High-efficiency low-frequency operating modes in avalanche diodes under low-current-density conditions

A theoretical model of the avalanche-diode oscillator, based on Read´s analysis is developed. It is shown that, with appropriate circuit constraints, a complex voltage waveform appears across the device terminals and high-efficiency low-frequency oscillations occur. The model is applicable at low current densities and the effects of carrier space charge on the electric-field distribution within the device are neglected in the computations. A switch from transit time to operation at a harmonically related low frequency, with increasing direct-current density and under constant-r.f.-loading conditions, is predicted by this theory. An experimental circuit by which such effects may be investigated is described, and avalanche-diode behaviour in qualitative agreement with the model is observed.