Anomalous low-frequency noise increase at the onset of oscillations in Gunn diodes

In this work, the presence of anomalous low-frequency noise effects in Gunn diodes has been studied and evidenced. Near the onset of Gunn instability, there is a limited range of bias voltages for which the noise significantly increases at frequencies well below the frequency of oscillation. For higher bias voltages, the oscillation becomes purer and such low-frequency noise drastically vanishes.