Microwave communication requires generating RF at microwave frequencies, not only for the transmitter but also in the receiver, where the incoming microwave signal has to be converted to a lower frequency for demodulation. Bill Rippard and his colleagues at the National Institute of Standards and Technology (NIST) in Boulder, Colorado, have come up with a new way of generating microwave that uses two magnetic films separated by a non-magnetic copper layer to generate RF from 5 GHz to over 40 GHz. An electric current applied to the first magnetic film causes the electrons to align their spins to match the magnetic orientation in the film. However, when the aligned electrons flow through the second magnetic film, the process is reversed and the alignment of the electrons is transferred to the film. The magnetization of the film rapidly reverses direction, oscillating at microwave frequencies.
The "Q" of this oscillator is 800, indicating the microwave signal from the oscillator is stable and has little noise. Adjusting the magnetic field varies the frequency of the oscillator.
Motorola is working with NIST and researchers at Cornell University to develop processes that might be adapted to allow the NIST-style "nano-oscillators" to be built on silicon chips, eliminating the need for larger external resonators or oscillators in radar systems, cell phones and other communication devices.
More information can be found in the NIST Techbeat article Cell phone still too big? Micro-oscillators may help and the American Physical Society's Physical Review Focus article, Timing is everything.
