By Will Soutter
Researchers at UCLA have developed a very powerful nanoscale microwave oscillator that could impact the mobile communication industry by paving the way for energy efficient and economical communication devices.
Magnetic Layers of spin-transfer microwave oscillator(Credit: UCLA Henry Samueli School of Engineering and Applied Science)
Microwave oscillators are employed in mobile phones and WiFi-enabled devices in order to generate the radio frequency signals needed for communication. These signals are converted to electromagnetic waves by the device’s antenna. As opposed to existing microwave oscillators which are silicon based and employ the charge of an electron for microwaves generation, the nanoscale oscillator developed at UCLA employs the spin magnetism of electrons to produce oscillations. The researchers were initially working on layered nanostructures meant for use as spin-transfer torque magneto resistive random access memory (STT-RAM) when they realized that it could be extended to microwave oscillators.
The nanoscale structure is labeled as spin-transfer nano-oscillators (STNO). It comprises two magnetic layers where only one layer has fixed magnetic polar orientation. Precise microwave oscillations are produced by manipulating the magnetic orientation of the other layer by means of electric current. In order to be eligible for practical applications, oscillators have to produce at least 1 µW of output power and good signal quality. Previous spin-transfer oscillators have not fulfilled these criteria. The tests conducted on the STNO reveal that it indeed meets the output requirement of 1 µW and also produces a narrow signal linewidth of 25 MHz which translates as cleaner voice and video signal sans interference. The STNO is 10,000 times smaller than current oscillators. There are not any major design changes that are required to incorporate them in existing circuits or chips.