Small-signal behavior of Gunn diodes

Calculations of small-signal impedance have been made for Gunn diodes over a broad range of length and bias current density, taking into account the spatial inhomogeneity of the dc electric field. The nature of the impedance functions was found to vary with the above parameters, and was distinctly different for amplifying diodes, oscillatory diodes, and diodes biased below the threshold for active behavior. Nyquist stability analysis was used to relate the impedance behavior to the effects of circuit and bias level on oscillatory and amplifying behavior. The results of this analysis are found to be in good agreement with the experimental observations of other authors.