Characterization of ion-implanted IMPATT oscillators

Recent experimental results on impact avalanche transit-time diode oscillators fabricated by ion implantation are presented. The technique and problems involved are given. The diodes gave CW X-band power output up to 1.4 watts with efficiencies up to 8 percent. AM sideband noise measurements indicate that the load admittance for minimum noise is not coincidental with that load for maximum power output, and that a reduction of 20 dB in noise may be achieved with a reduction of only 0.5 to 3.0 dB in power output from the maximum power point by the proper choice of the load. AM sideband noise as low as 130 dB below the carrier in a 1-kHz bandwidth and at a sideband of 50 kHz from the carrier has been measured utilizing this technique.