These kinds of self-repairing integrated chips, the researchers said, could lead to smartphones that recover by themselves from technical failures ranging from a battery problem to total transistor failure, among many other applications. The research at the California Institute of Technology is described in the March issue of IEEE Transactions on Microwave Theory and Techniques.

The team, composed of engineers from the university's High-Speed Integrated Circuits lab in the Division of Engineering and Applied Science, has demonstrated this capability in tiny power amplifiers. Seventy-six of these tiny amps, including the components needed for self-healing, could fit on a penny.

'Next Step' in Chip Evolution

The researchers zapped parts of the chips numerous times with a high-powered laser, and the chips were able to develop work-arounds to keep themselves going -- all in less than a second.

Professor Ali Hajimiri, one of the team members, said in a statement that the "first time the system kicked in and healed itself" seemed to be "like we were witnessing the next step in the evolution of integrated circuits." He added that the researchers "literally just blasted half the amplifier and vaporized many of its components," and the component recovered nearly its full performance. This moves the chips one step closer, Hajimiri said, to becoming "indestructible circuits."

To create such Lazarus-like properties in chips, a number of durable, on-chip sensors are deployed that keep track of temperature, current, voltage and power, which then feed updates into a custom-made application-specific integrated circuit (ASIC) on the same chip. If there are any changes in the variables, the ASIC runs through more than 250,000 possible configurations to find the best alternative workaround, including adjusting actuators on the chip.

'Let It Figure Out'

The ASIC acts as a "brain" for the chip, but it is not programmed for every possible situation involving the 100,000 transistors and other components on the chip. Instead, team member Steven Bowers told news media, "you tell the chip the results you want and let it figure out how to produce those results."

The team discovered that amplifier chips with self-healing only required about half as much power as regular chips, and their performance was more predictable. As it turns out, the self-healing setup also addresses several other problems besides destruction of parts of the circuits, including long-term aging following repeated use and short-term variations from changes in load, temperature and supply voltage.

By demonstrating this system in a power amplifier chip for millimeter-wave frequencies, which are used in high-end research and in next-generation applications, the researchers said the system should be able to work on chips with lesser requirements.