Experimental analysis for the large-amplitude high-efficiency mode of oscillation with Si avalanche diodes

This paper presents the result of an investigation aiming to clarify the large-amplitude oscillation mechanisms of a Si avalanche diode with high efficiency, a part of which was already reported in [6], by varying circuit conditons and the shapes of applied voltage pulses. Applying a pulse resistive, transient voltage across and current through the diode have been observed by varying the rise time of the source voltage. As a result, variations of these waveforms have been revealed with decreasing the rise time and if the slope of the diode voltage at the breakdown is large than 100 V/ns, damping oscillation has been observed with the amplitude increasing proportionally to this slope. This damping oscillation plays a significant role in initiating the stable large-amplitude oscillation. Using a resonant cavity, voltage and current waveforms at various points have been observed and analyzed for various cavity lengths and applied source voltages. The analysis shows that the voltage wave-form across the diode coincides with the superimposed waveforms of the wave incident on and the wave reflected from the diode, the latter being delayed about 60 ps with respect to the former. This oscillation mechanism is considered to be very close to the TRAPATT oscillation. The details of experimental results, oscillation characteristics, and their analyses are explained.