  Spin torque nano-oscillators are nanoscopic microwave frequency generators
which excel due to their large frequency tuning range and agility for amplitude
and frequency modulation. Due to their compactness, they are regarded as
suitable candidates for applications in wireless communications, where
cost-effective and CMOS-compatible standalone devices are required. In this
work, we study the ability of a magnetic-tunnel-junction (MTJ) based spin
torque nano-oscillator to respond to a binary input sequence encoded in a
square-shaped current pulse for its application as a frequency-shift-keying
(FSK) based emitter. We demonstrate that below the limit imposed by the spin
torque nano-oscillators intrinsic relaxation frequency, an agile variation
between discrete oscillator states is possible. For this kind of devices, we
demonstrate FSK up to data rates of 400 Mbps which is well suited for the
application of such scillators in wireless networks.
