MIT researchers built an experimental graphene chip known as a frequency multiplier, meaning it is capable of taking an incoming electrical signal of a certain frequency — for example, the clock speed that determines how fast a computer chip can carry out its computations — and producing an output signal that is a multiple of that frequency. In this case, the MIT graphene chip can double the frequency of an electromagnetic signal.
Frequency multipliers are widely used in radio communications and other applications. But existing systems require multiple components, produce “noisy” signals that require filtering and consume large power, whereas the new graphene system has just a single transistor and produces, in a highly efficient manner, a clean output that needs no filtering.
In order to make “faster and faster computers” and cellphones that can send data at higher rates, for example. “It’s very difficult to generate high frequencies above 4 or 5 gigahertz,” he says, but the new graphene technology could lead to practical systems in the 500 to 1,000 gigahertz range.
Running several of the frequency-doubling chips in series, it should be possible to attain frequencies many times higher than are now feasible.
While the work is still at the laboratory stage, Palacios says, because it is mostly based on relatively standard chip processing technology he thinks developing it to a stage that could become a commercial product “may take a year of work, maximum two.” This project is currently being partially funded by the MIT Institute for Soldier Nanotechnology and by the Interconnect Focus Center program, and it has already attracted the interest of “many other offices in the federal government and major chip-making companies,” according to Palacios.
Kong has been developing a method for growing entire wafers of graphene directly, which could make the material practical for electronics. Kong and Palacios’ groups are currently working to transfer the frequency multipliers to these new graphene wafers.
“Graphene will play a key role in future of electronics,” Palacios says. “We just need to identify the right devices to take full advantage of its outstanding properties. Frequency multipliers could be one of these devices.”