University Lab Creates Self-Healing Circuits

Enid Burns for — Your Universe Online

When a circuit goes, depending upon where it was located, you may be in for a nuisance, if not a headache. In the case of your house, you can just go flip the breaker. But for computers and other electronics, those circuits often mean replacing parts, or even the whole device. A team at the High-Speed Integrated Circuits laboratory in Caltech’s Division of Engineering and Applied Science has developed circuits in tiny power amplifiers with a self-healing capability. These self-healing circuits hint at a future where our electronics correct themselves.

The demonstration was shown with amplifiers so small that 76 of the chips — including the self-healing capabilities — fit on a single penny. To show off their power, the team destroyed various parts of the chips by blasting them multiple times with a high-powered laser. The chips automatically developed a work-around, a process that took less than a second.

“It was incredible the first time the system kicked in and healed itself. It felt like we were witnessing the next step in the evolution of integrated circuits,” said Ali Hajimiri, the Thomas G. Myers Professor of Electrical Engineering at Caltech, in a statement from the University. “We had literally just blasted half the amplifier and vaporized many of its components, such as transistors, and it was able to recover to nearly its ideal performance.”

In the future, chips made with self-healing circuitry could recover from problems such as insufficient battery power or total transistor failure.

The team’s work will appear in the March issue of IEEE Transactions on Microwave Theory and Techniques.

Caltech engineers worked on the project in order to give integrated-circuit chips a healing ability somewhat like that of the human immune system. The process gives the chips the capability of detecting and quickly responding to any number of possible assaults. This keeps the larger system working at optimal levels.

The system works to monitor and address issues that come up during operation. “The power amplifier they devised employs a multitude of robust, on-chip sensors that monitor temperature, current voltage, and power. The information from those sensors feeds into a custom-made application-specific integrated-circuit (ASIC) unit on the same chip, a central processor that acts as the ‘brain’ of the system. The brain analyzes the amplifier’s overall performance and determines if it needs to adjust any of the system’s actuators — the changeable parts of the chip,” the statement said.

The chip’s ability to adapt comes from a system that draws conclusions based on the aggregate response of the sensors. “You tell the chip the results you want and let it figure out how to produce those results,” said Steven Bowers, a graduate student in Hajimiri’s lab, and lead author of the new paper. “The challenge is that there are more than 100,000 transistors on each chip. We don’t know all of the different things that might go wrong, and we don’t need to. We have designed the system in a general enough way that it finds the optimum state for all of those actuators in any situation without external intervention.”

It’s still quite some time before the chip might find its way into your computer, but the work from the Caltech team shows promise.

“Bringing this type of electronic immune system to integrated-circuit chips opens up a world of possibilities,” said Hajimiri. “It is truly a shift in the way we view circuits and their ability to operate independently. They can now both diagnose and fix their own problems without any human intervention, moving one step closer to indestructible circuits.”