Revolution in a radar chip

Imagine driving down a twisty mountain road on a foggy night. Visibility is near zero, yet you still can see clearly. Not through your windshield, but via an image on a screen in front of you.

Such a built-in radar system in our cars has long been in the domain of science fiction, as well as wishful thinking on the part of commuters. But such gadgets could become available in the near future, thanks to Caltech’s High Speed Integrated Circuits group.

The group is directed by Ali Hajimiri, an associate professor of electrical engineering. Hajimiri and his team have used revolutionary design techniques to build the world’s first radar on a chip—specifically, they have implemented a novel antenna array system on a single, silicon chip.

Hajimiri notes, however, that calling it “radar on a chip” is a bit misleading because it’s not just radar. Having essentially redesigned a computer chip from the ground up, the technology is revolutionary enough to be used for a wide range of applications.

The chip can, for example, serve as a wireless, high-frequency communications link, providing a low-cost replacement for the optical fibers that are currently used for ultrafast communications. Hajimiri’s chip runs at 24 GHz (24 billion cycles in one second), which makes it possible to transfer data wirelessly at speeds available only to the backbone of the Internet (the main network of connections that carry most of the traffic on the Internet).

Other possible uses:

• In cars, an array of these chips could provide a smart cruise control, one that wouldn’t just keep the pedal to the metal, but would brake for a slowing vehicle ahead of you and avoid a car that’s about to cut you off.

• The chip could serve as the brains inside a robot capable of vacuuming your house. While such appliances now exist, a vacuum using Hajimiri’s chip as its brain would clean without bumping into everything, have the sense to stay out of your way, and never suck up the family cat.

• A collection of these chips could form a network of sensors that would allow the military to monitor a sensitive area, eliminating the need for constant human patrolling and monitoring.

In short, says Hajimiri, the technology would be useful for numerous applications, limited only by an entrepreneur’s imagination.

Perhaps the best thing of all is that these chips are cheap to manufacture, thanks to the use of silicon as the base material. “Traditional radar costs a couple of million dollars,” says Hajimiri. “It’s big and bulky, and has thousands of components. This integration in silicon allows us to make it smaller, cheaper, and much more widespread.

“The key is that we can integrate the whole system into one chip that can contain the entire high-frequency analog and high-speed signal processing at a low cost,” says Hajimiri. “It’s less powerful than the conventional radar used for aviation, but, since we’ve put it on a single, inexpensive chip, we can have a large number of them, so they can be ubiquitous.”

Hajimiri’s radar chip, with both a transmitter and receiver (more accurately, a phased-array transceiver) works much like a conventional array of antennas. But unlike conventional radar, which involves the mechanical movement of hardware, this chip uses an electrical beam that can steer the signal in a given direction in space without any mechanical movement.

For communications systems, this ability to steer a beam will provide a clear signal and will clear up the airwaves. Wireless phones, for example, radiate their signal omnidirectionally, which contributes to interference and clutter in the airwaves.
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