  Experiments, numerical simulations and an analytic model were developed to
elucidate the effects of noise in the synchronized state of a tunnel junction
based spin torque nano oscillator (STNO). It is demonstrated that in the in
plane magnetized structure, while the frequency is locked, much higher
reference currents are needed to reduce the noise by phase locking. Our
analysis shows that it is possible to control the phase noise by the reference
microwave current (IRF) and that it can be further reduced by increasing the
bias current (IDC) of the oscillator, keeping the reference current in feasible
limits for applications.
