of the receiver front-end are presented in this report.

 

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Electronically Tunable Distributed Active Filter
by :   Yongqiang He
Advisor :   Dr. Prasad N.Shastry
December 1998

ABSTRACT
    A design methodology for a novel, electronically tunable bandpass active filter, based on distributed amplifier topology, at microwave frequency, is presented. Edge-coupled microstrip line filter sections have been blended into the conventional distributed amplifier configuration. Interstage matching network has been used between cascaded transistors in each amplification cell. Varactor tuning scheme has been adopted for variable center-frequencies. The center frequency of the filter can be tuned in the range 1.7 to 2.3 GHz, which covers the PCS band. The filter has a minimum gain of 8.5dB, input and output return losses less than -6dB, in the tuning band. The filter consumes 120 mw. The guidelines for the design of the filter, as well as simulation and measured results are presented. The filter can be implemented in MMIC form, and has potential for applications in wireless communication systems.

 

Yong He at Work

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 Ali Imran working on his project

 

 

 

 

A 2.4 GHz CDMA Wireless Communication System
by :   Ali Imran Z.B.
Advisor :  Dr. Prasad N.Shastry
August 1998

ABSTRACT
   The field of wireless communications is rapidly growing with the emergence of personal pagers, cellular mobile radio systems, vehicle tracking, and commercial use of GPS. Multipath and interference from other users are the two basic problems the designer must face. Spread spectrum, Code Division Multiple Access (CDMA), is proving to be a viable technique for modern wireless communications due to its ability to effectively incorporate many users within a relatively wide bandwidth.
   The intent of the project was to design, construct, and test a network for Wireless Communication using Spread Spectrum technique. The goal was to make a network capable of transmitting information from a portable user unit to a receiving base station. Another goal for this project was to design the code generator and the data buffer using XILINX-FPGA, and provide an interface between the digital hardware and the RF system. Finally, an attempt was made to use Omnisys (and verify of HP EEsof Series IV Version 6.1) to investigate and verify the system's signal to noise ratio at various points in the system.

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A 2.4 GHz GaAs FET Oscillator
by :   
Advisor :   Dr. Prasad N.Shastry
In Progress

ABSTRACT
   Coming soon...

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Optimal Design of Low Crosstalk, Wideband, Bidirectional, Distributed Amplifier
by :   Z. M. Li
Advisor :   Dr. Prasad N.Shastry
May 1996

ABSTRACT
   In this project, an optimal approach to the design of low crosstalk, wideband, bidirectional, distributed amplifiers is proposed. The new technique based on Chebyshev scaling of device transconductances, gives considerably greater directivity bandwidth than the previously published approach using binomial scaling, for specified number of devices, and minimum directivity. The theory and design guidelines, as well as simulated and measured results are presented.

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MMIC Technology: Processing, Layout Design and Packaging
by :   G.Brubaker
Advisor :   Dr. Prasad Shastry
August 1993

ABSTRACT
   In this special topics course, the student is expected to learn GaAs MMIC layout design skills using EEsof CAE tools as well as obtain the knowledge on GaAs MMIC processing and packaging techniques by reading published material on the subject.
   Learning the layout design skills will involve working on selected MMIC layout design projects. Exposure to GaAs MMIC processing and packaging techniques will involve studies of published books and papers on the subject matter. The student is expected to keep a good record of his work. The student is expected to confer with the instructor at least once a week and report on the progress being made until the course in completed. The student is expected to: Give 3 seminar talks one each, on layout design, processing and packaging at the end of the course. Submit a report at the end of the course encompassing the topics covered by the course.

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GaAs FET Class-B Power Amplifier Study
by :   Surendra Makam
Advisor :   Dr. Prasad N.Shastry
May 1993

ABSTRACT
   Nonlinear characteristics of FET's cause harmonic distortion in power amplifiers and reduce the efficiency. In a Class-B amplifier, the efficiency can be increased by trapping the harmonics present in the amplified signal; this is achieved by using a quarterwave shorted microstrip line at the output. A Class-B amplifier was designed and analyzed with and without the harmonic trapping circuit. The results of the analyses are presented.

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Microwave Transistors and Circuit Applications
by :   G.Brubaker
Advisor :   Dr. Prasad Shastry
December 1993

ABSTRACT
   This paper presents linear and non-linear device models used to simulate the behaviour of MESFETs, HEMTs, and HBTs. Applications of the models are shown for amplifier design. Other microwave circuits are shown where models are used to simulate their behaviour.

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A Large Signal Model for GaAs FETs
by :   Lalitha G. Saraswathula
Advisor : Dr. Prasad N.Shastry
August 1992

ABSTRACT
    In this report an attempt is made to develop a large-signal model for GaAs FETs. Starting from measured DC-IV characteristics and small signal S-parameters of GaAs FETs the model developed is the one proposed by Curtice.W. The modelling procedures are illustrated by means of an example. The tuning and optimization of the model using EEsof CAE tools and the results obtained are discussed.

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Wideband Microwave Distributed Circuits
by :   G. Brubaker
Advisor :   Dr. Prasad Shastry
May 1992

ABSTRACT
   This paper presents distributed paraphase amplifier, oscillator circuit based on distributed topology, distributed mixer circuit, circulator/transmit-receive module based on distributed topology, noise considerations in distributed amplifiers, power and efficiency considerations in distributed amplifiers, cascode distributed amplifiers, band-pass distributed amplifiers, dual-gate distributed amplifiers and wideband power dividers and combiners.

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Band-Pass Distributed Amplifier Design Guidelines
by :   Ashok Kumar Kajjam
Advisor :   Dr. Prasad N.Shastry
May 1991

ABSTRACT
    In this project, GaAs FET Band-Pass Distributed Amplifier design guidelines are presented. The report focuses on fundamental design considerations. The design approach presented enables one to examine the trade-offs between variables and arrive at the appropriate design for a specified gain and bandwidth. The analysis enables the designer to predict the gain of the amplifier from the design curves for a given number of devices. The 3-dB bandwidth of the amplifier can be determined from the Normalized Frequency response curve.

Publications :  1) Prasad N.Shastry, A.Kajjam and Z.M.Li, " Band-Pass Distributed Amplifier Design Guidelines",
                                Microwave and Optical Technology Letters, Vol.10, No.4, November 1995, pp 215-218.
                           2) S.Reddy and A.Kajjam, "A 2-26 GHz Distributed Power Amplifier", submitted to Northrop
                                Grumman Corp., August 1992.
                           3) Prasad N.Shastry , A.Kajjam, S.Makam & S.Reddy, "Wireless LANs -- A Technology status Report"
                               submitted to Northrop Grumman Corp., August 1992.

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Design Considerations For Achieving Optimum Gate Voltages in Distributed Amplifiers
by :   Srinivas Reddy Ponnala
Advisor :   Dr. Prasad N.Shastry
May 1992

ABSTRACT
    This paper presents a report on the design considerations for achieving optimum gate voltages in Distributed Amplifiers. The analysis is carried out for an exponential distribution of series capacitors in the gate-line. This results in an increased gate voltage excitation till the last device as compared to an uniform distribution of series capacitors.

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