Obsolescence is the curse of electronics: no sooner have you bought a gadget than its hardware is outdated. A new, low cost type of microchip that can rearrange its design on the fly could change that. The logic gates on the chip can be reconfigured to implement an improved design as soon as it becomes available—the hardware equivalent of the software upgrades often pushed out to gadgets like phones.
The new chips—made by a startup called Tabula—are a cheaper, more powerful competitor to an existing type of reprogrammable chip known as a field programmable gate array (FPGA). FPGAs are sometimes shipped in finished devices when that is cheaper than building a new chip from scratch—usually things that are expensive and sell in low volumes such as CT scanners. More commonly, FPGAs simply provide a way to prototype a design before making a conventional fixed microchip.
If programmable chips were more powerful and less costly they could be used in more devices, in more creative ways, says Steve Teig, founder and chief technology officer of Tabula. His company’s reprogrammable design is considerably smaller than that of an FPGA. “FPGAs are very expensive because they are large pieces of silicon,” says Teig, “and silicon [wafer] costs roughly $1 billion an acre.” The time it takes for signals to traverse the relatively large surface of an FPGA also limits its performance, he says.
“It’s like being inside a very large, one story building—the miles of corridors slow you down,” he says. As with a building, stacking layers of circuit on top of each other helps, by providing a shortcut between floors, says Teig. But unfortunately, the technology needed to build stacked, 3-D chips is still restricted to research labs. Instead Teig found a way to make a chip with just one level behave as if it were eight different ones stacked up.
“Imagine you walked into the elevator in a building and then walked back out, and that I rearranged the furniture quickly while you were in there,” says Teig. “You would have no way to tell you weren’t on a different floor.” Tabula’s chips perform the same trick on the data they process, cycling between up to eight different layouts at up to 1.6 billion times per second (1.6 Gigahertz). Signals on the chip encounter those different designs in turn, as if they were hopping up a level onto a different chip entirely. “From its behavior, our [design] is indistinguishable from a stack of chips,” says Teig, who calls the virtual chip layers “folds.”