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Mmic power amplifier thesis proposal

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Masters Thesis Projects

Active Bias, Power Detector, and Voltage Controlled Attenuator MMICs
by. Scarlet Halabi
Advisor. Dr. Prasad N.Shastry
Summer 2003

ABSTRACT
The design and analysis of an Active Bias Circuit (ABC), a Power Detector Circuit (PDC), and a Voltage Controlled Attenuator (VCA) implemented using GaAs MMIC technology is presented in this thesis. These circuits are to be implemented with a previously designed 24 to 42 GHz MMIC Band-Pass Cascode Cell Distributed Amplifier. The active device used in these circuits is a 0.1 mm pHEMT. The ABC encountered the challenge of having a current minor circuit used for depletion mode FETs. The PDC encountered the challenge of designing the matching network for the wide frequency band. Finally, the VCA encountered the challenge of obtaining linear attenuation versus control voltage while achieving the specified attenuation dynamic range over the frequency band. The novelty of the VCA circuit is that a band-pass filter structure was used to achieve the bandwidth and eliminate the effect of parasitic capacitances. All three circuits were designed as stand-alone circuits and fabricated. Only the ABC and PDC have been tested, and the VCA is being fabricated and will be tested later. These circuits along with the Distributed Amplifier are to be used in European Local Multipoint Distribution Systems for driving power amplifiers.

Antenna Data Acquisition System and Anechoic Chamber Characterization
by. Badria Elnour
Advisor. Dr. Prasad N.Shastry
Summer 2003

ABSTRACT
The thesis presents the design of an automated system for the measurements of antenna radiation characteristics in an anechoic chamber. The antenna data acquisition system enables one to plot the radiation patterns of an antenna and determine its important parameters.

Mmic power amplifier thesis proposal using the same number

The thesis further addresses the issues of characterization of the anechoic chamber and presents the results of characterization.

A 24-42 GHz Monolithic Distributed Amplifier
Project Assistant. Shawn Parker
Project Director. Dr. Prasad Shastry
June 2001
This project was supported by a research grant from Fujitsu Compound Semiconductor, Inc.

ABSTRACT
The design and analysis of 24 to 42 GHz MMIC Band-Pass Cascode Cell Distributed Amplifiers as presented in this thesis. The amplifiers make use of a novel mixed topology consisting of a band-pass gate line and a low-pass drain line. The mixed topology provides the benefits of a band-pass topology without requiring additional elements in the drain line. The amplifier makes use of a pHEMT cascode gain cell capacitively coupled to the gate line. Two amplifiers, utilizing 200 micrometer and 300 micrometer pHEMTs, have been designed, fabricated and tested. The amplifiers are suited for application in European Local Multipoint Distribution Systems for driving power amplifiers.

Output Power and Efficiency of Distributed Amplifiers
by. Amir S. Ibrahim
Advisor. Dr. Prasad N.Shastry
May 2001

ABSTRACT
The development of broadband systems created an increasing demand for use of wideband amplifiers. Distributed amplifiers are critical components in many such systems because of their wideband performance. However, the low efficiency and low output power of distributed amplifiers made them unsuitable for high power applications.

Mmic power amplifier thesis proposal Shastry      May 2001


In this thesis, investigation of techniques to increase the efficiency and out power of distributed amplifiers is presented. A 20 dBm tapered drain line distributed amplifier is designed. The amplifier has a bandwidth of 4.5 GHz and power-added-efficiency of 24%. The performance of the amplifier is found to be comparable to a reactively matched power amplifier using the same number of transistors.
The amplifier was fabricated on a 30-mil thick board with dielectric constant of 3.1 for the gate line and a 25-mil thick board with dielectric constant of 10 for the drain line. The use of two different board materials was necessary to avoid inconsistencies in microstrip widths. Measured results of the fabricated amplifier have been found to be comparable to simulation results.

