Doug Lung / 06.29.2012 11:59AM
Nanoscale Microwave Oscillators Generate Close to 1 Microwatt at UCLA
UCLA-developed oscillators use the spin of an electron
Consumer electronic manufacturers are looking at microwave frequencies from 2.4 GHz to 60 GHz and higher to meet the ever-increasing demand for higher speed data connectivity. These efforts could be helped by a high-performance nanoscale microwave oscillator developed by a UCLA-led research team. Unlike current silicon-based oscillators that use the charge of an electron to create microwaves, the UCLA-developed oscillators use the spin of an electron, as in the case of magnetism, to gain “several orders-of-magnitude advantages over oscillators commonly in use today.”
The spin-based oscillators grew out of research at the UCLA Henry Samueli School of Engineering and Applied Science sponsored by the Defense Advanced Research Projects Agency (DARPA) looking into spin-transfer torque magnetoresistive random access memory (STT-RAM). Principal investigator and research co-author Kang L. Wang, UCLA Engineering's Raytheon Professor of Electrical Engineering, explains, “We realized that the layered nanoscale structures that make STT-RAM such a great candidate for memory could also be developed for microwave oscillators for communications.”
The spin-transfer nano-oscillators are composed of two distinct magnetic layers, one with a fixed magnetic polar direction and the other layer with a magnetic direction that can be made to gyrate by passing an electric current through it. This design allows the structure to produce a very precise microwave signal.
Pedram Khalili, project manager for the UCLA–DARPA research programs in STT-RAM and non-volatile logic, said, “Previously, there had been no demonstration of a spin-transfer oscillator with sufficiently high output power and simultaneously good signal quality, which are the two main metrics of an oscillator — hence preventing practical applications. We have realized both these requirements in a single structure.”
The spin-based nanoscale oscillators have an output of a bit less than one microwatt and, what the UCLA news release
, said was “a record narrow signal line width of 25 megahertz.” While this power output may not sound impressive, it is accomplished by a device that about 10,000 times smaller than the silicon-based oscillators used today.