Series interconnection of TRAPATT devices on insulating substrates

This report describes the results of a study of the diode-circuit interactions in TRAPATT oscillators which use series connected diode chips to produce higher power outputs than could be obtained from a single chip. The effects of package parasitics on series interconnections of TRAPATT diodes mounted on diamond substrates have been studied via time domain computer simulations and experiments at frequencies from 2 to 9 GHz. Guidelines for the selection of package parasitics have been identified, and application of these guidelines to series connected diodes has resulted in combining efficiencies approaching 100% at frequencies up to 9 GHz. A multi-diode configuration with six chips mounted thermally in parallel and electrically in series on a diamond substrate yielded 35.5 watts at 7.5 GHz. Multi-chip diodes with two, three and four chips yielded 12, 14 and 21 watts respectively near 8.7 GHz.