Stacked kilowatt avalanche-diode microwave oscillators

Avalanche-diode oscillators operating in the high-efficiency mode have worked successfully in series in a multiple-stacked geometry. Several five-stacked units made from a recent silicon wafer produced L-band pulsed power of over 1 kw. Among them the best results obtained are 1.2 kw at 1.1 GHz with an efficiency, of 25.6%. This result represents the highest power level achieved to date from the avalanche diode devices. The diodes are boron-diffused epitaxial "disks". The doping density of the N-epitaxial layer is about /cm³. Individual 0.022-in.-diameter disk-shaped diode-chips were mounted p-side-down in 0.050=in..height pill boxes before being stacked in series.