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Spring 2006 • Volume 12, Issue 2

Wireless wonders

Story by Nancy Ridgeway and photos by Duane Zehr

When our cell phones ring, as we pull out our laptops at our favorite trendy coffee houses, when we turn on satellite radios or access GPS navigation systems in our cars, or when we check our palm pilots, we rarely pause to consider all that goes into creating circuits that make wireless technology work. Bradley electrical and computer engineering professors and students are conducting research at the frontier of this technology, as they not only design monolithic microwave integrated circuits (MMICs), but also test and measure them.

Dr. Shastry and BalamuruganA new advanced microwave engineering laboratory has been established at Bradley with funding from a $265,000 Major Research Instrumentation grant from the National Science Foundation. The NSF’s highly competitive grant program drew proposals primarily from major research institutions, and receiving the grant is a significant accomplishment for Bradley. The proposal was one of 43 submitted for funding.

Dr. Prasad Shastry,professor of electrical and computer engineering, pictured at left with Balamurugan Sundaram MSEE ‘06, says one of the important criteria for the grant is that it not only promotes research, but also provides research training for students and collaboration between universities and industry.

The lab includes a microwave integrated circuit wafer probe station and a microwave network analyzer. The state-of-the-art equipment is used to test and measure MMICs, used in wireless technology. An MMIC chip is approximately one millimeter square in area and one- to two-tenths of a millimeter in thickness. While Shastry and his students have designed this kind of technology in the past, the new equipment also allows them to test and measure it. “Very few companies and universities have such sophisticated equipment,” says Shastry.

Program partners with industry

As part of the university-industry partnership, Bradley students are working with TLC Precision Wafer Technology, Inc., in Minneapolis, Minnesota, to create a 29 GHz MMIC amplifier that can be used in a broadband wireless system for high-speed data transmission and reception. “In this project, the company sent us the transistors. Students learned to use the wafer probe station, took measurements on the transistors, developed a model for the transistor, and are now designing the amplifier. We use state-of-the-art software tools to design the MMICs.”

Shastry explains how an amplifier is used. “Signals, when they travel in air over long distances, diminish in their strength. Amplification means boosting the signal strength. The signals are amplified at the transmitter, before transmitting them into air, and again at the receiver, after receiving them from air. When we measure an amplifier, we are measuring how much of a boost the amplifier is giving to signals at different frequencies. We want to make sure that it functions properly and meets the requirements for which it was designed.”

Advanced Microwave Lab labSundaram, Shastry’s graduate student assistant, says his master’s capstone research project involves integrating an amplifier into a duplexer circuit used in wireless systems. A duplexer circuit enables the system to transmit and receive signals simultaneously. Sundaram and Shastry have invented a tunable active duplexer for wireless systems. They are exploring the possibility of a patent for this new idea. They presented a paper on this research project at the European Microwave Conference in Paris, France, in fall 2005. An expanded version of this research paper will be published in the June 2006 special issue of IEEE Transactions on Microwave Theory and Techniques, the most prestigious journal in this field. (A research paper by Scarlet Daoud ’97 MSEE ’04, now an MMIC design engineer at U.S. Monolithics, Inc. in Chandler, Arizona, and Shastry, also will appear in the same issue. Work reported in this paper was done at Bradley as part of a master’s thesis project supported by a grant from Fujitsu).

Discussing other research projects, Shastry mentioned ongoing discussions with TLC Precision Wafer Technology about jointly writing project proposals to fund further research. In addition, he and his students are working with Northrop Grumman Corp. in Rolling Meadows, with whom Shastry has collaborated since 1991. “At that time, we could design MMICs, but we couldn’t test them.” Shastry is also negotiating a collaborative research contract with Mini-Circuits, Inc., in New York, and TriQuint Semiconductor, Inc., in Hillsboro, Oregon, to develop a broadband amplifier. Bradley would do the design and testing, TriQuint would manufacture it, and Mini-Circuits, who would fund the project, will sell the product.

Discussing the project, Shastry says currently four students are being trained to use the equipment in the new laboratory. “We want to implement more than one novel idea to meet the company’s specifications for the circuit.” Noting that students are designing the circuits, he explains, “The circuit design process is quite complicated. One must meet the specifications for the circuit. The design is done using state-of-the-art software tools. We check the design through simulations to confirm whether the specifications have been met. Once the design is done, we create a layout for the circuit. The layout is then sent to the manufacturer of the circuit. Once the circuit that we have designed has been manufactured, it comes back here and we do the testing and measuring.” Shastry comments, “We may also have a separate collaborative project with TriQuint that we will explore.”

He adds, “Wireless technology became commercial in the 1990s. Before that, it was used primarily for defense applications. There has been a boom in the wireless industry due to civilian applications. The Internet also is not new. It was invented in the 1970s. Today, Internet2 (which allows higher speed data transmission and reception than the Internet available commercially) is limited to a consortium of universities and industry. It may be available to everyone in the future.”

Shastry concludes, “I can confidently say Bradley has one of the best microwave and wireless engineering programs in the country, up to the master’s level. We continually update our curriculum, and all our projects are on the cutting edge of technology.” Shastry will offer a new course on MMICs in which the new equipment in the advanced microwave engineering laboratory will be used.

For additional information visit the Microwave and Wireless Engineering Program. Go>

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