Avalanche transit time microwave oscillators and amplifiers

The state of the art on avalanche transit time diodes is reviewed. Experimental results are reported on two different diode structures; (1) A simple PN junction and, (2) A hyperabrupt junction "Read" structure, both of which employ the avalanche transit time mechanisms originally proposed by Read. These results are compared with the theoretical predictions of Read and Misawa. Preliminary circuit results to date include 19 mw of CW power at 5 Gc with 1.4% efficiency from a Read structure, and 13 mw of CW 10.5 Gc power with 0.5% efficiency from a simple PN junction. PN junction amplifier operation at 11.5 Gc has produced 20 db of gain with 30 mc bandwidth. Noise figures in the 50 to 60 db range were obtained.