|
What's Needed for Teensy-Weensy Cell Phones
Business Week , November 5, 2001
The chips inside cell phones keep getting smaller. But the phones' size seems to be frozen, especially for multimode models that work on different continents. The reason is simple, says Clark T.C. Nguyen, an electrical engineer at the University of Michigan. Radio-frequency (RF) filters still hog a lot of space on the phones' circuit boards.
These quartz and ceramic filters grab a specific frequency for your phone calls while blocking all the others. They can vary in size, but often measure about 2 by 2 centimeters--and you need several to receive and transmit. Plus, if your phone is designed to function in different countries, it requires multiple sets for each format.
Nguyen says that he can shrink the filters way down by using the same fabrication technology that turns out tiny airbag sensors in automobiles. The technology carves mechanical devices in silicon gizmos known as microelectromechanical systems (MEMS). "It's the IC [integrated circuit] revolution for mechanical stuff," says Nguyen, who was once part of a team of scientists that road-mapped future communications for NASA. Now he has formed a startup, Discera Inc., to make MEMS filters for cell phones.
To be sure, there will be some challenges, including the vacuum packaging required for such devices. But ultimately, says Nguyen, the MEMS parts could be integrated with the silicon circuitry. Once that is achieved, cell phones will shrivel to the size of watches, or even finger rings.
By Neil Gross
|
