Traffic control for computer chips

Computer transistors have hit the wall. In the ongoing quest to make computers more powerful and efficient, engineers have shrunk transistors to the size of a common bacteria, and there simply isn’t a way to reduce them any further. So Laleh Behjat, associate professor of electrical and computer engineering at Schulich, is developing new ways to reorganize transistors, fitting even more of them onto a computer chip.

“It’s like planning a big city,” says Behjat. “When you have two billion transistors on a chip, you want to be sure it’s compact and efficient. You want lots of roads, but not too much traffic.”

Planning for efficiency
Decreasing traffic means increasing efficiency. Today’s computers tend to overheat as they’re asked to run faster and faster. Then the computer’s power-intensive fan turns on, putting even more demand on the battery. “If we can make computers use less power,” says Behjat, “the battery will last longer, you’ll use less energy and the computer will last longer.”

Behjat’s goal is to pack transistors inside a computer so they take up less space. As a result, they’ll produce less heat, take up less area, and use less power. To achieve that goal, Behjat and two of her graduate students are developing complicated mathematical techniques that optimize transistor placement and wire routing. “We have up to 12 layers of roads on top of each other,” says Behjat.

A winning strategy
Behjat’s team took their strategy to the International Symposium on Physical Design (ISPD), an Intel-sponsored gate-sizing competition that challenges entrants to optimize circuit design.  The Schulich team was one of only ten that successfully completed the challenge, and they were the only Canadian team to finish.

Behjat’s approach to transistor traffic control is unique, and it’s working. “No one else in world is doing it,” says Behjat. “And these techniques are helping us find better solutions.”