A Distributed MESFET Source Injected Mixer
by. Edward W. Cullerton
Advisor. Dr. Prasad N.Shastry
May 2001

ABSTRACT
Recent developments in broadband communications systems have led to the development of broadband components. A mixer is a critical component in any communication system, and with the development of broadband communication systems, a broadband mixer is needed.
In this thesis, the design and performance of a broadband active mixer is presented. The mixer is called “Distributed MESFER Source Injected Mixer”. Two GaAs MESFETs perform the mixing operation in the mixer. The mixing operation is achieved by injecting the LO signal into the source of each MESFET, and injecting the RF signal into the gate of each MESFET. A distributed topology is used to inject the RF signal into the gate of each MESFET, and Chebyshev impedance transformers are used to inject the LO signal into the source of each MESFET. The IF signal is extracted from the drain of each MESFET using a lumped element matching network.
The mixer was fabricated on a 20 mil dielectric substrate using photolithography. Packaged MESFETs and lumped components were soldered to the microstrip circuit board to create a hybrid circuit. The design of the mixer and measured results are described in the following chapters.

A GaAs FET Distributed VCO
by. Sunil Modur
Advisor. Dr. Prasad N.Shastry
July 2001

ABSTRACT
A novel design of a voltage controlled oscillator (VCO) based on the distributed amplifier topology for the ISM (Industrial, Scientific, Medical) band is presented. The VCO includes a distributed amplifier and a power divider built on Rogers RO3003 substrate and a varactor tuned passive bandpass filter with an amplifier gain block built on TMM10i ceramic substrate, in the feedback path. The amplifier and the varactor tuned bandpass filter in the feedback path provide and the appropriate magnitude and phase of loop gain necessary for oscillations. The distributed oscillator design and measured results are discussed. The novel idea can be implemented in the MMIC form and has great potential in the growing wireless communication market.

Active Antenna for Full Duplex Operation
by. Thirendra Rayamajhi
Advisor. Dr. Prasad N.Shastry
May 1999

ABSTRACT
Active antennas have been of growing interest in recent years. The use of active devices in passive antenna elements have helped to reduce cost and size, and improve the overall performance of the antenna. In practically all communication systems, full duplex operation has been achieved by using different frequencies for transmitting and receiving. Active antennas with full duplex functionality at the same frequency are relatively new. Bidirectional amplifiers such as distributed amplifiers though well known for their duplexing capability, have not been investigated for such applications.
This thesis work involved investigations into the possibility of integrating a distributed amplifier with an antenna for full duplex operation. In this presentation, the active antenna concept will be introduced. The possible system configurations for integrating a distributed amplifier and passive antenna, and design and performance issues involved therein will be discussed.

Design of a 2.4 GHz Digital Phase Shifting Network
by. John S. Novak, III
Advisor. Dr. Prasad N.Shastry
May 1997

ABSTRACT
A 2.4 GHz digital phase shifting network has been designed, simulated, and fabricated for use in phase shifting antenna arrays. The design technique incorporates the hyperbolic nature of the geometry of the Smith chart to create arbitrary phase shifting networks from arbitrary PIN diodes. The fabrication is accomplished in microstrip technology, and uses surface mount component technology where available.

A Class-B Push-Pull Distributed Microwave Amplifier
by. G.Brubaker
Advisor. Dr. Prasad N.Shastry
May 1997

ABSTRACT
A Class-B Push-Pull Distributed Amplifier for use in the 2-4 GHz band using NEC NE76084 GaAs MESFETs has been designed, simulated, fabricated and tested. A differential distributed amplifier (also with the NEC NE76084 GaAs MESFET), used as an active balun at the input, has been designed and simulated. Physical restrictions prevented fabrication of this design. Passive microstrip baluns were used to phase split the input signal and recombine the balanced output. The Curtice Cubic model was used to model the active devices during the design process. Guidelines to assist in the application of the Curtice Cubic model are presented.

A 2.5 GHz Programmable Frequency Divider
by. Srinivas Reddy Ponnala
Advisor. Dr. Prasad N.Shastry
May 1993

ABSTRACT
A 2.5 GHz Programmable frequency divider has been designed and simulated, for use in microwave frequency synthesis applications. The frequency divider uses a 1µm gate length E/D MESFETs, and Schottky diodes. The basic building block of the frequency divider is Direct – Coupled FET Logic (DCFL) gate. Graphical design approach is used for the design of frequency divider logic circuits. Using this approach test circuits have been designed, laid out and simulated. Transmission line interconnect designs are implemented in layout and its effects are simulated. A new analytical design approach for the design of DCFL inverter is presented. The frequency divider is capable of dividing an input frequency from DC to 2.5 GHz with any divisor between 2 to 127. The delays obtained from the test circuit simulations are used in the simulation of a 7-bit programmable frequency divider.


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