Sanjay Raman has always been fascinated by technology -- particularly as depicted in the science-fiction universes of Star Wars and Star Trek. Now he is working to develop that very technology.
While earning his Ph.D. at the University of Michigan, Raman developed an integrated 94 GHz polarimetric monopulse radar receiver. The entire receiver, including antennas and receiving circuitry, was fabricated on a single semiconductor chip less than 25 mm across.
"We were working with 94 GHz frequencies - roughly 100 times the frequency of first-generation cell phones," he said. "Integrating antennas and electronics on the same chip can be relatively straightforward at those frequencies due to the short operating wavelengths. The antennas are physically small, so they can be integrated on-chip."
Raman is currently exploring methods of integrating antennas on chips at the lower frequencies used for wireless applications (e.g. 900 MHz, 1.8 GHz, 2.4 GHz.). "If you use a conventional resonant antenna at those frequencies, it is no longer physically small. The antenna becomes much larger than the scale of the chip. So we are looking at using electrically small antennas. They are not as efficient, but they have potential for use in many emerging applications."
"Basically, we're trying to develop
a true single-chip radio for commercial applications without
any off-chip components," he said. "Such a radio would
potentially be quite cheap and could be placed anywhere."
"This technology could also potentially provide a way of communicating with smart structures," he said. "A 'smart' turbine engine could have distributed wireless sensors that track the flow of air through the engine or the strain on the turbine blades, then communicate data to a central processor which would modify engine control parameters for increased efficiency."
Like many issues in electrical and computer engineering today, Raman's work spans a variety of different areas, including communications, electromagnetics, electronics, and materials. Because of this, he collaborates with many of the department's research groups, including the Mobile and Portable Radio Research Group (MPRG), the Center for Wireless Telecommunications (CWT), and the Antenna Laboratory.
He is also involved in establishing the new advanced education and research laboratories and curriculum in microelectronics (see page 34) under development through the College of Engineering and the Virginia Microelectronics Consortium for Education and Research (VMEC).
Crossing disciplines is an old habit for Raman. After earning a B.S. from Georgia Tech, Raman spent five years in the U.S. Navy as a nuclear submarine officer - including two months spent under the Arctic ice and a visit to the North Pole. "It was a challenging and grueling experience, but very rewarding," he said. Submarine officers need a wide range of knowledge, he explained, including electrical, mechanical, radiation, controls, chemistry, and materials science. "And that's just for the nuclear propulsion. We also needed experience in navigation, sensors, communications, and weapons."
While in the Navy, he decided he wanted to get more involved in the research and design side of technology instead of operations.
One of his first actions as a new faculty member was to develop a new graduate-level course in radio frequency integrated circuit (RFIC) design. "The existing radio courses at Virginia Tech stress the fundamentals through a hybrid approach to radio circuit design. In this new follow-on course, I am concentrating on the design and implementation of radios at the integrated circuit level."
He plans to add a component where students design an RFIC chip, send the design out for foundry fabrication, and then characterize the fabricated chip at RF frequencies during the following semester. "It is important for students to get involved in courses that integrate diverse disciplines such as communications, RF engineering, and microelectronics."