Transferred Electron Oscillators Operating in the Transit Time and Limited Space-Charge Accumulation Modes

摘要

The state of the art of transferred electron oscillators, particularly those operating in the limited space-charge accumlation (LSA) mode, is reviewed. The LSA mode is of particular interest because devices operating in this mode enjoy the very significant advantage of being immune to what constitutes a fundamental limitation of all other types of solid state oscillators: the power-impedance product. The power output of an LSA device is limited only by two factors: (1) the heat transfer efficiency of the heat sink, and (2) the microwave skin effect of the semiconductor. The first is not a function of the device itself, but rather of its environment. The second usually comes into play only at very high rfs (above the mm-wave range). Beyond x-band the theoretically predicted peak power limit for LSA operation is about six orders of magnitude above that for Gunn or avalanche operation. For example, at 10 Ghz, peak power outputs as high as 400 kW are predicted from a homogeneous piece of material about 1 cm in length. (Author)